In few cases, a post-cure process is done by putting the part in an oven for a certain period of time. Epoxy Resins – Offer the advantage of higher physical and performance properties vs. urethane resins. But extraction levels after 4h@200°C are low enough to pass most food and water contact requirements. Allow to cool to room temperature before demolding. Warning: heat lamps can scorch or burn if not properly used. Ideally one should have separate ovens for individual material types to avoid cross-contamination due to out-gassing. Mold Making – Post curing any mold rubber will enhance the physical and performance properties of the mold rubber. Chemical interactions between silicone rubber and the small amounts of hydrogen fluoride generated during the post-curing of the Taikum and Luginsland [16] studied the role of silane-rubber coupling in sulphur, peroxide and metal oxide curing systems for EPDM rubber. MV International offers high precision Post Curing Oven that works at enormously high temperatures to produce effective post curing results. If ventilation is poor, high concentration levels of volatiles will occur, preventing proper out-gassing, as well as resulting in risk of fire or explosion! Procedure: flat castings and simple shapes can be post cured outside of mold if placed on a flat surface. The degree of crosslinking determines the rigidity and durability, as well as other properties of the material. Post-curing is habitually set at a higher temperature than that applied during curing in order to reach the optimal state of cross-linking of the thermoset [32,33]. 1000 Ljubljana, All rights reserved © Gomline 2020 / Authors, Peroxide and platinum curing VMQ and FVMQ compounds: 1 h rising time + 4 h @ 200°C, Bisphenol curing FKM black compounds: 4 h rising time + 20 h @ 240°C, Bisphenol curing FKM coloured compounds: 4 h rising time +20 h @ 220°C, Peroxide curing FKM: 2h rising time + 4 h @ 230°C, Peroxide curing FEPM: 2h rising time + 8 h @ 220°C, Peroxide curing HNBR compounds: 1 h rising time + 2 h at 160°C, Peroxide curing EPDM compounds: 1 h rising time + 3 h at 150°C. Tip: If you live in a warm climate, you can use the sun to your advantage. Post-Curing Post-curing is one of the principal tools to mitigate outgassing. Putting too much material in the oven can result in high volatile concentrations. Following the normal cure cycle for the plastic (consult product technical bulletin), casting can be exposed to mild heat 150°F (65°C) for 2 - 4 hrs. This prevents the chains from moving independently, allowing the material to stretch under stress and then return to its original shape when the stress is released. Platinum curing VMQ do not contain peroxide as such, but in order to meet the food contact demands, platinum curing VMQ compounds must be post-cured just as well, in order to remove the volatiles that remained in the material and to improve certain physical properties, especially the compression set and high temperature stability. Tip: a 100-watt light bulb in a cardboard box may be all that you need to generate enough heat to do the job. Post curing is the process of exposing a part or mold to elevated temperatures to speed up the curing process and to maximize some of the material’s physical properties. Extrusion is also used for sidewall profiles and inner liners. Post curing literally means “after cure”. Yellowing can also be expected in transparent and coloured VMQ compounds. Oven Post-Curing of Parts Introduction ... particular, parts made with silicone rubber should not be post-cured with a fluoroelastomer. Rubber Compounding Compression set and tensile strength are two of the properties most often improved by an oven post-cure cycle. Never put articles made out of different types of material together in the same post-curing oven, even if post-curing conditions are the same. Position as many heat lamps as necessary around the mold or casting to provide even heating. Area under tent can reach 150°F (60°C), depending on climate. To avoid aforementioned risks, we therefore recommend 120 liters of fresh air flow per kilogram of rubber per minute. Fabric calenders produce an upper and lower rubber sheet with a layer of fabric in between. Table I. Coagent identification and commercial products. 6) Flash Removal 7) Post Curing 8) Finishing & Inspection 9) Cleaning 10) Packaging . 1.1 Summary of previous works In general, three steps exist for rubber curing process, namely, induction, crosslinking and post-crosslinking (e.g. In case the material is compounded with food and water contact in mind, post-curing is absolutely mandatory in order to meet the demands of FDA, BfR, KTW or WRAS norms. Please avoid. Diffusion and evaporation of volatiles should be carried out at a temperature greater than the service temperature for the part. By definition, this means that there has already been an “initial” cure. Following the curing, the EASL decreased orderly depending on post-curing inflation time. Post-curing process is typically performed on peroxide andbisphenol curing compounds, but it can also be performed on sulphur curing compounds as well, to improve a particular physical property. Mold Making – Post curing any mold rubber will enhance the physical and performance properties of the mold rubber. We recommend that you do not use your kitchen oven! Heat curing can be used to accelerate the cure of polyurethane rubbers and plastics, platinum silicone rubbers, epoxy resins and other materials. Adjustments must be made by an experienced rubber engineer to compensate for all possible variables that can affect the state of cure. What is post-curing? 3-D or complicated shapes should be post cured in the rubber mold to prevent distortion. “Fundamentals of Curing Elastomers ... to impart selected properties to a rubber formulation, a minority of cases takes advantage of coagent blends to optimize the critical properties of the rubber compound. EPDM (ethylene propylene diene monomer rubber), is an elastomer characterized by a wide range of applications. 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