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以2-溴代异丁酸乙酯[2-(EiB)-Br]为引发剂,CuBr/2,2^1-bpy为催化体系,进行了甲基丙烯酸丁酯(BMA)在丙酮、丙酮/甲醇、丙酮/水中的原子转移自由基聚合,研究了溶剂、温度对聚合反应活性特征的影响.结果表明,水或甲醇的加入,使反应速率有所增加,水的影响最大;在其它反应条件相同时,水或甲醇对反应的影响在低温时更为明显. 相似文献
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Poly (n-octyl acrylate) with uniform polystyrene grafts (POA-g-PS) was obtained by radical copolymerization of n-octyl acrylate (OA) with PS macromer, in solution. The reactivity ratio and effects of copolymerization conditions on grafting efficiency were studied. The crude products were purified by extraction with cyclohexane and n-butanol successively. POA-g-PS exhibited a very good compatibilizing effect on the acrylic rubber/polystyrene blends. 2%-3% of the graft copolymer was enough for enhancing the tensile strength of the blends. DSC and SEM demonstrated the enhancement of compatibility in the presence of the graft copolymer. 相似文献
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介绍了以乙烯底油的HK~200℃馏分油为原料,用一种新配方的三氯化铝催化剂进行催化聚合,制取优质汽油的方法;对催化聚合反应的工艺条件进行了大量的实验研究,探索出生产中各种最佳的工艺参数.为中小型石油化工企业提供了一条经济效益显著的乙烯底油的综合利用途径。 相似文献
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本文通过锐钛矿对不同pH值溶液中甘氨酸的吸附和中低温条件下锐钛矿表面甘氨酸的缩合研究,探讨半导体矿物吸附诱导氨基酸聚合的能力及其机理。结果表明:在pH=6.0时,甘氨酸在锐钛矿表面的吸附量达到最大值(约80.1 mg/g);且在弱酸条件下,甘氨酸通过羧基基团与锐钛矿表面相关原子或基团键合而吸附在其表面。在80~120℃范围内锐钛矿主要催化甘氨酸缩合形成DKP(环状二肽)、Gly_2(Gly-Gly)、Gly_3(Gly-Gly-Gly)等寡肽,催化缩合形成产物受温度的控制。锐钛矿表面为甘氨酸的吸附缩合提供了活性位点,在提供一定能量(加热)条件下,能催化甘氨酸缩合。 相似文献
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琼胶寡糖聚合度对坛紫菜抗性诱导的影响 总被引:2,自引:1,他引:1
研究了琼胶寡糖聚合度对坛紫菜抗性诱导的效应。以琼胶3,6和12糖,3种聚合度的琼胶寡糖为材料,处理坛紫菜,通过观察叶片腐烂率比较坛紫菜生长状态;利用透射电镜观察处理后的细胞亚显微结构变化;并检测坛紫菜附生菌的数量变化;以对羟基苯乙酸(POHPAA)化学发光法检测坛紫菜H2O2释放量;利用实时定量PCR检测坛紫菜NADPH氧化酶基因(Phrboh)的差异表达。结果表明,经琼胶3糖和6糖处理,坛紫菜的Phboh表达出现上调,并产生H2O2暴发。经两种琼胶寡糖处理后,坛紫菜的附生菌数量明显减少,其中以琼胶6糖的效果最好,在较长培养时间内,坛紫菜能保护自身细胞亚显微结构的完整性,维持良好的生长状态。而琼胶12糖没发现任何诱导作用。综上所述,聚合度为3和6的琼胶寡糖能诱导坛紫菜的抗性响应,特别是形成单个螺旋结构的琼胶6糖的诱导作用最明显,但聚合度较大的琼胶寡糖则不能。 相似文献
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矿物聚合材料固化过程中的聚合反应机理研究 总被引:13,自引:2,他引:13
以粉煤灰、高岭石等为原料,制备出具有良好力学性能和耐酸性的矿物聚合材料制品,可代替部分硅酸盐水泥制品。根据矿物聚合材料制品在3 d、7 d、14 d、28 d的X射线衍射(XRD)、红外光谱(IR)、扫描电镜(SEM)、核磁共振(NMR)等测试分析结果,研究了该材料固化过程中的聚合反应机理。研究结果表明,矿物聚合材料在固化过程中的反应如下:(1)粉煤灰中的玻璃相在强碱的作用下首先发生溶解,其中部分Si-O、Al-O键发生断裂;(2)断裂之后的Si、Al组分在碱金属离子Na+、OH- 等作用下形成Si、Al低聚体(-Si-O-Na、-Si-O-Ca-OH、Al(OH)-4、Al(OH)2-5、Al(OH)3-6),而后随着溶液组成和各种离子浓度的变化,这些低聚体形成凝胶状的类沸石前驱体;(3)前驱体脱水形成非晶相物质。核磁共振分析结果表明,28 d制品中,Si的存在方式以Q4为主。研究结果为进一步揭示矿物聚合材料的形成机理、改善制品的性能奠定了良好的基础。 相似文献
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Takeshi Mizutani 《Geomorphology》1998,24(4):353-361
The formation mechanism of multiple erosional terraces which develop in the dissection process of sedimentary valley fills was investigated by laboratory experiments and computer simulations. Sequences of unpaired terraces were produced on experimental fan-like deposits under conditions of constant water discharge, no base-level change, and no sediment supply. The terraces developed as a result of the repetition of lateral shifting and stillstand of the stream channel at each cross-section during continuous downcutting. This mode of channel migration was caused by meander growth during which amplitude and wavelength increased with time. The terrace formation process was well-reproduced by computer simulations using a meander model having a similar wave mode. 相似文献
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Roll waves commonly occur in overland flow and have an important influence on the progress of soil erosion on slopes. This study aimed to explore the evolution and mechanism of roll waves on steep slopes. The potential effects of flow rate, rainfall intensity and bed roughness on the laws controlling roll wave parameters were investigated. The flow rates, rainfall intensities and bed roughness varied from 5 to 30 L/min, 0 to 150 mm/h, and 0.061 to 1.700 mm, respectively. The results indicate that roll waves polymerize significantly along the propagation path, and bed roughness and rainfall affect the generation and evolution of roll waves. The wave velocity, length and height decreased with bed roughness, whereas the wave frequency increased with increasing bed roughness under fixed flow rate and rainfall intensity conditions. Rainfall increased the wave velocity and wavelength and decreased the wave frequency. The wave velocity, height and wavelength tended to increase with an increasing flow rate. Rainfall promoted the generation of roll waves, whereas bed roughness had the opposite effect. The generation of roll waves is closely related to the Froude number (Fr) and flow resistance. In this experiment, the range of the Reynolds number for the roll waves generated in the laminar region was 142–416, and the range of the flow resistance coefficient was 0.64–4.85. The critical value of the Fr for flow instability in the laminar region was approximately 0.57. Exploring the generation and evolution law of roll waves is necessary for understanding the processes and dynamic mechanisms of slope soil erosion. 相似文献