Polyvinyl Chloride Modified With Core-Shell Polyacrylate-Grafted Vinyl Chloride Composites By Blending Method

Two kinds of crosslinked polyacrylate latices with relatively narrow distributions of particle diameters, which are abbreviated to P(BA-EHA), P(BA-EHA)/PDCPA, were synthesized by semi-continuous seeded emulsion copolymerization, respectively. Butyl acrylate or ethyl acrylate and 2-ethylhexyl acrylate were used as comonomers of polyacrylate core, and dicyclic pentenyl acrylate(DCPA) was used as shell comonomers of P(BA-EHA)/PDCPA, using 1,4-butanediol diacrylate(BDDA), allyl methycrylate(ALMA) and DCPA as crosslinking agents, respectively. In the presence of P(BA-EHA) or P(BA-EHA)/PDCPA latices, P(BA-EHA)/PVC or P(BA-EHA)/PDCPA/PVC as a modifying agent of PVC was prepared by grafting vinyl chloride copolymerization in an autoclave, respectively.Effects of different contents of three kinds of crosslinking agents and some factors of the synthesized composite particles on the mechanical properties of PVC blends were investigated in detail. And the influence of an adding of the stabilizer into the resultant modifier on the thermostability of PVC was investigated preliminarily. Particle diameter distributions and morphology structure of the composite and blending materials were characterized with the aid of dynamic laser scattering and transmission electron microscopy (TEM). The dynamic mechanical property, mechanical property, thermostability, rheological behavior, Vicat softening temperature and the broken profiles of the blending materials were determined and characterized with the aid of dynamic mechanical analysis (DMA), ZBC-4 type of impact test machine, TA-2000 type of thermal analyzer, HAAKE-R600 type of flow tester, XWB-300F type of Vicat softening temperature detector and Scanning electron microscope (SEM), respectively. The grafting situation of the composite particles was characterized through solvent extraction, elementary analysis and Vector-22 type of FTIR for it.The study results showed that P(BA-EHA)/PVC (BDDA, ALMA, DCPA crosslinked systems) composite particles have an obvious core-shell morphology. The particle diameterdistribution of the composite latex was similar to that of the P(BA-EHA) latex, and showed a relatively narrow single peak. The mean particle diameter of the composite latex increased, compared with that of the P(BA-EHA) latex. The grafting' ratio of VC grafted onto the P(BA-EHA) decreased while the grafting efficiency appeared a maximum value as the content of crosslinking agent in the P(BA-EHA) increasing. TEM showed that the morphology of the composite samples has a two-phase structure with micro-phase separation. Compared with the usual blending modification, the P(BA-EHA) rubbery particles with nano-sizes in this system was uniformly dispersed in the PVC matrix. DMA results revealed that the intensity of the mechanical loss peak tanS in the low temperature range markedly shifted to the higher temperature for the P(BA-EHA)/PVC composite modifier, and the glass transition peaks of the composite in the low-temperature region gradually shifted right following an increasing measuring frequency. The compatibility between the P(BA-EHA) rubber and the matrix polymer (PVC) was much well improved. SEM graphs showed that the fractured surfaces of the composite samples exhibited better toughness of the materials. The notched impact strength of the blending material with 6wt% of the P(BA-EHA)/PVC was increased whereas the tensile strength didn't almost decrease. The PVC blends modified by the modifier exhibited good processability.