polyvinyl chloride is a vinyl chloride monomer polymerization is made, is one of the commonly used thermoplastics. its trade name is abbreviated as "chloroplastic", english abbreviation is pvc.
pure polyvinyl chloride resin is a hard thermoplastic material, the decomposition temperature and plasticization temperature is very close, and the mechanical strength is poor. therefore, the pvc resin can not be used for plastic products, plasticizers, stabilizers, fillers and the like must be added to improve the performance, so as to make the pvc plastic, and then processed into various products. pvc, according to the amount of plasticizer added into the number of hard pvc and soft pvc.
(b) identify features
polyvinyl chloride film is more transparent than polyethylene, bright color products, hand touch smooth, wax-free feel, often smell special odor; case hardened significantly after cold, the use of temperature 60 ℃; relative density greater than 1, can sink underwater, which is a distinctive feature of pvc; hard and hard products, percussion bored sound; soft soft products, flexible.
(c) burning performance
pvc combustion performance is not good, from the fire that is off, belong to the flame retardant plastic; burning, irritating odor of hydrogen chloride release, softening when burning.
1. soft pvc plasticizers generally contain 30-50%. because of the soft texture, high strength; has a good air tightness and impermeability.
2. rigid pvc with a small amount of plasticizer made. it is characterized by hard texture, high mechanical strength, good chemical resistance. .
3. pvc plastic heat resistance is poor, the intensity of the larger temperature, -20 ℃ than when the intensity decreased by 80% 80%. therefore, the film products are not easy to store at low temperatures; soft products not exceeding 45 ℃, not more than 60 ℃ hard products, long-term light will become brittle aging.
4. pvc film in the processing, in order to prevent the heating decomposition, the need to add heat stabilizer, the heat stabilizer contains lead salts, pvc plastic is toxic, it can not be used as food packaging.
5. pvc plastic and organic solvents and naphthalene and other insecticide contact, will produce sticky, melting phenomenon, and easy to absorb odor; due to strong plasticizer volatility, it should not be stored too long.