Synthesis of montmorillonite-modified acrylic impact modifiers and toughening of poly(vinyl chloride)

Abstract

A series of Na-montmorillonite (Na⁺-MMT) modified acrylic impact modifiers (mAIM) were prepared by seeded emulsion polymerization. These mAIM modifiers were characterized by XRD. A 0.24 nm of increased interlayer distance of Na⁺-MMT was an indication of polymer chains intercalation within interlayer spacing. The notched Izod impact tests proved that the impact strength of the PVC/AIM composites prepared by melt blending was 43 J/m, markedly higher than the impact strength of pure PVC. Furthermore, with increasing content of AIM, the composites exhibited changes from brittle fracture to ductile fracture, with the impact strength increasing from 200 to about 1,000 J/m. The impact strength of PVC/mAIM also showed the same trend, although there were drops in some values. The impact strength of PVC/mAIM composites decreased with the increases in Na⁺-MMT content, but the yield strength and modulus of the composites increased with higher Na⁺-MMT content. The result also showed that the tensile strength of mAIM with 2 wt % Na⁺-MMT is lower than that of mAIM with 0.8 and 1 wt % contents, but still sufficiently large in comparison to the tensile strength of mAIM with 0 wt % Na⁺-MMT. The dynamic mechanical analysis (DMA) result showed that the glass transition temperature (T _g) of mAIM did not show obvious changes and the elasticity of mAIM was reduced with the additional Na⁺-MMT content.