Mechanism of poly(vinyl chloride) stabilisation

AbstractPoly(vinyl chloride) (PVC) thermal degradation is the result of a ‘zipper dehydrochlorination’ process that involves allylic chlorides as intermediates and is catalysed by hydrochloric acid. The degradation process can be stopped by PVC stabilisers, which either react with allylic chlorine atoms (primary stabilisers) or scavenge hydrochloric acid (secondary stabilisers). Scavenging HCl cannot stop the degradation process completely as it is diffusion controlled. However, HCl scavenging considerably reduces the rate of degradation and avoids the very fast process that eventually causes PVC blackening (catastrophic degradation). Stabilisers that scavenge HCl improve long term stability but do not give very good early colour. Compounds that substitute the allylic chlorine atoms can stop the degradation in its early stages and also maintain good early colour. They must be able to associate with PVC at the surface of primary particles where the mobility of PVC chains allows dehydrochlorination to occur...

[1]  S. MinskerKarl,et al.  Stabilization of poly(vinyl chloride) by β-dicarbonyl compounds , 1989 .

[2]  R. Bacaloglu,et al.  Degradation and stabilization of poly (vinyl chloride). V. Reaction mechanism of poly(vinyl chloride) degradation , 1995 .

[3]  R. C. Poller,et al.  The use of organotin compounds in the thermal stabilization of poly(vinyl chloride)—V. A radiochemical study of the reaction between PVC and di(butylthiolato)dibutyltin , 1975 .

[4]  R. Bacaloglu,et al.  Degradation and stabilization of poly (vinyl chloride). IV. Molecular orbital calculations of activation enthalpies for dehydrochlorination of chloroalkanes and chloroalkenes , 1995 .

[5]  R. Bacaloglu,et al.  Degradation and stabilization of poly(vinyl chloride). II. Simulation of the poly(vinyl chloride) degradation processes initiated in the polymer backbone , 1994 .

[6]  Z. Ahmad,et al.  Thermogravimetric analysis of ZnCl2 catalyzed degradation of PVC , 1992 .

[7]  M. Edge,et al.  The mode of action of metal stearate stabilisers in poly (vinyl chloride): II. Influence of pre-heating on induction times and carbonyl formation , 1995 .

[8]  R. Bacaloglu,et al.  Degradation and stabilization of poly(vinyl chloride). I. Kinetics of the thermal degradation of poly(vinyl chloride) , 1994 .

[9]  R. C. Poller,et al.  Mechanism of stabilization of poly(vinyl chloride) , 1970 .

[10]  E. D. Owen.  Degradation and stabilisation of PVC , 1984 .

[11]  N. F. Wood,et al.  An investigation of mechanisms of synergistic interactions in PVC stabilization , 1971 .

[12]  A. Michel,et al.  Etude de la stabilisation du polychlorure de vinyle avec des molecules modeles—IV. Composes epoxydes , 1976 .

[13]  R. C. Poller,et al.  Absence of free radical activity during reaction of organotin stabilizers with chlorohydrocarbons , 1972 .

[14]  R. Bacaloglu,et al.  Study of additive compatibility with poly(vinyl chloride) (PVC). 2: Dynamic mechanical analysis of PVC lubrication by stearic acid and its derivatives , 1998 .

[15]  B. B. Troitskiǐ,et al.  Mechanism of action of some stabilizers in the thermal degradation of poly(vinyl chloride) , 1971 .

[16]  B. W. Rockett,et al.  Mechanism of stabilization of poly(vinyl chloride). I. The cleavage of organotin compounds by aqueous hydrochloric acid , 1973 .

[17]  C. Mijangos,et al.  Configurational and conformational effects in the thermal degradation of poly(vinyl chloride) , 1991 .

[18]  T. Hjertberg,et al.  Catalytic effect of hydrochloric acid dehydrochlorination of PVC , 1988 .

[19]  R. Bacaloglu,et al.  Degradation and stabilization of poly(vinyl chloride). III. Correlation of activation enthalpies and entropies for dehydrochlorination of chloroalkanes, chloralkenes and poly(vinyl chloride) , 1994 .

[20]  G. R. Brown,et al.  Studies of the solid‐state thermal degradation of PVC. I. Autocatalysis by hydrogen chloride , 1992 .

[21]  K. Figge,et al.  Untersuchungen zum Mechanismus der PVC‐Stabilisierung mit Organozinn‐Verbindungen , 1975 .

[22]  R. C. Poller,et al.  The use of organotin compounds in the thermal stabilization of poly(vinyl chloride). Part III. Reactions of dialkyltin mercaptides, thioglycollates, and carboxylates with chlorohydrocarbons† , 1972 .

[23]  A. Guyot,et al.  Thermal dehydrochlorination and stabilization of poly(vinylchloride) in solution: Part IV—Synergistic effects of β-diketone compounds and metal soap stabilizers , 1989 .

[24]  T. Hjertberg,et al.  Thermal Degradation of PVC , 1984 .

[25]  B. W. Rockett,et al.  The mechanism of stabilization of poly(vinyl chloride). II. Cleavage of organotin sulfur compounds by anhydrous hydrogen chloride , 1974 .

[26]  B. B. Troitskiǐ,et al.  Investigation of stabilizing effectiveness of alkyl(aryl)tin maleates and thioglycolates in the thermal degradation of poly(vinyl chloride) , 1977 .

[27]  M. Edge,et al.  The mode of action of metal stearate stabilisers in poly(vinyl chloride). I. Influence of pre-heating on melt complexation☆ , 1994 .

[28]  W. H. Starnes,et al.  Six-Center Concerted Mechanism for Poly(vinyl chloride) Dehydrochlorination.Requiescat in Pace? , 1996 .

[29]  J. Summers,et al.  Panel 1: PVC Resins—past, present and future , 1980 .

[30]  A. Michel,et al.  Synergistic mechanisms of β-diketone derivatives and zinc-calcium soaps in PVC stabilisation , 1981 .