IR and Uv-Visible Study of the Thermal Stabilization for pvc Stabilized with ( Ho,Tb and Dy ) Stearate and Synergistic Mixtures

Three types of metal carboxylates (Ho,Tb and Dy) stearates were used as thermal stabilizers for PVC. Infrared spectra (1500-1900 cm1 ) were studied for PVC films stabilized with these metal carboxylates. Two types of oxygen were found -containing products that were formed during the thermal degradation .On the other hand , the presence of atmospheric oxygen leading to the formation of carbonyl groups on the chain seems to play a great role in the stabilization of PVC. It was found that IR spectroscopy was suitable to follow the consumption of the carboxylates within the thermal stress periods via antisymmctrical stretching vibration of COO. The thermal stability lor the PVC in present of synergistic mixtures (Ho-Tb,Ho-Dy and Tb-Dy) stearates was studied by Ultraviolet-visible spectra.The results indicate that these mixtures have considerable stabilization efficiency for the PVC.