共查询到16条相似文献,搜索用时 62 毫秒
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Mn^3+引发淀粉与丙烯腈接枝共聚物的研究 总被引:1,自引:0,他引:1
用过渡金属离子或其配合物引发淀粉的接枝共聚是一个饶有兴趣的课题。Ce~(4 )离子引发淀粉与烯类单体的接枝共聚已有广泛报道。Mehrotra等用稳定的[Mn(H_2P_2O_7)_3]~(3-)引发淀粉与烯类单体的接枝共聚取得了满意的结果。本文报道用电镜,x-射线衍射和热重分析等方法对这一接枝共聚物的形态、结构和热稳定性的研究结果。 相似文献
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吸水性淀粉-丙烯腈接枝共聚物的一步合成 总被引:6,自引:0,他引:6
以硝酸铈铵为引发剂,在几种水-有机溶剂体系中一步合成了吸水性淀粉-丙烯腈接枝共聚物。其中所含的PAN均聚物比水作溶剂时的多。在水-正丁醇溶液(V/V=1∶3)中,PAN的接枝效率为83%,淀粉的接枝效率为72%,产品的吸水倍数为820g/g。 相似文献
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丙烯腈在聚丙烯上接枝共聚 总被引:1,自引:0,他引:1
丙烯腈在聚丙烯上非均相接枝共聚,得杨梅形氰基树脂。研究了接枝共聚条件对单体转化率和接枝率的影响。表观聚合速度可表示为,碰撞频率因子和聚合活化能分别是1.36×1011s-1和99.2kJ.mol-1。从光学显微镜观察到改性树脂在水中接枝连束的分布状态。丙烯腈和二乙烯基苯在聚丙烯上接校共聚,再经二甲苯率取,得笼形氰基树脂。二乙烯基苯在单体中的相对含量对树脂的溶胀性能和笼孔尺寸有很大的影响,制取功能材料时应予适当调节。扫描电镜照片展示了笼形树脂的笼腔和网络结构形态。 相似文献
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腐植酸与丙烯腈接枝共聚的研究 总被引:2,自引:0,他引:2
研究了低pH水溶液中丙烯腈与煤腐植酸的接枝共聚反应。以K_2S_2O_8-Fe(Ⅱ)和K_2S_2O_8-AH_2(抗坏血酸)引发体系效果最佳;各种来源的腐植酸的接枝度差别不大,均大于75%,部分接枝物在强碱下降解。 相似文献
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[Mn(H_2P_2O_7)_3]~(3-)引发淀粉与丙烯腈接枝聚合反应的动力学研究 总被引:5,自引:2,他引:5
以[Mn(H_2P_2O_7)_3]~(3-)为引发剂,研究了丙烯腈与玉米淀粉的接枝共聚反应。由实验结果求出了反应速率与引发剂浓度、单体浓度、淀粉浓度和反应温度的关系,推导并验证了接枝反应动力学模型,探讨了反应机理,求得了接枝反应活化能。 相似文献
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GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO STARCH INITIATED BY TRANSITION METAL-THIOUREA REDOX SYSTEMS 总被引:5,自引:0,他引:5
In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiatedby Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in thepresence of sulfuric acid of different concentrations. It was shown that the grafting capabili-ty of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initia-tor, the effects of various acids (HClO_4, H_2SO_4, HNO_3, HCl) on the graft copolymerizationof acrylonitrile onto starch were discussed, and the capabilities of graft copolymerizationof methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch wereinvestigated. The experimental results show that the order of the influences of differentacids is HClO_4>H_2SO_4>HNO_3>HCl, and the order of grafting capabilities of differentmonomers grafted onto starch is MMA>AN>AM>AA. The structure and morphology ofgraft copolymers were studied with infrared spectroscopy and scanning electron microscopy.The size, shape and roughness of surface of the grafted starch granules are changed aftergrafting. 相似文献
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铬酸引发丙烯酸正丁酯与淀粉接枝共聚反应 总被引:6,自引:0,他引:6
作为淀粉改性方法之一 ,不饱和酸及其酯与淀粉接枝共聚反应是一个较新的研究领域 ,其中以 Ce4 +离子作为引发剂的较多[1,2 ] ,也有用Mn3+-H2 SO4 体系 [3]和 Mn[( H2 P2 O7) 3]3-引发体系的[4 ] 。铬酸是一种具有强氧化性的强酸 ,虽然它单独存在时并不引发乙烯类单体的聚合 ,有报道[5] 铬酸可以引发丙烯腈与苎麻纤维素接枝共聚 ,淀粉和纤维素同属于碳水化合物。本文对铬酸引发丙烯酸正丁酯与淀粉接枝共聚反应进行了研究 ,考察了反应条件对接枝反应的影响。1 实验部分1 .1 原料可溶性淀粉 (北京奥特生物技术责任有限公司 ) ,丙烯酸正丁… 相似文献
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《高分子科学杂志,A辑:纯化学与应用化学》2013,50(1-2):129-143
ABSTRACT A novel redox system, potassium diperiodatonickelate [Ni (IV)]‐chitosan, was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in alkali aqueous solution. The effects of reaction variables such as monomer concentration, initiator concentration, reaction time, pH and temperature were determined. By means of a series of copolymerization, the grafting conditions were optimized. The maximum grafting percentage obtained was 404.1% when 0.3 g chitosan was copolymerized with 1.8 mL monomer at 35°C for 5 hours with [Ni (IV)]=9.4×10?4 M and the total volume was 20 mL. Ni (IV)-chitosan system is found to be an efficient redox initiator for this graft copolymerization. A single electron transfer mechanism is proposed to explain the formation of radicals and the initiation. The grafted copolymers were characterized by IR and X-ray diffraction diagrams. The thermal stability of chitosan and chitosan-g-PMA was studied by thermogravimetric analysis (TGA). 相似文献
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铈盐作用下甲基丙烯酸甲酯在壳聚糖模型化合物上接枝聚合机理研究 总被引:4,自引:1,他引:4
铈盐作用下甲基丙烯酸甲酯在壳聚糖模型化合物上接枝聚合机理研究张国栋冯新德(北京大学高分子科学与工程系北京100871关键词壳聚糖,接枝共聚合,硝酸铈胺,接枝机理甲壳素是自然界中产量仅次于纤维素的一种多糖,而壳聚糖是其2位碳上乙酰氨基的乙酰基部分... 相似文献
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Functional monomers having phenylcarbamoyl and p-tolylcarbamoyl were synthesized. Binary initiation system consisted of Ce~(4+) and these functional monomers could initiate acrylamide polymerization. It was found that acrylamide could graft copolymerize onto macromolecules having these functional monomers units. The formation of graft copolymer has been verified by its percentage of water absorption, contact angle with water, XPS and SEM photographs. The reaction mechanism was proposed and the main reactive site of graft ocpolymerization initiated by Ce~(4+) would take place predominantly at the functional pendant group. 相似文献