Polypropylene raw material YHT30S

Three types of polypropylene are currently available. Each suits particular specifications and costing (although there is often some overlap). Homopolymers - A General Purpose Grade that can be used in a variety of different applications. Block copolymers - incorporating 5-15% ethylene, have much improved impact resistance extending to temperatures below -20oC. Their toughness can be further enhanced by the addition of impact modifiers, traditionally elastomers in a blending process. Random copolymers - incorporate co-monomer units arranged randomly (as distinct from discrete blocks) along the polypropylene long chain molecule. Such polymers typically containing 1-7% ethylene are selected where a lower melting point, more flexibility and enhanced clarity are advantageous. Different PP grades are available dependent on the application and chosen processing method.

Polypropylene (PP) resins are thermoplastic polymers, meaning they may be formed with heat and re-melted without losing their intrinsic characteristics. Thermoplastics differ in this way from thermosets, which undergo permanent change after hardening. Thermoplastics are generally recyclable for this reason. Other thermoplastics include polyethylene, polyvinyl chloride, polystyrene, polycarbonate, acrylic, acrylonitrile butadiene styrene, nylon, and polytetrafluoroethylene. Information about these thermoplastics and other thermosets may be found in our Types of Resins guide.

PP does not present stress-cracking problems and offers excellent electrical and chemical resistance at higher temperatures. While the properties of PP are similar to those of Polyethylene, there are specific differences. These include a lower density, higher softening point (PP doesn't melt below 160oC, Polyethylene, a more common plastic, will anneal at around 100oC) and higher rigidity and hardness. Additives are applied to all commercially produced polypropylene resins to protect the polymer during processing and to enhance end-use performance.