贴片胶的特性与使用方法

本文主要介绍贴片胶的特性 ,在各种工艺下的使用方法及使用中出现的不良与对策 ,并简要分析了贴片胶的未来发展趋势     

陶瓷釉浆的触变性及其调控措施

本文简要说明了对釉浆触变性进行调节和控制的重要意义，详细分析了导致釉浆触变性过大的原因，通过试验明确了解决釉浆触变性过大问题可采取的具体措施。     

Lateral stress exerted by fresh cement paste on formwork: Laboratory experiments

In the present paper, experimental results from laboratory testing on cement pastes are presented. The validity of both the predictions of the model proposed by Ovarlez and Roussel [Mat. and Struct. 39(2) (2006)] and the assumptions on which the model is based in the case of rough interfaces between the cement paste and the formwork surface are validated. The consistency of the underlying theory is tested in several different configurations (plate test with large and narrow gaps and a column test). Finally, the concept of a new test allowing the measurement of the structuration at rest of a cementitious material is proposed. Such a simple test might be used to assess the input parameters needed to predict formwork pressure without the need for a rheometer.     

乙基纤维素和聚酰胺蜡在晶硅太阳电池电极材料中的应用

通过分析乙基纤维素和聚酰胺蜡在不同溶剂和载体中的粘度及触变性能的作用规律,以研究其对太阳电池正银浆料的丝印特性和电池电极形貌、致密度及电学性能等的关系。发现乙基纤维素和聚酰胺蜡在溶剂中对溶液的粘度分别起到了不同的作用,从而影响着正银浆料的触变和流变性能。其中,乙基纤维素在溶液中的主要作用是提高浆料的整体粘度,而聚酰胺蜡在溶液中主要起着增强浆料剪切变稀的能力。由于浆料的丝印特性主要是通过调节浆料的触变性能来优化的。因此,乙基纤维素和聚酰胺蜡在浆料中的比例对浆料的丝印特性起着十分关键的作用。通过对比乙基纤维素和聚酰胺蜡在浆料中的不同比例对其触变性能及对电池正面电极形貌、致密度和电阻率的影响。结果表明,当乙基纤维素与聚酰胺蜡在浆料中的比例为1:5时,电池栅线电极的高宽比达到最大值,同时栅线电极的线电阻也达到最小值,因此正银浆料达到一个较好的印刷性能。     

溶聚丁苯橡胶/白碳黑复合料在高性能胎面胶中的性能研究

本文对充不同环保橡胶油溶聚丁苯橡胶(SSBR)在高性能轮胎胎面胶中的性能进行了研究,特别是SSBR(ZG-SSBR)与同类国产及进口产品在加工行为及物理性能等方面进行了对比。 结果表明,ZG-SSBR具有卓越的加工性能、优越的物理机械性能、较低的滚动阻力、优良的抗湿滑性、在低或高充油量下胎面胶的综合性能不亚于进口同类产品,ZG-SSBR是高性能轮胎胎面胶料的理想材料。     

疏水缔合聚合物压裂液稠化剂LP-3A的研究

采用反相乳液聚合方法,以AM、AMPS、带疏水链及聚氧乙烯基团的可聚合单体为原料,以过氧化苯甲酰（BPO）为引发剂,合成出新型疏水缔合聚合物稠化剂LP-3A。在室内通过单因素法得到了聚合反应最优单体比例、反应时间、反应温度、引发剂加量,并对LP-3A进行结构表征及耐温耐剪切性能、剪切恢复性能、黏弹性能、触变性能的研究。结果表明, LP-3A耐温耐剪切性能良好,在150℃、170 s-1下剪切2 h,剩余黏度为200 mPa·s ;剪切恢复率高,经过500 s-1、1 000 s-1剪切20 min后,停止剪切的黏度恢复率为90%;黏弹性能及分子网络结构稳定性优于瓜胶压裂液,相比瓜胶,破坏LP-3A结构所需的能量较大,结构恢复所需的时间也较长,在LP-3A压裂液中弹性占主导地位,且黏弹性优于瓜胶压裂液。      

Time-independent and time-dependent rheological characterization of vegetable-based infant purees

Flow behavior of vegetable-based infant purees was analyzed at different temperatures (5–65 °C) giving particular attention to their time-dependent properties in a shear rate range (5–200 s⁻¹). Power law model parameters describing flow behavior of samples depended on kind of infant puree, its water content and measurement temperature. Arrhenius model was used to explain temperature effect on apparent viscosity at 50 s⁻¹. Infant purees exhibited thixotropic behavior for all temperatures tested. For the same temperature, differences in hysteresis loop magnitudes were observed among purees, being more noticeable at lower temperatures. Two models were used to describe the time-dependent behavior, namely Weltman model, and second-order structural kinetic model. For all infant purees, the initial shear stress and the extent of thixotropy increased and decreased significantly with increases in shear rate and temperature. The breakdown rate of puree associations also accelerated at higher shear rates, but no trend was observed with temperature.     

Rheological behavior of blueberry (Vaccinium ashei) purees containing xanthan gum and fructose as ingredients

In the present work the influence of temperature, xanthan gum and fructose addition on rheological behavior in steady state of blueberry puree was evaluated. The blueberry pulp was formulated with addition of xanthan gum (1.6, 2.0, 2.5, 3.0 and 3.3%) and fructose (6.6, 10.0, 15.0, 20.0 and 23.4%). Rheological data were obtained by shear rate scan tests in a rotational rheometer, with geometry of concentric cylinders in temperatures of 27, 40, 60, 80 and 93 °C. The thixotropy analysis was made through the calculation of the difference between the areas under up and down cycles’ flow curves. The analysis of the formulation influence on puree viscosity was carried out in two stages: i) selection of an appropriate rheological model for representation of data obtained in experiments and ii) statistical analysis of formulation and temperature influence on rheological parameters of selected model. Three 2-parameter models (Bingham, Ostwald–de Waele and Casson) and three 3-parameter models (Herschel–Bulkley, Mizrahi–Berk and Sisko) were tested. Based on the values of correlation coefficients and variance of the estimated parameters, Casson model was chosen for fitting of experimental data. The content of xanthan gum appears as a determinant variable of the rheological behavior of the puree, both at short and long times. The correlation among the variables studied was represented through statistical models which could be used for the development of formulations with specified viscosity in the range of additive concentrations studied.     

Thixotropic mechanism of clay: A microstructural investigation

Clays with high sensitivity exhibit varied degrees of thixotropic characteristics. Previous research has been focused on dilute suspensions, but only a few studies have investigated normal clay with water contents lower than the liquid limit. Given the limited studies performed, the thixotropic behavior of clays and the underlying mechanism remain ambiguous, particularly in the microscopic scale. In this study, samples of Zhanjiang clay from southern China were used to elucidate the thixotropic process. The samples were agitated and then subjected to unconfined compressive strength and pocket penetrometer tests, scanning electron microscopy, and mercury intrusion porosimetry to evaluate their regain strength and microstructure. After 500 d of thixotropy, the strength of the Zhanjiang clay was 2.58 times higher than that after the disturbance and significantly higher than that of the other clays reported in the literature. These findings provide evidence that thixotropy is a process in which the dispersed structure is transformed into a flocculent structure through the homogenization of the pore size distribution caused by particle movement. This phenomenon may be due to the changes in the interaction of attractive and repulsive forces between particles. Given the experimental findings, a thixotropic mechanism for clay is proposed. This study will be beneficial for predicting the strength of disturbed soils.