Japan’s Polyplastics Group has introduced two Renatus polyethylene terephthalate (PET) grades that reportedly deliver superior mechanical properties, appearance, and weather resistance for automotive exterior components.
The two new glass-reinforced grades — RH030 (30% glass filled) and RH045 (45% glass filled) — maintain their jet blackness and reduce whitening on the surface of molded articles in outdoor environments, making them suitable for applications such as automotive side mirrors and rear wiper arms/blades. Since PET parts are not painted, weathering degradation can occur over time. The glass filler can start to become evident on the surface and the jet blackness can decrease. Accelerated weather resistance testing demonstrates that Polyplastics’ new PET materials maintain lower index values than the competition, thus indicating that whitening is being reduced.
Plastic resins that are reinforced with glass fiber are typically made stronger but glass filler can also have a negative effect on the surface appearance of molded articles. Renatus RH030 and RH045 PET are glass fiber–reinforced grades, but they can still produce molded articles with good surface appearance because of their mold transferability during molding.
Recent company testing shows that when compared to standard grade PBT-GF30, RH045 (PET-GF45) exhibits higher surface gloss even though it has a large amount of glass fiber added to the formulation.
In terms of mechanical performance, PET typically has superior properties compared to PBT. At similar glass loadings, RH030 and RH045 PET grades have higher mechanical properties including greater tensile strength, flexural modulus, and deflection temperature under load compared to PBT grades.