色谱光谱法测试超临界压力下穿心莲内酯的结晶规律

以30%和95%的穿心莲内酯为实验原料,采用超临界CO2萃取结晶法考察了不同压力下穿心莲内酯在结晶板上的分布规律,同时也考察了晶体的晶型和红外光谱的变化规律。研究证实： 高效液相色谱分析,不同压力下穿心莲内酯在结晶板上都按纯度梯度结晶分布;X射线衍射分析,压力越高,晶体越趋于向比较单一的晶面上择优生长;红外光谱分析,压力的变化,并没有引起穿心莲内酯化学结构的改变。     

退火与极化温度对尼龙11薄膜驻极体内陷阱能级分布的影响

用热释电技术研究了尼龙11薄膜驻极体制备过程中热处理与极化温度对驻极体陷阱能级分布的影响.结果显示，淬火驻极体的热释电流谱上存在四个空间电荷退陷阱电流峰，而在退火处理后则显示两个退陷阱电流峰.采用多点法对热释电流谱进行理论拟合可以将各个退陷阱电流峰分离并得到它们的陷阱深度参数.这些参数进一步表明，淬火尼龙11薄膜驻极体内存在四个空间电荷的陷阱能级，极化温度升高对它们的分布情况影响不大；退火处理后，陷阱能级减少为两个，且随着极化温度的升高，较浅的陷阱能级有明显向较深陷阱能级接近的趋势. 关键词： 尼龙11 薄膜驻极体 热释电 热处理     

DIELECTRIC RELAXATIONS IN FERROELECTRIC COPOLYMER VINYLIDENE FLUORIDE(65)/TRIFLUOROETHYLENE(35)

The molecular motion characteristics of ferroelectric copolymer vinylidene fluo-ride(65)/trifluoroethylene(35) have been investigated by means of dielectric relaxation. The frequency spectra of the copolymer consisting of low-frequency and high-frequency compo-nents are observed below room temperature. With the rise of crystallinity, the Curie point decreases while the dielectric constant increases in the region of ferroelectric-to-paraelectric phase transition. Based on the fitting results using one or two Cole-Cole functions, and cal-culating with the WLF equation and an Arrhenius formula, the glass transition temperature (= -28℃) and the activation energy of local relaxation (= 54.4 kJ·mol^-1) of the copolymer are obtained. It is found that the distribution of relaxation time in the molten and the ferroelectric phases is located at a same line, which complies with the Arrhenius rule. This indicates that the elementary motions are of the same type for molecular motions provided by the high-temperature process and the low-temperature local mode process.     

结构改变对聚对苯二甲酸乙二醇酯局域能级性质的影响

用双轴拉伸、热处理和γ射线辐照的方法制备了一系列具有不同平面取向度,不同结晶度和不同分子链长度的PET试样。通过热释电极化温度扫描法分离出对解俘获电流峰贡献的各局域能级峰。平面取向度、结晶度和γ辐照剂量的提高引起局域能级深度增加,结构缺陷种类的增多导致局域能级数增大(由二个增至六个),能级深度分布加宽。     

钛酸铅与偏氟乙烯-三氟乙烯共聚物形成的铁电复合物相变过程的热释电研究

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）」的热秋电流行为。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     

一道获奖命题的巧证

《首届全国数学奥林匹克命题比赛精选》一书中,有这样一个获奖题目:凸四边形ABCD的两组对边互不平行,线段P1P2位于四边形内部.如果P1、P2两点分别到四边距离之和都等于m,那么,P1P2上任意一点到四边距离之和也等于m.给出的解答较繁,笔者以引人参数巧证,简明得多. 证明设P1、P2到四边距离依次为a1、b1、c1、d1,a2、b2、c2、d2,P为P2上任一点, 设P1P/P1P2=λ,P到四边距离分别a、b、c、d.     

Effect of heating treatment on trap level distribution in polyamide 66 film electrets

The effect of heating treatment on the trap level distribution in polyamide 66 film electret is studied by thermally stimulated depolarization current （TSDC） technique. For annealed polyamide 66, there are three trap levels that respectively originate from space charge trapped in amorphous phase, interphase and crystalline phase. There is one peak that originates from space charge trapped in amorphous phase for quenched one. Using multi-point method to fit the experimental curves, the detrapping current peaks can be separated and the trap depth is obtained. The shallower trap levels trapped in amorphous phase and interphase are obviously close to the deeper trap level trapped in crystalline phase for annealed polyamide 66 as the polarization temperature increases, while the trap level distribution remains unaffected by polarization temperature for quenched one.