The effect of accelerator contents on the vulcanizate structures of SSBR/silica vulcanizates

Physical properties of rubber compounds are affected by the filler–rubber interaction, filler dispersion in the rubber matrix, and cross-link structure formed during vulcanization. In particular, the cross-link structure is closely related to the physical properties of vulcanizates and has been analyzed using the swelling test and Flory-Rehner equation. However, the relationship between the structure and physical properties of vulcanizates cannot be explained by the cross-link density obtained using these methods. The cross-link density obtained from the swelling test is a complex result of the filler–rubber interaction occurring during the compounding as well as the chemical cross-link structure formed by sulfur during the vulcanization. Moreover, the rubber vulcanizates that use silica need to be separately analyzed for each factor as its physical properties are affected more by the filler–rubber interaction than by carbon black. Therefore, this study determines the factors that contribute to the total cross-link density of vulcanizates into chemical cross-link density and filler–rubber interaction via quantitative analysis using the swelling test results and Flory-Rehner and Kraus equations. The vulcanizates used for the analysis were carbon black-filled and silica-filled non-functionalized SSBR compounds with varying cure accelerator for each filler loading. Their chemical cross-link density was measured and the effect of the filler–rubber interactions on their mechanical and dynamic viscoelastic properties was investigated. Furthermore, the relationship between the structure and physical properties of rubber vulcanizates was elucidated.     

砂轮约束磨粒喷射加工表面的分形及摩擦特性研究

对砂轮约束磨粒喷射精密光整加工(Abrasive Jet Precision Finishing,AJF)表面进行分形维数和摩擦磨损特性研究.试验在MB1332A外圆磨床上完成,加工式样为Ra为0.6μm左右的45#钢.加工表面形貌和微观几何参数用MICROMESVRE2表面轮廓仪测量;应用分形维数和功率谱密度函数评价磨削加工和光整加工表面的微观形貌特征;利用MG-2000型销盘式高速高温摩擦磨损试验机研究表面形貌和分形维数对摩擦系数和磨损性能的影响.试验结果表明:磨粒喷射精密光整加工使工件表面高度特性参数大幅度降低,轮廓波动平均间距减小,波纹细密性提高.随着加工循环的增加,Ra值由0.6μm下降到0.2μm左右.光整加工表面摩擦系数和磨损量与磨削加工表面相比明显降低,摩擦磨损试验结果和分形维数变化相吻合.     

不同组分下三乙烯四胺交联壳聚糖对重金属离子的吸附性能

三乙烯四胺;交联;壳聚糖;重金属离子;吸附     

圆钢高精度冷连轧的理论解析

利用主应力法推导出圆钢高精度冷连轧的轧制力理论计算公式，计算结果与实验结果相比较，两者吻合较好。该解析解可在工程上推广应用。     

一次性唾液α-淀粉酶生物传感器的研制

基于丝网印刷技术在PVC薄膜上制备了一次性碳电极,用Nafion固定二茂铁(Fc)作为电子介体,将α-糖苷酶和葡萄糖氧化酶(GOD)滴加于二茂铁修饰的电极上,滴加明胶晾干,戊二醛间接交联固定制成一次性唾液α-淀粉酶生物传感器,用计时电流法测定对α-淀粉酶的响应.实验结果表明,该传感器响应电流与α-淀粉酶活性在60～840 U/L之间呈现良好的线性关系,检出限为17 U/L.该生物传感器响应时间短,达到95%稳态响应时间不超过30 s,具有良好的一致性、准确性和稳定性.探讨了pH、缓冲液、温度及其它干扰物质等对该传感器的影响.该传感器可用于唾液α-淀粉酶浓度的快速、准确检测.     

Investigation of the flammability of different textile fabrics using micro-scale combustion calorimetry

Evaluating and analyzing the performance of flame retardant (FR) textiles are a critical part of research and development of new FR textiles products by the industry. The testing methods currently used in the industry have significant limitations. Most analytical and testing techniques are not able to measure heat release rate (HRR), the single most important parameter in evaluating the fire hazard of materials. It is difficult to measure HRR of textile fabrics using cone calorimetry because textile fabrics are dimensionally thin samples. The recently developed micro-scale combustion calorimetry (MCC) is able to measure the following flammability parameters for textile using milligram sample sizes: heat release capacity, HRR, temperature at peak heat release rate (PHRR), total heat release and char yield. In this research, we applied MCC to evaluate the flammability of different textile fabrics including cotton, rayon, cellulose acetate, silk, nylon, polyester, polypropylene, acrylic fibers, Nomex and Kevlar. We also studied the cotton fabrics treated with different flame retardants. We found that MCC is able to differentiate small differences in flammability of textile materials treated with flame retardants. We were also be able to calculate the limiting oxygen index (LOI) using the thermal combustion properties of various textile samples measured by the MCC. The calculated LOI data have yielded good agreement with experimental LOI results. Thus, we conclude that MCC is an effective new analytical technique for measuring textile flammability and has great potentials in the research and development of new flame retardants for textiles.     

大口径非球面元件可控气囊抛光系统

根据大口径非球面光学元件的实际加工需要,设计并制造可控气囊抛光系统,并对机构进行运动学仿真,仿真结果表明,气囊自转轴的运动空间可以满足大口径非球面光学元件的连续进动加工要求。为了证明所设计系统的可加工性,以直径320 mm的圆形平面光学元件进行加工实验。经过该气囊抛光工具24 h的抛光后,工件达到较好的面型精度,光学元件的表面粗糙度由0.272减小到0.068(＝632.8 nm), PV值从1.671降低到0.905。对光学元件的实际加工实验结果表明:可控气囊抛光系统在加工过程中结构稳定性好,符合设计要求,可有效提高加工工件面型精度。     

改性有机硅微乳的制备

采用特殊的生产工艺及预乳化方式，选择合适的表面活性剂和有机硅活性物，可以制得稳定，透明的改性有机硅微乳，改善了织物整理效果。     

Evaluation of physico-mechanical properties of precipitated polyurethane films in medium of free radical agents

Segmented poly(ester-urethanes) (PU) elastomers based on poly(ethylene diethylene adipate)diols as a soft segment and aromatic diisocyanates in the hard segment were synthesized by a conventional method. The precipitated PU elastomers films have been degraded after a limited exposure to free radical agents. An increase of the ratio of radical agents had an increase in the hard segment content which was associated with increased hard microdomain crystallinity, hardness and improvement in mechanical properties. It is suggested that the superior mechanical performance may be related to a interconnecting hard microdomain texture by a radical cross-linking process. The present study attempts to correlate the physical-mechanical properties of the precipitated PU films with the concentration of the free radical agents. In all cases, the effect of free radical cross-linking was to increase the ultimate tensile strain.