Structural Design And Toughening Mechanism Of AIM Toughened SAN Resin Blends

Toughening polymers with core-shell structured modifiers is a commonly used method for polymer modification.Acrylic impact modifier?AIM?is one of the important core-shell modifiers.As one of AIMs,ASA?PBA-g-SAN?modifiers were widely used.In this paper,a series of ASA modifiers were synthesized by emulsion graft polymerization on the basis poly?butyl acrylate??PBA?seed emulsion.The ASA/SAN blends were prepared by melt blending ASA modifiers with SAN resin.Through the testing of mechanical properties,characterization of dynamic thermo-mechanical properties?DMA?and the observation of scanning electron microscopy?SEM?,the properties of blends and the evolution of toughness mechanism were studied.The main conclusions are as follows:In order to investigate the effect of rubber content on the mechanical properties of blends,only the content of ASA modifier in ASA/SAN blends was changed.The results show that impact strength of blends increase with increasing of PBA rubber content.When PBA rubber content is 30wt%,the impact strength of blends reaches a maximum.When rubber content is over 15wt%,the tensile strength of blends was significantly reduced.The DMA of blends shows that the storage modulus of blends tends to decrease as the rubber phase content increases.When rubber content is over 25wt%,the storage modulus decreased slowly.At the same time,increasing rubber content facilitates compatibility between two phases and the impact fracture section shows a greater deformation of the matrix resin.The impact strength of ASA/SAN blends increased at first and then decreased with the cross-linking degree of rubber phase in ASA increases.The storage modulus of blends and the glass transition temperature?T_g?of the rubber phase increases with the cross-linking degree raise.When TAIC cross-linking agent content of ASA is 1.0wt%,Izod impact strength and SNEB resistance to crack growth of ASA/SAN blends reach maximum.The SEM results also showed that the rubber particles cavitation of ASA is beneficial to improve matrix deformation.The effects of different composition SAN resins on the properties and toughness mechanism of blends were studied.It found that molecular chain entanglement density of SAN matrix resin increases with the AN content raise in SAN resin.When the SAN composition of ASA modifiers grafted shell is the same as the SAN matrix,impact strength increases with the increase of SAN resin molecular chain entanglement density,tensile strength,K_max and elongation at break increase slightly.The DMA and SEM tests show that the ASA modifiers have good compatibility with SAN matrix resin.The impact fracture of SAN resin with high molecular chain entanglement density show more obvious deformation through the rubber particles cavitation of ASA.