Effect of the Shell Thickness of Methacrylate-Butadiene-Styrene Core–Shell Impact Modifier on Toughening Polyvinyl Chloride

Abstract

The shell thickness of methyl methacrylate-butadiene-styrene (MBS) graft copolymer with a core–shell structure is found to be the most important factor in the toughening of rigid polyvinyl chloride (PVC). When the total shell thickness is too thin, the shell layer is simply unable to fully protect and cover the inner rubbery core, and these MBS particles tend to connect with one another through the partially exposed core, which leads to the aggregation of MBS in PVC and results in the poor toughening efficiency of MBS. However, when the total shell thickness is too thick, the shell thickness results in a hard core of these core–shell MBS particles and the loss of the rubbery nature required of an efficient impact modifier. Both the PMMA thickness and PS thickness in the shell structure have also significantly influenced the toughening efficiency of MBS; the thickness of PMMA and PS should be between the critical values of 4.2 nm ∼ 6.7 nm for PMMA and 7.4 nm∼9.8 nm for PS, and MBS displays high efficiency in toughening rigid PVC. γc/Vf2 and γy/Vf2, which are relative to the critical characteristic ligament of polymer materials, are used as the criterions of the brittle–ductile transition, and the brittle–ductile transitions of PVC and MBS with various shell structures was investigated in this paper.