The latex doctor Harry F. Bader Testing of rubber films - Latest dipping technology - Anti-webbing agent We are one of the leading manu facturers of rubber goods, bal loons etc. Kindly inform the de tails about the production of rubber. MIS flisinilliab Rubber Works Chennai The answer to this question would take several volumes to do justice to the subject. I suggest you start with the books available in the local library. Books which I use as references are as follows: * The Vanderbilt Latex Handbook R.T. Vanderbilt Company Inc. 30 Winfielcl Street Norwalk, CT 06855 Tel. 203-853-1400 Fax 203-853-1452 * The Vanderbilt Rubber Handbook R.T. Vanderbilt Company Inc. 30 Winfield Street Norwalk, CT 06855 Tel. 203-853-1400 Fax 203-853-1452 * Polymer Latices - Science and Technology Second Edition - 3 Volumes D.C. Blackley Chapman & Hall India - R. Seshadri 32 Second Main Road CIT East Chennai 600 035, India * Polymers Latices First Edition Second Edition - 3 Volumes D.C. Blackley Chapman & Hall India - R. Seshadri 32 Second Main Road, CIT East, Chennai 600 035, India * Latex in Industry - Second Edition Roya J. Noble Rubber Age 250W. 57th Street New York, NY If you have any specific question, I would be glad to provide an answer. In the testing of rubber films e.g. latex gloves for tensile properties namely tensile strength, modulus and elonga tion at break, what’s the recom mended or allowed tolerance % between different operators in the same lab and between dif ferent labs with reference to ASTM, BS and ISO? Revertex Ltd. 0-412 the ASTM specification for tensile testing has a precision and bias statement on the last page which indicates the within labo ratory and laboratory-to-labora tory variations you can expect. With latex films the variations may be greater because of equipment and operator related problems. * The thickness gauges must be calibrated to the 22kPa foot pressure specified in ASTM 03767. * The die must be sharp and free of nicks. * The die must fit the 0-412 di mension specification. * The tensile tester must operate at twenty inches/minute. * The extensiometer must not slip from the test specimen. Harry F. Bader, Vice- President, Latex Services, Akron Rubber Development Laboratory. Akron, USA, and a world authority on latex, answers questions and doubts of readers on latex and latex products. Send your questions to: The Latex Doctor’ Rubber sia, Ohanam House, Cochin - 682 020, Kerala, India Fax: 94-484-317872 57 RubberAsia I July- August 2000
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The latex doctorHarry F. Bader
Testing of rubberfilms - Latest dippingtechnology -
Anti-webbing agentWe areoneof theleadingmanufacturersof rubber goods,balloonsetc. Kindly inform thedetails about the production ofrubber.
MISflisinilliab RubberWorksChennai
The answerto this questionwouldtakeseveralvolumesto do justiceto thesubject. I suggestyou startwith the books available in thelocal library. Books which I useas referencesareas follows:* The VanderbiltLatex
* PolymerLatices- ScienceandTechnologySecondEdition - 3 VolumesD.C. BlackleyChapman& Hall India -
R. Seshadri32 SecondMain RoadCIT EastChennai600 035, India
* PolymersLaticesFirst EditionSecondEdition - 3 VolumesD.C. BlackleyChapman& Hall India -
R. Seshadri32 SecondMain Road,CIT East,Chennai600035, India
* Latex in Industry - SecondEditionRoyaJ. NobleRubberAge250W. 57th StreetNewYork, NY
If you haveanyspecificquestion,I would be glad to provide ananswer.
In the testing of rubber filmse.g. latex gloves for tensileproperties namely tensilestrength, modulus and elongation at break, what’s therecommended or allowed tolerance% betweendifferent operatorsin the samelab andbetweendifferent labs with reference toASTM, BS andISO?
RevertexLtd.
0-412theASTM specificationfortensiletesting hasa precisionandbias statementon the last pagewhich indicatesthe within laboratory and laboratory-to-laboratory variations you can expect.With latex films thevariationsmaybe greaterbecauseof equipmentandoperatorrelatedproblems.
* The thicknessgaugesmust becalibrated to the 22kPa footpressurespecified in ASTM03767.
* The die must be sharpandfreeof nicks.
* The die must fit the 0-412 dimensionspecification.
* The tensiletestermust operateat twenty inches/minute.
* The extensiometermustnot slipfrom the test specimen.
Harry F. Bader,Vice- President,LatexServices,AkronRubberDevelopmentLaboratory. Akron,USA, and a worldauthority on latex,answersquestionsand doubtsofreaderson latex andlatex products.
Send your questions to:
The Latex Doctor’Rubber sia,Ohanam House,Cochin - 682 020,Kerala, IndiaFax: 94-484-317872
57RubberAsia I July- August 2000
* The clampsmust not allow thespecimento slip.
Remember,all thesewill producelower results. The higherresultsare the most valid. You can’tmake the film better than it is.You can, by all the above,makeit appearworse than it is.
Could you sendyour cataloguefor theapparatusfor analysingthe prevulcanisedlatex andthenecessarytests which can beusedto analysethelatex chemically andphysically?
Ing. Magdy Morsy AlyEgyptradeCompany
Alexandria, Egypt
Akron Rubber DevelopmentLaboratory Inc. is a testing anddevelopmentlaboratory. We havetwo or three very specializedpieces of equipmentbut we arenot equipmentsuppliers.We haveno equipmentcatalogues.Thereareseveralhundredtestsforlatex and latex products. If youcan tell me what you wish to accomplish, I will tell you whichtestsareneededfor thatpurpose.
Thereis no specialequipmentfortesting the degreeof prevulcanization. There are two simplemethods.
1 Chloroformcoagulation. Thisis asimple andrapidmeansforfollowing compoundingchangesafter storageor heattreatment. It consistsof mixing equalpartsof compoundedlatex and chloroform 10 ml.of each and stirring with aglass rod until coagulationiscomplete. Thecoagulumis allowed to standito 2 minutesandnumerically rated from 1to 4. No.1 is judged asuncured,andNo. 4 is precuredto anadvancedstage.
No.1 is a tacky lump which whenstretched apart becomesstringy.
No.2 is a tender lump whichbreaksshort whenstretched.
No.3 forms non-tacky large agglomerates.
No. 4 forms small dry crumbs.
A picture of these is in theVanderbilt Handbook.
2. Swellin2 DiameterTest. This
is a more sensitive test forprecure,performedin the following sequenceof operations:
a Spreada thin film 0.003 to0.010 inchesdry oo a glassplate.
b Dry film with fan for fortyminutesandallow tenminutesfor theremainingsteps. Makesure films are dry before removing from glassplate.
c Dust the dry film with talc-both sides.
d Die out two 1.5 inch diameterdiscs from film. Wipe off theexcesstalc.
e Placeeachdisc in a Petri dishhalf full of 730 Be naphtha.
1 Measurediameterof discsafter twenty-five minutesandnotmore than twenty-sevenminutesin solventby placing dishover graph paper with 0.05inch divisions: Measurediameter in two directions.
Noteaverageof eachdiscto nearest0.05 inches.
This diameter is the S.D. swollendiameter.
This test is frequently usedas aguideto maturing for processinge.g-S.D. of3.8" ± .1" indicatespropermaturing of a latex foamcompound.
Pleaseprovide us informationon the latest technologyfor latex dipping.
J.D. DeshmukhNagpur
I suggestthefollowing sourcesforstate-of-the-artlatex technology:
* Chemicals- Checktheadvertisements in RubberAsia orContactRubberAsia’s officein Bombay.
ACC is well known for its highvolume equipment. However,it also makes smaller automatic andsemi-automaticdipping equipment.
* LatexTechnology-
Polymer Latices by DC.Blacldey p.
58 RubberAsia U July - August 2000
ChapmanandHall IndiaR. Seshadris,32 SecondMain Road, CIT East,Chenai600 035. India.
Firstly, we haveultrasoniccavitation machine for cleaningof formers. Please suggestwhich chemical we should useto give best effect of aluminiumformers.
Secondly,pleasesuggesta goodwetting agent for aluminiumformersto put in’coagulant. Ourrecipeis:
Pleasealso advisewhethermilkpowderis to beaddedor not asI am afraid it might leadto putrefaction after sometime evenif it’s put Mong with bactericideammonia. What is the bestanti-webbingagentonecanaddif not milk powder.
Thirdly, with coagulant asabove, it is observedthat thelower portion of the formerpicks lesslatex. But it wasalsoobservedthat by adding morepartingagentinitial percentageof beutoniteclay was 1.5% andlater increasedto 3%, theproblemreducedfrom 30% to15%.
Pleasesuggestthe right type ofcoagulantrecipefor suchproducts so that the former is wetuniformly up anddown for uniform latex pick up
50 Valley RoadBerkeleyHeights.NJ 07922-2798
I believe they havean officein Asia.
* A wetting agentwhich I havefound good is:Triton X-l00Union CarbideSingaporeContactsTel. 65-265-2688Fax 65-265-6224
1-2% is usually sufficient.
* For de-webbingmaterialsIsuggest:CrusaderChemicalCo. Inc.2330 SevernStreetBaltimote, MD 21230Tel. 410-752-7602Fax410-547-8713E-mail:[email protected]
Seetheir advertisementin RubberAsia.
Therearemany new de-webbersavailable. The ones I use, mustbe used very carefully to avoid"fish-eyes". Crusadercanrecommend a product which will nothavethatproblem,
* Reducedpick-upof latex in thelower portion of the former isunusual. It usually is theopposite. Reducedpick-up couldbe due to lower former temperature in that areaor toslower "out" speedwhenthatareaof theformer is beingremoved from thecoagulant.
J.K. JaniCoscoIndia Limited
Reducedpick-up, which is different from thenormal situation of gradual increaseofthicknessfrom the top to thebottom of the former, mustbedueto a reducedamountof coagulant. I suggestyou look atyour processconditionsto detcrmine the source of thatproblem.
* The supplierof cleaningsolutions which I have used forover40 yearshasa wide rangeof productsandI’m sure theycan supply a chemical whichwould be satisfactoryfor aluminium formers.
*Your coagulantrecipeseemssatisfactory, I would preferpolyethyleneglycol to glycerine and a commercial dewebber in placeof milk powder. However, milk andglycerinearesuccessfullyusedbymanydippers.
