A novel zinc-containing additive for the long-term thermal stabilization of poly(vinyl chloride)

A Zn-containing complex ([ZnL 2 ]· x H 2 O, x  ≈ 4, abbreviated as ZnL 2 ; HL = 1,3-dihydroxy-2-hydroxymethyl-2-(salicylidimino)propane) was synthesized and used as a thermal stabilizer . Through discoloration and dehydrochlorination tests at 180 °C, ZnL 2 was proved to be a co-stabilizer of long-term thermal stability for poly(vinyl chloride) (PVC): compared with the PVC samples stabilized using typical metallic soap stabilizers with the mass ratio of calcium stearate (CaSt 2 ) to zinc stearate (ZnSt 2 ) ranging from 1.5/0 to 0/1.5, whose induction time ( t i ), stability time ( t s ) respectively ranged from 9 to 54 min, from 12 to 56 min, the PVC samples stabilized using combinations with the mass ratio of CaSt 2 to ZnL 2 from 1.5/0 to 0/1.5 showed apparent thermal stability with t i , t s ranging from 44 to 85 min, from 49 to 88 min. PVC sample (PVC resin = 50.0 g, ZnL 2  = 1.5 g, pentaerythritol  = 0.3 g, dioctyl phthalate  = 2.5 g) displayed a significant long-term thermal stability with t i of 102 min, t s of 105 min, and totally-turning-black time of 170 min.