Study On Improving The Thermal Properties Of PMMA

PMMA has such excellent properties as high light transmittance, colorlessness, chemical resistance, and dimensional stability. However, PMMA has a poor heat resistance. Considerable attempts had been made to modify the macromolecular structure to improve the heat resistance of PMMA. N-cyclohexylmaleimide (ChMI) has been known as the best monomer to copolymerize with MMA to enhance the thermostabilities of PMMA.In this article, polymers of ChMl/MMA were first synthesized and their thermal properties, mechanical properties, and Theological behavior were investigated. It was found that ChMI effectively increased the glass transition temperature and the decomposition temperature. The moderate decrease in the mechanical properties can be encountered by the decrease in the apparent shear viscosity and the improvement in the thermal properties.Second, the St was introduced to the system of ChMI/MMA and the properties of ChMl/MMA/St were investigated. The St made the ChMI reacted easily with MMA because the polar effect. The effect of the polymerization method on the macromolecular structure and hence on the properties of the resulting resin were also investigated. It was found that the polymer obtained by suspension polymerization method exhibited a heterogeneous structure proved by TBA, TGA measurement. While, the resin synthesized by semi-bath emulsion polymerization method show a homogeneous structure.Third, polymers of ChMl/MMA/AN with a homogenous structure were synthesized by suspension polymerization method. The result showed that the addition of AN improved the mechanical properties of the resin such as tensile strength and the impact strength.The polymers containing ChMI unit were also blended with PVC to improve its heat resistance. The SEM micrographies showed that the St decreased the compatibility between the PVC and the corresponding polymer.