Effect of thermal stabilizers (BaCdZn metal salts carboxylate and dibasic lead stearate)‎ on the kinetic of carbonyls formation of PVC films

Abstract EN

The study of the photo degradation of unsterilized and stabilized PVC films has been performed by means of artificial UV light.

Eight (8) mixtures of PVC have been prepared by compounding PVC powder with two kinds of stabilizers at varied concentrations.

The two stabilizers used are namely Ba / Cd / Zn carboxylate and dibasic lead stearate (DLS).

The IR spectroscopic analysis has shown that during processing (to produce the films), the Ba / Cd / Zn carboxylate salt reacts almost completely with PVC while the dibasic lead stearate (DLS) reacts only partially.

The exposition of the films to UV light leads to the formation of oxidation photoproducts such as hydro peroxides, carbonyls, and unsaturation.

The addition of stabilizers to PVC has modified the kinetic and the kind of the oxidation products.

For, example in the case of DLS it has been observed that the remaining concentration of this stabilizer after processing is consumed during UV exposure and it considerably increases the rate of carboxylic acids formation and their end concentration.

In the case of Ba / Cd / Zn, the rate of carbonyl groups formation is slowed and their end concentration is lowered too.