Study On The Preparation Of Vinyl Monomer-N-Cyclohexylmaleimide Copolymers And Their Application In Poly(Vinyl Chloride)

The copolymers of vinyl monomer-N-substituted maleimide have been paid much attention in the technological application as well as scientific issues due to their superior heat-resistance property. In this thesis, to improve the heat-resistance property of PVC, vinyl monomer-N-cyclohexylmaleimide copolymers were prepared and then blended with PVC.In our work, firstly, N-cyclohexylmaleimide (CHMI) was synthesized by one-step heat dehydrolyzing with maleic anhydride and cyclohexylamine as major raw materials. The effects of the reaction conditions on the yield of N-cyclohexylmaleimide were studied. CHMI was characterized by FTIR,1HNMR,HPLC,EA and DSC. The results showed that the purity of CHMI and the yield of CHMI reached to 98.7% and 68.5% respcetively.Copolymer of methyl methacrylate (MMA)-CHMI was synthesized by suspension copolymerization and characterized. The effects of the monomer feed on the properties of copolymers were investigated. The results showed that the glass transition temperature of copolymers increased obviously with the addition of CHMI.Third monomers such as styrene (St) and acryonitrile (AN) were added to the system of CHMI-MMA. Copolymers of MMA-CHMI-St and MMA-CHMI-AN were synthesized by suspension copolymerization and characterized by FTIR,EA and DSC. The results indicated that the activity of CHMI was improved by the introduction of third monomers and the glass transition temperature of copolymer was increased obviously with the content of CHMI, but decreased with the adding of the content of St and AN. The solubility parameter of copolymer changed with different monomer ratio. For MMA-CHMI-St system, when the weight ratio of MMA/CHMI/St equals to 70/25/5, the copolymer exhibits excellent heat-resistance property (Tg: 135.7℃) and compatibility (δ: 22.01(Jcm-3)1/2) with PVC. And for MMA-CHMI-AN system, when the weight ratio of MMA/CHMI/AN equals to 70/25/5, the copolymer exhibits excellent heat-resistance property (Tg: 130.6℃) and compatibility (δ: 21.98(Jcm-3)1/2) with PVC.The MMA-CHMI-St and MMA-CHMI-AN copolymers were blended with PVC respectively to improve the heat resistance of PVC. The results showed that the glass transition temperature and vicat softening point of blends increased with the content of the copolymers. When the content of the copolymers was 40wt%, Tg of blends was inhanced by 6.3℃and 4.6℃, the vicat softening point was inhanced by 14.4℃and 21.1℃respectively.