Effect of poly (butyl acrylate) rubber particle size on the mechanical and rheological properties of ASA resin and its underlying mechanism
摘要
The effect of poly(butyl acrylate) (PBA) rubber particle size on the mechanical and rheological properties of acrylate-styrene-acrylonitrile (ASA) resin was systematically investigated. A series of PBA latices with particle sizes ranging from 200 to 480 nm were synthesized via semi-continuous seeded emulsion polymerization, and then grafted with styrene-acrylonitrile copolymer (SAN) to form core-shell particles (PBA-g-SAN). The notched impact strength exhibited a strong particle size dependence, first increasing then decreasing, and reached an optimum of 11.6 kJ/m2 at 395 nm—a 141.7% improvement over the 200 nm sample. This enhancement could be attributed to the optimal particle size (395 nm) effectively inducing large-scale crazing and shear yielding in the SAN matrix, as confirmed by scanning electron microscopy. Dynamic mechanical analysis verified that all samples maintained a distinct two-phase morphology, with glass transition temperatures exhibiting only marginal variations, indicating that the performance improvement arises predominantly from geometric effects rather than matrix plasticization. Rheological measurements further revealed that the 395 nm particles achieve an optimal interfacial entanglement density, ensuring efficient stress transfer and melt homogeneity while avoiding the excessively constrained network formed by smaller particles. This study establishes a clear relationship between PBA particle size control and ASA resin performance improvement, providing a mechanistic basis for designing high-performance weather-resistant ASA resins.