PP has better heat resistance than PE, higher strength, and better transparency than PE. PP has poor aging resistance and can be used for food packaging. Modified PP is used for high-end packaging (BOPP). Most of the time, the price of ordinary PP is lower than PE, but the price of BOPP is very high. Ordinary PP is mostly used in woven bags

The price is similar to PE PP

PP polypropylene chemical and physical properties PP is a semi-crystalline material. It is harder than PE and has a higher melting point. Since the homopolymer PP temperature is very brittle when the temperature is above 0C, many commercial PP materials are random polymers with 1 to 4% ethylene added or clamp-type polymers with higher ethylene content. Polymer. Polymer PP materials have lower heat distortion temperature (100C), low transparency, low gloss, and low rigidity, but have stronger impact strength. The strength of PP increases as the ethylene content increases. The Vicat softening temperature of PP is 150C. Due to its high degree of crystallinity, this material has good surface stiffness and scratch resistance.

PP does not have environmental stress cracking problems. Usually, PP is modified by adding glass fiber, metal additives or thermoplastic rubber. The flow rate MFR of PP ranges from 1 to 40. Low MFR PP materials have better impact resistance but lower ductile strength. For materials with the same MFR, the strength of polymer type is higher than that of homopolymer type. Due to crystallization, the shrinkage rate of PP is quite high, generally 1.8~2.5%. And the directional uniformity of shrinkage is much better than that of materials such as PE-HD. Adding 30% glass additive can reduce the shrinkage to 0.7%. Both homopolymer and polymer PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance, and dissolution resistance. However, it is not resistant to aromatic hydrocarbon (such as benzene) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc.

PE is basically divided into three categories, namely high-pressure low-density polyethylene (LDPE), high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE). Films are its main processed products, followed by sheets and coatings, hollow containers such as bottles, cans, barrels and other various injection molding and blow molding products, pipes and wires, cable insulation and sheathing, etc. Mainly used in packaging, agriculture and transportation sectors.