Preparation and application of some carboxylates of heavy metals as thermal stabilizers and reducer plasticization migration in soft Poly(vinylchloride)

Different metal moncrboxylates such as Zinc, Calcium ,Cadmium , Lead and Barium stearates were prepared and applied as thermal stabilizers and reducerplasticizer migration in flexible poly(vinyl chloride) (PVC) films. Thermal stability of the stabilized PVC samples were determined by different methods which are measurement of released HCl and other vapor products from the heated samples ( with and without thermal stabilizers) , bythermogrvimertric analysis ,visual color comparison , IR spectroscopy and electron microscopy.All the results confirmed thermal stabilization , reducer migration additives and synergistic effects of the carboxylates. As it was clearly noted that, the thermal decomposition of PVC is a two-stage process , thermal decomposition in the first stage is mainly the evolution of HCl and the thermal decomposition in the second stage is mainly the cyclization of conjugated polyene sequences to form aromatic compounds. Two main kinds of mechanism of HCl suppression in PVC for metal containing compounds were proposed.

Keywords:

Polyvinyl chloride , thermal stabilizer , metal carboxylates , thermaldegradation