生物可降解聚乳酸增韧共混改性研究进展

聚乳酸有生物可降解、环境友好等特点，发展前景广阔。同时聚乳酸存在硬且脆、不耐冲击等缺点，限制了它在韧性要求较高领域的应用。增韧共混改性具有操作简单、工业上容易实现、经济性好的优点，因此，从天然橡胶、热塑性弹性体、刚性颗粒、热塑性塑料和生物可降解材料这5种增韧材料入手，分析了聚乳酸增韧共混改性的主要研究成果，并比较了各种方法的优点和不足，探讨了其增韧原理。聚乳酸增韧共混改性效果的评价，应兼顾其他性能指标，如拉伸强度、耐热性、生物可降解性等。     

工业评述生物降解性塑料-聚乳酸研究进展

综述了聚乳酸的合成方法、聚合工艺、聚合机理等。介绍了用生物发酵法从厨房垃圾中提取乳酸，合成聚乳酸的新工艺路线，为聚乳酸类产品找到了廉价的原料来源。该方法不仅可降低聚乳酸类产品的生产成本，而且解决了厨房垃圾的处理问题，减少了环境污染。     

化学合成全降解塑料——聚乳酸

聚乳酸是一种化学合成的新型降解塑料，它能完全生物降解生成CO2和H2O。聚乳酸的生产方法有丙交酯法和直接聚合法，介绍了聚乳酸的物理力学性能，用途，生物分解特性，以及国外的产业动态，研究和生产聚乳酸，对于解决“白色污染”具有积极意义。     

新一代100％生物可降解塑料聚乳酸概述

通过对聚乳酸类生物可降解塑料发展情况的概述，说明在国内原料市场丰富的情况下，生产以L－乳酸为原料的聚乳酸，开发其在生物可降解塑料领域中的应用，应该说具有广阔的发展前景。     

日本帝人公司将批量生产生物塑料

日本帝人公司最近公布了聚乳酸的批量生产计划。聚乳酸是以玉米等为原料生产的生物塑料，此产品以摆脱对石油的依赖及抑制二氧化碳排放量等环境友好性而备受瞩目。帝人公司的聚乳酸是自主开发的新型材料，通过改善晶体结构，提高了耐热性，熔点约为210℃，     

新型生物塑料可用于汽车内饰

据悉，马自达汽车公司和帝人合作，目前已开发出一种完全由非食用性植物制造的生物塑料，并可应用于汽车内饰。据介绍，这种生物塑料由100％聚乳酸制造，聚乳酸完全由非食用性的植物糖类发酵制取，有一定的抗磨损和抗紫外线能力，并添加了阻燃剂。马白达计划将这种生物塑料用于2007年款全新的Premac-Hydrogen RE混合动力车的座垫和车门装饰。     

聚乳酸基生物降解共混物的制备及应用

聚乳酸(PLA)是一种应用前景良好的生物基绿色高分子材料,具有良好的力学性能、生物相容性和生物可降解性,但PLA存在的韧性差、熔体强度低等性能缺陷很大程度上限制了其更广泛应用。通过与其他生物降解聚合物共混改性可以有效改善PLA的这些性能。文章综述了近年来国内外在聚乳酸与其他生物可降解物质共混改性材料的制备以及其在包装袋、生物降解地膜方面的应用,主要包括了聚乳酸/聚碳酸亚丙酯、聚乳酸/聚己二酸-对苯二甲酸丁二酯、聚乳酸/聚羟基脂肪酸酯、聚乳酸/淀粉等其混体系。     

生物降解性聚乳酸的催化合成研究进展

可生物降解的聚乳酸具有优良的生物相容性而应用于生物医学领域。论文综述了聚乳酸的合成方法以及聚乳酸材料的应用。重点阐述了乳酸聚合催化剂的研究进展以及近年来在乳酸催化聚合机理的研究上取得的成果。指出合成新型高效无毒的催化剂以及催化机理的研究是今后生物医用聚乳酸研究的重点。     

聚乳酸载药系统的研究进展

聚乳酸及其共聚物由于其生物相容性和生物可降解性,被广泛应用于医药和生物学领域。文章就国内外对聚乳酸及其共聚物作为新型载药系统的研究,进行了归纳总结。旨在说明聚乳酸作为药物载体的优势和发展前景。     

聚乳酸降解性能研究进展

聚乳酸是典型的"绿色塑料",因其良好的生物相容性、完全可降解性及生物可吸收性,是生物降解医用材料领域中最受重视的材料之一。本文介绍了聚乳酸的降解机理,着重对近年来有关聚乳酸降解性能的研究进行了综述。     

化学品结块的分析和防结块剂的选用

结块问题涉及到化工、轻工、材料、食品等多个行业,使用防结块剂是解决这一问题的方向和趋势。本文通过大量文献资料,提出结块控制机理,并对常见的化学物质的结块机理进行了分析,对防结块剂的开发有一定指导意义。     

结构施工时变内力分析

将使用阶段的结构作为受力分析对象是目前结构设计的常规做法,其结果是结构的最终内力、变位等与施工过程无关,这不符合工程实际情况,而现行的结构工程施工内力有限元法并没有提供相应的公式能解决这个问题。利用施工过程时变有限元分析方法对结构施工内力进行几何非线性分析,使计算结果更符合结构施工的实际情况,全过程跟踪分析结构在施工各阶段以及施工完毕时的变量,指出结构工程设计考虑施工过程时变效应影响的重要性。     

A review of salt scaling: II. Mechanisms

Salt scaling is a major durability issue for concrete. Despite this, and an extensive research effort, the cause of this damage is unknown. Therefore, no means for preventing salt scaling can be identified. One of the primary reasons for this shortcoming is the lack of a critical review on the state of the research in this field. Such a compilation is presented in this series of articles. In Part I, the characteristics of salt scaling were outlined. In this article, proposed mechanisms are discussed, and their adequacy is judged based on their ability to account for the phenomenology.     

化工过程稳态检验的区间拓展法

介绍了组合统计检验法的基本思想,提出了区间拓展法用于实际化工过程稳态检验的新策略。实例考核表明,新方法显著地降低了第一类错误的概率,可有效地用于实际化工过程的稳态检验。     

超临界CO_2流体萃取大豆油的研究与数值模拟

本文建立了一套超临界流体萃取的实验装置 ,在压力为 2 0MPa～ 30MPa ,温度为30 8K～ 32 3K的条件下 ,研究了用超临界二氧化碳萃取大豆油。试验证明用超临界流萃取的方法可以较为完全地得到大豆中的油分。基于固定床、积分柱塞流与微分混合流的假设建立了理论计算模型 ,使用这个模型可以根据装料量少耗时短的微分萃取试验结果来较为准确地计算出相同条件下积分萃取的过程。经本试验结果比较证明该方法简便可行 ,在本文条件下误差小于 6 % ,是对超临界流体萃取放大研究的一种探索     

线性聚醚溴化反应的动力学研究

本文报导热催化法制备烷基直链型溴代聚醚的溴化反应动力学。研究了各因子对溴代聚醚含溴量的影响,并建立了经验方程。     

Generalization of Takagi-Sugeno Fuzzy Controller and its Application to Control of MMA Batch Polymerization Reactor

In this research a generalization of Takagi-Sugeno fuzzy controllers is presented. In this generalization all or some of the inputs of the fuzzy controllers are fuzzy numbers. Also, it is proved that this generalization is well defined, which means that if the inputs of a generalized Takagi-Sugeno fuzzy controller are singleton fuzzy sets, then the generalized Takagi-Sugeno fuzzy controller will be reduced to a Takagi-Sugeno fuzzy controller. This controller was applied to temperature control of a methyl methacrylate (MMA) batch polymerization reactor, which uses jacket temperature error in addition to reactor temperature error. But the desired jacket temperature is affected by noise and disturbance. Therefore, there is uncertainty in the desired value of this variable. Fuzzy numbers are applied to model this uncertainty and a fuzzy trajectory was achieved for jacket desired temperature. After that an adaptation mechanism was designed. Experimental results present the fine performance of this controller in temperature control of solution polymerization of methyl methacrylate.     

Numerical investigation on the number of active surface sites of carbon catalysts in the decomposition of methane

The number of active sites on the surface of carbon catalysts is an important factor in determining their activity in the decomposition of methane. Although several studies have been performed to identify the nature of these sites, no method has been established to estimate their number. A method is presented to estimate this value, and its effect on hydrogen production is evaluated, along with that of temperature and residence time. For this purpose, the thermocatalytic decomposition of methane is modeled with the inclusion of the number of active sites of the catalyst in the kinetics. The results of the model indicate the high influence of variations of small residence times in this process, and the reduction of this effect at high temperatures. Also, the effect of the number of surface sites is shown to be more prominent at low residence times and temperatures. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2228–2234, 2014     

Supplementary transfer function of the transport of hydrogen in self-stressed metals

It is well established that the transport of hydrogen dissolved in metals is non-Fickian. This results from a non-zero partial volume of such hydrogen. Consequently, any gradient of hydrogen concentration in a metal causes its self-stress. Till now, the proposed transport equations taking stress into account have found analytical solutions only for quasi-equilibrium cases, and the transfer function (TF) spectroscopy is advocated as a unique technique for modelling the transport in question, and, in this way, estimating from experimental data the parameters that determine the kinetics of this process. In this paper, an additional TF – completing the set of previously proposed TFs – is presented and its applicability for estimating the values of the above parameters is numerically analysed with comparison to other analogous TFs. Although this TF is unique – being outwardly applicable also to the cases of foil and thin-layer specimens – it describes properly the transport in question solely in the case of membrane specimen.     

汽车内饰涂料涂层的散发性测试方法研究

介绍了一种简易可行的汽车内饰涂料涂层挥发性有机化合物散发量的测定方法,即试验箱-热解吸-气相色谱法,该方法选择合适的环境试验条件(如温度、湿度)进行材料的挥发试验,然后用TenaxTA吸附管定量采集挥发的挥发性有机化合物,经气相色谱分析,以甲苯为等当物、总碳量来表征挥发性有机化合物散发量,能有效评价材料在实际使用状态下...