Fluorosilicone liquid silicone rubber

Fluorosilicone Liquid Silicone RubberRonald Romanowski, Senior Industry SpecialistDow Corning Corporation, Kendallville, IndianaPaul T. Irish, Development ChemistCharles W. Olsen Jr., Global Marketing SpecialistLauren M. Tonge, Senior Development SpecialistDow Corning Corporation, Midland, MichiganInternational Silicone Conference 2003Akron, Ohio - USA

International Silicone Conference 2003Liquid Fluorosilicone RubbersRef Fuel B @ 23C.JP 4 @ 23C.300250253.9CopolymerPolymer Blends250200233.3CopolymerPolymer Blends% Volume Swell200150100206155101% Volume Swell15010017393.28450061.727.70 40 60 80 100Mole % Fluoro105031.615.305.70 40 60 80 100Mole % FluoroMil H5606 @ 70C.ASTM #3 Oil @ 150C.% Volume Swell1401201008060402000 40 60 80 100Copolymer127.9Polymer Blends804128.1124.10Mole % Fluoro% Volume Swell40CoploymerPolymer Blends3533.63026252018.815109.554.9200 40 60 80 100-5-10Mole % Fluoro-4.3Figure 1. Volume Swell Comparison of Copolymers and Blended Polymers in Oil, Fuels, and Fluids.Page 4 of 8

International Silicone Conference 2003Liquid Fluorosilicone RubbersSILASTIC® 5-8601 COMPARISONSSilastic® 5-8601 Fluorosilicone LSR was developed at 40 mole percent trifluoropropylmethylsilicone to achieve the desired oil resistance and fuel splash properties. Volume swell andpermeation are directly related to solubility of the test fluid in the rubber. In sealing applications,oil and fuel permeation is an important performance property. Low oil permeation results in lowweep, and low fuel permeation assists in meeting hydrocarbon emission standards.The effect of fluorine substitution on permeability can be measured in several different ways.The most common method is to prepare a rubber sheet, clamp it on top of the permeation cupcontaining the fuel to be evaluated, and measure weight loss. The permeation was done in CE10fuel at 60 °C to highlight the differences in fluorosilicones and dimethyl silicone rubbers. In thismethod, the performance of the 40 mole % Silastic® 5-8601 is about equal to the performance ofthe LoPerm VMQ only available as an high consistency rubber, HCR, while the LoPerm VFSR,FSR, and LoPerm FSR HCR’s have dramatically lower permeation rates.45,00040,00035,000Permeation Rate (gm*mm/m2*day)30,00025,00020,00015,00010,0005,0000VM QHCRLoPermVMQHCR50:50FLSR/LSRS ilastic5-8601LoPerm VFVM QHCRFVM QHCRLoPermFV M QHCRFigure 2. Uncompressed Permeation Results from Rubber Sheets – CE10 at 60 °CPage 5 of 8

International Silicone Conference 2003Liquid Fluorosilicone RubbersFigure 3. O-ring Permeation Testing Fixture for Variable CompressionSheet testing does not take into account the actual gasket or o-ring configuration. The O-ring testfixture allows the evaluation of the effect of compression. The results in Figure 4 clearlydemonstrate that the effect of compression varies from material to material. For example,fluorosilicone rubber shows less permeation reduction from compression of the gasket than doesthe dimethyl material. By comparing the flat plate permeation with the o-ring permeation, it isevident that compression has a very dramatic effect of lowering permeation rates of VMQ basedmaterials, while compression has a less dramatic rate of lowering permeation in the FSRmaterials i .6000Permeation Rate (mm*gm/m2*day)500040003000200010000Silastic5-8601LoPermVMQ HCRFVMQ HCRLoPerm FVMQ HCRVMQ HCR50:505-8601 /LSRLoPerm V FVMQ HCR-10% 0% 10% 20% 30% 40% 50%Nominal CompressionFigure 4. Effect of Compression on Permeation in CE10 at 60 °CIn some instances only slight modification of the volume swell resistance properties are required,and in these cases the blend of 5-8601 and a dimethyl LSR can provide an effective solution.Page 6 of 8

International Silicone Conference 2003Liquid Fluorosilicone RubbersSUMMARYThe desire for enhanced swell characteristics was balanced against the cost of increasingfluorosilicone content in order to meet a cost/performance profile that exactly meets the needs ofthe customer with Silastic® 5-8601. As part of the family of Silastic® LSR from Dow Corning,this FLSR offers advantages to the rubber fabricator particularly for applications in harshconditions. Enhanced flexibility is available to the fabricator through FLSR products formulatedto meet various solvent or oil resistance needs and through the addition of ingredient packages toenhance release or lubrication. Excellent heat stability can be obtained with color. Compressedfuel permeation rates of FLSR have been shown to be comparable to LoPerm VMQ andsignificantly better than uncompressed rates. The addition of mold release and ease of assemblyadditives allows the manufacturer to take full advantage of the higher-speed processing of FLSR.i Brumels, Mark D.; Olsen, Jr., Charles W.; Irish, Paul T.; and Altum, Stephen C., Dow CorningCorporation, Midland, Michigan, SAE Paper 2003-01-0945, The Effect of Compression on Permeation ofHydrocarbons through Dimethyl and Fluorosilicone RubberRubber FabricationSolutionsLIMITED WARRANTY INFORMATION – PLEASE READ CAREFULLYThe information contained herein is offered in good faith and is believed to be accurate.However, because conditions and methods of use of our products are beyond ourcontrol, this information should not be used in substitution for customer’s tests toensure that Dow Corning’s products are safe, effective, and fully satisfactory for theintended end use. Suggestions of use shall not be taken as inducements to infringe anypatent.Dow Corning’s sole warranty is that the product will meet the Dow Corning salesspecifications in effect at the time of shipment. Your exclusive remedy for breach ofsuch warranty is limited to refund of purchase price or replacement of any productshown to be other than as warranted.DOW CORNING SPECIFICALLY DISCLAIMS ANY OTHER EXPRESS ORIMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE ORMERCHANTABILITY.DOW CORNING DISCLAIMS LIABILITY FOR ANY INCIDENTAL ORCONSEQUENTIAL DAMAGES.Dow Corning and Silastic are registered trademarks of Dow Corning Corporation.We help you invent the future is a trademark of Dow Corning Corporation.©2003 Dow Corning Corporation. All rights reserved. Ref: 45-1237-01

International Silicone Conference 2003Liquid Fluorosilicone Rubbers