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FROMDistribution authorized to U.S. Gov't.agencies only; Test and evaluation; May1975. Other requests shall be referred toAir Force Materials Laboratory,Nonmetallic Materials Divsion, PolymerBranch, Attn: AFML/MBP, Wright-PattersonAFB, OH 45433.
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AFWAL ltr, NOV 1982
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Part I
/B• o 09 3 99OFFICIAL FILE COPY
CORRELATIONS BETWEEN POLYMERSTRUCTURE AND GLASS TRANSITIONTEMPERATURE I. POLYSILOXANES,POLYARYLENESILOXANES ANDPOLYXYLYLEN ESILOXAN ES.
POLYMER BRANCHNONMETALLIC MATERIALS DIVISION
OCTOBER 1975
TECHNICAL REPORT AFML-TR-75-202 Part I
Distribution limited to U.S. Government agencies only; (test andevaluation). May 1975. Other requests for this document must bereferred to the Air Force Materials Laboratory, NonmetallicMaterials Division, Polymer Branch, AFML/MBP, Wright-PattersonAir Force Base, Ohio 45433.
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Copies of this report should not be returned unless return isrequired by security considerations, contractual obligations, or noticeon a specific document.
This technical report has been reviewed and is approved forpublication.
G! F. L. EHLERSProject Monitor
FOR THE COMMANDER
R. L. VAN DEUSEN, ChiefPolymer BranchNonmetallic Materials DivisionAIR FORCE - 9-2-76 - 100
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I. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER
AFML-TR-75- 202 , Pt. I4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED
Correlations Between Polymer Structure and Progress ReportGlass Transition Temperature. I. Polysiloxanes September 1973-April 1975
Polyarylenesiloxanes and Polyxylylenesiloxanes I. PERFORMING ORG. REPORT NUMBER
7. AUTHOR(s) 8. CONTRACT OR GRANT NUMBER(s)
Gerhard F. L. Ehlers and Kurt R. Fisch
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT, TASKAir Force Materials Laboratory (AFML/MBP) AREA & WORK UNIT NUMBERS
Air Force Systems Command 7340/734004/734004/02Wright-Patterson Air Force Base, Ohio 45433
11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE
Air Force Materials Laboratory October 1975Air Force Systems Command 13. NUMBER OF PAGES
Wright-Patterson Air Force Base, Ohio 45433 2414. MONITORING AGENCY NAME & ADDRESS(if different from Controiling Office) 15. SECURITY CLASS. (of this report)
Unclassified
15a. DECLASSI FICATION/DOWN GRADINGSCHEDULE
16. DISTRIBUTION STATEMENT (of this Report)
Distribution limited to U. S. Government agencies only; (test and evaluation).May 1975. Other requests for this document must be referred to the Air ForceMaterials Laboratory, Nonmetallic Materials Division, Polymer Branch,AFML/MBP, Wright-Patterson Air Force Base, Ohio 45433.
17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, if different from Report)
IB. SUPPLEMENTARY NOTES
19. KEY WORDS (Continue on reverse aide if necessary and identify by block number)
Polymer PolysiloxanesStructure Polyarylenesiloxane sGlass Transition Temperature Polyxylylenesiloxanes
20. ABSTRACT (Continue on reverse side it necessary and identify by block number)The glass transition temperatures of a number of polysiloxanes,
polyarylene siloxane s, poly(fluoro)alkylene siloxane s and polyxylylene siloxane swere determined to provide much needed structure-property correlations forconcurrent research efforts focused upon the tailoring of molecular backbonestructures as a means of achieving desired property balance in novel polymersThese data supplemented with data from the literature were used to determinethe effect of structural features on the glass transition temperature.
FORMDD I JAN 7, 1473 EDITION OF I NOV 65 IS OBSOLETE UNCLASSIFIED
SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)BESTAVAILABLE COPY
UNCLASSIFIEDSECURITY CLASSIFICATION OF THIS PAGE(Wnen Data Entered)
20. ABSTRACT (continued)
Increases in glass transition temperatures were observed for polymerswith larger and bulkier substituents on the silicone. The presence ofaliphatic and aromatic moieties in the siloxane chain also coincided withhigher glass transition temperatures. For the general structure
-sdt- 0 -R - sio
I2 64
- x n
discussed in this report, the following order of increasing Tg was observed'bymodif ying R as shown below:
- < -CH 2CH 2(CF 2) nCH 2CH 2- < CH 2- C6 H4- CH - <-C 6 H4- <
-C6H4-O-C6H4- <-C6H4--O-CO--C6H4-'
UNCLASSIFIEDSECURITY CLASSIFICATION OF THIS PAGE(fhen Data Entered)
Of
FOREWORD
This report was prepared by the Polymer Branch, NonmetallicMaterials Division. The work was initiated under Project No. 7340,"Nonmetallic and Composite Materials", Task 734004, "New Organic andInorganic Polymers". It was administered under the direction of theAir Force Materials Laboratory, Air Force Systems Command, Wright-Patterson Air Force Base, Ohio, with Dr. G.F.L. Ehlers (AFML/MBP) asProject Scientist.
This report covers work conducted from September 1973 to April 1975by G. F. L. Ehlers and K. R. Fisch. It was submitted for publication by theauthors in April 1975.
liii
TABLE OF CONTENTS
SEC TION PAGE
I Introduction 1
II Discussion and Results 2
1. Polysiloxanes 2
2. Polyarylenesiloxanes 5
3. Poly(fluor o)alkyl ene siloxanes 12
4. Polyxylylenesiloxanes 12
III Experimental 16
IV Conclusions 17
V References 19
v
ILLUSTRATIONS
FIGURE PAGE
1. Glass Transition Temperatures of Polydimethyl-phenylmethyl siloxanes 20
2. The Effect of the Number of Siloxane Units on theTg of Polyarylenesiloxanes .21
3. The Effect of Increasing Trifluoropropyl Content onthe Tg of Polyxylylenesiloxanes 22
4. The Effect of the Number of Siloxane Units on theTg of Polyxylylenesiloxanes 23
5. Actual and Projected Glass Transition Temperaturesof Polysiloxanes, Polyarylenesiloxanes and Polyxylylene-siloxanes 24
TABLES
TABLE
I Glass Transition Temperatures of Polysiloxanes 3
II Glass Transition Temperatures of Polyarylenesiloxanes 9
IIl Glass Transition Temperatures of Poly(fluoro)alkylene 12siloxanes
IV Glass Transition Temperatures of Polyxylylene- 13siloxanes
vi
SECTION I
Introduction
The glass transition temperatures of novel research polymers fromAFML inhouse and contractual polymer synthesis programs are an importantcriterion for determining the specific use and use temperature rangeof these polymers., Transitions of a wide variety of polymers have beeninvestigated in this laboratory during the last several years, initially bydifferential thermal analysis, but more recently by differential scanningcalorimetry and thermomechanical analysis. While the results could notinitially be correlated to any great extent, the data obtained from increasingnumbers of structurally related groups of polymers has provided the basisfor deriving currently emerging interrelationships.
Based on the collected data and data supplement from the literature,attempts will be made in this and future reports to elucidate the relation-ships between glass transition temperatures and structures of variousclasses of polymers. It is anticipated that these structure-property correla-tions will pro'ýide much needed guidance to future polymer synthesis researchaimed toward obtaining candidate materials with improved use temperatureranges and better balances of mechanical and physical properties.
I
SECTION II
Discussion and Results
1. Polysiloxanes
While there is general agreement about the glass transition temperatureof polydimethylsiloxane at infinite molecular weight (-123°C, references 1-5),other polysiloxanes show vast discrepancies in the Tg's obtained by differentauthors. Polmanteer and Hunter (reference 2) determined the glass transitiontemperatures of dimethyl and phenylmethylsiloxane copolymers (with 0.4mole % methyl vinyl siloxane) by dilatometry and obtained progressivelyhigher Tg's with increasing phenylmethylsiloxane content (Figure 1). Apolymer consisting of 99. 9% phenylmethylsiloxane had a Tg of -86°C. Later,Polmanteer and coworkers (reference 3) determined the Tg's of filled andvulcanized dimethyl -phenylmethyl siloxane copolymers through linear expan-sion measurements. Here a Tg of -30°C was found for the oriented (byunidirectional milling) and a Tg of -41°C for the nonoriented phenylmethylsiloxane elastomer. Figure 1 shows the effect of orientation on the Tg's ofthe copolymers.
Russian workers obtained quite different results for phenyl substitutedsiloxanes. Andrianov and Yakushkina (reference 6) obtained a Tg of -72'Cfor a copolymer of dirnethylsiloxane with 25% phenylmethylsiloxane (Pol-manteer's results are in the -100'C range), and Borisov and coworkers(reference 7) reported a Tg of -129°C for Polyphenylmethylsiloxane (Polmanteer'svalues are -30 and -86*C). It is believed that discrepancies like these resultfrom the presence of low molecular weight (cyclic) materials or impurities.Differences in the degree of crosslinking may also contribute to the widescatter of results.
Work by Lee and coworkers (reference 5 and 8) showed that largeralkyl substituents resulted in increased Tg:
Tg (°C)Polydimethylsiloxane -123Polydiethylsiloxane -72Polydipropylsiloxane -46
Dolgoploskand coworkers (reference 9), on the other hand, found a T of -123°Cfor polydiethylsiloxane. Recently, Beatty and Karasz (reference 10) cearlyidentified a discontinuity in Cr at 130'K (-143*C) as the T of polydiethylsiloxaneand considered the transition found by Lee and coworkers at -720 C to be relatedto a solid-solid transition.
2
Table I summarizes the glass transition temperatures found in theliterature, as well. as AFML data:
TABLE I
Glass Transition Temperatures of Polysiloxanes
Structure T (°C) Reference
CHg3
100% -Si- 0- -123 1, 2, 3, 4, 5
CH 3
3
90% , 10% Si - 0- -112 to -121 2, 3
C6H5
75% ti , 25% -97 to -102 2, 3
-72 6
70% , 30% -93 to -100 2, 3
40% , 60% -65 to -91 2, 3
100% -30 to -86 2, 3-123 7
CRH2 5
-123 9- Si - 0- -72 8
I -143 102H5
-Si - 0 -- 468CRH
3 7
373
Table I (continued)
Structure T (°C) Reference
I ICH 3 CH 2
cH2CH2
cH3
75% , 25% - Si -0- -125
0
H(CH3)3
- 0- -131 (?) 7
C 1 H-7
Dow Corning LS-422 (pliable gum)
c$I3presumably - Si - 0 - + 2 mole % -74 AFML data
I vinyl pendantCH 2 groups
CHc12
CF 3
Dow Corning LS-53 (filled, cured rubber sheet)
CH
presumably - Si - 0 - -75
CICH2
3
4
Table I (continued)
Structure Tg( C) Reference
GEC Polymer (highly viscous liquid)
CH
-Si - 0 ...- 85 AFML data
CF 3
CH2CH2CH20 CF
CF3
GEC Polymer (tacky gum)
CHi CH CH
Si 0 -Si 0 Si 0 -50i I
CH 3 CH 3 I CF3
CH 2CH2 CH 20-CF
CF 3
Differences in molecular weight may account for the fact that the laststructure in Table I has a higher Tg than the-preceding one; the oppositewould have been expected. It is also remarkable that LS-422, LS-53 and thefirst GEC polymer listed in Table-I, which range from a liquid to a solid rubberat room temperature, have Tg's of about the same magnitude.
In view of the discrepancies observed for the Tg's of polysiloxanes,very little can be said about structure -Tg relationships. Increasing amountsof bulkier substituents on the silicon increase the glass transition temperature,with the possible exception of the lowest members of the homologous series,such as polydiethylsiloxane.
2. Polyarylene siloxanes
In the polymer system
CH 3 CH 3
-Si ''' Si -0
CH 3 CH 3 n mn
5
the glass transition temperature decreases with increasing n, as expected(references 11, 12, 13):
n Tg(°C)
1 -232 -53
-633 -62
-62-81
4 -72-72
5 -80
The scatter of these data, as also shown in Figure 2, is believed to bemore the result of impure or differently crosslinked polymers than causedby differences in the method, or by the accuracy of the Tg determination.For n = infinite, the Tg's are expected to approach the -123,C value of poly-dimethyl siloxane.
The replacement of p-phenylene by m-phenylene in the above structureseems to have no distinct effect (references 11, 12, 13):
CH
13C2 c Si m S 0S~In
CH3 CHn
n meta or para Tg (0 .C)
2 p -53; -632 m -46
4 p -724 m -75
Replacing two of the methyl groups, attached to silicone atoms adjacentto the phenylene ring, by phenyl results in a considerable increase inTg (reference 13):
CH ýHTg(0 C)
Si Si - 0-75CH 3 C3- - n
Tg( 0 C)
[S i7 Si 0 (Si 0-42
C6H5, C6H5 CH3jn
Very remarkable is the fact that the introduction of a diphenylether
linkage for the phenylene linkage increases the Tg (reference 13; see also
Figure 2):
- Si 0 Si - 0.
CH3 CH Y
m
n Tg(OC)
3 -374 -525 -65
It appears that, in spite of its flexibility, the large aromatic diphenyl-ether unit increases the rigidity of the very flexible siloxane chains more thanthe shorter phenylene moiety. The same observation has been made with thepolyxylylene siloxanes (See under 3).
An even larger increase of the glass transition has been observed byintroducing the diphenylcarbonate linkage:
Si -0 -C -0- S'i 0 -U Tg 49'C
CH CH1
3 3
7
Finally, the polymer
vGH CH3
3 CC3 3 3
can be visualized as the structure of Lexan, with every second -0-C--C-CR 3 CH3
moiety replaced by -Si-0-Si- . The replacement resulted in a lowering of theC64 3 CeH 3
Tg by 70'C (Tg of Lexan: 150 'C).
A comparison of the glass transition temperatures of polyarylene-siloxanes with fluoroaliphatic pendant groups (and 3%7 vinyl)
Tg (°C)
[C H 3 C C H
S31 3f-6-Si Si - o
FCH 3C 3 113 C F CH 3
j-Si Si -04
[Rf 7Rf /3jseems to suggest that the replacement of methyl groups on the silicone by-CH 2 CH 2 CF 3 increases the Tg (compare also the first structure with theprevious described structure
8
CH3 - CH3[~3 1J3 1
Si Ig-2CCHkCH 3jT
Introduction of -OF3 into the ring in 2-position increases Tg considerably.
In the polymers
Tg (°C)
CH3 CH3
-Si c- CF CFsi - o- -Z2 z
33
CH3 CH 3
-Si -CF, CFF CF- N Si -O0 -81 2 2 1.
CH: . CH333
the introduction of another -CF 2 - moiety in the chain results in a slight increase
in flexibility (decrease in Tg)(reference 11).
Table II summarizes the Tg data on polyarylenesiloxanes.
TABLE II
Glass Transition Temperatures of Polyarylenesiloxanes
Structure Tg(°C) Reference
3 3C H1 -3 3
n:
1 -23 102 -53- 10
-63 11
9
(Table II continued)
Structure Tg(°C) Reference
n:3 -62 10
-62 12-81 AFML data
4 -72 10-72 12
5 -80 12
OCH3 CH HI Lý-Dl I
siSi - -401
CH3 3CH 3
n.2 -46 AFML data4 -75 12
CH CH CH
1 33 1131S, S4-0 S -42 12
5 -65 12
/C ! /9 49 AFML data
103 rn
S 10L
(Table II continued)
Structure Tg(°C) Reference
C3 CH30 CH
CH CH 3 CH
GE 1-3-j --Si - 0 80 AFML data•k=- I
CH3 n
3 13 1-68
Rf (,E\R )j Rf=CH 2 CH2 CF 3 -0t
GHET __ CF3 GCHE 0 -32"
-Si - S. i- 0 Si - 0
Rf H Rf / Rf=CH CH CF
32 2 3
C ~- t3 • . , • .. C H 3
- S i -p 'N•- CF 2 C F 2 / •" S-0- -2
CH3~ CH 3
CH CH
Si 3 ~ C C C v-Si 300 -8o
~2 2 3~
CH CF CH C32
3 33S - --CFC F CF .- _S - 0 -2811 2 1 :
3. Poly(fluor o)alkylene siloxanes.
Contrary to the observations at the end of the previous chapter, theincrease of CF 2 groups in the nonaromatic poly(fluoro)alkylene siloxane system,does not result in a significant change of Tg, as Table II shows.
TABLE III
Glass Transition Temperatures of Poly~fluoro)alkylene siloxanes
Structure Tg(9C1) Reference
CH C
Si-CH2 CH 2 (CF 2)CH 2 CH 2 Si - 0-
CH CH
CH CH
CF3 CF 3
n:
*) 2 -26 AFML**) 8 -24 "
*) assumed to be the structure of FCS 210**) assumed to be the structure of FCS 810
4. Polyxylylene siloxanes.
A series of polyxylylene siloxanes synthesized by Rosenberg and Choein our Polymer Branch Laboratories (reference 14) permit some conclusionsas to the effect of the number of siloxane units, and the effect of siliconesubstituents, on the glass transition temperature. The results are listed inTable IV. All of the determinations are AFML data.
12
TABLE IV
Glass Transition Temperatures of Polyxylylene Siloxanes
Structure Tg(cC)
-Si - CHz 0 CH2 -Si - 0 -- 18CH CH3 3
CH3 CH
-Si - CH2 CH2 -Si 0 ]R R
R R R2
F Ri=R2
CH 3 CH3 -41
CF3 CH2 CH2 CF3 CH2 CH2 -19
CH CH 3 CH 3
-Si - CH CH Si- 0 Si- 0
R1 R2 R3
R1 R2 R 3
CH 3 CH 3 CH 3CH3 CH3 CF 3CH zCH2 -62
CF3CH2CH2 CF3CH2CH2 CH3 -52
CF3CH CH CF3CH2CH CF3CH2CH -443 2 2 3 2 2- 3 2 2
CF CH CH CF CH CH CF3CH CH2(97%) -353 2 2 3 2 2 3 2 2
CH = CH (3%) -35.5
13
(Table IV continued)
Structure -Tg(°C)
CH 3 OH 3 CH 3 CH3--Si - CH 2 H2 -Si - 0 -Si - 0 -Si - 0
III IR1 R2 R3 R4
R R2 R3 R 4
CH 3 CH 3 CH 3 CH3 -77
CH3 CH3 CF3CH2CH CF 3 CH CH 2 -59CF3CH2CH2 CF3CH3 CH CF3CH2CH CF3 CH CH2 -38
Table IV shows again, as discussed before, the rigidifying effect of thediphenylether linkage compared to the phenylene linkage. By replacing methylgroups with trifluoropropyl groups, the glass transition temperature increasesrather consistently by 90C per replaced unit. (See also Figure 3). Increasingthe number of dimrethylsiloxane units from I to 2 decreases the Tg by 21'C,and from Z to 3 units by 15'C. (Figure 4). The effect of additionaldimethylsiloxane units is expected to decrease slowly, and for an infinitenumber of units the Tg is identical to that of polydimethyl siloxane (-123°C).The Tg of the trifluoropropyl substituted polymer system
OH OH
-Si-OH- CH OH2 b
OH -CH
OH OH
CF CF 3 nm
also decreases with increasing n, but, as Figure 4 shows, the glass transitiontemperature begins already to level off at n = 3. At n = infinite, the Tgwould be -75°C (see Chapter 1).
Another comparison can be made between three of the xylylene siloxanepolymers and their phenylene counterparts described in Chapter 2. Althoughthe former are meta substituted, and the latter para, it has been shown in
14
Chapter 2 that m-phenylene siloxanes give Tg's in the same order of magnitudeas p-phenylene siloxanes.
CH C CH C
-Si - Si C C Si - CH0
CH CH n CH CH3
n Tg(°C) Tg(°C)
1 -23 -41
2 - 5 3x) -62
3 - 6 7 x) -77
x) from plot 1 in Figure 2
The comparison shows the flexibilizing effect of the CH 2 group to avarying extent.
15
SECTION III
EXPERIMENTAL
The glass transition temperatures of the polymers, as far as they hadbeen determined in the PolymerBranch were obtained almost exclusivelyby differential scanning calorimetry (DSC), using the duPont 990 ThermalAnalyzer. Heating rates of A T = 20'C/min were applied, and theextrapolated onset of the baseline shift in DSC was taken as the glasstransition temperature. Only in isolated cases was thermomechanicalanalysis (TMA) used for clarification, either with the expansion mode (pointof rate change of expansion) or penetration mode (point of highest rate ofpenetration). All measurements were made at least in duplicate.
The methods and conditions which were used to determine the Tg datareported in the literature - and used here - were not explored. Strictlyspeaking, only data obtained by the same author under the same conditionscan be compared.
16
SECTION IV
CONCLUSIONS
Polysiloxanes
R
-St 0
R n
Widely scattered glass transition temperatures of dimethyl-methylphenylsiloxane copolymers suggest that the polymers investigated by some authorswere impure or ill defined.
Introduction of larger alkyl substituents or phenyl for methyl in dimethyl-siloxane increases Tg, with the possible exception of the lowest members ofthe homologous series, such as polydiethyl siloxane.
The physical nature of a polysiloxane at room temperature may notgive a clue as to its glass transition temperature. Materials of widelydifferent physical conditions, from highly viscous liquids to rubber sheets,had Tg's of the same order of magnitude.
Polyarylenesiloxane s
R R
Si- Ar- Si 0
K R n m
The introduction of arylene units into the siloxane chain increases theTg considerably. The stiffening effect of this moiety is so strong thatdifferences between m - and p - phenylene are of negligible effect.
Introduction of a CF 3 group into the 2 -position of a m-phenylene linkageincreases the Tg considerably. The diphenylether linkage, being a largeraromatic unit than phenylene, increases the Tg even more, in spite of its flexibleether linkage. The same observation has been made for the polyxylylene-siloxanes. The introduction of the diphenylcarbon ate moiety produces astill higher glass transition temperature. Even the 0 - C - 0 -
-0- C -0- oe~itself is relatively rigid compared to the siloxane unit: replacement of a
17
CH CH
-Si - 0 - Si - bya -0 -C -0- group increased the Tg by70°C.I I
CH3 CH3
As far as the silicon substituents are concerned, the replacement of amethyl group by phenyl increases Tg considerably, but the introduction ofCF 3 -CH 2 -CH 2 linkages seems to have relatively little effect ('- 4 to 7VC perreplaced methyl group).
Poly(fluoro)alkylene siloxanes.
The number of perfluoromethylene groups in a structure as shown in Table
III seems to have little effect on the glass transition temperature.
Polyxylylene siloxane s
CH RCH
R = CH3 or CF3 -CH 2 - CH2
Increasing amounts of CF 3CH2 CH2 increase Tg by about 9 °C percH3
replaced methyl group, while the addition of another - Si - 0 - unitICH3
decreases Tg, initially by 15-20°C, but less so with larger amounts ofCH 3
- Si - 0 - units.
GH 3
The xylylene moiety in the chain, compared with the phenylene moiety,lowers the Tg by 10 to 20°C.
Figure 5 gives an overview of the observed and projected glass transi-tion temperatures of polysiloxanes. polyarylenesiloxanes and polyxylylene-siloxanes.
18
SECTION V
REFERENCES
1. G. M. Konkle, R. Selfridge and P.C. Servais, Ind. Eng. Chem. 39,1410 (1947).
2. K. E. Polmanteer and M. J. Hunter, J. Appl. Pol. Sci. 1, 3 (1959).
3. K. E. Polmanteer, J. Thorne and J. D. Helmer, Rubber Chem. andTech, 39, 1403 (1966).
4. R. F. Boyer, Rubber Chem. and Tech. 36, 1303 (1963).
5. C. L. Lee, O. K. Johannson, 0. L. Flaningam and P. Hahn, Pol.Preprints 10, 1311 (1969).
6. K. A. Andrianov and S. E. Yakushkina, Vysokomol. Soyed. 4, 1193(1962).
7. S. N. Borisov, A. V. Karmin, Ye. A. Cheruysheyev and V.S.Fikhtengol'ts, Vysokomol. Soyed. 4, 1507 (1962).
8. C. L. Lee, 0. K. Johannson, O.L. Flaningam and P. Hahn, Pol.Preprints 10, 1319 (1969).
9. B. A. Dolgoplosk, A. L. Klebanskij, L. P. Fomina, V. S. Fikhtengol'tsand Ye. Yn. Shvarts, DAN SSSR 150, 813 (1963).
10. C. L. Beatty and F. E. Karasz, J. Polym. Sci., Polym. Chem. Ed.'13, 971 (1975).
11. V. C. R. McLoughlin and Patricia A. Grattan, Royal AircraftEstablishment Technical Report TR 71224 (1971).
12. R. E. Burks Jr., E. R. Covington, M. V. Jackson and J. E. Curry,J. Polym. Sci., Polym. Chem. Ed. 11, 319 (1973).
13. L. W. Breed, R. L. Elliot and M. E. Whitehead, J. Polymer Sci.A-I, 5, 2745 (1967)..
14. H. Rosenberg and E. W. Choe, AFML-TR 75-182 (1975) (in print)
19
_ 0
0
0)
0 - U
cI 0
co U)
0 0 0) 0a%. - 6-0
14-4--'I4-40)0)00
-0-
4-q
P 0) 0
00
Cj
4)
ai)
"-I0
0 H
4-4
4-4
14-1
(00) 612
21~
CH3 H-SiCH~CH2 Sli--
RR n
R=CH 3 OR CHp CH2CF3
-20- X n I
-30-,n 2
-40 n=:30 x
-50-
-60-
-70-
x
01 1 2 3 4No.of R=CH2CH2CF3
Figure 3: The Effect of Increasing Trifluoropropyl Content on the Tg ofPolyxylylene Siloxane s
22
CC
0ro I CC 4
tI...LL0U) u~ u L
C))N LC) ý
Nc~
1.-4I
4-,
0 0 0 0 00
(00) 6L
23
6 0,0.
In010 1 $
O-U)-cf U 0I
4)
to 41
En 0 r
0 All
I tywin
X :L II
0(1
UIL 0(n) 0 ~ X N.!o() 0 I ..
.0 0 1.00 .d (d
X ) 1/\ 0 0
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244U. S. /OE~4r PRNTN /FIE 196 5760/
