Low Thermal Expansion Plastic Alloy for Exterior Parts

Recently, R-PP (Rubber modified Polypropylene) has been often used in automotive exterior parts, but is difficult to use for longer parts because of the limit of it's dimensional stability.

Studies of the thermal expansion mechanism of R-PP by the rule of mixtures and FEM indicated that optimization of the volume elasticity ratio of PP/rubber is a key point to design the low thermal expansion alloy. And the selection of rubber which is partially compatible with the PP is also important.

The developed new alloys are used for automotive longer exterior parts such as the rocker panel and side moldings which have better dimensional stability than the usual R-PP and R-RIM(Reinforced Reaction Injection Molding).