乙烯基单体-N-取代马来酰亚胺共聚物玻璃化温度研究

用差示扫描量热仪对乙烯基单体/N-取代马来酰亚胺共聚物的玻璃化温度(T_g)进行测定.研究了共聚物组成、序列结构、乙烯基单体和N-取代马来酰亚胺种类对共聚物T_g的影响.提出了含共聚物组成和序列结构的T_g预测方程,该方程不仅适合于无规共聚物,还适合于具有严重交替倾向的共聚物.     

含侧链苯炔基的热固性聚酰亚胺薄膜

聚酰亚胺;苯炔基;热稳定性;玻璃化转变温度;力学性能     

丙三醇浓溶液玻璃化转变与结构松弛参数DSC分析

In order to examine the effects of water contents and heating/cooling rates on the glass transition and the structure relaxation parameters of glycerol/water mixtures, five aqueous solutions (60%, 70%, 80%, 90% and 100%) were investigated using the differential scanning calorimetry. Four scanning rates (10, 15, 20, 25 K/min) were used to obtain the glass transition parameters. The fitting results of plasticization constants indicated that Gordon-Taylor relationship could not be used effectively without considering scanning rates and that point on calorimetric step was chosen as the glass transition temperature. The specific heat changes during glass transition processes were relative not only to water content but also to heating rates. With the increasing of water contents in glycerol aqueous solutions, the structure relaxation activation energies and dynamic fragilities were decreased. Since the thermodynamic fragilities were increased with the increasing of water content, so the dynamic fragility and thermodynamic fragility were changed inversely if the water contents were changed in glycerol/water mixtures.     

玻璃化液体中构型熵与展宽弛豫函数关系的研究

The relationship between the transport properties and thermodynamic properties in glass forming liquids was investigated. The configurational entropy of Adam-Gibbs theory on cooperatively rearranging regions and the theoretic function derived from extremal value model were used to propose a brief that non-exponential stretched exponent in KWW form relaxation function is equal to the relative configurational entropy of cooperatively rearranging region in liquids, and is inversely proportional to the critical number of molecules occurring configurational transformation in a cooperatively rearranging region. Therefore, the new physical significance on glassy configuration is imposed on the stretched exponent, and theoretical developments and empirical correlations between the structural relaxation and configurational entropy are established. Further, an improved expression of β(T) was proposed to eliminate the deviation of the fit by using Vogel-Fulcher-Tammann equation from viscosity data at higher temperatures, which conforms well over 200 K temperature range. The improvement on β(T) is correspondent to the improvement on the difference in thermal capacities between isobaric and isochoric processes.     

邻甲酚醛环氧树脂/聚氨酯互穿聚合物网络的形态与性能

邻甲酚醛环氧树脂/聚氨酯互穿聚合物网络的形态与性能;互穿聚合物网络; 邻甲酚醛环氧树脂; 聚氨酯; 力学性能; 玻璃化转变温度     

超支化聚醚的支化度对玻璃化转变温度的影响

聚合物的分子结构对聚合物性能影响很大.支化度不同的同种聚合物,必须通过不同的催化体系合成,很难得到既具有相近分子量又具有不同支化度的系列聚合物样品,因此对聚合物性能与支化度的依赖关系的研究报道不多.     

溶剂调控布洛芬乙烯酯酶促水解的立体选择性的热力学研究

采用高效液相色谱研究了不同溶剂体系中褶皱假丝酵母菌脂肪酶（CRL）催化布洛芬乙烯酯水解反应的立体选择性.研究发现,在单一溶剂体系中Eyring曲线呈线性,在10~50 ℃的实验温度内均呈S选择性;在混合溶剂体系中Eyring曲线呈非线性,且观察到不同的转变温度（T_inv）.研究还发现：在亲水性有机溶剂二氧六环/水均相混合溶剂体系中,Eyring曲线的T_inv处立体选择性E 值为极小值,在疏水性有机溶剂异辛烷/水两相混合溶剂体系中,T_inv处E 值为极大值,而在氯仿/水两相混合溶剂体系中,随着温度的变化,立体选择性发生了反转.     

高温退火对蓝宝石基片的表面形貌和对CeO缓冲层以及Tl-2212超导薄膜长的影响

研究了蓝宝石(1102)基片在不同温度和时间下退火时表面形貌和表面相结构的变化,以及它对CeO2缓冲层和T1-2212超导薄膜生长的影响.原子力显微镜(AFM)研究表明,在流动氧环境中1000℃温度下退火,蓝宝石(1102)的表面首先局部区域形成台阶结构,然后表面形成叠层台阶结构,随着退火时间的延长.表面发生了台阶合并现象,表面形貌最终演化为稳定的具有光滑平台的宽台阶结构.XRD测试表明,通过高温热处理可以大幅度提高蓝宝石基片表面结构的完整性.在1000℃温度下热处理20 h的蓝宝石(1102)基片上可以生长出具有面内取向的CeO2(001)缓冲层.在具有缓冲层的蓝宝石基片上可以制作出高质量c轴织构的外延11-2212超导薄膜,其临界转变温度(Tc)为104.7 K,液氮温度下临界电流密度(Jc)达到3.5 MA/cm2,微波表面电阻R(77 K,10 GHz)约为390μΩ.     

超支化聚缩水甘油的合成及性能

以三羟甲基丙烷为引发剂、缩水甘油(2,3-环氧-1-丙醇)为单体、无水N-甲基吡咯烷酮(NMP)为溶剂,采用阴离子开环聚合、一步法制备了超支化聚缩水甘油(hPG)。通过调控单体与引发剂的物质的量之比,成功合成了3种不同数均分子量的hPG;通过核磁共振氢谱、凝胶渗透色谱、傅里叶红外光谱等表征了hPG的支化结构、分子量及分布、化学官能团;采用差示扫描量热仪、热重分析仪、粒径-电位分析仪等分析了hPG的玻璃化转变温度(T_g)、热降解温度(T_d)及热稳定性和溶液性质等参数。结果表明,溶剂NMP的引入有利于hPG数均分子量的快速增加和单分散性的提升;hPG的T_g和T_d随着数均分子量的增加略有增加。     

临界现象的突破

法国Grenoble的CEA实验室和Grenoble强磁场实验室（GHMFL）的A．Huxley教授所领导的研究组将一块 锗-铑-铀（URhGe）样品的温度冷却并使其转变为超导体，在不施加磁场的条件下，它的超导转变温度Tc是280mK．正如预期的一样，将磁场逐渐加大到2T的过程中，超导转变温度也在逐渐降低．由于磁场是会破坏物质的超导性的，所以当磁场超过2T时URhGe样品的超导行为消失了,然而当研究组继续加大磁场到8T时，URhGe样品的超导行为又恢复了，当然这时的超导转变温度也变为400mK,将磁场继续增大到13T时，样品的超导性又一次消失了，Huxley的研究组发现UrhGe样品在磁场为12T附近经受了两种不同的相变。