Dispersibility of Macromolecular Polyols as Co-Stabilizer in Poly(vinyl Chloride) and their Stabilization Effect Combined with Synergetic Metal Soap

Abstract

In order to delay the undesirable discoloration of poly(vinyl chloride) (PVC) by heating, the synergetic effect of poly(vinyl alcohol) (PVA) as co-stabilizer with a mixture of zinc and calcium stearates was clarified. Usually, the abrupt discoloration was caused by the formation of a π-complex between the cool colour-producing metal chloride, i.e. the zinc chloride from the metal soap, and double bonds from the dehydrochlorination of the PVC chain. Firstly, the effect of using various PVA having different degrees of polymerization before melt blending with PVC was investigated. When the PVA and PVC were pre-mixed in the powder state, the compound obtained showed a lower stabilization effect on the discoloration of PVC. On the other hand, when a PVA aqueous solution was prepared and the PVC powder was added to the PVA solution, and dried, the resulting compound showed an excellent stabilization effect. Secondly, the dispersed PVA domain size in the PVC sheets was measured quantitatively by image processing analysis, using the optical micrographs of the sheets. As a result, it was found that there was a good relationship between the dispersibility of PVA and its stabilization effect. That is, the co-stabilizing effect of PVA increased with a decrease in the domain size. This fact was also confirmed by using different polyols as co-stabilizer.

Thermal stabilization of polyvinyl chloride by calcium and zinc carboxylates derived from byproduct of palm oil refining

“…Stabilizers #3 and #5 are used to observe the effect of doses at the same Ca/Zn ratio. It has been reported that, in the case of stearate, the efficacy of mixed Ca/Zn stabilizers can be enhanced by using a co-stabilizer ( El-Ghaffar et al., 2019 ; Gao et al., 2012 ; Ikeda et al., 2003 ). It is known also that pentaerythritol is a good co-stabilizer and has synergistic effects with mixed Ca/Zn stearates ( Liao et al., 2011 ; Liu et al., 2007 ; Schiller, 2015 ).…”

Influence of Polyols as a Co-Stabilizer on Stabilization Efficiency of Calcium/Zinc Stabilizers to PVC

“…With the adding of hydroxyl compounds, the complex of polyol and ZnCl 2 is formed. So the Congo red time is postponed, and the stability of PVC become better [7,8]. But there is no more precedent report on the influence of polyols as a co-stabilizer on stabilization efficiency of Ca/Zn stabilizers to PVC.…”

Influence of Polyols as a Co-Stabilizer on Stabilization Efficiency of Calcium/Zinc Stabilizers to PVC/ACS Blend

“…The hydroxyl groups of polyhydric alcohol can form neutral ligand with metal ion, which will remits the catalytic action of ZnCl 2 and formation of colored ligand that generate from metal ion reaction with PVC polyene structure. With the increasing hydroxyl compounds content, the more "zinc burning" time is postponed, and the stability of PVC is more better [8,9]. But there is no precedent report on the influence of polyols as a co-stabilizer on stabilization efficiency of Ca/Zn stabilizers in PVC/ACS blend.…”