共查询到17条相似文献,搜索用时 78 毫秒
1.
2.
3.
用单晶X射线衍射分析方法测得1,4-二苯氧基苯(Ⅰ)和1,4-双(4-甲氧基苯氧基)苯(Ⅱ)的晶体结构。它们的晶胞参数分别为:(Ⅰ)α=5.876(2),b=7.832(2),c=1.5455(6)nm, β=95.33(3)°;空间群为P2_1/c,Z=2。(Ⅱ)α=6.017(1),b=7.577(1),c=3.6404(5)nm;空间群为Pcab,Z=4.(Ⅰ),(Ⅱ)的分子构象、键长和键角数据表明氧桥两边的苯环的共轭极化效应不能贯通,而苯氧基只是分子中的一个独立片断。从而也阐明了此类聚苯醚体系的电子吸收光谱的同系直线斜率小的原因。 相似文献
4.
研究了聚苯醚PPO、羧化PPO、苯酰化PPO、苯磺酰化PPO和磺化PPO在不同溶剂中的溶解能力,分别讨论了各种取代基以及取代度对聚合物溶解性能的影响,由PPO衍生物的特性粘数估算了它们的溶度参数。 相似文献
5.
6.
聚苯醚离聚体水基微乳液粒径及稳定性的研究 总被引:2,自引:0,他引:2
以乙酰磺酸为磺为磺化剂制备了磺化度为3~17mol%的磺化聚苯醚(SPPO),并中和成盐,在一定的温度和搅拌速度下,加水将SPPO离聚体溶液乳化成水包同的稳定水基微乳液。用光散射法及航向电镜法(TEM)测定了SPPO离聚体水基微乳液的粒径及粒径分布,研究了磺化度、溶剂的极性、因含量等因素对微乳液粒径及稳定性的影响。 相似文献
7.
用DSC分别探讨了苯酰化聚苯醚(PPO)(BA~(31.0)-PPO和BA~(43.4)-PPO)/PPO共混体系的热焓松弛变化规律与差异.发现已知是相容体系的BA~(31.0)-PPO/PPO在低于T_g等温退火过程中只出现一个吸热峰;典型的相容体系PPO/PS也表现出类似的行为.而未知相容性的BA~(43.4)-PPO/PPO在等温退火过程中出现两个吸热峰,此两峰的T_p值随退火时间的变化类似于各纯组分相应条件下的变化.电子显微镜结果表明,BA~(43.4)-PPO/PPO是相分离体系.因此对T_g非常接近的较刚性主链的PP0及其改性物的共混体系可用热焓松弛行为确定其相容性. 相似文献
8.
9.
10.
研究了同时具有最高临界互溶温度和最低临界互溶温度的羧化聚苯醚/聚苯乙烯共混体系随退火温度的变化而发生的相形态结构的变化.研究了此共混体系的相分离机理.并发现了此特殊共混体系低温和高温区的相分离机理是不同的.从分子的结构和分子间特殊相互作用上探讨了此共混体系产生特殊相行为的原因. 相似文献
11.
Thermal transitions in epoxy networks prepared by reaction of α, ω‐diamino terminated poly(propylene oxide)‐block‐poly(ethylene oxide)‐block‐poly(propylene oxide) and diglycidyl ether of brominated Bisphenol A, swollen in water, were studied by differential scanning calorimetry (DSC) in a broad temperature range (from ?100 °C to 20 °C). Networks of two different values of initial molar ratio of amino and epoxy groups were prepared, r (r = 1.00, 2.00), and swollen with different amounts of water up to equilibrium concentration values. The qualitatively different kinds of experimental thermograms have been obtained for two networks and classified according to the amount of water in the sample on the basis of the phase diagram of the system. Also, the concentration dependence of the curves in this diagram (glass transition, melting, and crystallization) as well as the fraction of noncrystallizable water supply some information about the morphology of the system. In this sense, the existence of a microphase separated structure of swollen networks is suggested. The structure consists of hydrophilic and hydrophobic domains and depends on the initial molar ratio of the reactive groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 699–708, 2005 相似文献
12.
13.
14.
PPO/SEBS-g-MAH共混体系的形态结构与冲击性能 总被引:8,自引:0,他引:8
从亚微相态和冲击性能出发 ,对比了采用熔融挤出法制备的PPO/SEBS和PPO/SEBS g MAH两种共混物 .结果表明 ,在本文所研究的弹性体用量范围内 ,PPO/SEBS为“海 岛”型结构 ,而PPO/SEBS g MAH呈现网状结构 ;PPO/SEBS体系无脆韧转变现象 ,PPO/SEBS g MAH体系则在弹性体用量为 10 %~ 15 %时出现明显的脆韧转变 ,缺口冲击强度达到 95 0J/m ,这种超韧现象源于其网状结构的形成 .文中进一步用DSC和毛细管流变仪对共混体系的热性能和流变性能进行了测试 ,探讨了PPO/SEBS g MAH共混物网状结构的形成原因 相似文献
15.
聚苯醚的溴化及其对富氧性能的影响 总被引:3,自引:0,他引:3
利用亲电反应及自由基反应分别对聚苯醚进行了不同程度的溴化。测定了不同温度下对O_2和N_2的透过率及相应的玻璃化转变温度和密度。发现苯环上的溴化有利于提高O_2和N_2的透过率,而选择性基本不变。甲基上的溴化大大提高了O_2、N_2的选择性,但透过率下降较多。苯环上溴含量与Tg呈很好的线性关系,密度亦随溴含量的增加而增加。透过率与温度的关系符合Arrhenius方程。溴化后的聚苯醚其透过活化能略有下降,并计算了溴化聚苯醚的摩尔自由体积和摩尔内聚能,发现其比值越大,O_2、N_2的透过率越大。 相似文献
16.
E. Morales M. Salmern J. L. Acosta 《Journal of Polymer Science.Polymer Physics》1996,34(16):2715-2721
Isothermal and nonisothermal crystallization kinetics of different poly(ethylene oxide)/poly(propylene oxide) blends were investigated by means of differential scanning calorimetry (DSC). Glass transition temperature of quenched samples have also been reported. Phase morphologies and poly(ethylene oxide) spherulite growth rates were analyzed by polarizing light transmission microscopy. Results show morphological changes along with regime transitions of poly(ethylene oxide) crystal growth. Kinetic analyses of the data suggest that, although the blend behaves as a noncompatible, phase-separated system, there exists a certain degree of interaction between polymer chains. © 1996 John Wiley & Sons, Inc. 相似文献
17.
Semi-IPN's based on linear poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and diamine crosslinked poly(styrene-co-maleic anhydride) (PScoMA) copolymers containing small amounts of maleic anhydride (PSA=4.7wt.-% MA, PSB=5.8 wt-% MA) are studied with respect to the influence of cross-linking on the phase behavior. Temperature-dependent dynamic mechanical analysis (DMA) and DSC show that the semi-IPN's prepared from concentrated solution show weak crystallinity of the PPE phase. After heating above the PPE melting transition the semi-IPN's remain amorphous and the relaxation in the glass transition region as well as the terminal relaxation of the free PPE chains in the network is studied as a function of PPE concentration and network density. 相似文献