共查询到20条相似文献,搜索用时 15 毫秒
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用毛细管流变仪和显微摄影方法以及稳定自由基标记法研究了苯乙烯和4-(甲基丙烯酸)2,2,6,6-四甲基哌啶醇酯(简称PDS)共聚物共混聚丙烯的流变性能和形态分布,发现PDS相于聚丙烯相中的分布呈典型的分散球状颗粒,颗粒尺寸与流动条件有关,两相的分布状况与PDS分子量大小有关。同时也探讨了PDS共混比例对熔体流动性能的影响。添加少量PDS可改善聚丙烯熔体的流动性能。 相似文献
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The grafting of copolymer of styrene and 2, 2, 6, 6-tetramethyl-4-piperidinyl methacrylate onto polypropylene during heating was studied by IR and ESR. It is found that the graft reaction is going through the stable free radical > NO mechanism. 相似文献
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Jiao-liLi Xing-heFan Yong-fengZhao Xiao-fangChen Qi-fengZhou 《高分子科学》2004,(3):289-293
The random copolymers of styrene and 2,5-bis[(4-methoxyphenyloxycarbonyl)styrene] (MPCS) with different copolymerization ratio were synthesized by conventional free radical polymerization. The copolymer having high molecular weight was experimentally elucidated using a combination of proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The liquid crystalline behavior of the copolymer was studied using differential scanning calorimetry, X-ray diffractometry and polarized optical microscopy. It was found that the liquid crystalline behavior was dependent on the content of styrene. Experimental results show that the copolymer could turn into a liquid crystalline phase at about 180℃ when the content of styrene was less than 20%. The mechanical properties of the copolymer were also studied. Preliminary results indicate that the tensile strength decreases while the tensile modulus increases as the content of MPCS is increased. 相似文献
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Ethyl-cyanoethyl cellulose ((E-CE)C)/styrene solution could form anisotropic system when the concentration was high enough. The (E-CE)C/polystyrene(PS)multiphase polymer could be obtained by radical polymerization of the styrene in the solution. The (E-CE)C/PS multiphase polymer maintained both the crystalline structure of the (E-CE)C and the amorphous structure of the PS. In the multiphase polymer produced from the isotropic solution, however, the (E-CE)C formed spherulites and spread in the PS amorphous phase. While, in the multiphase polymer produced from the anisotropic solution, the (E-CE)formed cylinderic crystalline aggregates. Moreover, the ordered lamellar texture was also observed in the multiphase polymer produced from the anisotropic solution. 相似文献
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The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃or 37℃have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copoly-mer and pH value of hydrolysis medium. 相似文献
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苯乙烯-甲基丙烯酸四甲基哌啶醇酯共聚物(PDS)与紫外吸收剂并用对聚丙烯光防护行为研究 总被引:2,自引:0,他引:2
本文采用IR、UV、SEM等实验方法,研究了高分子受阻胺PDS与紫外吸收剂UV-531(2-羟基-4-正辛氧基二苯甲酮)和UV-327(2-(2′-羟基-3′,5′,-二叔丁基)-5氯代苯并三唑)并用对聚 烯薄膜的光防护作用,实验表明,PDS与UV-531并用有较好的协同效应,这种协同效应被证明主要是PDS对UV-531的光氧分解有抑制作用所致。PDS与UV-327并用有弱的反协同作用。这种作用被证实是PDS在聚丙烯中的分相作用导致UV-327分散不均所致,实验还发现,PDS对UV-327的光氧分解同样具有抑制作用。并提出了在二种体系中协同与反协同的作用机理。 相似文献
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Two new unbridged zirconocenes, bis(2,4,7-trimethyl indenyl)zirconium dichloride (Met-Ⅰ) andbis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-Ⅱ) were prepared in order to investigate thesteric effects of substituents on the nature of the catalysts for the polymerization of propylene. A mixture ofmethyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)_3] was used as cocatalyst to activate thesecatalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted inan increase of both activity and molecular weight as well as the isotacticity. 相似文献
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THE EFFECT OF CLAY DISPERSION ON THE CRYSTALLIZATION AND MORPHOLOGY OF POLYPROPYLENE/CLAY COMPOSITES
QinZhang Xiao-linGao KeWang QiangFu 《高分子科学》2004,(2):175-182
PP/clay composites with different dispersions, namely, exfoliated dispersion, intercalated dispersion and agglomerates and particle-like dispersion, were prepared by direct melt intercalation or compounding. The effect of clay dispersion on the crystallization and morphology of PP was investigated via PLM, SAXS and DSC. Experimental results show that exfoliated clay layers are much more efficient than intercalated clay and agglomerates of clay in serving as nucleation agent due to the nano-scale dispersion of clay, resulting in a dramatic decrease in crystal size (lamellar thickness and spherulites) and an increase of crystallization temperature and crystallization rate. On the other hand, a decrease of melting temperature and crystallinity was also observed in PP/clay composites with exfoliated dispersion, due to the strong interaction between PP and clay. Compared with exfoliated clay layers, the intercalated clay layers have a less important effect on the crystallization and crystal morphology. No effect is seen for samples with agglomerates and particle-like dispersion, in regard to melting temperature, crystallization temperature, crystal thickness and crystallinity. 相似文献
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本文采用IR、UV、SEM等实验方法,研究了高分子受阻胺PDS与紫外吸收剂UV-531(2-羟基-4-正辛氧基二苯甲酮)和UV-327(2-(2′-羟基-3′,5′,-二叔丁基)-5氯代苯并三唑)并用对聚丙烯薄膜的光防护作用。实验表明,PDS与UV-531并用有较好的协同效应。这种协同效应被证明主要是PDS对:UV-531的光氧分解有抑制作用所致。PDS与UV-327并用有弱的反协同作用。这种作用被证实是PDS在聚丙烯中的分相作用导致UV-327分散不均所致。实验还发现,PDS对UV-327的光氧分解同样具有抑制作用。并提出了在二种体系中协同与反协同的作用机理。 相似文献
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The structure and switching properties of liquid crystalline side chain copolymers of cholesteric ester of 1,2-hydroxypropyl 2,4-di-isocyanatoluene methylmethacrylate (PHCPM) have been studied in detail. The cholesteric mesophase of PHCPM is shown by polarizing microscopy, X-ray diffraction and selective light reflection. Solution of PHCPM in CHCl_3 is optically anisotropic; its optical properties were determined by specific rotation [α], circular dichroism (CD) and wide-angle hght scattering (WALS) methods. 相似文献
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Sulfur-containing monomers have received special interest from researchers because of their outstanding opticalperformance. Using the reaction between 2-phenylthioethyl-1-mercaptan and p-chloromethylstyrene, a new vinyl monomer4-(2-phenylthioethylthiomethyl)styrene (PTETMSt) was synthesized. Its structure was characterized by FT-IR and NMR.Copolymerization of styrene and PTETMSt was investigated. The data show that poly(styrene-co-PTETMSt) has higher refractive index, lower density and percentage of water absorption. The copolymer can be used on optical materials. 相似文献
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In this paper the synthesis of linear and crosslinked N-substituted acrylamide copolymer is reported. In order to obtain the terpolymer with appropriate hydrophilicity, the conditions of aminolysis of St-MMA copolymer have been selected.It is shown that the copolymer with predictable hydrophilicity possesses good blood compatibility. 相似文献
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Based on a series of morphological studies of blends of homopolymer (Homo) and a variety of block and graft copolymers (Cop), the nature of phase separation, interface, emulsification and inner morphology of copolymer-dispersed phase etc. in the blends are discussed. In the cases of Cop AB/Homo A/Homo B systems, in which one homopolymer forms matrix, it is observed that the dispersed homopolymer phase is exclusively associated with Cop AB, i.e. no Homo A-Homo B interface exists. This phenomenon is believed to be caused by minimizing the interfacial energy of the systems. Meanwhile, preferential solubilization or anchoring of the like chains of copolymer into homopolymer matrix leads to stabilization of the dispersed phase in the matrix. In addition, regular variation of the inner morphology of the dispersed copolymer phase with the composition and molecular parameters of the component polymers is observed. When the two components have comparable proportions, alternating concentric shells are the most common feature which is associated with minimizing the interfacial energy in the Cop/Homo systems. 相似文献
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Radiation-induced emulsion polymerization of styrene in soap-free system has beenstudied and the monodisperse polystyrene lattices were obtained. Both its purity and emulsionconversion are better than that of chemically initiated polymers. 相似文献
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A new reactive graft copolymer, poly (dimethyl siloxane )-graft-ω-hydroxyl-poly(ethylene oxide) (PDMS-g-(PEO--OH)), was synthesized by the hydrosilylation reactionof α, ω-bifunctional PEO macromonomer (CH_2=CH--CH_2--PEO--OH) with poly(hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comb-like structure as indicated by the result of detailed characterization and the neededreactivity as demonstrated by the result of esterification between PDMS-g-(PEO--OH)and aminoacetic acid. This reactive graft copolymer is expected to be very useful in thepreparation of new bioactive polymer materials. 相似文献