.pvc / Asa / Dop Blends Structure And Properties

Poly(vinyl chloride)(PVC) belongs to a major class of engineering plastics that possess many unique properties that are suitable for a wide variety of technical and industrial products. It is available at a relatively low cost, is nonflammable, and has good chemical resistance and corrosion resistance. However, the notch sensitivity and low impact resistance are deficient for PVC expanded applications. PVC has been blended with rubbery polymers to improve its impact strength, thus making it suitable for rigid application. Hence,modifing PVC resin has received substantial attention.ASA(Acrylate-styrene-acylonitrile) resin is a rubber-toughened thermoplastic, including the dispersed rubbery phase of polybutylacrylate (PBA) and the continuous rigid phase of acrylonitrile-styrene copolymer (SAN). As a kind of elastomer, polybutylacrylate should be grafted with SAN copolymer in order to improve the adhesion between ASA copolymer and PVC resin for excellent properties.The preparation of PVC/ASA blends included the following process, the production of PBA latex by emulsion polymerization, the emulsion grafting copolymerization of acrylonitrile and styrene onto PBA latex,the coagulation and drying of the grafted latex.By melt blending these copolymers with PVC resin and di-isooctyl phthalate (DOP), PVC/ASA and PVC/ASA/DOP blends were prepared. In this thesis,we studied the mechanical properties and morphology of the blends.The conclutions are as follows:(1) ASA graft copolymers with different AN content were obtained to melt-blend with PVC resin for PVC/ASA blends.We study the influence of AN content on structure and property of PVC/ASA blends. It was found that the impact strength of all PVC/ASA blends increased and then decreased with an increase in the AN content. When the AN content was 37%, the impact strength of the PVC/ASA blends had their maximum values.The yield strength and elongation at break increased with the AN content. The morphological observations showed that in all cases PVC and ASA were immiscible with different AN content, and which agree well with the results of mechanical properties and dynamic mechanical analysis.(2) The effect of AN content on dynamic mechanical property of PVC/ASA/DOP blends was investigated by DMA. It is found when AN content is lower than 25%,the PVC/ASA/DOP blends have single glass transition peak. When AN content is 25%,the blends become partial miscible. When AN content exceed 25% the blends have two Tg peaks.(3) We had a test on the heat deflection of PVC/ASA/DOP soft materials.The results indicate, in the range from 70℃to 100℃, with AN content increases the storage modulus increases and the heat deflection property of soft materials improves.(4) With the increase of rubber content in PVC/ASA blends,the blends have became the brittle-ductile transition when rubber content is 9%.But the PVC/ASA blends with TDDM have not changed obviously.Scanning electron microscope have been used to study morphology of the PVC/ASA blends of surface.It was found that ASA graft copolymer particles without TDDM are disspersed in PVC matrix relative uniformly.Thus,TDDM has affected the mechanical property of PVC/ASA blends.