Influence of lanthanum stearate as a co-stabilizer on stabilization efficiency of calcium/zinc stabilizers to polyvinyl chloride

Influence of lanthanum stearate (LaSt(3)) as a co-stabilizer on stabilization efficiency of calcium stearate (Ca)/zinc glutarate (Zn) stabilizers to polyvinyl chloride (PVC) at 180 degrees C in air was investigated. The results showed that combination of LaSt(3) with Ca/Zn stabilizers presented an obvious improvement of stabilization efficiency to PVC compared with the Ca/Zn stabilizers. Moreover, addition of LaSt(3) to the Ca/Zn stabilizers could significantly enhance static stability time of PVC. Incorporation of 2 phr LaSt(3) co-stabilizer to PVC containing 3 phr Ca/Zn stabilizers resulted in marked increase of onset degradation temperature and reductions in average degradation rate as well as the dynamic storage modulus (G') and loss modulus (G '') at 180 degrees C. Influence of Ca/Zn ratio on tensile strength of PVC in the absence or in the presence of LaSt(3) was discussed in detail. At low Ca/Zn ratios LaSt(3) had an obvious improvement in the tensile strength, while at high Ca/Zn ratios this effect became inconspicuous. (C) 2009 Published by Elsevier Ltd.