Shulin Sun

Toughness and Transparency of Poly(vinyl chloride)/Methyl Methacrylate-Butadiene-Styrene Blends with Varied Shell Phase Composition of Core-Shell Theories

Methyl methacrylate-butadiene-styrene (MBS) were prepared by emulsion polymerization method through grafting of styrene (St) and methyl methacrylate (MMA) with varied ratio on polybutadiene (PB) particles. The effect of St/MMA weight ratio of the shell in MBS on the property of PVC/MBS blends was investigated. It was found that when St/MMA weight ratio was 0/40 and 10/30, brittle-ductile transition occurred firstly for PVC/MBS blends. Transparency of PVC/MBS blends enhanced with the increase of St content in the shell of MBS. TEM results showed that MBS composition in the shell affected disperse morphology of MBS particles in PVC matrix and the deformation behavior of PVC/MBS blends. With the increase of MMA content of the shell in MBS, the deformation mechanism of PVC/MBS blends take place transition from debonding in the interface between MBS particle and PVC matrix to the cavitation of MBS followed by shear deformation of PVC matrix.

Morphology and mechanical properties of PA6/organoclay nanocomposites toughened by bulk rubber and core-shell rubber

Reactive bulk rubber (EOR-g-MA) and reactive core-shell rubber (ABS-g-MA) are selected as toughening agents to toughen PA6 nanocomposites. The two blends are designed with 20u200awt-% rubber phase and 3u200awt-% organoclay. X-ray diffraction, transmission electron microscopy and scanning electron microscopy were used to evaluate the degree of exfoliation of organoclays and morphology of the nanocomposites. The organoclay platelets are well exfoliated in the nanocomposites. At the same time, the size of the elastomer particles and interfacial adhesion between polyamide 6 and elastomers are dramatically affected by the existence of organoclay. ABS-g-MA is found to promote the toughness efficiency of PA6 than does EOR-g-MA, which reveals higher impact strength and elongation at break. However, tensile strength and Youngs modulus of PA6 blends based on EOR-g-MA elastomer are higher than those based on ABS-g-MA elastomer.

A novel approach to prepare large-scale and narrow-dispersed latex particles by emulsion polymerization based on particle coagulation mechanism

Abstract In order to understand the mechanism of narrow particle size distribution of the final latex during particle coagulation, a series of experiments were performed to investigate the effect of polymer nature on particle coagulation capability. In particular, thermodynamics and kinetics in aqueous phase were considered to illustrate the detail process of particle coagulation. The final particle size decreased with the increasing side chain length of alkyl methacrylate from 181.5 nm in MMA to 131.6 nm in EMA, 119.3 nm in PMA, and 115.1 nm in BMA, indicating that the particle coagulation capability was proportional to the hydrophilicity of polymer. With increasing polymer hydrophilicity, the affinity between surfactant molecules and particle surface decreased, thus enhancing the particle coagulation capability. Moreover, the critical length of oligomer radical also increased with increasing hydrophilicity and the efficiency of radical capture decreased, thus increasing the saturation of monomer concentration in the inner part of particle, promoting particle coagulation. Combining these results and the La Mer Diagram, a novel approach was developed to prepare large-scale, narrow-dispersed, and high solid content polymer latex based on particle coagulation mechanism. Three criteria, namely, rapid nucleation, fast coagulation, and a long growth period, should be met to produce latex with a narrow particle size distribution.