Thermomechanical study on toughened PVC with an impact modifier based on the acrylonitrile-styrene-acrylate core-shell particles

Development of impact modifiers with the core-shell structure for enhancing toughness of rigid polymers have attracted a great deal of interest. In this study, poly(butyl acrylate) (PBA) as the core was prepared via emulsion polymerization and subsequently grafted with styrene and acrylonitrile (SAN) to construct the shell layer through seeded emulsion polymerization and to produce ASA particles. Then, ASA particles containing 40, 50, and 60 wt% of PBA core and those with non-crosslinked shell were compounded with PVC through melt-blending technique in different compositions. DLS, SEM and TEM analyses revealed uniform spherical core-shell morphologies with average particle size of 170–190 nm. Cross-sectional SEM images exhibited a well-distribution and dispersion of ASA particles in PVC matrix relative to the non-crosslinked one. This can be attributed to the formation and grafting of the rigid thermoplastic SAN layer on the PBA core. Impact results of the prepared compounds showed an increasing trend with the increase in core content and also amount of ASA. The highest impact strength (135 kJ/m2) was found for the compound containing 15 wt% of ASA (with 60 wt% of PBA core) particles, which was 26 times higher than the neat PVC (5 kJ/m2). A comparative study between PVC compounds demonstrated higher heat deformation temperature, elastic modulus, and impact strength for those containing ASA with the crosslinked shell. Remarkable compatibility with PVC matrix and enhancement in thermomechanical properties for the prepared core-shell ASA particles revealed their promising potential for toughening of PVC.