Mechanism of organotin stabilization of poly(vinyl chloride). 6. Compatibility of organotin stabilizers with PVC

Abstract

Compatibility of PVC with liquid alkyltin alkylthioglycolate stabilizers was studied by thermal methods, including isothermal calorimetry of mixing, DSC, DMA, and dielectric relaxation. The enthalpy of mixing of PVC with the series of alkyltin alkyl thioglycolates was measured over the entire concentration range at ambient conditions. It was found that all tested compounds are compatible with PVC in a broad concentration range and form homogeneous mixtures. The results are discussed in terms of the superposition of glassy state and molecular interaction contributions to the enthalpy of mixing of the glassy polymer with liquid additives. The influence of organotin stabilizers on the glassy structure of PVC films was studied by means of DSC and the dielectric relaxation spectrum. The enhancement of the glassy structure of PVC by alkyltin alkyl thioglycolates is interpreted as the result of strong multi‐site molecular complexes between organotin molecules and PVC chains, which act as additional clips in the entanglement network of polymer chains.

Principles of Stabilization

“…Gupta 61 gave details of the conditions of sample preparation; e.g., dispersion of the stabilizer in PVC resin, concluding that the degree of dispersibility was determined by physical properties of the stabilizer and, in turn, affected the stabilizing efficiency of the composition. 233 It was found that all tested compounds are compatible with PVC in a broad concentration range. Brecker 211 stressed the importance of dialkyltin bis(isooctyl mercaptoacetate) because of the socalled resin plasticizing effect manifested by lower melt viscosity and the need to adjust lubrication when the stabilizer is changed.…”

“…Szabo, 232 discussing the properties of dibutyltin bis(isooctyl thioglycollate), pointed out that it is an efficient stabilizer because of its compatibility with polymer. 233 Tin stabilizers were found to form homogeneous mixtures with PVC. Safronov et al 233 published results of physical studies of compatibility of PVC and tin stabilizers.…”

“…Brecker 211 stressed the importance of dialkyltin bis(isooctyl mercaptoacetate) because of the socalled resin plasticizing effect manifested by lower melt viscosity and the need to adjust lubrication when the stabilizer is changed. 233 The saturation concentration of stabilizers is much higher than concentrations normally used in PVC stabilization. Compatibility of PVC with liquid alkyltin alkylthioglycolate stabilizers was studied by isothermal calorimetry of mixing, DSC, DMA, and dielectric relaxation.…”

“…233 Starnes 212 pretreated PVC with Bu 2 Sn(SC 12 H 25 ) 2 or its mixture with Bu 2 SnCl 2 , using much higher than usual quantities of these compounds in order to eliminate labile chlorines if possible. When a chlorine atom of the PVC chain associated with tin is allylic it is rapidly substituted by the thioglycollate group, which is one of important principles of stabilization.…”

Synthesis, characterization and in-vitro antimicrobial evaluation of thermally and photostable Schiff base-modified PVC/nanocomposites

“…In order to reduce this disadvantage some additives are applied to retard both thermal and photodegradation of PVC polymer, namely thermal and photostabilizers. Basic salts [14], soaps [15] and some organic stabilizers [16] are used as thermal stabilizers. Toxicity, environmental pollution and high cost of these additives have imposed a limitation on their use.…”