Extended information polypropylene is a non-toxic, odorless, tasteless, milky white, highly crystalline polymer with a density of only 0. 90-"0.9 1g/cm3 is one of the lightest plastics at present. It is particularly stable to water, and its water absorption in water is only 0. 0 1%, and the molecular weight is about 80,000-1.5 million. The formability is good, but due to the large shrinkage rate (1%~2.5%), thick-walled products are easy to sag, and it is difficult to meet the requirements for some parts with high dimensional accuracy, and the surface gloss of the products is good.
Polypropylene has high crystallinity and regular structure, so it has excellent mechanical properties. The absolute value of mechanical properties of polypropylene is higher than that of polyethylene, but it is still a low variety in plastic materials, and its tensile strength can only reach 30 MPa or slightly higher. The tensile strength of polypropylene with large isotactic index is high, but with the increase of isotactic index, the impact strength of the material decreases, but it does not change after falling to a certain value.
Resource Polypropylene _ Baidu Encyclopedia