Study On Unsaturated Carboxylic Acid Metal Salts' Homopolymerization And In-Situ Preparation Of Methylacrylic Acid Samarium/NBR Composites

This thesis was mainly divided into two parts:the first part was about the homopolymerization ability study of unsaturated carboxylic acid metal salts, which are reactive fillers. In the second part, methylacrylic acid samarium/NBR composites were prepared by in-situ reaction way, and did some researches about their reactive processes and properties.The main results of the first part were as follows:(1) As first, we studied the structural features of four commonly used methylacrylic acid salts, including sodium methacrylate, magnesium methacrylate, zinc methacrylate and samarium methacrylate. The focus was on obtaining the thermal stability information of these four methylacrylates via thermal analysis methods combined with infrared spectrum analysis.It was showed that all of four salts had crystal features, the double bonds started to crack generating radicals above 290℃, and polymerization exothermic reaction occurred in the meanwhile.(2) Methyl acrylate/2,5-di-tert-butyl 2,5- methyl-hexane (abbreviation: D2,5) mixture were prepared by direct mixed methods, and Methyl acrylate/ dicumyl peroxide (Abbreviation:DCP) mixture were made by spray drying. Through the thermal stability investigation of these two kinds of mixed systems and infrared spectra of mixed samples after thermal scanning, we found that with peroxides adding, the polymerization effect of methylacrylic acid salts was brought forward to the vicinity of 175℃, namely the temperature area of D2,5 and DCP generating free radicals fastest.(3) In addition, we investigated the thermal stability of acrylic acid salt (taking acrylic acid samarium as representative) and the mixed system (acrylic acid samarium/ peroxide mixture). The experiments displayed that the cracking reaction of acrylic acid samarium's double bonds were occurred at 270℃, which means the thermal stability of acrylic acid samarium was worse than that of methylacrylic acid samarium.Therefore, acrylic acid samarium had higher polymerization reactivity.In the second part, we prepared methylacrylic acid samarium/NBR composites using in-situ reactive method. Through infrared spectrum, wide-angle X-ray diffraction, thermal analysis, electron microscope, X-ray machines and so on, the reactive process and properties of composites were investigated. The results were as follows:(1) During the vulcanization process, methylacrylic acid samarium was homopolymerized with the effect of free radicals from peroxide, and generated serval nanoparticles whose average particle size was 20 nm-30nm.(2) Morever, study on the composites'cross-linking types indicated that the ionic cross-linking existed in methylacrylic acid samarium /rubber.It could strengthen the interfacial bonds between fillers and the matrix. (3) Compared with the sulfur vulcanization system, which didn't have in-situ polymerization effect, the composites prepared by in-situ reaction had excellent shielding performance and mechanical properties.