Tris(hydroxymethyl)aminomethane, a pure organic thermal stabilizer for poly(vinyl chloride)

Thermal stabilization effect of tris(hydroxymethyl)aminomethane (TRIS) in poly(vinyl chloride) (PVC) is studied. Discoloration tests and dehydrocholorination tests show that PVC films containing TRIS as the unique main stabilizer present excellent initial color and long-term stability, compared with all their control samples, PVC films containing pentaerythritol (PER), within the ingredient range of 50 g PVC, 0.2 g stearic acid (HSt), and x (x = 0.1, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5) g TRIS or PER. Nucleophilic substitution reaction between TRIS and unstable chlorine in PVC resin and neutralization reaction between TRIS and HCl generated subsequently during heating is respectively suggested as the mechanism of the initial and long-term stabilization.