Influence of iron(III) chloride on the degradation of the polyisoprene and polybutadiene

• Published in: Polymer degradation and stability Vol. 67; no. 2; pp. 239 - 247
• Main Authors: Dragunski, D.C., Freitas, A.R., Rubira, A.F., Muniz, E.C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2000; Elsevier Science
• Subjects: Applied sciences; Chemical reactions and properties; Degradation; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Chemical solution; Molecular structure; Crosslink density; Thermooxidative degradation; Competitive reaction; Crosslinking; Experimental study; Thermal stability; Iron chloride; Cis stereoisomer; Butadiene polymer; Solid state reaction; Reaction mechanism; Doped polymer; Property structure relationship; Isoprene polymer; Thermal degradation
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/S0141-3910(99)00119-6

The influence of iron(III) chloride, FeCl 3, on the degradation of polyisoprene and polybutadiene was investigated. From a 2 3 factorial design the effects of polymer concentration, FeCl 3 concentration and temperature on the polymer degradation were evaluated. In solution, efflux time measurements, unsaturation degree and viscometric molar mass determinations were combined with 1H NMR and infra-red spectroscopies. In the solid state, films of polymers doped with FeCl 3 were exposed for several temperatures for different periods in air. It was verified that in solution the FeCl 3 induces more degradation of polyisoprene than of polybutadiene. In the solid state, where the mobility of polymer chains is lowered, the FeCl 3 induces more cross-linking of polybutadiene than of polyisoprene, if the polymers are exposed, for the same period, at temperatures equal or superior to 80°C. The results lead us to conclude that the degradation occurs by scission of the double bonds of the polymers, which is judged to be initiated by cationic species. It is suggested that the intermediate species formed in the polybutadiene chains are less stable than in the polyisoprene ones. The difference in stability would be due to the methyl group on the polyisoprene chains.