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Innovation | high temperature plastics


exchanger components and resonators and electrical applications including high-temperature electrical insulation and lead-free soldering components. Evonik Industries has developed a highly transpar-


ent polyamide, based on an as yet undisclosed mono- mer composition, which can withstand higher tempera- tures than previous grades in the Trogamid CX family of transparent polyamides. Trogamid RS6121 (its develop- ment name) allows for steam sterilisation at 134°C and at a pressure of 2 bar. Evonik says the improved performance “allows for applications that used to be reserved for other polymers such as polysulphones because of temperature resistance requirements.” Trogamid CX polyamides incorporate polymer


components that reduce the customary crystalline polyamide morphology or form micro-crystalline structures that have no infl uence on transparency. While retaining such properties as excellent resistance to chemicals, high static and dynamic durability as well as abrasion resistance, high impact resistance, good weather resistance and scratch resistance, Evonik says the new grade has a few additional characteristics that make it especially suited for applications with higher temperature requirements. Glass transition tempera- ture of Trogamid RS6121 in the dry state, for example, is around 30°C higher than in Trogamid CX7323, which translates into a higher maximum continuous use temperature. “Thanks to the signifi cantly reduced water absorption of below two percent, the Tg does not fall below 134°C, even when saturated,” the company says. Evonik envisages applications in medical technology, the electrical industry, as well as automotive and mechanical engineering.


With a water absorption of less than 2%, components made of the new Trogamid RS6121 transparent PA from Evonik can be steam-sterilized at 134°C and 2bar without any impact on mechanical properties.


Source: Evonik Polyphthalamides are polyamides that have an


aromatic content of at least 50%, giving them extra-high thermal resistance. EMS-Grivory says its new Grivory HT2VS-HH modifi ed PPA was developed in response to increasing requirements in the car engine compartment that it claims will bring materials based on aliphatic polyamides to their limits in the medium term.


Long term durability


The new PPA is designed specifi cally for long-term use under extreme continuous temperatures. It has very high resistance to heat ageing over the temperature range from 180°C to 250°C, showing an almost constant breaking stress over 3,000 hours at 250°C. Stress-strain behaviour is said to be on a par with a similarly reinforced polyphenylene sulphide, PPS, and Grivory HT2VS-HH has a higher elongation at break. “When the heat-ageing resistance of the two materials is compared after 1,000 hours at 250°C, Grivory HT2VS-HH has far greater resistance,” the supplier says. “Starting from mechanical properties that are already higher in the un-aged state, the property retention of Grivory HT2VS-HH with regard to breaking stress is more than 60% greater, and with regard to elongation at break is up to more than 100% higher than for a corresponding PPS type.”


Results of break tests comparing breakage stress properties of a 30% glass fi bre-reinforced grade of Grivory HT2VS-HH (XE 4216) and a 45%-reinforced (XE 4217) grade compared to a standard PPA with 30% glass-fi bre reinforcement. Tensile strength is measured at 23°C at several points during the 3000h ageing process. Source: EMS-Grivory


www.compoundingworld.com


Solvay Specialty Polymers says it is hopeful of soon securing commercial applications for two Amodel HH grades of PPA that were launched in late 2012 for high heat applications such as automotive air managements systems in turbocharged engines. Tests for these applications call for the ability to retain at least 50% of original mechanical properties after several thousand hours at temperatures around 220-230°C.


Amodel A-4133HH (33% glass reinforced) and Amodel June 2014 | COMPOUNDING WORLD 65


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