Preparation, Structure And Property Of Methyl Methacrylate-N-Cyclohexyl Maleimide-Styrene Copolymer And It's Montmorillonite Nanocomposites

Poly (methyl methacrylate) (PMMA) is a kind of transparent materials. It has a variety of interesting and desirable properties compared to inorganic materials. But the poor thermal properties of PMMA have been point out to be a main disadvantage of these materials. In order to extent it's application fields, more and more attentions have been focused on the research of improving heat resistence for PMMA.In our work, two ways were adopted to improve the thermal properties of PMMA: incorporating rigid N-cyclohexyl maleimide into the chain of PMMA by copolymerization and compounding the organic-inorganic components by means of nanocompouding technique.Firstly, N-cyclohexyl maleimide was synthesized in high yield and purity (mp: 90.2C, literature: 90.2C) by dehydration of maleimic acid at hight temperature. Binary copolymers of MMA / CHMI at different feed content were synthesized by bulk copolymerization. The results show that as the content ratio of CHMI increased, the glass transition temperature and thermal decomposition temperature of copolymers are all higher than PMMA, and the yellow index of the copolymer is also increased. The resident CHMI in the copolymer leads to the yellow index of the materials. The introduce of St as the third monomer into the copolymerization improves the activity of the CHMI, so the yellow index of the copolymer decreased. Transparent materials with well integration properties will be obtained by controlling the ratios of monomers properly.Secondly, a new two-step intercalation with aqueous soluble cationic free-radical initiator 2,2'-azobi(2-methyl-propionamide) hydrochloride (AIBA) and hexadecyltrimethyammonium bromide (CTAB) or hexadecyltri-n-butylphosphonium bromide (HTPB) was used to modify montmorillonite (MMT), and two kinds of active organic montmorillonite ANMMT (AIBA-CTAB-MMT) and APMMT (AIBA-HTPB-MMT) were obtained. The absorptionamounts of AIBA in the above montmorillonite maining depended on the content ratio of AIBA, and the interlayer distance of the active organic montmorillonite was influenced by the ratio of intercalation agents and the cationic character.PMMA / ANMMT and PMMA / APMMT nanocomposites were prepared by bulk intercalation polymerization. XRD and TEM studies showed that montmorillonite is as nanostructure in PMMA matrix. The glass transition temperature of PMMA / ANMMT nanocomposites was increased with the addition of ANMMT while no glass transition could be observed for PMMA / APMMT nanocomposites, but their heat decomposition temperature were all increased with the introduce of active organic montmorillonite. PMMA / APMMT nanocomposites exhibited better light transmittance than PMMA / ANMMT nanocomposites.We introduced CHMI into the bulk intercalation copolymerization and prepared MMA-CHMI / ANMMT and MMA-CHMI / APMMT nanocomposites. It was found that the dispersibility of montmorillonite in polymer matrix and the interaction of between the montmorillonite layers with copolymer was greatly improved with the incorporation of polar unit CHMI. Thermal properties and light transmittance of copolymer nanocomposites were superior to those of the homopolymer nanocomposites .Methyl methacrylate (MMA)-jV-cyclohexylmaleimide (CHMI)-styrene (St) copolymer / Na-montmorillonite (MMT) composites were prepared by soap-free emulsion copolymerization using 2,2'-azobi (2-methyl-propionamide) dehydrochloride (AIBA) as initiator. The influences of the amount of montmorillonite, initiator and the temperature of reaction on the copolymerization rate, molecular weight of copolymer and the glass transition temperature (Tg) of the composite were investigated. The results indicated that MMT can accelerate the copolymerization rate, increase the molecular weight of the copolymer, and enhance the thermal properties of composites. MMA-CHMI-St / MMT composites, using as heat resistance modifier, can improve the thermal property of PVC.