| Poly(butylenes terephthalate)/polycarbonate ( PBT/PC ) has been widely used, but because of the brittle problem of its low-impact strength at low temperatures and thus limits its applications. Therefor, we have developed a low-temperature impact modifier MBS resin for PBT/PC alloy, which is synthesized by butadiene, styrene and methylmetharylate through emulsion polymerization. It has the typical core-shell structure in its submicroscopic structure morphology.Polybutadiene latex (PBL) had been first prepared by two-step seeded emulsion polymerization, and the effect factors, such as the dosage of seed-latex, emulsifier, crosslinking agent and monomer feeding method in the polymerization process were investigated. And tnen, the MBS shell was formed by a two-step graft polymerization on PBL, during which methylmetharylate and butyl acrylate were first grafted, and then styrene was grafted. The effect factors of graft polymerization, such as the proportion of rubber, initiator, crosslinking agent, the third monomer, the order and method of monomer feeding had been investigated. The MBS latex with more rubber in its core and a uniform graft shell had been prepared. In the following process, MBS latex was agglomerated at 40℃and dried at 40-50℃, so that the MBS resin powder were formed.For the PBT/PC alloy modified by this MBS, the Izod impact strength is not less than 240J/m at -40℃and not less than 700J/m at 23℃. Analysis method of particle morphology and size distribution for PBL, MBS latex, MBS powder and MBS/PBT/PC alloy had been established in the process.
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