Mechanical properties and toughening mechanisms of the PS/LDPE/SBS blends with a cross-linked interface
Gordon Cheng, Jingshen Wu, Kai-Mo Ng, Chi-Ming Chan
Department of Chemical Engineering, HKUST
Hong Kong

Keywords: PS/PE blend, impact strength, crosslinked interface


The mechanical properties and morphology of the blends consisting polystyrene (PS), low-density polyethylene (LDPE) and styrene-butadiene-styrene (SBS) were studied. When PE was first mixed with dicumyl peroxide (DCP) and then blended with PS and finally with SBS, the mechanical properties of the blend increased dramatically. The impact strength of the blend was 192 J/m, which was about 13 times higher than that of the PS/PE blend. The reaction mechanisms were studied. Electron Spin Resonance (ESR) was employed to monitor the presence of PE radicals. From the ESR spectrum, the PE radicals were detected in both LDPE/DCP and LDPE/DCP/PS blends. The PE radicals were found terminated only after the LDPE/DCP/PS was mixed with SBS. It is proposed that the PE radicals reacted with the butadiene groups of the SBS, forming a crosslinked PE-SBS interface, which enhanced the impact strength of the PS/PE blends.