Mechanochamical Preparation Of "Core-Shell" Microstructure Particles And Their Effects On The Properties Of Poly (Vinyl Chloride) Composites

In this paper, a new route to preparation of core-shell particles was introduced, and core-shell particles with inorganic rigid particle (nano-CaCO3, nano-SiO2) as core and elastomer as shell were prepared by mechanochamical method. Different interface between core and shell was also obtained through mechanochemical modifying surface of inorganic nano-particles. The effects of interfacial interaction between rigid particles and elastomer, including category and content of modifier, and the effects of technological parameter of preparing core-shell microstructure particles, including vibro-milling time and ratio of elastomer to rigid particles, on morphological structure of core-shell particles and mechanical properties of PVC/core-shell particles composites were studied. In addition, the influences of interface between rigid particles and matrix on dynamic mechanical property, rheological behavior and stability of PVC composites were studied too. And the parameter charactering interfacial interaction was calculated.The results of XPS, TGA, FT-IR indicate that the surface of modified inorganic rigid particles contain acrylate or it's polymer. Hydrophilic test, wetting test and contact angle test approve that the surface property of rigid particles has been changed from hydrophilic to hydrophobic. XPS, TEM and dissolving experimental results indicate the formation of [(inorganic particle)/(elastomer)] core-shell structured particles.Generally, the addition of hard-core/soft-shell microstructure particles isadvantageous to enhance mechanical properties of PVC composite. But the addition of core-shell microstructure particles in which the surface of core (inorganic particles) wasn't modified, can only improve the tensile strength while decrease the impact strength. When the surface of core (inorganic particles) was modified by acrylate, the addition of these core-shell particles can enhance both the tensile and impact strength at the same time.The mechanical properties of composites filled with core-shell microstructure particles are higher than those of composites directly blended with inorganic particles and elastomer. To enhance the mechanical properties, MMA as surface modifier is better than BA, and content of modifier exhibited an optimum value. The impact strength and tensile strength of PVC/CaCO3-g-MMA-ACR, PVC/CaCO3-g-BA-ACR composites increased with prolongation of vibro-milling time. In our studies, for mechanical properties of PVC/core-shell particles composites, optimum ratios of elastomer(ACR) to CaCO3 and ACR to SiO2 are 20/80 and 50/50, respectively.The interface between rigid particles and matrix greatly affects the mechanical properties, rheological behavior, etc. of PVC composites. When shear rate is low, the addition of filler will enhance the apparent viscosity of melt, but the apparent viscosity of PVC/core-shell particles composites is lower than that of PVC composites obtained by blending directly with rigid particles and elastomer. When the shear rate is enough high, the filler will almost not affect the apparent viscosity. In addition, filler will enhance the dynamic viscosity of composites. But the dynamic viscosity will be decreased when the interfacial interaction is strong enough to make polymer molecular chains disentangle.The parameters charactering interfacial interaction indicate that core-shell microstructure particles will reinforce the interface interaction between rigid particles and matrix.