components. In the medical technology, automotive and food industries, silicone rubbers are often used as media carrying components in the form of hoses or profiles. All applications have in common that high demands are placed on the material, as well as on the geometric dimensions, and thus on the manufacturing process.
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The potential of Superior Graphite (RGC39A graphite) in a model lip seal formulation was evaluated for abrasion resistance for a wide range of loads. The abrasion testing was based on the ASTM D3702 test method for wear rate and coefficient of friction (COF) of materials in self-lubricated rubbing contact using a thrust washer testing machine. The role of graphite type on key properties was determined. The evaluations included tensile properties, hardness, Phillips dispersion, abrasion resistance and coefficient of friction. The abrasion and COF test varied the counter surface conditions (dry, wet and oily) and the load (pressure) from 30 to 625 psi.
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Patents as compiled by the editors of Rubber World for May 2022
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Patents listed in the May issue of Rubber World Magazine
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Chlorinated polyethylene (CPE) polymers were developed by DuPont in the late 1950s by a simple chlorination of polyethylene (PE) in a solution process using a solvent. In 1971, Dow Chemical Company introduced Tyrin CPE using a more efficient and cost-effective aqueous suspension chlorination known as the slurry process. The polyethylene feedstock is in a powder form and the final CPE product remains in powder form. The chlorination process can be modified to produce amorphous (non-crystalline) products or products that contain residual crystallinity
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Recent developments in stimuli-responsive or “smart” materials offer the opportunity for major advances in material design that could impact markets for latexes. One of the lesser known, but simpler technologies includes polymers and latexes whose properties can be dramatically, and reversibly, switched simply by adding or removing CO2. The processes used offer advantages in sustainability without requiring expensive materials or catalysts, and are based on currently used materials and production methods. This article will give a general overview of three examples relevant to latexes and coatings
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An extrusion die is a purpose built tool designed by cutting shapes in plates to reflect an intended extruded rubber product. In advance of an extrusion project, a process engineer designs the die according to specifications of the project and those of the customer, and installs it on an extruder. Often, an extrusion die is made from hard metal, like steel, polished and with sharp edges. Once all plates of the mold or die are created, rubber is forced through them under high pressure in a high temperature zone
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It has long been established that unvulcanized solid elastomer compounds can be expanded to sponge forms by the incorporation into the formulation of thermally activated gas releasing chemicals known as blowing agents. During controlled heating of the compound, there is molecular dissociation of these blowing agents, and this is often designed to occur in conjunction with the onset of vulcanization of the compound, enabling the production of a range of sponge structures.
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Royalene EPDM, a terpolymer of ethylene, propylene and a
non-conjugated diene, is one of the most versatile specialty
elastomers in commercial use today. The main attributes of
EPDM are its outstanding resistance to oxidation, ozone and
the effects of weathering. It is also highly extendable, allowing
high levels of fillers and plasticizers to be added, while still
maintaining good physical properties