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PP Chemical and Physical Properties
- Jan 23, 2019 -

PP is a semi-crystalline material. It is harder than PE and has a higher melting point. Since the PP temperature of the homopolymer type is very brittle above 0 °C, many commercial PP materials are random copolymers of 1 to 4% ethylene or clip copolymers having a higher ethylene ratio.

The copolymer type PP material has a low heat distortion temperature (100 ° C), low transparency, low gloss, low rigidity, but has a stronger impact strength. As the ethylene content increases, the strength of PP increases. The Vicat softening temperature of PP is 150 °C. Due to the high crystallinity, the material has excellent surface hardness and scratch resistance. There is no environmental stress cracking problem in PP. Typically, the PP is modified by the addition of glass fibers, metal additives or thermoplastic rubber. The flow rate of PP has a MFR of 1 to 40. Low MFR PP materials have better impact resistance but lower elongation. For materials of the same MFR, the strength of the copolymer type is higher than the strength of the homopolymer type.

Due to crystallization, the shrinkage of PP is very high, usually 1.8-2.5%. The uniformity of the direction of shrinkage is much better than materials such as PE-HD. The addition of 30% glass additive reduced the shrinkage to 0.7%. Both the homopolymer type and the copolymer type PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance and solubility resistance. So pp plastic is the ideal raw materials  for plastic container