Adhesion Mechanisms of Polyurethanes to Glass Surfaces. III. Investigation of Possible Physico-Chemical Interactions at the Interphase

Surface free energies of polyurethanes made from toluene diisocyanate and 1, 4 butanediol-based hard segments and caprolactone polyol-based soft segments were calculated using additive functions. Good agreement was found between the calculated values based on additive functions and the calculated values based on contact angle measurements. The phase-separated polyurethanes were found to have a higher polar surface free energy component (γ^P). This was linked to the preferential segregation of butanediol/butanediol-derived moieties to the polyurethane surfaces due to phase separation. The adhesion values of these polyurethanes to soda-lime glass were correlated with their respective γ^P values and a linear relationship was found. It was also shown that the adhesion values of the low γ^P polyurethanes improved substantially when the glass surfaces were coated with a thin layer of butanediol prior to the bonding. The modulus of the interphase region rich in butanediol was evaluated. Although a modulus increase was found at the interface, this increase was found to play a secondary role in the adhesion. The chemical interactions at the polyurethane/glass interphase were investigated by pre-treating the glass surfaces with methyl-trimethoxysilane and trimethylchlorosilane prior to adhesion testing. The adhesion data showed no significant difference between the uncoated and the silane-treated glass substrates. Based on this experimental evidence, the possibility of any covalent or ionic bonding at the polyurethane/glass interphase was assumed negligible. It was determined that the mechanism of adhesion between the polyurethanes and the glass surface could be through the formation of an interphase region in which hydrogen bonding between the butanediol-rich interphase region and the hydroxylated glass surface plays a key role.     

掺Tb_2O_3法拉第旋转玻璃

本文研究了掺Tb_2O_3的法拉第旋转玻璃的组成、物理化学性质及制备技术,实验结果表明维尔德常数V随着Tb_2O_3浓度的增大而增大,硼硅酸盐玻璃中Tb_2O_3含量大于20％(mol)时,维尔德常数可以达到-0.0030min/A/m·cm,从熔制试验结果0.5L铂坩埚可以获得质量较好的φ50×25mm的样品。     

气垫性能及平板玻璃缓冲包装

对我国发明的缓冲包装气垫进行静态试验,测其载荷-变形曲线,表明它属于正切型;对气垫作为内衬的PZOV型平板玻璃包装件进行冲击和振动试验,证明具有优良的防震缓冲性能,适于平板玻璃的运输包装。     

新型梳形电缆防火墙的应用

通过新型梳形电缆防火墙的实施，有效地限制了电缆火灾范围，增强了电缆防火、隔火能力，并详细地介绍了梳形电缆防火墙的原理结构、安装使用和注意事项。     

电容器介质吸收电流的测量和表征

在外电场作用下，电容器介质的吸收电流和漏电电流混杂而难以分开，但外电场除去后吸收电流对电容器放电总电荷所贡献的百分比具有确定值，吸收电流的释放遵从自由弛豫规律。可用响应时间ｒ’表征。实验给出了一些常见介质的吸收电流表征参数。     

填充HDPE复合材料基体结晶形态的控制因素

本文以HDPE/玻璃微珠和HDPE/CaCO₃体系为研究模型,通过扫描电镜、红外光谱、偏光显微、小角激光散射和材料力学性能实验等方法考察了这两种体系的界面粘结性、填料含量、粒径及试样成型冷却速率等与其材料性能及基体结晶形态变化间的关系。实验结果表明;在复合材料试样成型过程中,因基体树脂冷却收缩而产生的界面应力可干扰基体中球晶的生长环境,应变诱导填料颗粒周围基体树脂的结晶,促使其表面伸展链晶体结构的形成,并由此而明显改变了复合材料的耐热性;复合材料的界面粘结性是产生这种应变诱导作用,并控制异相结晶的关键。     

多功能新材质屋面板设计施工

通过设计一种具有透明、保温、防水、防腐等多功能,且自重仅为原预应力砼屋面板10%的钢框玻璃钢罩屋面板,解决老厂屋面改造存在的生产与施工难题.     

Sidechain liquid crystal polymers

Research has continued in the field sidechain liquid crystal polymers over recent years, but it is becoming clearer that this research is being directed away from the traditional technology areas of electro-optic devices and researchers are developing new and exciting applications for this novel state of matter.     

Extremal optimization vs. learning automata: Strategies for spin selection in portfolio selection problems

Nowadays, various imitations of natural processes are used to solve challenging optimization problems faster and more accurately. Spin glass based optimization, specifically, has shown strong local search capability and parallel processing. But, spin glasses have a low rate of convergence since they use Monte Carlo simulation techniques such as simulated annealing (SA). Here, we propose two algorithms that combine the long range effect in spin glasses with extremal optimization (EO-SA) and learning automata (LA-SA). Instead of arbitrarily flipping spins at each step, these two strategies aim to choose the next spin and selectively exploiting the optimization landscape. As shown in this paper, this selection strategy can lead to faster rate of convergence and improved performance. The resulting two algorithms are then used to solve portfolio selection problem that is a non-polynomial (NP) complete problem. Comparison of test results indicates that the two algorithms, while being very different in strategy, provide similar performance and reach comparable probability distributions for spin selection. Furthermore, experiments show there is no difference in speed of LA-SA or EO-SA for glasses with fewer spins, but EO-SA responds much better than LA-SA for large glasses. This is confirmed by tests results of five of the world's major stock markets. In the last, the convergence speed is compared to other heuristic methods such as Neural Network (NN), Tabu Search (TS), and Genetic Algorithm (GA) to approve the truthfulness of proposed methods.     

On the use of the WLF model in polymers and foods.

The validity of the WLF model with fixed "universal" coefficients was tested against that of the model original form with variable coefficients using published coefficients of polymers and amorphous sugars crystallization and viscosity data. The disagreement between the two versions of the model is particularly large at temperature ranges starting about 20 to 30 degrees K above the glass transition or reference temperature, excluding the former from being a model of general applicability. Because the WLF model mathematical structure entails the existence of an almost linear region near the reference temperature, establishment of its validity as a kinetic model and meaningful determination of its constants requires data spread over an extended temperature range, especially when the experimental results have a scatter.