The new polymer modifier claims not to reduce modulus or impact resistance

The new polymer modifier claims not to reduce modulus or impact resistance

Dow Chemical has developed a new polymer modifier for improving the flow properties of TPO compounds without reducing the modulus or impact resistance of the material. The modifier is based on the company’s Affinity polyolefin plastomer (POP) technology and is an ultra-low-viscosity ethylene-octene copolymer, produced using its Insite single-site catalysts.

Higher flow levels can reduce cycle times for TPOs, allow thinner walls or permit the production of larger, more complex parts. The traditional routes to improve flow rates have been to use a high-flow PP or a high-flow elastomer. However, the former route typically leads to reduced modulus and impact resistance, while the latter also reduces impact performance.

Brian Walther of Dow said Affinity POP gives an increase in flow with “no negative influence on physical properties”. The material is used to replace around 25% of the elastomer, which in turn makes up 30% of the TPO compound. This means that the loading of Affinity POP in the complete compound is around 7.5%.

Tests have shown that this loading gives a decrease in viscosity of 10% to 30%, depending on the Affinity grade used. Other potential benefits include improved surface gloss and enhanced paintability, because of surface modification effects.