Emulsion Polymerization Interpenetrating Network-type Styrene-butadiene Thermoplastic Elastomer Films

This paper was aim at preparing thermoplastic elastomer (TPE) through two stage emulsion polymerization which based on natural rubber latex or styrene-butadiene rubber latex.A new kind of mosaic latex particles with gradient distribution of hard polymer had been synthesized and the effects of emulsifiers and the initiators on the polymerization were studied. St, MMA St+MMA, St+MMA+AN. St+AN, St+IBA+AN were used as hard monomer in order to prepare latex interpenetrating polymer network. When oleic acid was selected as emulsifier, t-butylhydroperocide/tetraethylene pentamine as oxi-reduction initiation system, the polymerization proceed 6hr in natural rubber latex smoothly with the 99% conversion of monomer. The result of morphology analysis of the latex showed that the latex particle was mosaic structure if two or three of hard monomer was used. If one monomer was used only, core-shell latex structure will be observed. The mechanical properties of the NR/P(St+IBA+AN) LIPN with crosslinker DVB for the hard monomer equaling 1.0 mol% reached the tensile strength 8.7MPa, elongation 300-600%. The corresponding TPE was processed several times. The results showed that mechanical properties were best of all NR.At the same time, complex latex and polymer based on SBR was prepared. Effects of extent of crosslinking of both plastomer and elstomer on mechanical properties were investigated. The SBR/P(St+MMA+AN) LIPN-TPE with crossliker DVB for the SBR equaling 0.5% and for the hard monomer equaling 1.0mol% reached the tensile strength 11 4MPa The mechanical properties of corresponding TPE after four times reprocessing reached the permanent set 32%.The morphology of the materials by TEM showed no changes after several times processing.