PP has good heat resistance, and can be sterilized and sterilized at a temperature above 100 ℃. It will not be deformed at 150 ℃ under the condition of no external force. The embrittlement temperature is -35 ℃, and embrittlement will occur below -35 ℃.
PE has good low-temperature resistance and low heat resistance. The brittleness temperature can generally reach below -50 ℃, and the lowest can reach -140 ℃. degree
It is known that PP caps are used for hot drink bottles. The dimensional stability of the PP cover is better; PE is cheaper than PP, so it is necessary to use PE in addition to PP.
PP plastic refers to polypropylene, which is a kind of thermoplastic resin made by polymerizing propylene. According to the arrangement of methyl groups, it is divided into three types: isotactic polypropylene, random polypropylene and syndiotactic polypropylene.
PE plastic refers to polyethylene is a kind of thermoplastic resin made by polymerization of ethylene. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance, good chemical stability, and can withstand the erosion of most acids and alkalis. It is insoluble in common solvents at room temperature, has low water absorption, and has excellent electrical insulation.