Study Of Acrylate Copolymer (ACR) Process Aid

For the excellent mechanical properties and the advantage of low price, polyvinyl chloride (PVC) has been widely used in construction and packaging industry. PVC can be among the world's top five general-purpose plastic, and have been attracted much attention due to its potential applications in many areas. As a polar polymer, PVC has disadvantages of high melt viscosity and poor thermal stability, so it can be hardly plastified at high temperature. In order to inprove the processing performance of high-strength PVC materials, plastics processing aids needed to add; high performance PVC materials, especially the processing of alloys of high toughness PVC, flexibilizer should be added to improve its impact strength. In recent years,the production process of acrylic processing aids in China has fell behind the international level and the production costs is higher. In this thesis, we described a simple process to prepare polyacrylate (ACR) with methyl methacrylate (MMA) and butyl acrylate (BA) as the monomers which suitable for the high-performance requirements of rigid PVC materials. As a lot of researches of synthesis and application about Styrene (St) and acrylonitrile (AN) have been studied and their production costs is lower than acrylic monomers, Styrene (St) and acrylonitrile (AN) can be used instead of parts of acrylates during the synthesis process in order to obtain low-cost and high-performance acrylic (ACR) processing aids.Increasing the molecular weight of ACR will improve the effect of melting for the mechanism of ACR processing aids in PVC plastics processing. In this paper, high molecular weight modifier ACR was synthesized through emulsion polymerization process with butyl acrylate (BA) and methyl methacrylate (MMA) as monomers and potassium persulfate (KPS) as initiator. The inherent viscostity of ACR as the main indicators, the solid content of emulsions, gels rate, conversion percentage of monomer and the relationship of the polymer molecular weight in the emulsion polymerization system as the other factors, we got the optimum conditions of emulsion polymerization: (1)The molecular weight of ACR resin can be increased through the appropriate way of increasing the amount of emulsifier. It should be noted that the excessive amount of emulsifier will do adversely affect on the molecular weight of ACR resin; (2) The molecular weight of ACR gradually increased with decreasing the amount of initiator in appropriate range; (3) The molecular weight of ACR gradually increased with decreasing the trigger temperature in this system; (4) The molecular weight of ACR can be increase with the reaction time after the improvement of polymerization; (5) The molecular weight of ACR gradually increased with increasing the amount of soft monomer butyl acrylate (BA). It should be noted that the product obtain will be hard to powdered as excessive BA added.We used acrylate monomers instead of parts of styrene (St) to make St-ACR processing modifier, then used acrylate monomers instead of styrene (St) and acrylonitrile (AN) to make AS processing modifier. As the type and the amount of the emulsifier and initiator, polymerization temperature, reaction time and ratio of hard/soft monomers all have impacts on the intrinsic viscosity of processing aids, we determined the optimum conditions and a easy-to-powder drying method. The structure of polymer ACR was characterized by Infrared spectroscopy (IR). In order to investigate of advantages and disadvantages of the synthetic conditions, we used laser particle apparatus to test the distribution of particles size of the emulsion.The composite materials were prepared by the mix of three different acrylic monomers and PVC processing aids. The plasticizing properties of modified PVC processing modifier, impact resistance, tensile properties and heat resistance were also tested. The adding amount of processing modifier has an impact on the properties of PVC. The dispersion of the section of the composite materials were characterized by scanning electron microscopy (SEM). The compatibility with PVC and ACR can also be observed by SEM. We can further explained the mechanism that the processing aids could improve the PVC properties. The plasticizing properties of PVC can be significantly improved by these three kinds of ACR processing modifier. The more shares of ACR, the better plasticizing properties of PVC. It is worth mentioning that there is a certain gap between ACR processing modifier and professional impact modifier in improving the mechanical properties of PVC.