Study on stabilization of pvc In the presence of (Ho,Tb and Dy) stearate by uv-visible spectroscopy

This study describes preparation of three metal carboxylate complexes, holmium stearate,Terbium stearate and Dysprosium stearate,which are used as thermal stabilizers for pvc.These complexes are identified by their infrared spectra, elemental analysis and by DSC technique. It is found that these complexes have some indication for same transition of polymers have liquied crystal properities. Uv-Visible spectra are used to study the thermal unstabilized pvc and stabilized pvc degradation of reprecipitated from THF by methanol. This was done by the investigation of the absorption of the polymers resulted from the losing of HCL from the polymers chain at 275 and 385 nm, which were corresponded to three and seven conjugated double bonds respectively. Mechanisms for thermal stabilization process of prepared complexes have been suggested, these stabilizers reduce the autocatalysis for hydrogen chloride or formation of esteric bonds on polymer chain or formation of coordination complexes.