How many kinds of polypropylene are there
The polymer produced by polymerization of propylene is called polypropylene, or PP.Polypropylene particles look like white wax, lighter and slightly more transparent than polyethylene.It is flammable, melts and drips as it burns and gives off the smell of oil.According to the difference of the spatial arrangement of side methyl groups, polypropylene is divided into isogameter, interstitial gauge and random substance in the main configuration.Industrial polypropylene is mainly composed of 94 ~ 98.5% isotactic substances, and its content of isotactic substances (isometric degree) is often approximated by the percentage of polymers (isometric index) insoluble in boiling n-heptane.The national standard GB/ t2412-80 provides a method for the determination of polypropylene index.Random polypropylene is usually a by-product separated during the production of industrial PP by solution method.It is a transparent rubber-like substance that cannot be used to make products.It is often used as carrier resin in polypropylene filled masterbatch.Most industrial polypropylene is obtained by polymerization of only one type of propylene monomer, that is, homogeneous polypropylene.Sometimes a small amount of ethylene monomer (or butene-1, hexene-1, etc.) is introduced to copolymerize polypropylene in the process of polypropylene synthesis to meet various performance requirements.The most important copolymer of polypropylene is the copolymer of ethylene and propylene.