作者：RuJun Dai, GuangHui Gao and HuiXuan Zhang
关键字：modified polystyrene; deformation mechanism; mechanical properties; polymer blends; core-shell rubber particles
论文来源：期刊
具体来源：Polymer International
发表时间：2010年

It is well known that the dominant toughening mechanism of rubber-modified polystyrene is multiple crazing. Some researchers

have investigated polystyrene that can be modified by rubbers with dual particle sizes, leading to better mechanical properties.

That is, the way to absorb energy during the deformation process is crazing and cavitation induced by rubber particles. Two

types of polybutadiene-graft-polystyrene (PB-g-PS) rubber modifiers which have core-shell structures were synthesized via an

emulsion graft polymerization using redox and oil-soluble initiators, respectively. To balance the yield strength, general-purpose

polystyrene was blended with the PB-g-PS modifiers, as well as commercial high-impact polystyrene. Blends were defined

as R-bimodal and O-bimodal corresponding to dispersed PB-g-PS particles formed using the redox and oil-soluble initiators,

respectively. The impact strength of R-bimodal was improved significantly by altering the ratio of core to shell. However,

little change of impact strength was observed for O-bimodal. Transmission electron microscopy images of fracture surfaces

indicated that the deformation mechanism of R-bimodal is shear-yielding induced by multi-crazing. Moreover, PB-g-PS particles

dispersed in O-bimodal can form a ‘cluster’ structure, leading to crazing to absorb energy. Scanning electron microscopy images

also showed obvious distinctness between the R-bimodal and O-bimodal systems due to different deformation mechanisms.