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用铜试剂(N,N-二乙基二硫代氨基甲酸钠)取代聚氯乙烯中的部分氯原子制备了N,N-二乙基二硫代氨基甲酸聚氯乙烯酯(PVC-SR),研究了紫外光照下PVC-SR引发甲基丙烯酸甲酯(MMA)的聚合反应,考察了光照时间、单体浓度、PVC-SR用量及官能度的影响。结果表明,PVC-SR能有效地引发MMA聚合,其产物是交联型接枝聚合物,且具有高接枝率和接枝效率。 相似文献
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2-(N,N-二乙基二硫代氨基甲酰氧基)乙酸苄酯存在下苯乙烯光聚合 总被引:2,自引:2,他引:0
研究了2 N, N 二乙基二硫代氨基甲酰氧基乙酸苄酯( Bz D C A) 引发的苯乙烯光聚合反应,发现单体转化率和数均分子量( Mn) 都随反应时间而增加,在反应时间相同时随着 Bz D C A 浓度的增加单体转化率升高而 Mn 降低.聚苯乙烯( P S) 的 Mn 同单体转化率成线性关系并同理论计算值符合得较好.以2 甲基 2 亚硝基丙烷( M N P) 为捕捉剂用( E P R) 技术对聚合反应机理进行了研究.认为 Bz D C A 引发的 St 光聚合是一个“活性”聚合过程 相似文献
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STUDYONTHESORPTIONBEHAVIOROFN-METHYL-2-THIO-IMIDAZOLERESINFORRh(Ⅲ)ANDSEPARATIONOFRh(Ⅲ)WITHCOMMONMETALIONSBYUSINGMTIRChenYiyon... 相似文献
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可交联PVC的合成及其交联反应 总被引:5,自引:2,他引:3
N,N-二乙基二硫代氨基甲酸钠(铜试剂,简称NasR)取代PVC链中的部分氯原子,制得不同官能度的功能高分子PVC-SR.在热的作用下,实现了PVC-SR的自交联和PVC-SR/NBR共混体系的共交联.研究了温度、铜试剂用量对取代反应的影响及PVC-SR官能度对交联反应硫化曲线、产物的凝胶含量、玻璃化温度、拉伸性能和压缩永久变形的影响,并初步探讨了交联反应机理. 相似文献
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Tatsuro Ouchi Tamio Nishimura Minoru Imoto 《Journal of polymer science. Part A, Polymer chemistry》1976,14(11):2695-2702
It was found recently that the system of nylon 3, copper(II) ion, and water could initiate a radical polymerization of methyl methacrylate(MMA). In the present paper, the effect of average chain length of the molecules of nylon 3 on the rate of polymerization of MMA was studied. The rate increased with the chain length of nylon 3. This result was explained well by the fact that the shorter nylon 3 forms a complex with copper (II) ion more easily than longer nylon 3. It was assumed that the shorter nylon 3 fills three or four coordination sites of copper(II) ion and loses the ability to initiate the polymerization. The efficiency of grafting of MMA and the degree of polymerization of MMA homopolymer were independent of the chain length of nylon 3. 相似文献
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A novel route for producing polymer blends by reactive extrusion is described, starting from poly (vinyl chloride)/methyl methacrylate (PVC/MMA) dry blend and successive polymerization of MMA in an extruder. Small angle X‐ray scattering (SAXS) measurements were applied to study the monomer's mode of penetration into the PVC particles and to characterize the supermolecular structure of the reactive poly(vinyl chloride)/poly(methyl methacrylate) (PVC/PMMA) blends obtained, as compared to the corresponding physical blends of similar composition. These measurements indicate that the monomer molecules can easily penetrate into the PVC sub‐primary particles, separating the PVC chains. Moreover, the increased mobility of the PVC chains enables formation of an ordered lamellar structure, with an average d‐spacing of 4.1 nm. The same characteristic lamellar structure is further detected upon compression molding or extrusion of PVC and PVC/PMMA blends. In this case the mobility of the PVC chains is enabled through thermal energy. Dynamic mechanical thermal analysis (DMTA) and SAXS measurements of reactive and physical PVC/PMMA blends indicate that miscibility occurs between the PVC and PMMA chains. The studied reactive PVC/PMMA blends are found to be miscible, while the physical PVC/PMMA blends are only partially miscible. It can be suggested that the miscible PMMA chains weaken dipole–dipole interactions between the PVC chains, leading to high mobility and resulting in an increased PVC crystallinity degree and decreased PVC glass transition temperature (Tg). These phenomena are shown in the physical PVC/PMMA blends and further emphasized in the reactive PVC/PMMA blends. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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在实际应用中,大部分光敏引发系统只对紫外光敏感.近年来,随着Ar+(488nm)、YAG(532nm)以及HeNe(633nm)激光技术的不断发展,高效的长波长光敏引发体系成为研究的重点.其中之一的方法是使引发剂直接感可见光,然而取得的结果并不显著.所以染料敏化又一次成为焦点.其中最重要的技术是使光敏引发系统的吸收波长移向长波长,并且具有高的灵敏度.大部分的光敏引发系统是由二个或三个组分组成,长波长的光引发聚合是通过以下两种不同过程得到实现[1]:(1)光敏系统直接吸收光并激发,(2)光引发系… 相似文献
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本工作对两种不同的2-芳基苯并 唑化合物溶液荧光被四氯化碳所猝灭的机理进行了详细研究,通过多种途径研究表明该猝灭过程具有光诱导电子转移性质,工作还利用此电子转移所形成的活泼自由基来引发烯类单体的聚合,得到了有一定聚合度的聚甲基丙烯酸甲酯。 相似文献
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Benzyl N-ethyldithiocarbamate(BEDC) and xylylene bis(N-ethyl-dithiocarbamate)(XEDC) were prepared, and used as mono- and bi-functional photoiniferters, respectively, of the polymerization of styrene and methyl methacrylate. These photopolymerizations were performed via a living radical polymerization mechanism in homogeneous system. The polymers obtained by BEDC and XEDC still contained one and two reactive N-ethyldithiocarbamate end groups, respectively, bonded at their chain ends. When these polymers were reacted with nucleophiles and copper(n) ion, the chain extension reactions were observed to occur depending on their functionality. By using the polymers obtained by BEDC and XEDC as mono- and bi-functional polymeric photoiniferters, the AB and ABA block copolymers were also obtained, respectively. Similar results were obtained by using benzyl N,N-diethyldithiocarbamate(BDC) and xylylene bis(N,N-diethyldithiocarbamate)(XEDC) as mono- and bifunctional photoiniferters, respectively. These results were also compared and discussed. 相似文献
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AbstractCertain complexes of some transition metal cations in the high oxidation state could oxidize some organic substrates with labile C-H moieties, leading to the corresponding cations in the lower" oxidation state and some carbon-centered radicals. The former would form oxidative complexes with molecular dioxygen to continuously oxidize organic substrates, while the latter would initiate polymerization of vinylic monomers. Such catalytic oxidation is adopted to initiate radical polymerization of methyl methacrylate (MMA) and styrene (St) with cyclohexanone (CyHO) and benzylic hydrocarbons as both the solvent and the substrate. Although, a large array of complexes could trigger the polymerization, CuII/2,2′-bipyridine complexes display a maximum turnover frequency above 200?h–1 during the catalytic aerobic radical polymerization of MMA in CyHO at 70–80?°C, but only less than 0.4% of CyHO is involved in chain formatting. CuII/ligand-catalyzed aerobic radical polymerization of St in CyHO exhibit comparable behaviors. Only CoII complexes could catalyze the aerobic radical polymerization of MMA in para-xylene and cumene at 90?°C, but only 0.1% of PX and 0.3% of cumene are involved in chain forming. 相似文献