Microstructure Of Core-shell Particles Of Pa6 Fracture Toughness

The stiffness and toughness of polymers are very important for their practical applications. Toughening of plastics is still a focus of polymer material science. Nylon 6 (PA6) is a kind of important thermoplastic and the toughening of the material has important academic and applied values. PA6 belongs to notch-sensitive materials. It has high crack initiation energy and low crack propagation energy, so the notched impact strength is low especially. Core-shell modifiers can act as impact modifiers to overcome the notch sensitivity of PA6 and improve their notched impact strength.The particle sizes of core-shell modifiers have been set during their synthesis and kept constant when they are dispersed in matrix resin, which differs from other impact modifiers. The dispersed phase particle sizes of linear polymers and bulk rubbers lie with the processing condition to a great extent. Furthermore, the particle sizes of core-shell modifiers can be controlled during their preparation and the distribution of particle sizes is narrow, which is convenient to the toughening of plastics. The core-shell modifier used in this thesis is acrylonitrile-butadiene-styrene (ABS) copolymer with polybutadiene (PB) rubber as core and styrene-acrylonitrile (SAN) copolymer as shell. The main research works of this paper are exhibited as follows:1,Reactive ABS-g-MA core-shell particles with different core-shell ratios were synthesized by emulsion polymerization method and the effect of core-shell ratio on the toughening of PA6 was studied. The result demonstrated that when the core-shell ratio was 70/30, the notched impact strength of the polymer blend was improved apparently, and super-tough PA6 alloy was obtained.2,ABS copolymers with core-shell ratio of 50/50 were used to toughen PA6, and various compatibilizers were added to alter the structure and performance of the blends. The result confirmed that compatibilizer SAM302 improved the performance of the PA6 blends and enhanced the toughness remarkably compared to blends made from other compatibilizers.3,Brittle-ductile transition and fracture behavior of PA6/ABS blends with different interface properties were studied. The result proved that PA6/ABS-g-MA had higher interface strength compared with PA6/ABS-g-AA and better mechanical properties.4,ABS core-shell modifiers with different interior structures were prepared by emulsion polymerization technology, and then blended with PA6 and compatibilizer SAM302. Results showed that under the same ratio, thinner strip sample performed better mechanical properties than the thicker one; the notch impact strength of the thinner strip sample was clearly higher.5,Based on the compatibility between epoxy resin and PA6, influence of the epoxy resin content on the performance of PA6/ABS-g-MA blends was examined. It was proved that as the rubber content of ABS-g-MA was 25%, appropriate dosage of epoxy resin could notably increase the mechanical properties of the blends.