PP is a semi crystalline material. It is harder than PE and has a highermelting point. Because of the type of PP homopolymer temperature higher than 0 ℃ very brittle, so many commercial PP materials is clamp copolymerethylene random copolymer with 1~4% or higher ratio of ethylene content.Copolymer type PP materials with low thermal distortions of temperature(100 ℃), low transparency, low gloss, low rigidity, but the impact strength isstronger. The strength of PP

Increases with the increase of ethylene content. PP VEKA softeningtemperature is 150 ℃. As a high degree of crystallinity, surface of the stiffness of the material and anti scratch properties is very good. PP is free from environmental stress cracking. Usually, by adding glass fiber, metal additives or thermoplastic rubber methods to modify PP. PP MFR flow ratein the range of 1~40. Impact of low MFR material property of PP is better but with low tensile strength. For materials with the same MFR, the strength of copolymer is higher than that of homopolymer type. Due to crystallization,PP contraction rate is very high, generally 1.8~2.5%. And uniformity of shrinkage in the direction other than PE-HD material is much better. With 30% glass additive can make the shrinkage rate down to 0.7%.Homopolymer and copolymer type PP materials have excellent resistance to moisture absorption, anti acid and alkali corrosion resistance, solvent resistance. However, the aromatic hydrocarbon (such as benzene) solvents,