68
TECHNUC. REPORT 6-2-CM W; NITROSO RUBBER HANDBOOK by Malcolm C. Henry and Charles B. Griffis, C L' AJI.CD ~ /January 1966 Clothing and Organic Materials Division Ci-OM-15
TECHNUC. REPORT6-2-CM
W; NITROSO RUBBER HANDBOOK
byMalcolm C. Henry and Charles B. Griffis,
C L'
AJI.CD
~ /January 1966
Clothing and OrganicMaterials Division
Ci-OM-15
The findings in this report are not to be construed as anofficial Department of the Army position unless so designatedby other authorized documents.
Citation of trade names in this report does not constitutean official indorsement or approval of the use of such items.
DDC AVAILABILITY NOTIC11
Distribution of this document is un1imited.
Destroy his report when no longer needed, Do not returnit to the originator.
- •w
Distribution of this ADdocument is unlimited
STECHNICAL REPORT
66-2 CM
NITROSO RUBBER HANDBOOK
byU
Malcolm C. HenryMaterials Research Branch
andCharles B. Griffis
Rubber, Plastics and Leather Engineering Branch
Project reference: C&OH-151C024401AK'29
January 1966
Clothing and Organir. Materials DivisionU. S. ARMY NATICK LABORATORIESNatick, Mas~achusett 01760
FOREWORD
Military operations conducted on a global scale require avariety of equipment that must operate under all climatic condi-tions. This imposes severe requirements on construction materials,particularly rubber whose properties are severely affected bytemperature extremes. To assure that rubber materials are available
*that meet requirements, a continuing Army research program is main-tained. Out of this research, new rubbers are developed. Work bothin-house and under Army contract has contributed to the availabilityof these new types of rubbers, the result of many and varied effortsof a number of persons. This report deals with such a new product,"nitroso" rubber, which is not a single polymer but rather a familyof many rubbery polymers.
The story of nitroso rubber development is spread over a numberof contractor repoi'ts, published and unpublished papers, scientificmeeting presentations and laboratory notebooks. This handbooksummarizes in one convenient volume all of the work performed on thissubject. It is designed for the use of materials engineers lookingfor specific applications and for research scientis'-s interested insynthesizing new materials.
S. J. KENNEDYDirectorClothing and Organic Materials Division
G. R. THOMASAssoci.te DirectorClothing and Organic Materials Division
APPROVED:
DALE H. SIELING, Ph.D.Scientific Director
W. W. VAUGHANBrigadier General, USACommanding
ii
TABLE OF CONTENTS
Page No.
List of Tables vi
List of Figures viii
Abstract ix
I Introduction 1
II Terminology and Nomenclatu.re 2
III Historical Development 2
IV Nitroso Rubber Chemistry 4
A. Monomer Syntheses 4
1. Tetrafluoroethylene, C2F4 62. Trifluoronitrosomethane, CF3NO 63. p-Bromotetrafluoronitrosobenzene, p-BrC 6F4 NO 74. Methylperfluoronitrosopropionate 75. P-Nitrosoperfluoropropionic Acid, HOOCCF2CF2NO 76. "r-Nitrosoperfluorobutyric Acid, HOOC(CF2)3NO 87. Miscellaneous 8
B. Polymerizations 8
1. Kinetics and Postulated Mechanisms 82. Copolymerizations 103. Terpolymerizations 11
C. Pilot Plant Scale-Up 11
D. Basic Polymer Property Studies 25
1. Solvent Properties 262. Infrared Spectroscopy 263. Nuclear Magnetic Resonance Spectroscopy 264. X-ray Diffraction 285. Glass Transition Temperature (reboudd method) 286. Thermogravimetric Analyses 287. Linear Thermal Expansion Coefficients (apparent) 32
iii
_ _ _ _ _ _ _ _
TABLE OF CONTENTS (continued)
Page No.
V Properties of Nitroso Rubber 32
A. Copolymers 33
B. Properties of Nitroso Rubber Terpolymer 36(carboxyl-nitroso rubber)
C. Properties of Special Interest 37
VI Compounding Studies 42
A. Materials and Test Methods 42
B. Results and Discussion 42
C. Conclusions 53
VII Future and Potential Uses of Nitroso Rubber 53
VIII Summary 53
IX Acknowledgments 54
X References 55
iv
LIST OF TABLES
Page No.
I Synthesis of Nitroso Monomers 5
II Copolymers with CF3NO 13
III Nitroso Copolymers Other Than CF3NO 16
IV Nitroso Terpolymers (CF3NO/F2C=CF 2/A) 18
V NMR Spectroscopy of Nitroso Rubbers 28
VI Apparent Linear Thermal Expansion Coefficients of 32CF3NO/CF 2 Nitroso Gums
VII Nitroso Rubber (raw polymer) 33
VIII Nitroso Rubber (compounded) 34
IX Glass Transition Temperatures for Various Nitroso 35and Fluorocarbon Polymers
X Carboxyl-Nitroso Rubber 36
XI Carboxyl-Nitroso Rubber (compounded) 37
XIA Nitroso Rubber Copolymer CF2NO/CF 2CF2 38
XIB Resistance to ClF 3 Gas of Various Vulcanizates of 39Carboxyl-Nitroso Elastomers
XIC Resistance to ClF 3 Gas of Carboxyl-Nitroso Elastomers 40Cured with Cr(CH3COO) 3 or with Cr(CF3COO) 3
XID Fluid Resistance of Carboxyl-Nitroso Elastomers 41Cured with Cr(CF3COO) 3
XII Compounding Recipes and Test Results Amine Cures - 44HiSIL 303 Filler
XIII Compounding Recipes and Test Results Amine Cures - 45Carbon Black Fillers
v4
4
LIST OF TABLES (continued)
Page No.
XIV Compounding Recipes and Test Results Amine Cures - 46Amine and Filler Variations
XV Compounding Recipes and Test Results Other Than 48Amine Cures
XVI Mooney Viscosity of Various Batches of Nitroso Rubber 49
XVII Cure Characteristics as Determined with Mooney 50Viscometer (large rotor)
XVIII Differential Thermal Analysis Results 52
k
LIST OF FIGURES
No. Title Page No.
1. Equipment flow chart for CF3NO production 24
2. Equipment flow chart for C2F4 production 24
3. Material flow chart for nitroso rubber 26
4. Equipment flow chart for nitroso rubber production 26
5. Infrared spectrum (2-15u) of 56703-3 nitroso gum 27
6. Nuclear magnetic (F19 ) resonance spectrum of 56703-3 27nitroso gum
7. Rebound tester for 1000 cycles per second modulus 29
8. 1000 cycle per second modulus by rebound on sample XP5675 30
9. Thermogravimetric analysis in air and helium of an amine- 31cured nitroso copolymer
vvii
____ ____ ___ ____ ____ ___ ____ __
- - ~ -~-...
ABSTRACT
"Nitroso" rubber is the generic name for a family of rubberyhigh polymers having the common structural denominator of a repeat-ing nitrogen-oxygen-carbon atomic sequence as follows:
~N-0-(C-)
Architecturally these nitroso polymers are the first of a wholenew class of materials. Nitroso polymers, as currently known, arehighly fluorinated or completely fluorinated and as such are membersof a specialty type of elastomer since only a limited number offluorinated elastomers are known. It is becoming increasingly evident,however, that the combination of "nitroso" groups in the highlyfluorinated linear polymer chain is responsible for the introductionof interesting and novel combinations of properties. Thus, nitrosoelastomers have good low temperature properties, solvent resistance,stability to corrosive environments, and flame resistance.
Nitroso polymers have been developed to their present state bythe cooperative effort of Army scientists and contractors. Over thepast eight years, considerable insight has been gained as to thenature and potential uses of nitroso rubbers. This handbook is anattempt to assemble a summary of this accumulated knowledge. It ishoped that the contents so compiled will aid in the future develop-ment of this new family of specialty elastomers.
Sq
NITROSO RUBBER IANDBOOK
I. Introduction
The foundation upon which the U. S. Army's Research and Develop-ment Program is based rests upon the requirements of its tactical andsupport forces- As a result of these requirements a continuing programis carried out in an attempt to develop new and improved materialsz
Materials required by -the Army often must have properties or com-binations of properties not required by others. Military operationsare rcutinely carried out in envircnments presenting severe stress uponboth personnel and equipment. Arctic Cperations at -651F and lower aretyTical of the Low temperatures met in Am.y operations. On the otherhand, extremes of ground temperatures may reach 120cF while 1000OF isa common temperature encountered in operating components of militaryequipment.
Experience has shown that comercially available rubbers, bothnatural and synthetic, are unsatisfactory in many cases. One specificrequirement for improved elastomers is that of low temperature flexi-bility and petroleum fluid resistance. Elastomers are not commerciallyavailable that have the combined properties of low temperature flexi-bility and gaszl-_ne or oil resistance. Elastomers having these com-bined properties are required for many military items such as fuel lines,pump diaphragms, rubber covered cables and wire, chemical warfare pro-tective clothing, gas masks, gaskets, flexible containers and liners.
Additional properties required in elastomers in addition to thosealready cited are ozone resistance, flame resistance, resistance toh .gh the:mal flux and radiation and both acid and oxidizer resistance.In short, elastomers are required having combinations of propertiesthat will maintain their integrity in a wide range of temperature andcorrosi-ve environments.
The development of new elastomers with the best possible combina-tion of properties has thus been the goal of the U. S. Army NatickLaboratories research program since its inception some years ago.Nitroso rubbers were recognized to belong to a unique system both asa generalized chemical structure and as a material with desirablecombinations of properties that have potential use in military opera-tions. This report is the story of the development of nitroso.ruhberto its present state. Many people have contributed to the nitrosorubber program that has been carried out by the U. S. Army NatickLaboratories. It "s hoped that recognition of indi'idual efforts havebeen made within the text of this report,
II. Terminology and Nomenclature
The terminology for the class of polymeric structures now com-monly known as nitroso rubber has evolved primarily as a result ofconvenience. In one sense this is unfortunate since the implicationis to a single structure. In reality, it is a generalized class ofstructures. Nitroso rubber is derived from material having a co-onstructural denominator, namely a repeating trivalent nitrogen-oxygen-carbon sequential atomic arrangement of the following type:
{ -o-(c~
n
As currently known, it is highly or completely fluorinated. However,many structural variations are theoretically possible and a largevariety of structures have been prepared all having in common the re-peating nitrogen-oxygen-carbon linkage.
Many structures containing this repeating unit are not elastomeric.Depending upon other incorporated structural features, these productsmay range from viscous oils to resinous plastics. From a structuralpoint of view nitroso elastomers are unique as the only known exampleof a nitroso group entering into a polymer chain as an integral entity.
III. Historical Development
The history of the d velopment of nitroso rubbers began in 1955when Barr and HazeldineI- reported the discovery of a reaction be-tween tetrafluoroethylene and trifluoronitrosomethane. One of thereaction products was reported to be a viscous polymeric oil. Sub-sequent work established the elastomeric nature of one of the reactionproducts4 and extended the scope of the reaction.
In 1956 the first patent was issued to Rose 5 for the productresulting from the reaction of tetrafluoroethylene and trifluoro-nitrosomethane.
A summary report by Fitt 6 was also published in 1957 on both thepreparation of nitroso compounds and the addition reactions of nitrosocompounds to olefins.
Published reports in the early literature described nitrosoelastomers as having novel combinations of properties. Resistance tothe action of corrosive chemical environments such as solvents,oxidizing chemicals and ozone coupled with good low temperature prop-erties were typical of the properties that created the initial interestfor Army scientists. In 1957 the U. S. Army Natick Laboratories (then
- the Quartermaster Research and Development Command) funded its first
2
contract to investigate the possibilities of developing these nitrosopolymers into useable or practical elastomeric materials for militaryuse. Complimentary interest in these unique elastomers has resultedin further investigations by Hazeldine7 ,8 and Rose9. Since that timeto the development of the present state of the art the followingindustrial and academic laboratories under contract to the U. S. ArmyNatick Laboratories, have contributed considerable data toward thedevelopment of these nitroso containing elastomers: The Central Re-search Laboratories of the Minnesota Mining and Manufacturing CompanylThiokol Corporation' Peninsular Chemical Research Corporation;Monsanto Research Corporations University of Florida and the Universityof Colorado. Throughout this report repeated references will be foundrelating to these contractors and the results obtained under theirresearch programs with the U. S. Army. For convenience these referenceshave been abbreviated using a sequence of a capital letter indicatingthe company, a number indicating the report number and finally a pagereference thus: T7-p-32 indicates Thiokol Corporation, Report #7,page 32.
Contractors referenced in this report are as follows:
1. U. S. Army Contract DAl9-129-M-1043, 15 October 1957 -
15 August 1960.Minnesota Mining and Manufacturing Company, Arctic Rubber,G. H. Crawford, -t. al. Final Research Report 1960.
2. U. S. Army Contract DAl9-129-QM-1684, 24 August 1960 -23 December 1962.Minnesota Mining and Manufacturing Company, Arctic Rubber,H. A. Brown, et. al. Final Research Report 1962.
3. U. S. Army Contract DAl9-129-AMC-69(X)0.19044, 27 February1963 - 28 February 1965. Nitroso Rubber, Research Develop-ment and Production, Thiokol Chemical Corp., Trenton, N. J.J. Green, et. al. Final Research Report 1965.
4. U. S. Army Contract DAl9-129-AMC-151(N) 0.1. 9115, Physical,and Rheologic-1 Properties of Nitroso Rubbers, MonsantoResearch Corp., Everett, Mass., G. L. Ball, et. al, 1963 -present; 9 reports.
5. U. S. Army Contract DA19-129-AMC-152(N) 0.1. 9116, Synthesisand Polymerization of Fluorinated Sulfur Modified NitrosoRubber, Peninsular Chemical Research, Inc., Gainesville,Florida, G. Stump, et. al. 1963 - present; 8 reports.
6. U. S. Army Contract DA19-129-QM-1926 0.1. 6028-62, Synthesisof Special Fluorine Containing Monomers, University of Colorado,Boulder, Colorado, J D. Park and J R, Lacher, 1964 - 1966period.
3
7. U.S. Army Contract DA19-129-ANC-79(N) Research on Synthesisof Unsaturated Fluorocarbon Compounds, University of Florida,P. Tarrant, et. al. April 1 1963 - 1966 period.
Abbreviations:
a. Minnesota Mining and Manufacturing Company 3Mb. Thiokol Chemical Corporation Tc. Monsanto Research Corporation Md. Peninsular Chemical Research, Inc. Pe. University of Florida Ff. University of Colorado C
IV. Nitroso Rubber Chemistry
In 1957 the U. S. Army Natick Laboratories funded a program withthe Central Research Laboratories of the Minnesota Mining and Manu-facturing Company to begin to investigate the potential of nitrosopolymers as a military elastomer.
Early work was substantiated that trifluoronitrosomethane, CF3 NO,reacts with tetrafluoroethylcue to form an oxazetidine as the mainproduct,
CH3 - N - 0
i ICF2-CF2
at temperatures above 1000C. At temperatures below O°C a linear polymerpredominates containing alternating CF3NO and CF2CF2 groups.
N - 0 - CF2 F
CF3 n
Both the polymer and the oxazetidine were found to be stable towards acidsas well as oxidizing and reducing agents. Additionally the polymer hadgood low temperature properties. From this initial study it became ap-parent that methods of synthesizing nitroso-containing monomers and otherpotentially useful fluorocarbon comonomers was of some importance.
A. Monomer Syntheses
The course of this investigation has resulted in the syntheses ofimnumerable monomers. Only those monomers most pertinent will be discussedin detail. A number of the synthesized nitroso monomers are shown inTable I along with reference to information concerning their syntheses,
4
Table I
SYNTHESIS OF NITROSO MONOMERS
MONOMER METHOD REFERENCE
1. p-BrC6F4 NO H 6F4 NH2 + D2 CH-COOH) BrC6FNH2 70% T7,pIO
BrC6Fr4 NH2 + HCOOOH H2-i BrC6 F4 NO 64%
2. C6 F5NO C6F5NH2 + HCOOOH - C6 F5NO T3, p11G.M. Brooke et. al.Chem & Industry1961, 832
3. C6HsNO owkrcally available Chemical ProcurementLaboratories
4. CH3CF2NO CF2 z CH2 + HI - CH3CI 3H Final Report 1962
CH3CF2 I + NO Hg CH3CF2NOU.V.
5. H(CF 2 )4 NO H(CF 2 )41 + NO Hg H(CF 2 ),NO 3m Final Report 1962U.V.
6. CICF 2CF2NO F2C a CF2 + NOCI - & ClCF2CF2NO 31M Final Report 1962Pierce Chemical Co.
7.N2r3NO NCCFO7. NO2CF2CF2NO C2F4 33M0 02NCF2CF2N0 3M Final Report 1960
8. C8H17NO C8FI71 + NO Hg C8H17NO 3 N Final Report 1960
9. C3H7NO C3F7I + NO HS C3H7NO 3m Final Report 1960U°Vo
10. CF 2CICFCLNO CF2 - CFCI + NO Fe1 3 CF2C1CFC1NO 3m Final Report 1960Pierce Chemical Co.
CH302C(CF2 )2N0 CF2 - c.00+ CH3 NO2 - CH30 2C(CF2 )2COONO
CF2 - c%
CH302C(CF 2 )2COONO pR2olysi CH302CCF 2CF2NO P8,p7
p.
1. Tetrafluoroethylene, C2F4
Tetrafluoroethylene may be obtained commercially as a com-pressed gas (Peninsular Chemical Research Corporation, Gainesville, Florida)or by the debromination of Freon 114-B2 , tetrafluorodibromomethane, in thepresence of activated zinc dust in methanol.
CF2BrCF2Br + Zn CHqOH) CF2 = CF2 + ZnBr2
The synthesis of nitroso compounds is somewhat restrictiie.The more successful procedures usually involve one of the following methods:pyrolysis of acetylnitrites; oxidation of amino groups under selective con-ditions and the addition of nitrosyl halides or n.tric oxide to olefins.Typical syntheses that have been used for preparing nitroso compounds aredescribed in the following paragraphs and in Table I. A recent review byGowenlock and Luttke describes the general structure and properties ofC-nitroso compounds 1 o.
2. Trifluoronitrosomethane, CF3NO
Trifluoronitrosomethane is a deep blue gas with a boilingpoint of -840C. It was first prepared by Ruff and GieseII by the fluorina-tion of silver cyanide in the presence of silver nitrate. Barr andHazeldineI synthesized it from the reaction of trifluoroiodomethane,CF3I or CF3BrL2 and nitric oxide, NO, in the presence of ultraviolet lightusing mercury as a catalyst. The pyrolytic decarboxylation of trifluoro-acetylnitrite13 has been the most successful procedure used to date.
Trifluoroacetylnitrite is formed by the reaction of trifluoro-acetic anhydride with dinitrogen trioxide by mixing equivalent quantitiesof the two reactants, using autogeneous pressure or a reflux condenser tomaintain the N203 in the liquid pbaseo The.reaction is complete in a fewminutes and may be followed by the change in color from blue (N203) toamber (CF3C)ONO)o
(CF3CO) 20 + N203 -- 2CF 3COONO
CF3COONO ) CF3NO 4 CO2
The pyrolysis is carried out in refluxing FC-43, tri(perfluorobutyl)amine. The overall yield is approximately 30%, Trifluoronitrosomethaneobtained this way is amenable to scale up and can be purified readily toa state satisfactory for participation in polymerization reactions(See Sec. IVC)oS S. Trifluoronitrosomethane may currently be obtained commercially
from Peninsular Chemical Research Corporation, Gainesville, Florida.
6
3. p-Bromotetrafluoronitrosobenzene ip-Br C6F4NO' (Table I)
A bromine-glacial acetic acid solution was added toa solution of 2,3,5,6-tetrafluoroaniline at room temperature. Theproduct 4-bromo-2,3,5,6-tetrafluoroaniline was obtained as color-less crystals, mp 57-800C, and was characterized by infraredspectra and elemental analysis. The brominated product was re-fluxed together with a mixture of 98% formic acid and 90% hydrogenperoxide for five hours followed by a chromatographic separationon acid washed alumina. The pure 4-bromo-2,3,5,6-tetrafluoronitro-sobenzene was obtained as colorless crystals that melted to agreen liquid at 39-400C. Thermochromism of this type is common inaromatic nitroso compounds due to dimer formation in the solidstate.
4. Methylperfluoronitrosopropionate (Table I)
Equimolar amounts of methyl nitrite and perfluoro-succinic anhydride were condensed in a Fisher Porter tube andallowed to come to room temperature for 1-1/2 hours. Unreactedmaterial was removed at reduced pressure. Yield, practicallyquantitative,
Analysis for CH302CCF 2CF2NO: %C, 25.76; %H, 1.29; %F, 32.60Found: %C, 25.34; %H, 1o33, %F, 36,91.
A two-neck flask fitted with a Vigreaux column andan addition funnel was connected to an air cooled condenser ventedthrough a 183 0C trap. A vacuum was maintained while the nitritewas dropped into the flask heated :o 2000C. After the pyrolysishad been going for several minutes a blue liquid collected in the-183 0C trap. The blue product was separated and distilled twice.GLC and an infrared spectrum showed it to be pure CH302C(CF 2)2NO.
5. f-Nitrosoperfluoropropionic Acid, HOOCCF 2CF2 NOI',
One preparation of HOOCCF 2CF2NO was carried out by thephotolysis of dinitrosyl perfluorosuccinate utilizing a quartz
(CF2COONO) 2 hv > ONOOC CF2CF2NO + CO2
HOOCCF2CF2NO<- H20 --
ampoule kept at OC with irradiation from a sunlamp. The reactionrate was very slow and in all cases considerable N203 was formedindicating decomposition of the dinitrite as follows:
(CF2COONO) 2 > (CF2CO) 2 0+ N20 0
7
-~~ ..----- ..-- - . ........- ~ - -
The rate of decomposiion Qas increased at higher temperatures. Vary-ing conditions did not result in improved yields which were in all casesvery low.
T 6. -itoserfluorobutric Acid, HOOC(CF2)3NO14
The photlysis of di Utrosyl perfluoroglutarate,
(CF2) (COONO)2 , derived from the reaction product of perfluoroglutaricanhydride and N200, Proceeded at a much faster rate with less reversionto N203o The reacticn product 1fnitrosoperfluorobutyric acid,HOOCCF2CF2CF2NO, could be purified by distillation.
7. Misceilanecus
Alteratve methods may also e used for the synthesesof nitros -containing cocpourds such as those described by Andreadesi5and Park1g utilizing additiao reacticns cf nitrosyl halides to fluoro-olefins and fluoroketones.
B. Polymerizations
Nitroso elastomers ray he prepared using standard bulksolvent or water emulsion polymerization techniques. Hazeldinef79,has also reported the formation of hi.gh molecular weight elastomerscontaining the nitroso group as an integral part of the elastomer.Both bulk and solution polymerizations of CF3,NO/C 2F4 have the dis-advantage of poor heat transfer (leading to uncontrolled reactions)or low molecular weight product when used on a larger scale. Methodsof carrying out these polymerizations in aqueous medium indicatedthat satisfactory conditions could be obtained when using low tempera-tures. Thus an aqueous suspension system employing an organic sus-pending agent such as magnesium carbonate and a soluble inorganic saltsuch as lithium chloride or lithium broei-de as a freezing point de-pressant was found to be a good polymerizing medium. Using thissystem the polymer is obtained in the fon of small particles. Thepolymer is separated from ths water phase by filtration and freed ofsuspending agent by acid treatment. The resultant molecular weightof the product compares favorably with that obtained by small scalebulk polymerizations. As will be seen (IVC) this polymerization systemwas found to be the most advantageous for "scale-up" and was used inthe pilot plant facility when larger quantities of nitroso rubber co-polymers were being prepared, Materials obtained via this methodhave been shown to have intrinsic viscosities of greater than one,indicating molecular weights over one million.
l.. Kinetics and Postulated MechanismseThe mechanisms involved in the copolymerization of
8
nitroso monomers have as yet not been resolved to any degree ofcertainty. The dependence of initial polymerization rate on the con-centration of CF3NO and C2F4 was determined approximately by polymerisolation techniques. The rates obtained best fit a reaction whichis first order in CF3NO concentration and one-half order in C2F4 con-centration. Experiments have shown rather conclusively that mechanismof initiation is not due to impurities being present in the monomers.Rather, the initiation is probably due to the radical character of thenitroso compound itself.
A partial scheme for this mechanism might be:
1. CF3NO CF3N-Oko.
2. CF3N-O " C2 F4 .N-O-CF2-CF2.
ICF3 A
or.O-N-CF2-CF2.I
CF3 B3. N-OCF 2CF2. + CF3N O 3 -_ N-OCF2CF2N-O.
CF3 CF3 CF3
4. .N-OCF2CF2N-O. + C2F4 -_h-- N-OCF2CF2-N-OCF 2CF.I I 2
CF3 CF3 CF3 CF3
Termination steps might include:
-,-,CF2 CF2 . + -*--CF2CF2. --
k+ -F + -N- k .
CF3
A biradical mechanism is reasonably plausible based on existingdata, the stability of CF3NO and the formation of oxazetidine underconditions of elevated temperatures. (3M-Final Report 1960).
A number of interesting features concerning the nitroso co-polymers have been observed that are of interest. As shown in re-action step No. 2 there are theoretically two different ways inwhich the nitroso group can attach to the C2F4 . In a polymeric
L
species one might expect to find either a random sequence or aregular preferred orientation. W. T. Flowers19 has done consider-able work having to do with the thermal degradation of nitrosopolymers and in particular the CF3NO/C 2F4 copolymer. Inside a massspectrometer volatile fragments with molecular weights up to 6000have been produced. There is nothing to suspect that the structureis other than a regular one. These mass spectrometric results alsoshow a repeating regular pattern for every molecular weight of themonomer, that is 199. If one were to have a unit in the reversesequence with fragmentation occurring at the N-0 bond (which itdoes being the weakest link in the polymer) then one would getmolecular weights which do not correspond to the 199 difference andthese have not been seen.
Another interesting feature, also having to do with the direc-tion of addition of the nitroso group to an olefinic carbon bond,has been noted by Sutcliffe20. Using unsymmetrical olefins thedirection of addition of the N=O group of CF3NO to a C=C bond inoxazetidine formation is opposite to that involved in formation ofthe predominant copolymer. This can be explained by postulatingthat copolymerization occurs by a free radical mechanism and thatoxazetidine is produced by either a free radical or molecular processpreceded by formation of a 1:1 complex of nitroso compound witholefin21 °
Finally, the effect of small amounts of chain transfer agentson the polymerization rate and molecular weight were determined.The transfer agents used had no significant effect on the polymeriza-tion rate, which is normal for a radical type polymerization providedthe radical formed after transfer is capable of initiating new chains.In all cases the transfer agents significantly lowered the molecularweight of the polymer. Initial polymerization rates in CF2CICFCl2solutions were determined and found to be lower than in (C4F9 )3N.The rate dependency on monomer concentrations was found to be thesame in CF2ClCFCL 2 as in (C4F9)3No These results also seem to be con-sistent with the polymerization mechanism already proposed earlier inthis section (3M-Final Report 1962).
2. Copolymerizations
A variety of nitroso copolymer systems have been studiedunder a variety of conditions. Both laboratory scale and pilot plantscale procedures have been worked out in considerable detail. Thepilot plant copolymerizations are described in section IVC of thisreport. Typical laboratory procedures for bulk polymerizations aredescribed by Crawford22 and Brown (3M-.Final 1962) for trifluoronitro-somethane and tetrafluoroethylene,
t1.
10
* 3
The monomers are condensed into pyrex ampoules, sealed and thereaction carried out at subambient temperatures. Unreacted monomersare vented and the sol-rent, if any, removed.
Copolymerization systems that have been prepared are noted inTables II and III and are referenced within the table for source in-formation.
3. Terpolymerizations
In contrast to copolymerizations the experimental pro-cedures for terpolymerizations are relatively undeveloped. Ter-polymerizations studies to date have been primarily bulk polymeriza-tions using nearly molar equivalent quantities of comonomers with arelatively small molar proportion of added termonomer. Experimental-ly the reaction conditions are essentially similar to copolymerizationconditions. Table IV describes and references the variety of ter-polymer systems that have been studied thus far. Termonomers areusually selected as participating members of the polymerization basedon structural considerations for subsequent compounding studies.
The termonomet selected must have a reactivity such that thereactive groups will be distributed randomly along the polymer chain.Very few olefinic compounds then qualify as termonomers. Nitrosocompounds containing functional groups in the side chain are suitabletermonomers since all nitroso compounds have about the same reactivitytowards C2F4 provided the nitroso group is adjacent to a -CF2- group.
C. Pilot Plant Scale-Up
The requirement for extensive compounding studies concomitantwith the requirement for relatively large quantities of the trifluoro-nitrosomethane/tetrafluoroethylene copclymer suggested a need for apilot plant facility, In 1963 the U. S. Army funded an extensiveprogram with Thiokol Chemical Corporation (T-Final 1965) to produce asizeable quantity of this copolymer for the purpose of carrying outextensive compounding evaluations. Thiokol reports to the U. S. Armyreflect this effort.
11
~ ~-
One of the main efforts in this work deal with the scale-up
synthesis of the trifluoronitrosomethane as well as determining thehazard involved in the synthesis and handling of this relativelyunexplored chemical compound. Thiokol's past experience in propel-lants was recognized as being somewhat unique as a result of the manyprocedures that have been developed for the evaluation of potentiallyhazardous materials. Both the art and the science of those skilled in
*these safety tests were made available tc the program.
The preferred route for trifluoronitrosomethane production wasthrough the formal-ion and decarboxylation of :rifluoroacetylnitrite,CF3CO2NO1 5. Nothing to date has been uncovered that has resulted inany change in this approach. Trifluoroacetylnitrite can be preparedby the interaction of dinitrogen trioxide, N2C3 , or with nitrosy!chloride, NOCI, with the former method being preferred because ofsuperior yields.
(CF3CO)20+ N203 -- 2CF 3CO2NO
The N203 was obtained from the Matheson Company, Inc., and used asreceived. The purity was greater than 99 percent. Since N203 dis-sociates readily it was removed from the storage cylinders as theliquid phase. Trifluoroacetylnitrite was decomposed to CF3NO bypyrolytic techniques. In Trauzl block tests trifluoroacetylnitritecould be detonated although the detonation was not very brisant.Additional detonation testing by a card gap test to ascertainwhether or not this material will propagate a detonation wave (andat what rate) showed that the critical diameter of trifluoroacetyl-nitrite is greater than 11/16 incn with metallic confinement.Ignition limits of the vapors were determined over the range of 25-1000C as a function of concenzration in nitrogen. No detonationswere experienced. The data from these tests indicated that CF3CO2NOignites on initiation at concentr-ations greater than 50 percent upto about 650C and at lower concentrations at higher temperatures.The lower temperature limit for the ignition of CF3CO2NO vaporappears to be about 400C. Thermal decomposition rate of CF3CONOwere determined up to 1840C at which temperature the time requiredfor complete decomposition is of the order of 5 - 6 minutes. Sparktests indicated that dilution of the CF3CO2NO vapors by FC-43(3M producz-perfluorobutyl tertiary amine isomer mixture) had re-sulted in a process operable without undue hazard (Thiokol ReportsNos. I and 3)
Satisfactory completion of the safety test- along with studiesof the pyrolysis of CP3CO2NO resulted in a unitized operation capableof producing one pound/hour of the deep blue gaseous CF3NO whichcould ultimately be stored in gas storage bottles. Thus it became
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232
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possible to continuously produce CF NO of at least 99 percent purityby metering trifluoroacetylnitrite into a reactor containing an inertdiluent at reflux. Decarboxylation is affected in the vapor phase andthe CF3NO swept continuously from the reactor zone through a purifica-tion train into traps at liquid nitrogen temperature where it is con-densed. The inert diluent (triperfluorbutylamine-FC-43) is returnedto the reactor by a condenser. CF3NO purification is affected by a5 percent caustic scrubber to remove CO2 and N02, a drying tower andfinally a molecular sieve column at -10COC to remove non-acidic nitro-gen oxides and CF3NO2 . This unitized operation was capable of produc-ing one pound per hour of pure CF3NO which could be stored in gasstorage bottles for extended periods of time at -200C without changeor detrimental effect on its use in polymerizations.
Figure 1 illustrates the equipment flow chart for CF3MO production.Tetrafluoroethylene, C2F4 , for the scaled up production of nitrosorubber was manufactured in the Thiokol TFE facilities in Moss Point,Mississippi. For the initial polymer program tetrafluoroethylene wasprepared by the debromination of tetrafluorodbromce-hane. This wasaccomplished by a refluxing suspension of activated zinc in methanol.The efficient vapors were precooled by a cold water condenser and thenpassed through a -350C condenser to remove any dimethyl ether whichmight have been produced by the reaction of zinc and methanol. Theproduct was then condensed at liquid nitrogen temperatures under a
slight helium pressure to preclude contamination by atmospheric oxygen.When the reaction was complete the condensate was warmed to -760Ctransferred in vacuum to a stainless steel storage cylinder containing
an inhibitor. The Equipment Flow Chart for the tetrafluoroethylenepreparation is shown in Figure 2.
IS 1"
Col. Col. pitFi e Ei nf c tf catfobbl-
tIt
(CF, CO,NO) 48V",4 Zi1 t - g4
Itlo 9 W1 . , 1.., _
Pm, T~flloB- o
Figure 1. Equipment flow chart for Figure 2. Equipment flow chart forCF3NO production C2F4 production
24
7111.I
Thiokol's copolymer facility consisted of two reinforced ccncretebays in which the glass monomer production equipment and the 25 gallonstainless steel polymerization reactor were housed. A circulating brinesystem cooled by direct injection of CO2 furnished refrigeration for thepolymerization and necessary cold traps. This was accomplished by a 100gallon tank equipped with a stainless steel 7-1/2 HP brine pump. A 12 kwoil heating system was piped to the pyrolysis unit. The equipment flowchart is given in Figure 4.
In evaluating the reaction variables which could have significanteffect upon the product it was found that the purity of the CF3 NO wascritical. In addition certain solvents could act as chain transfer agentsas for example, carbon disulfide or those containing hydrogen or chlorine.The optimum polymerization time at -25 0 C was found to be abcut 24 hours.The purity of lithium bromide used as a freezing point depressant was foundnot to be critical. The quantity of magnesium carbonate used did not par-ticularly effect better suspensions or yield significantly variable products.The heat of polymerization was determined to be 74.8 + 0.5 K cal/mole usingthe CF3NO/C2F4 monomer ratio.
Since the nitroso monomer is itself the initiator in the polymerizationof the nitroso rubber, very special polymerization conditions are requiredto assure the formation of a high molecular weight polymer. Suspension,bulk and solution polymerizations have been investigated. The suspensionprocedure described herein is typical of one that has consistently producedhigh molecular weight nitroso rubber: a 150 cc. stainless steel cylinderis charged with 70 cc. of Li Br solution (53g. Li Br/10Og. H20, freezingpoint -450C), 2.0g. MgCO3 and 8.0g. each of CF2CF2NO. The cylinder isagitated at a temperature of -250C for 20 hours. At the end of this time,the unreacted monomers are vented and the contents of the cylinder removed.The resulting suspension is allowed to settle and the supernatant liquiddecanted. The precipitate is washed in water and then stirrad in concen-trated HCl until no further reaction is noticed. The conversion may be ashigh as 86 percent of the expected high molecular weight polymer. Thematerial flow chart for the scale-up of this process is given in Figure 3.Two hundred pounds of CF3NO/CF2CF2 copolymer have been produced in thisfacility in lots of approximately 30 pounds. Yields run as high as 85percent.
D. Basic Polymer Property Studies
In 1962 the U. S. Army Natick Laboratories began funding a programwith Monsanto Research Corporation to carry out certain physical andrheological properties on the CF3NO/CF2CF2 copolymer gumstock. The goalof this program was to obtain basic information about the chemical structureof this polymeric systems in order to have a fuller understanding of itspotential.
25
fF
"~4V i L I : = '
- rnC
15.1
Figure 3. Material flow chart Figure 4. Equipment flow chart forfor nitroso rubber nitoso rubber production
1. Solvent Properties
Useful solvents for measuring physical and rheologicalproperties of CF3NO/CF2CF2 gumstock were found to be FC-75, (a mixtureof isomers of perfluorocyclic ether, C8F160, manufactured by 3M Co.),Freon 113, trichlorotrifluoro ethane and-perfluorotributylamine, FC-43.
2. Infrared Spectroscopy
Inasmuch as no infrared frequency assignments were foundfor the perfluorocarbons in standard sources, only tentative conclusionshave been drawn. Absorptions for CF3NO/CF 2CF9 copolymer gumsIockappear at 830 cm-1 believed due to -CF -CF 2 end, at 745 cm due toeither -CF2-CF= or =CF-CF= either of weich appear in the idealizedaverage structure obtained by NMR. Significantly, no -CF(CH3)2which would appear at 730 cm-1 , was seen nor was -CF CF present whichwould appear at 735 cm-1 . Figure 5 shows a typical F2RO/CF2CF2spectrum.
3. Nuclear Magnetic Resonance Spectroscopy
Shown in Figure 6 is a typical NMR spectrum obtained fora CF3NO/CF 2CF, nitroso rubber gumstock. Listed in the following tableare these pears and their assignments. The structure is defined as
{N(CF3 )CF2CF20}x
26
t' ' "" -- " -: ,-% . ..
I a 9 t a a-I a
a, 9, a I I ~ a m ; i. a a f
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2 I1
0 I a..i a I I a # i s
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itoo.ua v I 27
I a a z
Table V
NMR SPECTROSOOPY CF NITROSO RUBBERS*
Sample No Chemiz.=- Shift of Peaks, ppm Area Ratio of Peaks
2 3 ! 2 3
XP5675 -11.iL : E r24 C 3.0 19 2.GXP5702 -11o4 +.i. -242 3 0 2,0 1.9XP5812 -ll,3 1l - -2i,8 3,0 1.9 2 0XP5887 -11.5 --" 5 .2!0 3 0 2.0 1.9
-N(CF, )- -N-CF2CF2-
-OCF2CF_-
*F19 Resonance @ 40 MC
Reference trifluoro acet-: acid
4. X-ray Diffract on
All samples of CF3NO/CF2CF2 were found to be non-crystalline as shown by the;r diffuse diffrac cn patzerns
5. Glass Transi.:cn Texrera-_re ,rebo-.nd methcd,
Figure " shows the rebz-nd tester used to determine theglass transiticn of a materia_ at 1000 cps by measuring the reboundof a small ball bearing fromi. the s-.rfaze cf the specimen The per-cent rebound correlates to the logarithhmic deoremen-: sinze thisdecrement goes through a maximum where :he elast:c modulus de-creases rapidly from a glassy state to a :ubbery s:ate Data ofpercent rebound versus temperature for a typical CF3NO/CF 2CF2 co-polymer is shown in Figure 8. The specimen was tested from -0C"Cup to 400C, The minimum rebound region cf -16C is the £000 cpsglass transition tempera-ure Using an equ.'aler:e of 70C perdecade of frequency kapproximati:.r' the 0.1 ops giass transition(such as determined by the zorsion pendulaxm, wcid be -460 C,
6. Thermogravimerric Anaiyses
A TGA in helium and in air was conducted on curedCF3NO/CF 2CF2 samples, the results of whizh are shown in Figure 9.In air the rubber violently decomposed at 270 C
28
Automatic ball lifter
Bell Jar,
1/8" diameter ball-
Retaining RingSpecimen
Anvil Base - Thermocouple
Temperature Controller
Figure 7. Rebound tester for 1000 cycles per second modulus
29
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
100
V. 90Rebound TesterSample YP-5675
80 0.5 mil Al coveringTemperature Rate -
6.8oF/min
60
r-50
.0
4o0
30
20
10
01-100 -80 -.60 -4J0 -20 0 +20 4
Temperature, OC
Figure 0. 1000 cycle per second modulus by rebound on sample XP5675
30
0
mm~ 0 .% . rL. 0\
00
00
o C.
-3 6
00
o0 0'Sul 4SS0
31E
I7. Linear Thermal Expansion Coefficients (apparent)
Coefficients of linear thermal expansion by means of a
dynamic modification of ASTM-D696-44 were conducted on samD!es of
PCF 3NO/CF 2CF2 gumstock. A quartz dilatometer was used. The dynamic
modification consisted of periodic determinations of expansion as afunction of temperature at a rate of 1C/min. The term "apparent"is used because of the non-equilibrium nature of these determinations.A temperature range of -75°C up to about 100C above the glass tran-sition temperature was covered. Glass transition temperatures Tg,where (Oah/0i:O were determined as a result of expansion measure-ments and is shown in Table VI.
Table VI
APPARENT LINEAR THERMAL EXPANSION COEFFICIENTS
OF CF3NO/CF 2 NITROSO GUMS
Apparent LinearSample Expansion Coefficient OC-1 Temperature Range TgOOC Tg,cOoC
XP5675d (7.2 x 10-5) -67 to -52 -46 -60c
(1.2 x 10-4) -52 to Tg
XP5702 (8.2 x 10-5) -67 to -52 -46 -45(1.2 x 10-4) -52 to Tg
XP5812 (7.6 x 10-5) -72 to Tg -49
XP5887 (5.7 x 10-5 -72 to -62 -48(8.8 x 10-5) -62 to Tg
a. "Apparent" due to temperature use of 1C/min.b. From thermal expansion datac. From Clark-Berg determinationsd. Devolatilized 16 hr at 800C and 3 mm Hge. Sample contained volatiles
V. Properties of Nitroso Rubber
- For the great majority of nitroso elastomers prepared to dateonly mininal data has been compiled. Certain selected systems havebeen subjected to intensive investigations and considerable data hasbeen accumulated. This is particularly true for the CF3NO/CF 2CF2copolymer system and to a lesser extent the CF3NO/CF 2CF2/NO(CF2 )(3 or 4) COOH terpolymer systems. The properties of fluorinatedelastomers have received considerable attention and reviews byMontermoso22 ,23 and others 24-26 describe their, properties in some
32
Tt
detail. Summations of various phases of the U. S. Army sponsoredNitroso Rubber Program have been described in publications byMontermoso27-29. Recent results describing the chemical and physicalproperties of nitroso rubber co- and terpolymers have been reportedby Griffis and Henry30 ,31.
A. Copolymers
The properties of the raw polymer of nitroso rubber obtainedfrom the reaction of CF3 NO and CF2=CF 2 are described in Table VII.As an equimolar copolymer it is a colorless, transparent rubber thatcan be processed on regular rubber compounding equipment. The rubberis completely nonflammable. When directly exposed to a flame, somegas is evolved which tends to put out the flame; however, no charringof the rubber takes place.
Table VII
NITROSO RUBBER (raw polymer)
Structure -+CF2CF2N-O+n
CF3Crystal structure AmorphousMol. Wt. Approx. 1.3X106
Specific gravity 1.93Dielectric constant 2.41 @ 60 cyclesTg -510CSolubility - soluble in - fluorocarbons, FC-43, Freon 113
insoluble and unaffected in hydrocarbons
Reaction: aliphatic and aromatic amines degrade or crosslink.
Thus far, the only successful cure has been with triethylenetetramineand even this cure requires extended periods of time at temperaturesnear the decomposition temperature of the copolymer. Higher molecu-lar weight copolymer samples are definitely more difficult to cure,using the amine treatment, than lower molecular weight materials.Above 2120F. sponging occurs rather rapidly.
The properties of the compounded rubber and the recipe used forcompounding is given in Table VIII.
33
Table VIII
NITROSO RUBBER (compounded)
Recipe:Polymer 100Hi Sil 303 15TETA 1.25HMDA 2.5
Properties:Tensile strength, (Psi) 1230Stress at 300% Elongation, (Psi) 410Ultimate elongation, % 640Hardness, Shore A 60Tensile set at break, % 34
Low temperature properties:Temperature retraction, TR50 -360CGehman stiffness, T5 -410C
Chemical resistant properties, volume swell, % in following:70/30: isoctane/toluene 2MEK, ether 2Perchloroethylene 3Nitrogen Tetroxide 1
Ozone resistance: after 24 hrs @ 175 ppm @ 1500F. No cracksFlammability: will not ignite
In its uncompounded state nitroso rubber copolymer is a whiteto amber colored dense elastomer with a fluorine content of 66.8%.Its low glass temperature results from the low attractive forces be-tween chains and to free rotation about the -N-O bonds in the re-peating unit. A study of the glass transition temperatures forvarious nitroso and fluorocarbon polymers has been compiled by Thiokol(T-l) and as shown in Table IX.
Hypothetical Tg values such as those found in Table IX are subjectto considerable variation. The Tg of tetrafluoroethylene for examplehas been calculated to be anywhere from -112°C to 1300C. Stump32
and Boyer33, believe it to be -500C based upon exTerimentai evidenceand subsequent use of the Fox equation (TgI 2 = wl/Tg, + w /Tg2). Thevalues as shown in Table IX, in a relative manner, do indicate thetheoretical potential for developing lower temperature flexible fluoro-elastomers.
. 34
Table IXGLASS TRANSITION TEMPERATURES FOR VARIOUS NITR
AND FLtKO-C-ARBON POLYMERS
Polymer Tz. OC Comments
1. -!NOCFiC4. -51 literature
x
2. -OCFzCF - -9 literaturerF, CFTJ
I
3. {cjFCFz so literature
4 16S literature
x
5. - , -108 calculatedF based on
x I and Z
6. --FNOCFZiF- -51 Assumption
LF CFJ same as 1x
7. -NO -184 calculated
x
8 .{-NOCFZCFz - -95 calculated
x
9. ..[NOCFzCF]. .fOCFzCF] -90 calculatedTi _F L , T
I 0.9* 0.1*
10. -{,OC FZC FZ- {NOCFZCFZ7 - -86 calculated
0.75 0.25
l1-NOCFCFz-- -fOCF F- -91 calculated
0.9 0.1
12. -OCFZC Fj-" -OCF -- -86 calculatedT i o L F :F,0.75 0.25
weight fractions
35
B. Properties of Nitroso Rubber Terpolymer (carboxyl-nitrosorubber)
Properties of the carboxyl-nitroso raw polymer are givenin Table X. The beginning of a family of these terpolymers have beensynthesized, in which nitrosoperfluoropropionic acid and nitrosoper-fluorobutyric acids have been used in varying mole ratios of 0.5 to 2.
r: Table X
CARBOXYL-NITROSO RUBBER
Chemical Structure:-NO-CF 2CF2-NO
L L(CF2)3COO
Mole Ratio: 48/50/2
Crystal Structure: AmorphousMolecular Weight: 0.62 (FC43); - 0.81 X 106
Solubility: Soluble in fluorocarbons, FC43 and Freon 113
The compounding recipe and the properties of the vulcanized carboxyl-nitroso rubber are given in Table XI. The incorporation of the acidtermonomer into the nitroso polymer has resulted in decided improvementof tensile strength properties, while retaining the excellent chemical,low temperature and flammability characteristics. It is interesting tonote the increased volume swell of this compound in methyl ethyl ketoneover the copolymer.
Nitroso rubber gumstock appears to be resistant to chlorine tri-
fluoride ClF 3. Amine cured vulcanizates of nitroso rubber copolymer andmetal salt vulcanizates of carboxyl-nitroso rubber terpolymer, are con-verted by chlorine trifluoride, to substances resembling the original gum-stock, with losses of weight approximately corresponding to the amountof curing agent present. The rate of degradation appears to depend upon themetal salt used in the vulcanization and upon the temperature34 .
Nitroso elastomer gumstocks containing no hydrogen atoms (completelyfluorinated) are extremely resistant to corrosive environments. Ofparticular note are the resistance to strong oxidizing agents such as N204
or fuming acids. In the presence of strong bases the elastomer degrades.Table XYA indicates the stability of nitroso elastomers to a variety ofatmospheres.
36
Table XI
CARBOXYL-NITROSO RUBBER (compounded)
Compounding Recipe: Polymer - 100Silstone 110-20Chromium triperfluoroacetate 8
Properties of compounded polymer:Tensile strength, psi 2170Ultimate elongation, % 720Set at break (10 min.), Z 30Hardness, Shore A 57
Low temperature properties:Temperature retraction, TR-50 -41CGehman stiffness, T5 -44"C
Chemical resistance:Volume swell, %, in following:70/30: isooctane/toluene 2MEK 52Dichloroethane 4Nitrogen tetroxide 6
Flammability - *ill not ignite
C. Properties of Special Interest
Storable Oxidizers: Nitrogen tetroxide, N204 , has noeffect.*Elemental Fluorine: unaffected byfluorine at room temperature.
Ozone Resistance: No cracks after 24 exposure to 175 ppm@ 150*F.
Sunlight Resistance: No cracks after 2 months of exposure@ 20% elongation.
*Various nitroso elastomers have been evaluated for N204 resistance.The nitroso rubber copolymer gum has shown no indication of degradationafter 60 days immersion in liquid N204 at 150*F. Carboxy-containing nitrosoterpolymers cured with chromium triperfluoroacetate appear to be unaffectedafter three weeks in liquid N204 at 100"F 35. A summation of t'..se resultswith carboxyl nitroso elastomers is shown in Tables XIB, C and D. It wasnoted that although the cured carboxyl nitroso elastomers swelled in manyliquids, in most cases the liquid was a solvent of the curing agent(CF 3COO)3Cr. It was thus possible to speculate that the solvation of the(CF COO)3Cr caused the swelling.
37
L
:qI.
Table XIA
NITROSO RUBBER COPOLYMER CF2NO/CF2CF2
(Unvulcanized Gumstock)
Solvents and chemical agents having no significant affect,solvation, swell or degradation.
Temperature50:50 xylene hexafluoride:chloroform steam bath2-Butanone (MEK) steam bathTrichlorobenzene steam bath1,4-Dioxane steam bath3:1 Heptane:MEK steam bathChlorocyclohexane steam bath3:1 MEK:Heptane steam bath50:50 MEK:Heptane steam bathXylene Hexafluoride (XHF) steam bath1,4-dichlorobutane steam bathBenzotrifluoride (BTF) steam bathTrifluoroethanol (TFE) steam bathCarbon tetrachloride steam bathDiethyl Ether steam bathn-Butyl Chloride steam bathTetraethyl orthosilicate (TEOS) steam bathpara-chloro-benzotrifluoride steam bathChlorobenzene steam bathTrichloroethylene steam bathChloroform stea.n bathMethyl chloroform steaw; bath6,0 -dichloroethyl ether steam bathMethyl Perfluoro Butyrate (MFB) steam bathDistilled water 212OFConc. ammonium hydroxide refluxFurfural 212OFSkydrol 212OFSkydrol 500 212OFJP6 Fuel 212OFASTM ref. oil #1 212°FASTM ref. oil #3 2120FMIBK 212OFXylene 212OF10% aq. acetic acid 212OF10% aq. sulfuric acid 212FConc. hydrochloric acid 158OFConc. nitric acid 158 0F
38
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Q me i 0u z d)
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c-- CLO 0 I- I I IC4 r '
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0 0 0 " I'-4 >) "-Y0 5- r: 0d4 lZc
LS.. 4-Ln' Q0 00i e -C' c 'C) C' 41 cc- C,- 1 111 11 H *I10
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(2 0 > E SU). *- - .0 :3com 0 0.-'
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Cw -4C4 CC-
01 0 X--dl T C. 04' 1V'- ' C)) C'j 00 ('4: O .. 0L
LI) c C ) * 4 I I4- I I1 1 IC I E1-E- '-'L 0 40' 0 0
-) 0 0-4 0-4 r-. X9a -4 0-
C)0 CL.00
* 0: -4 C..- CI 4-' 0 4-' 0
. 4 E 0 to ra 0c 0o 0o 0a >to0 Q IC., P C P 4J Cj 4- -4 4AJ - -I OE
I tn .0 C VX urc:,ato a 0 0 0 >0 W
U) 0..,4 CL -4 134-4 j:4 -,4 0.*.-4 in..-I I0 00 00C.00).00 (.0V0I. 000.. CLQ
-r: r-40 c c - .14 4
0CI1 CC-4 C) C) C) C)£0 ~~ ~C C. UC )0
co0C.rv 0C *J 0 0 0 tn) 04 4- C ' I Uf) 0 0 m 0 V) C0~~~ ~~ 0-'- 0 0
-(4 L' --V, 0 V) -- q CN n r4 ) - 4 -a)
w (o
'40
'Nit..' .
Table XIDFLUID RESISTANCE OF CARBOXYL-ITITROSO ELASTOMERS()
CURED WiTH Cr(CF 3COO)3(8 p. by wt. Cr(CF 3COO) 3/100 p. by wt. ELASTOMER)
Original Properties Appearance - Strength Elong.Dk. Green - 330 psi 600%
Aging Conditions: Samples (small dumbells) were placed in 50 ml. of liquids in100 ml. single neck flasks fitted with the reflux condensers. All flaskswere kept in an oil bath for 7 days at ll0OC.
(**)
Testing: Aged samples were tested wet (ASTM D471-57T)
Liquids Weight Strength Elong.(Samples were aged in) Appearance Change, % Retained, % Retained,
1 Distilled water No change +26 70 922 Skydrol-500 Swollen +109 - -3 JP-4 Fuel Brown 0 109 1074 FC-43 Solvent, Tech. Swollen +500 - -5 NH4OH, 10% aq. soln. Degraded - - -
6 DMF Solvent, Tech. Bleached Swollen Weak -
7 Xylene, Tech. Bleached Swollen Weak -8 Carbon-Tetrachloride, Reag. Sl. Bleach +4 67 729 Heptane, Tech. Brown 0 .27 110
10 Trifluoro-Ethanol, Tech. Swollen +39 5C 78ii H2 S04 , 30% aq. soln. No change -2 285 13212 NaOH, 10% aq. soln. No change +6 164 13013 DMSO solvent, Tech. Bleached Swollen Weak -
14 Phenol, 5% aq. soln. Swollen +25 58 7315 Ethylene Glycol, Reag. No change 0 141 12516 1,2-Dichloroethane, Reag. No change +4 83 8717 Ethyl Alcohol, 50% aq. No change +8 73 8818 Acetic Acid, 10% aq. Swollen +33 39 S219 Ethyl Acetate, Tech. Swollen +53 36 6620 MIEK, Tech. Swollen +52 142 6521 Benzene, Tech. No change +3 64 6022 HC1, 10% aq. soln. No change +12 71 8823 1940 3 , 10% acL. soln. No change +15 79 95
1 N204, at room temp.(l) No change - 194 1312 N204, at 5-150C No change +6 186 1363 UDMH, at room temp. Degraded - - -
Notes: (*) Terpolymer: C2F4/ONCF 3/ON(CF2 )3COOH, mole ratio 1 J00/99.5/0.5(1) Under pressure. t
(*~) Liquids boiling at lower temperatures refluxed.
41
'Auk-mo
7
VI. Compounding Studies
Although nitroso elastomers have interesting combinations ofproperties it was clear from the initial studies that certainphysical properties, such as tensile strength, have to be improvedbefore they become useful items. Accordingly work was initiatedwith the Thiokol Corporation to develop techniques for producingnitroso rubber in pilot plant quantities. This was successfullycarried out by Thiokol as already described in earlier sectionsof this report. The following paragraphs report the work concernedwith the research compounding of nitroso elastomers.
A. Materials and Test Methods
The Thiokol Chemical Corporation produced six batches ofnitroso rubber that were used in this study. These rubbers, allcopolymers of trifluoronitrosomethane and tetrafluoroethylene,were made in the pilot plant of the company.
Compounding studies have been conducted on only two of thebatches. Their physical properties and the test methods used areas follows:
Property ASTM Test Method Number
Tensile strength )Ultimate elongation ) D412-62TStress at 300% elongation)Hardness D676-59TMooney viscosity D1646-63
The differential thermal analysis data were obtained with aDuPont Model 900 differential thermal analyzer under the followingconditions:
Samplc "oze: 4mm Atmosphere: AR2 @ 760 mmReference: glass beads Temperature scale: 50Program mode: heat Temperature scale: 0.5Rate of heating: 100/min Base line slope: 0
I B. Results and Discussion
It was noted early in the compounding studies that theproperties of the vulcanizates produced from the pilot plant facilitywere not similar to those of the compounds from the laboratory pro-duced rubber (Minnesota Mining and Mfg. Coo) even though the compound-ing recipe used was the same. For example, while tensile strengths
42
of 1000 psi or more had readily been obtained from the earlierrubber (3M), tensile strengths of 300 psi represented the maximumobtainable from the Thiokol rubber. There were differences incuring characteristics (scorch time, time of cure, and cure index)as well. To compensate for these differences, a series of aminecure studies were made.
The compounding and curing recipes, cure times and tempera-tures, and subsequent physical properties of various compounds ofbatch 5702 are given in Tables XII and XIII, and of batches 5702and 5675 in Tables XIV and XV. Table XII gives the test resultsof amine-cured, HiSil 303-filled vulcanizates and Table XIII theresults with amine-cured, carbon black-filled vulcanizates.Table XIV lists the vulcanizates with amine cures and amine andfiller variations, and Table XV those with other than amine cures.
In the Table XII series (HiSil 303 filler) the triethylenete-tramine (TETRA) was varied from 1.25 to 5 pphr (parts per hundredrubber) and the hexamethylenediamine carbamate (Diak #1) from 1to 2.5 pphr. Press cure temperatures varied from 2200 to 2600F.The Thermax black filler (MT), which had been found to increase therate of cure of the Thiokol rubber, was tried in combination withthe HiSil 303 in compound 57. This vulcanizate proved to be tooweak to test. Compound 79, which had the smallest amount of TETA(1.75 pphr), was the best of this series but even this showed atensile strength of only 245 psi.
In the second series using the amine cure Table XIII, variouscarbon black fillers were used: medium thermal (MT) furnace black"Thermax", an easy-processing channel (EPC) black, and a high-
abrasion furnace (HAF) black. Press cure temperatures varied from1800 to 2500F. None of the black fillers gave vulc3nizates thatwere superior to those using HiSil 303 Table XII or to those usingLinde silicone-treated HiSil 233 or Silstone 101. When the curing
time was kept below 250"F, only the HAF black among the black-filledcompounds did not sponge but it failed to cure.
143
U, OLf)0
j 0
HH N> N
0 Otf .- 1 tn 0 LAO
H N H(N
cc L 0 * O CN )0 C>OOm0 to- C\JC 0 0 0
~C Nq 0C4 HL LA 'f -
0o w
U-)
EnH- C"% C^ 'JLA (r)
LA 0- *H
=f-I Hf C) e'JA4(
0 CN 00 0D 4C 0 C(N (J oN Co a)
0c U)4 04 (NJ CN( (N
00(X
0) c LO LOAH --tc CCflALO0 N N'' V.) (ClC4 N C' CN
0
OEE-
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4-) 0 P,.-I :% a 4- M 0
to 0 4) , r_ r:* ~ 0 0.,4 -4-J r 4-) F- D 0 0.0) . 0 0 a) ra$ -4 HCY) (
4J :3 E- r. 4 1 4-J 9. 0) 4C:4)>),i, m p 0 94 (D C) 4-'
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4J C' H a- +jI0r 0 94 (./) 10 0 JC
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4J r 00q 4- r-0~ . Q 0 4 0 c.~ ~4-J'~ :? --- J4 0 CO rO 4 ;4c4J
00 u ti0 0--f0 4-' *44 C/) 04*r- *H.'- 4 E~ (D~.~ H- -1 >ICY)4 00Od).)0) £C 0 0 -Mr- ,Q, N( 0 0 0E 4-C')to
V)' U-. C a) X) >N H 1 0 C/ 4-i M ) a) *Hto 0 0 >4-1 E U 0) -4 ) 4 0 (n EnJ C:
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146
A --
1--f C1K
OD c 0n1 l
r) ul ~ l; ;)n3 ol
C
r- o'. -l 4 0: U n I(
C
C" 0 Qn Ot
< N *ano om(> 1-4 1-1
> C4
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0 t
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tN 0-4 04L N 00 %
to
0
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to 00
H~ ~ CU..)X 41 0 5 oV N ) W tc413o4-' 4) E. a 40 r4 - .r
-' *'4 -A () 4 c Q E- a)(NX 0 -4 r-0 V 0 c :
0 10 mt. -' t*4 X r C-4 r. ) ( -4-J.'4.4 0 410 0o 4 l , ' 'qE 0 - : .4 41 V, -a w~.- 0 ) nC' 4 : n4s >N C- , o o- 4)0
00f) 0 F '0 -1Zr i0:30 -4 1d UD 4 - c n -4E 0nr4-) .C0000JM > -4 C(1)4 X*H- CC1 41 (A c- (1-H ')C
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Table XV
COMPOUNDING RECIPES A14D TEST RESULTSOTHER THAN AMINE CURES
Compound NumberIngredientParts by Weight ... 82 83 84 85 86 ,_87 88
. Nitroso, Thiokol 5675 100Nitroso, Thiokol 5702 100 100 100 100 100 100
S Chromium triperfluoroacetate5
CaO 2
Cab-O-Sil 15Hexamethylenediamine Carbamate .1Diethylthiourea 2IMAPO 5HiSil 303 15 15 15 15 15B SN C12 3
DiCup 40c 9Trimethylolpropane trimethacrylate 3Pyrometalicanhydride 114DI 1 1MgO 5Cadox BSG Paste 3
Press Cure, Time, min/Temp OF 60/24_0 60/250 60/300 60/300 60/250 60/250 60/250
Tensile Strength, psi XVUltimate Elongation, $:4
Stress @ 300% Elong, psi 0 100 100
Hardness Shore A i 0 a b m a 0
iu4c48
Tr-t-oirpn tiehcrltPyoeaianyrd
Table XIV describes the compounds made with a variety of aminecrosslinking agents, fillers, and stabilizers. It had been foundthat the addition of more than 2 pphr of triethylenetetramine usuallyproduces-sponging and this always lowers the tensile strength. Spong-ing often is not readily discernible; sometimes it can be detectedonly by means of a microscope. To ensure against sponging, compound14 was made using only 1 pphr of triethylenetetramine and 0.33 pphrof hexamethylenediamine carbamate. To achieve maximum cure with th slow level of curative, the compound was press-cured for 240 minutesat 210OF and then oven-cured for 24 hours at 195 0 F. The tensilestrength of this compound (300 psi) was the highest obtained with theThiokol nitroso rubber. Compound 14 showed no signs of sponging.None of the other variations produced a vulcanizate with more than200 psi tensile strength.
Table XV shows the results when compounds were vulcanized withother than amine crosslinking agents. None of these vulcanizatescould be tested; from visual examination none appeared to have beencured.
To determine the curing characteristics of the nitroso rubber,the viscosity, not only of batches 5702 and 5675 but also of the re-maining four batches, was determined on the Mooney viscometer TableXVI. Batch 5675 gave the lowest result, a viscosity of only 22.The curing characteristics of a variety of compounds are given inTable XVII. Compounds 12 and 13, which represent 3M and Thiokolnitroso rubbers, respectively, showed great differences in curingcharacteristics. Compound 7 is a compound in which 1 pphr of 1.4cyclohexane bis (methylamine) replaced 1 pphr triethyletramine andthen 3 pphr of zin oxide stabilizer was added. This compound gavethe best curing characteristics, hence the same formula was used ina series of compounds (8,9,11, and 12) in which the fillers werevaried by the use of different carbon blacks and the effect of zincfluoride was investigated.
Table XVI
MOONEY VISCOSITY OF VARIOUSBATCHES OF NITROSO RUBBER
Thiokol Chemical CorporationBatch Identification Mooney Viscosity (ML-4+l 0 2120F)
5702 355812 355812 (9/14/64) 365812 (9/15/64) 355812 (Part #3) 365675 22
49
v)4 0 r- Mfu *4 0 ,rC%4 In ' tJ -* ;
9-4
H - 0. ri cr) 0 (7~ ) Lf) Ln CV
C H0 Hn CV 0coCDH CN
0 0' anC'
0 L1, Lo *4 -H CN _r
x W)
PACOLA LAC.:4 C) C ) r4 O HL cE- E:- 2 C1 H N1 .r -i U)LC/30j 0) H- r_4 C
C-):e. LA U
>4C) Y NH O ') ulA! HHLC
H _ 0 H- Hr- I . .
Ni C O to LA
N H C O H 00 0'
HqL CNHOO
4J
2 H 0
04J LA
OH 4j*.-4CN H.- LA ho4) C/3O 0E T CV
+1 ( ;4-HV .(L) 0('r.. j) Ir)0 4) x 41' 0 41
Z -40 a +~C.-r-i - 4) flO () 4 414)4 4 - W 4J ) F4r.~ 1HJ-14 0 E- .14 :3xIV~ >1 00 - J-4 ;
4- E-4 -4o
>i 4 9 04X 1( 0 U-r_
oj 0 (411
1 0n 0 0OI0 i nu-41h l U
r-('. cvN
~ OtCC0
0~~ u* w ocA~
C: N2 0 *H(L O 0 0mt OcrEj CY Hc. F4 C)
0j 0 H C C * '144
4-' Z E- 0r. "o: C-)o r. w .I 0 LO O( CN P-A (
H C14
1-4 wl
0'4 OH H-q H- ) r . O co
f-i C4- :
C/*O0 0H N 0 ('4 (Y) cot-s0
0C, H l r-4 CH) CC r, I o0
0'sD 0
cjE (a
(0 0Jr N4u.. H) EC H 0q 1H4 (NH., r
E I- E *C- 4 u
(v .a10 0LA(Y Y
W (0 04 tH 4 * Lj0 A.H ol 4J r. r= u 4)co 4
Hr-0 4 ' )0 04 - 'cvc4- 0O 1 1 mr.0r. m 00 4-1 a*,-4 j *4- X Q)>1 c r ) )0 H0 :3 a0)E ~04J E0 -4 r -0 0C:.
*H.0 4(1 o Q > 0>- 4-' .,q~cv 02 94 4
51 -
With Thermax black as a filW-v, compeund 9, the zinc fluorideiproved the curing chatracteristics of the nitroso rubber, as isshown belou.
NO. Time for Cure (beyond 35 min)
8 No filler, no zinc r1hcAd;e no cure9 Thermax black with zinc flucxrai 5.5
12 No filler with zin1- fluoride no cure13. Therax black, no zinc f-laoride 14.5
Zinc fluoride in HAF black filler systems (compounds 13, 14,and 15) did not change the curing characteristics of these compoundsto the same degree that it did with the Thermax black and it did notimprove the physical properties of the vulcanizates. In compounds38 and 41, 2.5 pphr of triethylenetetramine and mixtures of carbonblack and silicone-treated fillers were used and the temperature wasreduced to 210OF (to eliminate sponging). The cure characteristicsproduced were excellent but the physical properties were poor ,
Results of attempts to identify crosslinking of the nitrosorubber by the use of differential thermal analysis techniques aregiven in Table XVIII. Triethylenetetramine was the only materialtested that indicated crosslinking, and this occurred at 600C. Usingthis method of analysis, the second order transition of -500C compareswith that previously reported on the 3M rubber. Table XVII shows thatthe addition of triethylenetetramine reduced the temperature for theonset cf deterioration from 2200C to 2000C. The addition of Diak #I(hexamethylenediamine carbamate) significantly reduced the temperaturefor the onset of deterioration. This was also true when other amineswere used, and when d; umylperoxide was added.
Table XVIII
DIFFERENTIAL THERMAL ANALYSIS RESULTSSample Identifi 3tion T&OC
Thiokol 5702 -50 -- 220Thlokol 5702 with TETA -49 60 200Thiokol 5702 with Diak #1 .. .. 155Thiokol 5702 with H2N F F NH2 .. .. 168Thiokol 5702 - TETA and UROTROPIN ... .. 137Thiokol 5702 - dicumylperoxide .. .. 133Thiokol 5702 - TETA, Diak #1, DPG, CAB-O-SIL -. .. 138
Tg = Second order transition temperatureTc = Onset of crosslinking temperatureTd = Onset of degradation temperature
52
&
C. Conclusions
The Thiokol Chemical Corporation nitroso rubber has differentcuring characteristics from that made by the Minnesota Mining andManufacturing Company.
The phLsical properties of the compounds made and reported here,using the Thokol Chemical Corporation nitroso rubber, were extremelypoor.
The reinforcing fillers HiSil 303 and the silicone-treated HiSil233 were superior to the'medium thermal furnace blacks, the high-abrasion furnace blacks, and the easy-processing channel blacks.
VII Future and Potential Uses of Nitroso Rubber
The future of nitroso rubbers depends upon the types of uses thatcan be developed for this unique elastomer. These uses, in turn, arelargely dependent upon the specific combinations of properties thatcan be evolved from this architecturally unique molecular system. Un-doubtedly nitroso elastomers are to be considered specialty rather thangeneral purpose elastomers.
Nitroso rubbers appear to have potential utility for applicationswhere corrosive environments are found, such as in the aerospacendustry, use in expulsion bladders and for valves exposed to rocketuels and oxidizers. As a low temperature elastomer whose petroleum
resistance is required, nitroso elastomers may also have practicalutility. As a metal coating material nitroso elastomer may havepractical advantages in certain areas where extremely corrosive environ-ments predominate.
VIII Summary
The syntheses of nitroso monomers and the practicability of carry-ing out pilot plant syntheses of nitroso polymers has been demonstrated.Nitroso elastomers have unique combinations of properties not held byan elastomer to date. These elastomers are the only completely fluorinatad"rubber" materials known and indeed the only known case where a nitronogroup enters into a polymerization reaction to yield a -N-0-chain se-cuance in a Unear polymer. Tc retain these desirable properties anda' the same time develop yet new elastomer systems with high tensilestrengths is the goal of the present effort. Current applications re-quire materials having tensile strength superior to those now currentlyknown in the nitroso elastomer systems.
53
I
~IX Acknowledeents
The authors would like to acknowledge their appreciation toDr. Stephen Kennedy, Director, and Dr. George R. Thomas, AssociateDirector of the Clothing and Organic Materials Division for theircontinuied support of this program;-also the authors appreciation is
expressed-to the National Acadenrj of Sciences and its ElastomeriiAdvisory Panel which followed the progyeg-, of the work from its
earliest conception.
54
X. References
1. Barr, D.A. and R.Wo Hazeldine, J. Chem. Soc., 1881 (1955).
2. Barr, D.A. and R.Wo Hazeldine, J. Chem. Soc., 2532 (1955).
3. Barr, D.A. and R.W. Hazeldine, Nature, 175, 991 (1955).
4. Barr, D.A. and R.W. Hazeldine, J. Chem. Soc., 3416 (1956).
5. Rose, J.B. Crosslinked Reaction Production of Tetrafluoro-ethylene and Trifluoronitrosomethane and Process thereof.Filed Oc-. 12, 1956, awarded 1962, U.S. Pat #3,065,214.
6. Fitt, PoS. Copolymers of Fluoronitrosoalkanes and Fluoro-alkenes, Part I - Literature Survey Royal AircraftEstablishment, Farnborough, England, 1320 (1957).
7. Barr, D.A., R.N. Hazeldine, and C.J. Willis, Proc. Chem.Soc., 230 (1959).
8. Griffin, C.E. and R.N. Hazeldine, Proc. Chem. Soc., 369, (1959).
9. Rose, J.B. Rubbery Polymers to ICI Ltd. Brit. Pat #789,254Jan. 1958.
10. Gowenlock, B.G. and W. Luttke, Quarterly Reviews, 12, 321 (1958).
11. Ruff, 0. and M. Giese, Ber., 69, 598684 (1936).
12. Crawford, G.Ho to Minnesota Mining and Manufacturing Company,U.S. Pat #3,072,592 Jan, 1963.
13. Rue, D.N. and GoH. Crawford, J. Org. Chem. 28, 872 (1963).
14. Brown, H.A. U.S. Army Contract DA-19-129-QM-1684, MinnesotaMining and Manufacturing Co. Final Report, Aug 24, 1960 toDec 23, 1962. p 13.
15. Andreades, S. U.S. Pat #3,040,085, June 19, 1962.
16. Park, J.Do and AoPo Stefani, U.S. Pat #3,072,705, Jan. 1963.
17. Barr, D.A., R.N. Hazeldine, and C.J. Willis, J. Chem. Soc.,1351, (1961).
18. Hazeldine, R.N. U.S. Pat #3,083,237, Feb 1963.
55
qi
JAI
X. References (continued)
19. Flowers, W.T. Manchester University, England private com-munication.
20. Sutcliffe, H. Royal College of Advanced Technology, England,private communication.
21. Barr, D.A. R. N. Hazeldine, and C.J. Willis, J. Chem Soc.,1351 (1961).
22. Crawford, G.H. D. E. Rice, and J. Montermoso, Paper pre-
sented at 137th ACS Meeting (1960). Cleveland, Ohio.
23. Montermoso, J.C. Rubber Chem. & Tech., 34, 1521 (1961).
24. Barson, G.A. and C.R. Patrick, Brit. Plastics, 36, (1963).
25. Latlow, J.C. Rubber Plastics Age 39, 33 (1958).
26. Bartholemew, S. R. et. al., Rubber Chem & Tech 32, 1585 (1959).
27. Montermoso, J.C. Chem. Eng. Progress 57, 98 (1961).
28. Montermoso, J.C. et. al., Rubber & Plastics Age 42, 514 (1961).
29. Montermoso, J.C. et. al., U.S. Dept. of Commerce OTS Pub.PB 181094, Proceedings of the Sixth JANAF Conference, Natick,(1960).
30. Griffis, C.B. and M.C. Henry, Seventh National SAMPESymposium, Los Angeles, Calif., May 1964, Section 12,Properties of Nitroso Elastomers.
31. Griffis, C.B. and M.C. Henry, Rubber and Plastics Age 46,.
63 (1965).
32. Stump, G. et. al., Polymer Letters 3, 831 (1965).
33. Boyer, R. Rubber Chem. Tech. 36, 1303 (1963).
34. Green, J. and N.B. Levine, Elastomeric and Compliant MaterialsFor Contact with Liquid Rocket Fuels and Oxidizers, ASDTechnical Report Part II, November 1961; Part III, July1963, Tech. Documentary Report, Part I, March 1964.
35. Levine, N.B. et. al., Elastomeric and Compliant Materials forContact with Liquid Rocket Fuels and Oxidizers, Technical
F Report ML-TDR-64-107 Part II, February 1965; RMD Report5062-Q6, Jan-Mar, 1965; RMD Report 5062-Q7, April-June 1965.
56
UnclassifiedSecurity Classification
DOCUMENT CONTROL DATA - R&D(Security clasiflication of title, body of abstract a.d indexing annotation must be engered when the overnll report is claeified)
I OqIGINATIN G ACTIVITY (Corporate author) 2a. REPORT SECURITY C LASSIFICATION
U.S. Army Natick Laboratories UnclassifiedNatick 2b GROUP
Massachusetts 01760 I3 nEPORT TITLE
NITROSO RUBBER HANDBOOK
4 DESCRIPTIVE NOTES (Type of report and inclusive date#)
January 1957 - December 19655 AUTHOR(S) (Lost namie. first name, Initial)
Henry, Malcolm C. and Griffis, Charles B.
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January 1966 56 1 35Sa CONTRACT OR GRANT NO. 9a. ORIGINATOR'S REPORT NUMBER(S)
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11 SUPPLEMENTARY NOTES 12 SPONSORING MILITARY ACTIVITY
U. S. Army Natick LaboratoriesNatick, Mass 01760
13 ABSTRACT"Nitroso" rubber is the generic name for a family of rubbery high polymers having
the common structural denominator of a repea+ing nitrogen-oxygen-carbon atomicsequence as follows:
-N-O-(C-)I I x
Architecturaiy these nitroso polymers are the first of a whole new class ofmaterials. Nitroso polymers, as currently known, are highly fluorinated or com-pletely fluorinated and as such are members of a specialty type of elastomer sinceonly a limited number of fluorinated elastomers are known. It is becoming in--creasingly evident, however, that the combination of "nitroso" gro,,.- in thehighly fluorinated linear polymer chain is responsible for the introduction ofinteresting and novel combinations of properties. Thus, nitroso elastomers havegood low temperature properties, solvent resistance, stability to corrosive en-vironments, and flame resistance.
ANitroso polymers have been developed to their present state by the cooperativeeffort of Army scientists and contractors. Over the past eight years, consider-able insight has been gained as to the nature and potential uses of nitrosorubbers. This handbook is an attempt to asTsemble a summary of this accumulatedknowledge. It is hoped that the contents so compiled will aid in the future de-velopment of this new family of specialty elastomers.
DD IJAN4 1473 U s. . I I..f, ..
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