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B. Wolska, W. M. Rzymski

Use of in situ generated Lewis acids in crosslinking of elastomers

Polimery 2004, No 7-8, 514


DOI: dx.doi.org/10.14314/polimery.2004.514

Summary

New unconventional method of crosslinking of styrene-butadiene rubber (SBR) and epoxidized natural rubber (ENR) was elaborated. To initiate the crosslinking process, Lewis acids generated in situ in reaction of acid precursors - chlorosulfonated polyethylene (CSM), differing in chlorine content (CSM), and ZnO were used. The following properties of SBR/CSM/ZnO blends were determined: vulcametric moment (M), equilibrium swelling (Qv) as well as the content of a fraction soluble in chosen solvents [2-butanone - MEK (QvMEK), toluene - TOL (QvTOL), or tetrahydrofurane - THF (QvTHF)], the content of chlorine bounded in the blends investigated, Mooney-Rivlin elasticity constants (2C1N) as well as tensile strength (TSb). The effects of the type and amount of CSM and ZnO as well as SBR/CSM ratio on SBR curing rate and degree were investigated. For comparison, ZnO in SBR/CSM blend was substituted with another oxides: MnO2, CuO, SnO or Fe2O3. Only in the cases of SnO or Fe2O3 acceptable while significantly worse results were obtained. Effect of ZnO content on ENR/CSM blend curing rate and degree has been also determined. Courses of SBR and ENR curing were analyzed using FTIR spectroscopy, dynamic thermomechanical analysis (DMTA) and SEM. SBR curing is a result of its phenyl rings' alkylation with polymeric halide (CSM) and autoalkylation with SBR chains containing 1,2- and 1,4-cis-butadiene monomer units, catalyzed with ZnCl2 formed in situ from ZnO and CSM. IR spectra analysis leads to the conclusion that ENR curing is a result of oxirane groups' polymerization also catalyzed with in situ formed ZnCl2.


Keywords: styrene-butadiene rubber, epoxidized natural rubber, chlorosulfonated polyethylene, zinc oxide, unconventional curing, Lewis acids generated in situ, zinc chloride


B. Wolska, W. M. Rzymski

Use of in situ generated Lewis acids in crosslinking of elastomers