双旋Y切石英振子厚度模式的频温特性的研究

本文利用描述固体中弹性声波的克里斯托费尔方程,建立了双旋Y切石英振子厚度模式的频温特性分析方法,并编制了相应的计算机程序。该程序可给出双旋Y切石英振子在任意切角(ф_3ф_1)下的厚度模(a、b、c模)的频率温度特性曲线。文中给出了单旋AT切、BT切(b模)、双旋SC切(b、c模)、FC切、IT切、LC切、NL_1切、NL_2切、AK切等各已知切型的频温特性曲线。对石英谐振器的切角灵敏度和切角误差进行了分析。     

Local Structure of Alkaline-Earth Boroaluminate Crystals and Glasses: II, 11B and 27Al MAS NMR Spectroscopy of Alkaline-Earth Boroaluminate Glasses

¹¹B and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra of alkaline-earth boroaluminate glasses show that the structure of these glasses are far more complicated than previously thought. The relative concentrations of 3- and 4-coordinated boron vary as found by previous investigators using continuous-wave NMR methods, but the ²⁷Al NMR spectra indicate the presence of Al in 4-, 5-, and 6-fold coordination, in contrast to previous assignments. Analysis of the data based on local charge balance considerations provides a qualitative model that correctly predicts compositional variations of the NMR peak intensities and ²⁷Al chemical shifts for a wide range of boroaluminate glass compositions.     

Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide

The glass‐transition temperature as a function of curing conversion for a modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide (BMI) resin was investigated at different temperature regimes and modeled using a modified Di Benedetto equation. Although the relationship between the glass‐transition temperature and conversion of the BMI system conforms to the Di Benedetto equation for α < 0.6 and at lower cure temperatures, at higher cure temperatures the results deviated significantly from the equation; thus, it was an inadequate model for the system. Fourier transform IR analysis showed that the major crosslinking reactions did not occur during cure for the modified BMI at and below 150°C. However, as the cure temperature was increased, the crosslinking reactions responsible for 3‐dimensional network structures became more dominant. At 190°C the C? N? C_stretch vibration of the uncured maleimide ring converted into succinimide rings in the curing process. Simultaneously, a decrease was observed for the absorbance bands of ? C? H_bending (maleimide). The higher cure temperatures induced a significantly faster initial crosslinking rate and also resulted in a shorter period of time after which further crosslinking was retarded, because the increase in the crosslinks also physically slowed further crosslinking activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 227–235, 2002     

Experimental evaluation of the strength distribution of E-glass fibres at high strain rates

A bimodal Weibull distribution function was applied to analyse the strength distribution of glass fibre bundles under tensile impact. The simulation was performed using a one-dimensional damage constitutive model. The results show that there were two concurrent flaw populations in the fracture process. The regression analysis using the bimodal Weibull distribution function was in good agreement with experiment.     

Dynamics of hydrated iron(II) cations in nafion polymer membranes

Mössbauer studies of Fe²⁺ in water-soaked nafion polymer membranes in the temperature range between 90 K and 250 K have been performed. Above a critical temperature (～ 180 K) the spectra exhibit both elastic narrow absorption lines and quasielastic broad lines. These spectra are typical of bounded diffusion phenomena observed by Mössbauer spectroscopy in macromolecular systems like haemoglobin, myoglobin and ferritin. Similar spectral shapes have been observed by quasielastic neutron scattering from water in nafion membranes. Within 50 K above the critical temperature the total Mössbauer absorption area decreases by an order of magnitude whereas the narrow absorption line decreases by two orders of magnitude. The results are interpreted in terms of bounded diffusive motion of the iron. Using a model based on overdamped harmonically bound Brownian motion, the essential parameters of the iron motion can be derived as a function of temperature. The iron motion most probably reflects the motion of a large Fe²⁺ complex, e.g. Fe(H₂O)²⁺₆, which is attached to the polymer side chains via the sulphonic group.     

拉伸速率对PP/GB复合材料力学性能的影响

应用Instron材料试验机考察了室温下拉伸速率对玻璃微珠填充聚丙烯复合材料的弹性模量和屈服强度的影响，结果表明，随着微珠含量的增加，试样的弹性模量（Ec）增大，且与拉伸应变速率呈近乎幂律函数关系，而屈服强度（бyc）则随着微珠体积分数（Φf）的增加呈线性函数形式下降，并随着拉伸应变速率的增加呈幂律函数形式提高，此外，讨论了Ec、Φf与бyc三者之间的关系。     

玻璃工业中的计算机应用

本文对国内外微机在玻璃工业中的应用现状进行了综述与评价 ,主要讨论微机应用对玻璃工业的影响 ,并初步探讨了玻璃工业中微机应用的前景     

Sol-gel processing: A versatile concept for special glasses and ceramics

The various parameters related to sol-gel processing are discussed with special reference to those which usually attract less attention but depending on the final product in mind, can play important roles. The versatility of the sol-gel technique in materials preparation is demonstrated by discussing the various products developed at the author’s laboratory by using this processing method.     

改性玻纤增强尼龙610,1010塑料

研究了采用(准)中粘度级尼龙做基体树脂,加入成核剂改善尼龙的结晶过程,提高结晶速率和初始熔融温度;添加光、热氧稳定剂,防止尼龙在成型加工和使用过程中产生降解与老化,提高塑料制品的质量和减少性能的分散性;采用合理的工艺条件,确保添加剂的均匀分散与减少玻纤的磨损,得到适于军工、航空和机电等领域需要的高性能的受力结构工程塑料。     

Ce3+离子对掺Er3+碲酸盐玻璃光谱性质的影响

研究了Ce3 + 对掺Er碲酸盐玻璃荧光光谱性质的影响 ,比较了不同的Ce3 + 掺杂浓度下Er3 + 离子荧光发光强度的变化 ,分析了Ce3 + 离子对Er3 + 离子作用的原理 ,应用经典方程计算了Er3 + 离子 4I1 1 / 2 能级的荧光寿命及其变化