Pure PVC resin is very sensitive to heat, when heating temperature reached 90 degrees above, there will be a slight thermal decomposition reaction, when the temperature rises to 120 DEG after decomposition reaction increases, at 150 degrees, 10 minutes, PVC from the original white resin will gradually become yellow to red - Brown - black. The decomposition process of PVC resin is a series of chain reactions caused by the off HCL reaction, leading to the fracture of macromolecular chains. Thermal stability mechanism to prevent PVC thermal decomposition is realized by the following aspects.
By capturing PVC produced by thermal decomposition of HCl to prevent the catalytic degradation of HCl.
Lead salts mainly by this mechanism, in addition to metal soap, organotin, phosphite lipids and epoxy class.
Replacement of active allyl chloride atoms. Metal soaps, phosphite lipids and organotin compounds can act on this mechanism.
Reaction with free radical, termination of free radical. Organotin and phosphite lipids act on this mechanism.
Addition of conjugated double bonds inhibits the growth of conjugated chains.
Organotin and epoxy compounds act on this mechanism.
Decomposition of peroxide to reduce the number of free radicals. Organotin and phosphite lipids act on this mechanism.
Passivation of metal ions catalyzed by HCl.
The same stabilizer can achieve the purpose of thermal stability according to several different mechanisms.
In food additives, stabilizer is a kind of additive which can stabilize food structure and enhance food viscosity solid.
