PVC resin, low softening point, about 75-80 ℃, embrittlement temperature below -50 ~ -60 ℃, most products should not exceed the long-term use temperature of 55 ℃, the special formula of up to 90 ℃. If the polyvinyl chloride resin is purely a head-to-body contact surface afraid of linear structure, internal branches and unsaturated bonds, although the C-Cl bond can be relatively small, the stability of polyvinyl chloride resin should be relatively high . However, even if the purity of PVC resin, long-term above 100 ℃ or UV radiation began to hydrogen chloride gas escape. Explain the existence of a sharp group or unstable structure in its molecular structure. The longer the time, the more degradation, the higher the temperature, the faster the degradation, the faster the degradation in the presence of oxygen or air.
Polyvinyl chloride is a polar polymer that has a high affinity for conductive materials such as water and therefore has lower resistance than non-polar polyolefins but still has a high volumetric cathodic and breakdown voltage. Polyvinyl chloride polar groups attached directly to the main chain, below the glass transition temperature, the dipole segments by the frozen structure of the main chain atoms, can not move, and thus does not produce dipolar effects can be room temperature High frequency insulation material. When used for wire insulation, the electrical insulation of the suspension resin is 10 to 100 times higher than that of the float resin. The presence of chloride ions from degradation degrades electrical insulation.
PVC generally modified granulation first, with the screw extruder unit prepared into particles, more fully plasticized, processing easier, especially the injection molding process is the product. Screw extruder is one of the most important equipments in plastic molding. It transfers the solid by the external power transmission and the heat transfer of the external heating element, compaction, melting and shearing. The screw extruder occupies an important position both as plasticizing and pelletizing machine and forming and processing machine. Strictly speaking, PVC products and PVC modified formulations with special requirements are tailor-made according to customer requirements. There is in the PVC production process derived derivatives, such modified varieties are vinyl chloride copolymer, PVC blends and chlorinated polyvinyl chloride