EMS Grivory Q & A

EMS Grivory answers questions on the latest product developments covering the trends in the engine compartment.

Q) First of all, what are the trends in the engine compartment?

A) One of the big trends in current automotive development is downsizing. Due to increasingly stringent statutory requirements, automotive manufacturers must reduce CO2 emissions and thus also the fuel consumption of their vehicles. To achieve the balancing act between lower consumption and unchanged or even higher performance, car manufacturers rely on smaller engine and cylinder sizes, with higher-performance turbocharging ensuring an equally high or often even greater level of performance. There is no sign of an end to this trend. Peak temperatures of up to 250°C will be more the rule than the exception. As a result, thermal stresses in the engine compartment will rise to near the melting point of aliphatic polyamides.

Q) How have EMS-GRIVORY reacted to these trends?

A) During a period of intensive research activity, EMS R&D department analysed and tested various processes to raise EMS-GRIVORY’s highperformance polymers to the next level of performance. The breakthrough finally came. Using a method borrowed from flame retardants, Grivory HT2 was modified, which has been marketed successfully for many years, in such a way that it has no problems withstanding constant temperatures of up to 250°C.

Q) How does this new mechanism work?

A) The basic principle is simple: if the thermal stress on a component made of Grivory HT2VS-HH increases, a barrier layer forms on its outer surface and stops the process of thermal oxidation from damaging the polyamide. Heat ageing of the new material and of a 30% glass fibre-reinforced standard PPA at 230°C gives an impressive demonstration of the mechanism. After 1,000 hours, it is apparent in the case of the conventional PPA that the process of thermal oxidation has already penetrated deep into the polyamide. After 2,000 hours, the test piece is almost completely charred, and at 3,000 hours it is entirely carbonised. The situation is different with the heat-stabilised Grivory HT2. As a result of the protective layer, the test piece is largely intact even after 2,000 hours, and in contrast to the standard PPA, there are no surface cracks. The picture is comparable even after 3,000 hours.

Q) What benefits is this thermal oxidation layer having on the properties?

A) The higher the temperature, the quicker the thermal oxidation protective layer is formed. This fact leads to astonishing results. Heat ageing experiments at 180°C for 2,500 hours show the well-known performance ability of Grivory HT2, with only a slight reduction in mechanical properties. At 200°C, the durability is already well above that of standard PPA. This picture is even clearer at 230°C and finally culminates at 250°C. In this case, Grivory HT2VS-HH shows almost constant strength during 3,000 hours, whereas after 1,000 hours, the breaking stress of conventional polyphthalamide has already dropped to around half of its original value, and after 2,000 hours it has reached zero.

Q) What advantages does this product offer versus other high performance polymers?

A) High-heat polyamides look impressive when compared to other high-performance polymers. The stress-strain property is on a par with a similarly reinforced PPS, whereby the EMSGRIVORY material has higher elongation at break. When the heat-ageing resistance of the two materials is compared after about 1,000 hours at 250°C, Grivory HT2VS-HH shows far greater resistance.

Q) What was the feedback from the automotive industry?

A) The automotive industry’s response was correspondingly positive. The material has already been validated by numerous OEMs and TIER 1 companies, with extremely pleasing feedback. For example, it has achieved testing approval in Volkswagen’s Central Laboratory with a laboratory mark of 1 for 230°C and also for 250°C.





Author
EMS Chemie (UK) Ltd

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