Crystallization behavior,heat resistance,and mechanical performances of PLLA/myo‐inositol blends

In this work, use of myo‐inositol as a biobased nucleating agent (NA) for PLLA was researched. Effects of myo‐inositol on non‐isothermal and isothermal crystallization behaviors of PLLA at temperatures ranged from 85 °C to 130 °C were studied by using DSC, POM and WAXD. Isothermal crystallization kinetics results showed that the incorporation of myo‐inositol enhanced significantly the crystallization rate of the PLLA samples. It was confirmed that the optimum isothermal crystallization temperature range was 100 to 110 °C. The above results were instructive to confirm proper heat treatment time and temperature for compression or injection molding to fabricate highly crystallized PLLA articles. The relations among heat treatment time, crystallinity, heat resistance, and mechanical performances of the neat PLLA and PLLA/1% myo‐inositol specimens prepared by compression molding were investigated. Compared with the PLLA specimens, the PLLA/1% myo‐inositol specimens showed a shorter heat treatment time to reach the maximum crystallinity. Vicat softening temperature, as well as tensile strength, modulus, and toughness of the PLLA/1% myo‐inositol specimens was improved when crystallinity increased from 5.4% to 38.1%. Considering the nontoxicity and biocompatibility of myo‐inositol, PLLA/myo‐inositol blends would be potential to prepare some products, which are required higher health standard and can be used in elevated temperature environments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44732.     

玻璃熔窑池壁侵蚀机理的研究(二)

运用X射线衍射分析,对池壁各特征点处侵蚀前后的耐火材料试样通过受侵材料的X谱图所呈现出的衍射峰图进行所含晶相的分析,研究玻璃窑池壁的侵蚀机理以及不同点处的差异.     

聚碳酸亚丙酯/壳聚糖熔融共混改性研究

采用熔融共混法将聚碳酸亚丙酯(PPC)与壳聚糖(CS)共混改性,研究了CS含量对PPC/CS共混物相容性、玻璃化转变温度(Tg)、热失重温度和拉伸性能的影响,并探讨了CS改性PPC的作用机理。结果表明:PPC与CS的共混属于简单物理共混,CS对PPC的Tg影响不大,但可显著提高PPC基体的耐热性能,扩大复合材料的加工温度范围。同纯PPC相比,PPC/CS共混物的TGA曲线向高温区偏移,共混物的5%分解温度(T-5%)较PPC提高了51⁵9℃,其50%分解温度(T-50%)提高了1259℃,其50%分解温度(T-50%)提高了12²1℃;另外,共混物的TGA曲线只存在一个高温区的失重台阶,这是由于CS的引入抑制了PPC在低温区的解拉链式降解,因而只有高温区的无规降解发生。此外,随着CS含量的增加,PPC/CS共混物的拉伸强度不断增大,当CS含量增至20%时,材料的拉伸强度由纯PPC的4.7 MPa上升至12.5 MPa。     

Isothermal melt crystallization and performance evaluation of polylactide/thermoplastic polyester blends with multi‐functional epoxy

A multi‐functional epoxy (ADR) was used to improve compatibilization of poly(lactic acid) (PLA)/ thermoplastic polyester elastomer (TPEE) blends. Influence of ADR on isothermal melt crystallization of the blends was investigated. The results show that isothermal melt crystallization rate of the samples increases with ADR loading. It can be attributed to a nucleation enhancement resulted from an increase of molecular weight and melt viscosity created by the chain extension/branched process of PLA in the presence of ADR. In addition, the maximum crystallinity of the samples shows a decrease with increasing ADR loading because of the chain extended and branched reaction. Quenched and crystallized samples were fabricated using compression molding under different cooling conditions in‐mold. Effects of crystallinity and ADR on mechanical performances of the PLA/TPEE sample were investigated. With increasing the crystallinity, the PLA/TPEE sample shows a marked enhancement in heat resistance. However, the tensile ductility of the crystallized PLA/TPEE sample drastically decreases due to the formation of firm crystal crosslinking and the incompatibility between PLA and TPEE. It is notable that the tensile ductility of the crystallized samples is improved with the introduction of ADR owing to its reactive compatibilization effect. Finally, the crystallized PLA/TPEE/ADR samples with improved heat resistance and relative higher ductility are obtained. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46343.     

新型易溃散改性水玻璃砂的研究

介绍了水玻璃工艺研究取得的最新进展，研制的新型改性水玻璃是一种无机和有机相复合的铸造粘剂，具有常温强度高，残留强度低，抗吸湿性好等优点，生产实际表明，采用新型改性水玻璃粘结剂的酯硬化工艺，可使水玻璃的加入量降为2．5％－3．0％，水玻璃砂的溃散性显著改善。     

上海源水中DOM的分子质量及去除特性

采用分子质量排除高性能液相色谱仪 (SE—HPLC)对长江和黄浦江原水及经常规处理出水中溶解性有机物 (DOM)的分子质量分布进行了测定 ,原水中DOM分子质量分别为 80 0～ 44 0 0u和 80 0～ 1130 0u。长江原水经常规处理后的DOM分子质量分布基本不变 ,对不同分子质量的物质均有不同程度的去除 ,且分子质量越低 ,常规处理对UV2 60 的去除率也越小 ;而黄浦江原水经常规处理后有机物的分子质量分布向低分子侧推移 ,表明对大分子的去除率优于小分子 ,特别是对分子质量 <30 0 0u有机物的去除率极低。     

人本管理与激励政策之我见

高校教师肩负着培养国家建设需要的高级人才和专门人才的重大历史使命，如何调动他们教书育人的积极性和热情，是一个非常重要的问题。实践证明，调动高校教师工作的积极性和热情，实行人本管理加激励政策是有效和科学的策略。     

绿岩型金矿地质特征成因及找矿方向初探

本文通过对加拿大赫姆洛金矿与吉林夹皮沟金矿的矿床地质特征及控矿条件的分析和讨论,认为两个矿床的成因类型均属前寒武纪绿岩型变质热液金矿床,并指出了在我国寻找本类矿床的方向。     

隐蔽通道发现技术综述

本文首先解释了隐蔽通道的概念，介绍了隐蔽通道的分类。然后花主要精力，结合实例概述了当代国际上已经使用过的隐蔽通道的方法。并且对目前已有的这些方法从不同的方面给出了对比性的评价。在文章的讨论部分，作者基于目前的形势以及传统发现方法的限制给出了针对隐蔽通道发现方法建设性的见解和展望。     

On discrete dynamic output feedback min-max controllers

The paper considers output feedback min-max controllers for non-square discrete time uncertain linear systems. Based on previous work, it is demonstrated that static output feedback min-max controllers are only realizable for a specific class of systems. To broaden this class, a compensator based framework is proposed to introduce additional degrees of freedom. The conditions for the existence of such dynamic output feedback min-max controllers are given and are shown to be relatively mild. Furthermore, a simple parameterization of the available design freedom is proposed. An explicit procedure is described which shows how a Lyapunov matrix, which satisfies both a discrete Riccati inequality and a structural constraint, can be obtained using Linear matrix inequality optimization. This Lyapunov matrix is used to calculate the robustness bounds associated with the closed-loop system. A simple aircraft example is provided to demonstrate the efficacy of the design approach.