Pure PVC resin is very sensitive to heat, when the heating temperature reaches above 90 ℃, there will be a slight thermal decomposition reaction, when the temperature rose to 120 ℃ decomposition reaction worsened at 150 ℃, 10 minutes, PVC resin from the original The white gradually turned yellow - red - brown - black. PVC resin decomposition process is due to de-HCL reaction caused by a series of chain reactions, and finally lead to macromolecular chains fracture. To prevent thermal decomposition of PVC thermal stability mechanism is achieved through the following aspects.
By capturing the thermal decomposition of PVC generated HCl, to prevent the catalytic degradation of HCl.
Lead salts mainly by the mechanism of action, in addition to metal soaps, organic tin, phospholipids and epoxy and so on.
• Replacement of lively allyl chloride atoms. Metal soaps, phosphites and organotin can play a role in this mechanism.
• Reacts with free radicals to stop free radical reactions. Organotin and phosphite fat according to this mechanism.
• Addition with conjugated double bonds inhibits the growth of conjugation chains.
Organotin and epoxy based on this mechanism role.
• Decompose peroxide to reduce the number of free radicals. Organotin and phosphite fat according to this mechanism.
Passivation of metal ions that catalyze the removal of HCl.
The same stabilizer can achieve several thermal stabilization objectives by several different mechanisms.