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81.
聚苯乙烯—钛酸钡复合材料介电性能的研究   总被引:4,自引:0,他引:4  
以聚苯乙烯与化学沉淀法钛酸钡陶瓷为基本组成,采用溶液共混,溶液聚合,表面处理后溶液聚合三种方法进行复合,发现后两种复合的钛酸钡颗粒表面发生界面变化,形成活性界面,使得溶液聚合法和表面处理后溶液聚合所得到的材料具有较低的介电损耗,在高频下能保持较高的介电系数。  相似文献   
82.
In this study, new functionalized polysiloxane material was synthesized. The polysiloxane-based electrooptic material with side-chain charge-transporting functionalities and nonlinear optical chromophores was investigated through a three-step synthetic route. Elementary analysis and NMR spectra indicate that the polymer has a high degree of substitution. Detailed physical properties showed that the polymer has a glass transition of around 91°C, and its photoconductivity and electrooptic coefficient increase with the increasing applied electric field. Photorefractivity of the system has been demonstrated through the asymmetric energy transfer in a two-beam coupling experiment. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3854–3860, 1999  相似文献   
83.
不对称方酸菁的合成、性质和应用   总被引:1,自引:0,他引:1  
综述了不对称方酸菁的合成、中间体的制备、光谱、光导性能以及应用研究。  相似文献   
84.
Nylon-6 substrates were coated with SiO2 thin films by the sol-gel method and their water permeability coefficient was evaluated. Methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS) were used as starting materials. The addition of MTES to TEOS has enabled the formation of crack-free thin films on the substrates. The thin films strongly adhered to the substrates. The water permeability coefficients of nylon-6 substrates coated with these thin films decreased with the increase in the ratio of TEOS to the total alkoxides. The pretreatment of the nylon-6 substrates with -aminopropyltriethoxysilane was found to be effective to suppress the water permeability. The water permeability was suppressed by about 40% under the optimal condition.  相似文献   
85.
Poly(styrene) nanospheres having poly(N-vinylisobutyramide)s (PNVIBA)s, which are structurally the same composition as well-known thermosensitive poly(N-isopropylacrylamide)s (PNIPAAm)s and show the thermosensitive property as well, on their surfaces were synthesized by the free radical polymerization of hydrophilic PNVIBA macromonomers and hydrophobic styrene with AIBN as a radical initiator in ethanol as a polar solvent and were characterized in regard to their thermosensitive properties. Both the NVIBA oligomers and PNVIBA macromonomers that we synthesized showed a lower critical solution temperature (LCST) at around 40°C, as was predicted by our previous research. The nanospheres were spherical in form and have a narrow size distribution. Their sizes could be controlled by varying the molecular weight of the macromonomers and the amount of it in feed. The size in the nanosphere became small above the LCST of the corresponding macromonomer, possibly due to thermosensitive shrinking of the PNVIBA on the nanosphere surface, while transmittance of its dispersion did not change at all at studied temperature range. The nanospheres having the PNVIBA on their surfaces, which response sharply to atmospheres such as dispersion temperature, can be significant and useful materials in technological and medical fields. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2581–2587, 1998  相似文献   
86.
通过苯基甲基二乙氧基硅烷和苄基甲基二乙氧基硅烷的缩合反应制备了聚苯基甲基和聚苄基甲基硅氧烷。研究了它们与含氟酰基过氧化物间的反应。经酸碱滴定及IR、^1H NMR和^19F NMR光谱分析确证反应主要生成苯环上氟烷基取代产物。通过测定经氟烷基化后聚硅氧烷处理的玻璃表面的接触角,初步评价了氟烷基化率对其表现性能变化的影响。  相似文献   
87.
4-Hydroxy-2,3,5,6-tetrafluorobenzoic acid/6-hydroxy-2-naphthoic acid copolymers (FHBA/HNA copolymer) with different copolymer compositions were prepared and the influence of FHBA residue on the thermal properties and structures of the copolymers were investigated. Introduction of FHBA decreased the crystal/nematic phase transition temperatures(TCNs) of the FHBA/HNA copolymers. TCNs of the copolymers were in the temperature range between 200 and 250°C, depending on the copolymer composition. They are approximately 40°C lower than those of 4-hydroxybenzoic acid/HNA copolymers. FHBA/HNA copolymers exhibited low crystallinity, and annealing treatment hardly influenced the crystalline natures. FHBA residue possibly interferes with the recrystallization during annealing. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 413–419, 1998  相似文献   
88.
阮玉忠 《结构化学》1998,17(3):230-234
本实验采用磨具废砂和炉皮SiC废砂生产SA耐火材料,通过XRD分析和计算机处理确定各试样中的晶相(4H-SiC,33R-SiC,3C-SiC,α-Al2O3,β-石英和Al6Si2O13)及其各相的含量。通过材料性能与结构综合分析,确定较好的配方,其含量:磨具废砂50%,炉皮砂45%,结合剂5%,外加矿化剂2%。  相似文献   
89.
投料顺序对动态硫化PP/EPDM性能影响及其机理的研究   总被引:13,自引:0,他引:13  
针对PP降解在PP/EPDM动态硫化中对体系产生的不利影响。考察了四种不同投料顺序对PP/EPDM动态硫化物的冲击韧性,加工流动性,交联程度和断面形貌等宏观和微观性能,并进行了不同EPDM含量的动态硫化和非硫化PP/EPDM的性能比较。结果表明,优化投料顺序能实现对动态硫化体系中化学反应对象和化学反应程度的有效干预。  相似文献   
90.
The mechanical properties of glass bead filled low density polyethylene (LDPE) composites in tension have been investigated by using an Instron material testing machine. It is found that with increase of the glass bead weight fraction (φ) the tensile modulus (Ec) and the tensile yield stress (σyc) increase as a form of nonlinear function but contrary to the elongation strain at break; the correlation between Ec and φ accords with the logarithmic mixing rule and the relationship between σy and the volume fraction (φf) can be described by means of a second order equation; the effects of the glass bead diameter on the mechanical properties are not large; when φ and the bead size are suitable, the enhanced toughness effect of the filled-systems is more significant; the tensile strength of the glass bead filled system pretreated with a coupling agent are somewhat greater than those of the untreated system. In addition, the morphology of the samples is studied to explain the relationship between the micro-structure and the mechanical properties of the composites.  相似文献   
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