Functionalized liquid rubber for tire formulations

Plasticizers are one of the key components of the rubber and adhesives industries. Plasticizers are used to lower hardness, improve processability and reduce raw material costs. On the other hand, mechanical properties deteriorate with plasticizer content. In addition, plasticizers often cause changes in properties with time and staining due to volatilization or bleeding. Phthalate plasticizers and aromatic oils are or possibly will be regulated due to environmental and human health issues. Kuraray liquid rubbers (KLR) are plasticizers which are co-vulcanizable with solid rubbers. Therefore, it is very unlikely that KLR will be subject to these bleeding or volatilization issues. As a result, KLR is expected to have a growth potential as an environmentally friendly plasticizer.

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Processing promoters: Additives for rubber compounds improve mixing and processing

The efficient mixing of rubber compounds comes with many challenges. These include effectively blending the individual raw materials, which involves breaking down and blending different types of elastomers, adequately dispersing large fractions of fillers, oils and small weighments of chemicals in a relatively short time in the internal mixer. Once mixed, the compound then must be processed, e.g., extruded, calendered or molded to form the desired shape which is then vulcanized to produce the final product. The choice of the correct processing promotor will assist in these efforts. Certain promotors function primarily as dispersing agents, whereas others act more as lubricants to speed the mixed compound through the production process. Both types improve overall compound quality and production efficiency. Compound viscosity typically is also reduced. This article will focus on a number of processing promotors offered by Rhein Chemie and their effects on rubber compound quality and processability.

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FKM and FFKM crosslinking methods and their effect on upper use temperature of seals

Fluoroelastomers (FKMs) were first introduced to market more than 50 years ago in response to performance needs in the aerospace industry. Their increased thermal stability and chemical resistance, and comparable mechanical properties relative to hydrocarbon rubber materials provided significant performance benefits. Not surprisingly, FKM compounds soon became widely adopted in seals and gaskets for many other applications across the automotive, oil and gas, semiconductor and pharmaceutical/ food processing industries, where long term durability and reliability in challenging environments was critical.

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Dynamic mechanical properties and crosslink density testing of silicone elastomers

Material evaluation tests for this article were performed using the recently developed Dynamic Mechanical Yerzley Oscillograph (DMYO). Just like the Yerzley Oscillograph (YO), the DMYO supports the ASTM D945 standard. Its design is an evolution of the YO with additional sensors,
electronic data acquisition and computer control, including automated data evaluation.

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Medical rubber tubing process and die optimization: Die redesign and fine tuning

Part 1 of this contribution, published in the May 2021 edition of Rubber World, investigated a real manufacturer’s process that was set to produce medical tubing. It was found (through trials at the extruder, then through simulations) that the equipment available to the manufacturer was too large for the relatively low output that was required for this project, and consequently the polymer was degrading on the screw surface. It was ultimately determined through simulation that a smaller extruder, with a screw optimized for the low rate, would work better.

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