>> Sunday, 11 January 2009
Polypropylene is thermoplastic polymer consisting mainly of propylene come from a low pressure process based on catalysts and have generally linear polymer chain. There are three general types of polypropylene: homopolymer, random copolymer and impact or block copolymer.
Random copolymer is produced by statistical insertion of units mainly ethylene. Through this, the glass transition temperature and melting point are lower than in homopolymer.
Additionally we receive better mechanical properties in the temperature below zero (e.g. impact) and optical (transparency). Processing of random copolymer by injection molding considering properties mentioned above characterizes lower temperature (lower cycle time) and pressure. Application, e.g. thin wall and transparent products on the other hang thick wall, because of lower crystallization ratio (amorphous structure).