葡聚糖水溶液流变性研究

本实验研究了葡聚糖水溶液的流变性能,选取了五种不同分子量的葡聚糖,分别考查了分子量、溶液浓度、溶液温度等因素对葡聚糖水溶液流变性的影响。结果显示,多数葡聚糖水溶液表现出牛顿流体的特性,而当葡聚糖分子量为531000,溶液浓度为30%时,溶液则表现出假塑性流体的性质,黏度随着剪切速率的提高而降低。当葡聚糖浓度较低时(≤1%),水溶液均表现出一种特殊的流变性,即黏度随着剪切速率增加先降低后升高,本研究对出现这一现象的原因进行了分析。     

试论教学中的简单性原则

本文所谓“简单性原则”是指在教学过程中一切推导、表述、叙述都应是最简单的,即采用最简单的方法,最简单的语言,最简单的逻辑和最简单的形象。笔者以《高分子物理》教学中的教学实践为例,进行浅析。     

含侧基聚酯型聚氨酯耐水解性的研究

通过对比4种含有不同侧基结构的聚氨酯胶膜的力学性能和耐水解性,发现以含有较大空间位阻侧基的2-乙基-1,3-己二醇与己二酸合成聚酯二元醇（PEPO。EHO）为原料制备的聚氨酯胶膜具有较优异的耐水解性,而以1,3-丙二醇与己二酸合成聚酯二元醇（PEPO—PPD）为原料制备的聚氨酯胶膜具有较好的力学性能。选取PEPO-EHO与PEPO-PPD混合后制备出的聚氨酯胶膜力学性能和耐水解性较好。当PEPO-EHO与PEPO-PPD在软段中混合的质量分数分别为50％时,所制备的聚氨酯胶膜具有较好的综合性能。     

Effect of doping elements on catalytic performance of CeO2-ZrO2 solid solutions

CeZr, CeYZr, LaCeZr, LaCePrZr, LaCePrYZr, and LaCePr solid solutions were prepared via the coprecipitation method, and characterized by means of X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) techniques. The oxygen storage capacity (OSC) of the solid solutions was evaluated by the pulse technique and the catalytic activity was assessed using a 4-channel catalysis device. It was seen that the solid solutions presented cubic structure. The specific surface area and thermal stability could be enhanced by doping Y into the solid solutions. Doping a small amount of La had a positive effect on the thermal durability while doping a large amount of La decreased the specific surface area and the thermal stability. LaCePrZr and LaCePrYZr solid solutions synthesized using Baotou rare earth mineral residue enriched with LaCePr after Nd extraction presented a certain higher value in specific surface area and thermal stability, thereby enabling to be used as economic catalysts for automobile exhaust purification. Coating Al2O3 or SiO2 layer on the surface of ceria-zirconia solid solutions increased the specific surface area and thermal resistance.     

超高分子量聚乙烯增韧聚丙烯的“原位复合”增韧机理

用四螺杆挤出机制备了超高分子量聚乙烯增韧聚丙烯的共混合金。研究发现，合金中ＵＨＭＷＰＥ的形态是由沿其分子链形成的串联微晶粒和松散的分子链段束组成，并在ＰＰ基体中形成一种特殊的物理“互穿网络”结构。     

聚砜/环氧树脂体系的双连续相结构及其应变激励下的修复性能

研究了聚砜含量为10%的E-51/PSF/MTHPA/2,4-EMI共混体系在等温固化时双连续相相结构的演变过程及在不同应变下的自修复性能。扫描电子显微镜(SEM)和倒置相差显微镜照片验证了双连续相相结构的演变过程。倒置相差显微镜测试的结果表明,90℃固化3 h后聚砜/环氧固化体系伸长率较高,回弹及应力松弛性能较好,后固化样品的自修复性能较理想。