共查询到17条相似文献,搜索用时 62 毫秒
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测量了聚丙烯的极化冷冻效应 ,发现冷冻过程极化强度增加 .用循环变温极化的热刺激电流方法分析 ,结果表明 ,在极化温度低于峰温时峰值增大 ;高于峰温时峰高温侧的电荷量增加 .认为极化冷冻过程促进了聚合物的极化 . 相似文献
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我们将低密度聚乙烯试样暴露在湿空气中一定的时间,不管在用直流高压极化的前后,甚至在极化后对其经过72h的真空干燥处理,在中温区也存在一个附加的湿致热释电流峰,它可能是由俘获在晶区-非晶区界面的离子热释放所致。 由分析在极化前对含无机填料(经表面处理的高岭土)的低密度聚乙烯试样进行干燥或润湿处理后的热释电流谱表明,聚乙烯中的无机填料与吸收的水分子都可作为电子的受主,前者为电子深陷阱,后者为电子浅陷阱。 相似文献
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热致性液晶乙基纤维素和聚丙烯共混物的结构与性能 总被引:5,自引:0,他引:5
乙基纤维素(EC)和聚丙烯共混物沿取向方向有明显的絮条状结构,EC含量增加使Tc提高,△H和Tm有所降低,共混物的成核能力降低,结晶度下降,(110)晶面尺寸减小,(040)晶面尺增大。EC/PP共混物的ηa、τa值更接近于PP结果。力学测定结果给出,EC/PP=10/90的共混物抗张模量有所增加。 相似文献
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聚苯乙烯的热释电行为盛京,李凤奎(天津大学材料科学与工程系天津300072)关键词聚苯乙烯,松弛现象,热释放电流谱聚苯乙烯(PS)的松弛过程有大量研究。应用热释电法(TSC)研究聚苯乙烯的松弛报道较少[1,2]。无规PS是典型的非晶态聚合物,它的玻璃... 相似文献
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我们将低密度聚乙烯试样暴露在湿空气中一定的时间,不管在用直流高压极化的前后,甚至在极化后对其经过72h的真空干燥处理,在中温区也存在一个附加的湿致热释电流峰,它可能是由俘获在晶区-非晶区界面的离子热释放所致。 由分析在极化前对含无机填料(经表面处理的高岭土)的低密度聚乙烯试样进行干燥或润湿处理后的热释电流谱表明,聚乙烯中的无机填料与吸收的水分子都可作为电子的受主,前者为电子深陷阱,后者为电子浅陷阱。 相似文献
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聚苯乙烯及其合金的热释放电流研究 总被引:3,自引:0,他引:3
聚苯乙烯及其合金的热释放电流研究盛京,李凤奎,胡静(天津大学材料科学与工程系,天津,300072)关键词聚苯乙烯,聚苯乙烯松弛,热释电谱,聚苯乙烯合金,乙丙橡胶合金用热释放电流(TSC)法研究聚苯乙烯(PS)的松弛过程只见Shinichi的报道[1]... 相似文献
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J. Bayard J. Grenet C. Cabot M. Jutigny E. Dargent 《Journal of Thermal Analysis and Calorimetry》1997,50(3):441-453
In this paper we present an electrical model of simulation. This model is used to simulate Thermally Stimulated Depolarization Current measurements. The time constant of the model shows the same temperature behaviour as that observed for amorphous materials. The computations by means of SPICE software give results which are very close to be behaviour laws used in the theory of relaxation in amorphous materials. 相似文献
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研究了偏氟乙烯-三氟乙烯共聚物与钛酸铅形成的铁电复合物PT/P[VDF(70)-TrFE(30)]的热释电流行为。P[VDF(70)-TrFE(30)]室温下存在两个铁电相,即较无序的铁电相和较有序的铁电相,升温经过各自的相转变点后转变成较有序的顺电相和较无序的顺电相。热释电流谱上出现在95℃和108℃的两个电流峰,分别由两个铁电相的结构陷阱以及部分取向的偶极所贡献。采用Tc以上温度极化并冷却到不同温度的方法可明确鉴别出该试样两个顺电相降温转变过程,转变点分别为62℃和50℃。实验证实陷阱仅存在于铁电相而不存在于顺电相中。钛酸铅的引入虽不导致新电流峰出现,但可使共聚物的Tc降低、电流加大。热释电流方法可非常灵敏地跟踪铁电共聚物的相变过程。 相似文献
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Molecular mobility of the comb-shaped copolymer poly(4-[6-(acryloyloxy)hexyloxy]benzoic acid-co-butyl acrylate) and Li- and Rb-containing LC ionomers based on this polymer was studied at low temperatures by the methods of dielectric spectroscopy and thermally stimulated depolarization current. The above copolymers are shown to experience the γ2, γ1, and β-processes, which are related by the reorientation of the end СООН groups, by the mobility of a spacer, and by the reorientation of mesogenic fragments (dimers of oxybenzoic acids) with respect to a long axis, respectively. The formation of multiplet structures in ionomers leads to a suppression of the intensity of the β-process that relates with a partial breakdown of hydrogen-bonded dimmers and with a decrease of their molecular mobility. 相似文献
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Summary Thermally stimulated depolarization currents (TSDC) of atactic (a), syndiotactic (s) and isotactic (i) PMMA and mixtures ofs- andi-PMMA were measured. In pure tactic PMMA, TSDC peak was obtained at a temperature corresponding to the glass transition temperature of each PMMA. TSDC of mixtures isolated as precipitates from 1/1 and 1/2 (i/sweight ratio) mixed solutions showed a peak which can be attributed to the glass transition temperature of the stereocomplex. TSDC of original l/1 mixture showed two peaks which are ascribed to the glass transition temperature of residual i-PMMA and the stereocomplex. The results suggests that stereocomplex formation occurs ini/s weight ratio of 1/2 independent of the way of preparation.With 9 figures and 1 table 相似文献
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A novolac phenol-formaldehyde resin was investigated via the thermally stimulated depolarization current, using integral and partial measurements in the temperature range from 137 to 270 K. Tow broadened peaks, assigned as Β1, and Β2, appeared at about 160 and 190 K. The influence of water and ¯Mn was investigated. The activation energy Ea vs. T relationship was analysed, and a search was made for compensation phenomena. The distribution of the relaxing dipolesN vs. Ea was approximated. Three different relaxation ranges were distinguished. All the motions were attributed to the rotation of the phenyl rings. The differences found are due to the heterogeneity in the resin. Contamination with water increases the polarizability, decreases the structure differences and relieves the motions in the resin. A resin with a smaller ¯Mn exhibits a higher polarizability and a decreases in structure variety. 相似文献