The Preparation And Properties Of Ageing-resistant Polystyrene/polycarbonate Microcellular Material

PS has excellent processing flow ability, rigidity and mechanical strength, but at thesame time, it has low impact strength, poor resistance to stress cracking. While PC has highimpact strength, good mechanical strength, excellent heat resistance. PS/PC is an alloy whichcan achieve excellent performance, improving the impact resistance and thermal stability ofPS while maintaining the rigidity and mechanical strength of PS. PS/PC microcellularmaterials can not only reduce the weight, but also further improve the ductility and toughnessof the alloy. PS and PC will inevitably experience an ageing in the process of preparation,processing, storage and use which will lead to material performance deterioration.The purpose of this paper is to improve toughness and impact resistance of the PS byblending modification and microcellular foaming, and to optimize its anti-ageing properties,thus achieving the application of PS as engineering plastics in the outdoor environment.The research content and the main results are as follows:(1) Prepared the PS/PC alloy with PS and PC as raw materials, SEBS-g-MAH ascompatibilizer, SEBS as toughener. Studied the structures and mechanical properties of PS/PCblends with different compositions and discussed the effect of SEBS-g-MAH and SEBS onthe structure and properties of blends. The results show that the blend composition has greatinfluence on the morphology of the blend; a two-phase co-continuous structure is formedwhen the blend is symmetric or close to symmetric; a single continuous structure which is inthe form of particles dispersed in a continuous phase is formed when the blend composition ishighly asymmetric. SEBS-g-MAH has a good compatibilization and toughening effect forPS/PC blends. SEBS has evident toughening effect for PS/PC blends. The blends get the bestoverall performance when PC content is10parts, PS content is90parts, SEBS-g-MAHcontent is9parts, SEBS content is13.5parts, and the notched impact strength of the PS/PCalloy is about2.6times that of pure PS.(2) Prepared the PS/PC microcellular material by injection molding foaming methodwith AC as a blowing agent. Studied the effects of content of blowing agent and nucleatingagent, molding temperature, dwell time, dwell pressure on the cell structure and mechanicalproperties of materials. The results show that nucleating agent is conducive to bubble nucleation, and smaller particle size of the nucleating agent, more difficult to nucleate. ThePS/PC microcellular material has the ideal cell morphology and optimum toughness whenmolding temperature is180℃,225℃,225℃,230℃, dwell time is30seconds, dwell pressureis30MPa with5parts of325mesh CaCO3as nucleating agent and0.5parts of AC HH3000as blowing agent. The tensile fracture energy of PS/PC microcellular material is almost asthree times as that of PS/PC alloy.(3) Studied the ageing characteristics of the materials with mechanical properties andoxidation induction and discussed the effect of antioxidants and light stabilizers onthermo-oxidative ageing properties and optical oxygen ageing properties of PS/PCmicrocellular material. Explored the best stabilizer formula and discussed the changes ofmaterial properties with ageing time increased. The studies show that the tensile strength andflexural strength of PS/PC microcellular material are improved, while the notched impactstrength decrease to some extent, the tensile elongation at break decrease significantly afterageing for4days. Various antioxidants and light stabilizers have a certain degree ofanti-ageing effect when used alone or used together. WhenIrganox1076/Irgafos168/Tinuvin234/Tinuvin770/Tinuvin P is used in the the ratio of2.5:2.5:2.5:1.5:1, the PS/PC microcellular material has the best anti-ageing effect and longestof the oxidation induction period; after ultraviolet ageing for4days, the material elongation atbreak is2.10times as pure material’s, and the notched impact strength is1.32times as purematerial’s; after thermo-oxidative ageing for4days, the material elongation at break is1.38times as pure material’s, and the notched impact strength is1.23times as pure material’s.With ageing time becomes longer, the notched impact strength and elongation at break godown overally, the tensile strength and flexural strength change little and have the overallupward trend.