Studies On The Thermo-mechanical Degradation And Color Retention Of Acrylonitrile-Chlorinated Polyethylene-Styrene Terpolymer

ACS is one kind of modified ABS. With replacing the unsaturated polybutadiene (PB) in ABS by the saturated and chlorine contained (CPE) elastomer, ACS resin owns some excellent properties, such as superior weathering resistance, high flame retardant and good anti-electrostatic effect. However, similar to other polymers containing chlorine, ACS is liable to dehydrochlorinate during the high-temperature mixing and subsequent forming process, leading to the undesired color change and processing machine/mold corrosion. This paper investigated the degradation behavior and ways to stabilize the color change of ACS during high-temperature processing which should help for the application of ACS.FTIR, GPC, DSC, TEM and the extraction experiment results showed that the major effect on ACS due to thermal degradation and mechanical shearing were the chain scission of the SAN copolymer and the dehydrochlorination and oxidization of the CPE component. The Uv/vis test confirmed the relationship between the discoloration of ACS and the formation of conjugated structure. It was found that the thermo-mechanical degradation induces the in-situ grafting of SAN to CPE resulting in the formation a fine salami-like structure in which many CPE-g-SAN micelles are embedded in the fine CPE domain. This change provides a significant improvement in the impact strength of the ACS resin.The shearing time, temperature and specific input mechanical energy greatly influence on degradation procedure of ACS. It was confirmed that the shearing temperature plays a key role. Kinetic analysis on the ACS degradation implied that the formation of conjugated structure on the CPE chain is very fast at the beginning of degradation and the grafting of SAN to the CPE chain follows closely. The activation energy is116.5and105.4kJ/mol, respectively.To stabilize the color change of ACS during the high temperature injection molding, an optimized formula was testified by selecting CPE species, adding acid absorbent, antioxidant and thermal stabilizer. These effective approaches well stabilize ACS and the final product met the color requirements during high-temperature processing.