扩链剂ADR4370S对聚对苯二甲酸丁二醇酯的动态流变行为及力学性能的影响

以ADR4370S为扩链剂,通过双螺杆挤出机熔融制备扩链改性聚对苯二甲酸丁二醇酯(PBT),采用旋转流变仪、电子万能拉伸试验机和摆锤冲击试验机等测试分析手段,研究扩链改性体系的动态流变行为和力学性能。实验结果表明,随着ADR4370S含量的增加,体系的储能模量、损耗模量、复数黏度和松弛时间均提高;Han图说明ADR4370S的加入有利于提高熔体的强度;当ADR4370S含量为1.25%,体系出现了溶胶凝胶转化,并最终呈现"类凝胶"行为;Cole-Cole图显示了PBT支化结构的形成,并且vGP图进一步预测PBT扩链支化产物具有梳型的拓扑结构;静态力学性能分析表明ADR4370S有利于提高扩链体系的缺口冲击强度,在PA1.5体系中缺口冲击强度从6.08kJ/m2提高到10.46kJ/m2,相对纯PBT提高72.18%,但体系的拉伸强度因结晶度的减小变化不大。     

扩链改性对聚(3-羟基丁酸酯-co-4-羟基丁酸酯)性能的影响

以多苯基多亚甲基多异氰酸酯(PAPI)为扩链剂,采用熔融共混法扩链改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]。使用凝胶渗透色谱、热失重分析仪、电子拉力机、毛细管流变仪、旋转流变仪等研究了PAPI添加量对P(3HB-co-4HB)的相对分子质量、热稳定性、力学性能以及流变性能的影响。结果表明,PAPI的使用能够提高P(3HB-co-4HB)的相对分子质量和熔体黏度,并能有效改善P(3HB-co-4HB)的热稳定性和力学性能,成功实现了对P(3HB-co-4HB)的扩链改性。PAPI的添加量为2.0phr时,体系综合性能最佳,其起始分解温度和最大分解温度分别比纯P(3HB-co-4HB)提高了16.7℃和11.4℃,其拉伸强度和断裂伸长率分别比纯P(3HB-co-4HB)提高了21%和218%。     

扩链改性对聚(3-羟基丁酸酯-co-4-羟基丁酸酯)性能的影响EI北大核心CSCD

以多苯基多亚甲基多异氰酸酯(PAPI)为扩链剂,采用熔融共混法扩链改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]。使用凝胶渗透色谱、热失重分析仪、电子拉力机、毛细管流变仪、旋转流变仪等研究了PAPI添加量对P(3HB-co-4HB)的相对分子质量、热稳定性、力学性能以及流变性能的影响。结果表明,PAPI的使用能够提高P(3HB-co-4HB)的相对分子质量和熔体黏度,并能有效改善P(3HB-co-4HB)的热稳定性和力学性能,成功实现了对P(3HB-co-4HB)的扩链改性。PAPI的添加量为2.0phr时,体系综合性能最佳,其起始分解温度和最大分解温度分别比纯P(3HB-co-4HB)提高了16.7℃和11.4℃,其拉伸强度和断裂伸长率分别比纯P(3HB-co-4HB)提高了21%和218%。     

回收聚乳酸树脂的扩链改性

以转矩流变仪为反应器,采用环氧类扩链剂对聚乳酸回收料进行熔融扩链改性研究。考察了扩链剂加入量、反应时间、反应温度对扩链反应的影响;并以冲击强度和熔体流动速率作为主要考核指标,通过正交实验对扩链反应条件进行了优选。结果表明,反应温度和扩链剂用量是影响扩链效果的主要因素。在优化反应条件下制备的扩链产物,其重均分子量从5.8万提高到了30.3万,相应的熔体流动速率从8.28g/10min降低到了2.13g/10min,冲击强度比扩链前提高近3倍,显示出良好的扩链效果。     

过氧化二异丙苯硫化制备增强耐热聚乳酸

聚乳酸的链段结构对其热力学性能有重要影响。过氧化二异丙苯(DCP)作为自由基引发剂,通过反应性共混可以诱导聚合物分子链支化、交联,进行功能化改性。文中制备了一系列不同DCP添加量的PLA/DCP共混物,重点研究了DCP含量对聚乳酸(PLA)熔融结晶行为、流变行为、耐热性能和力学性能的影响。结果表明,DCP可以诱导PLA的分子链支化和交联。当DCP质量分数大于0.5%时,交联反应占据主导作用,共混扭矩显著升高、复数黏度增大。DCP引发PLA分子链自交联,不熔的PLA链段可以作为成核中心,大幅提高了PLA成核密度,进而提高其结晶速率和结晶度。DCP的添加可以有效地提高聚乳酸的拉伸强度,但对断裂伸长率和冲击强度的影响较小。经过退火,共混物的力学性能保持不变,共混物的耐热性能大幅提高。当DCP质量分数大于0.5%时,共混物的维卡软化温度可以提高到155℃。     

环氧树脂含量对废旧ABS塑料性能的影响

环氧树脂ADR-4370S是一种含有缩水甘油酯型环氧基团的扩链剂。文中采用ADR-4370S,经双螺杆挤出机对废旧ABS(R-ABS)进行扩链,通过力学性能测试、熔体流动速率测试、傅里叶变换红外光谱、凝胶渗透色谱研究了ADR-4370S对R-ABS结构与性能的影响。此外还通过索氏提取法分析了ADR-4370S对R-ABS凝胶含量的影响。研究表明,ADR-4370S的加入改善了R-ABS的力学性能,当ADR-4370S用量为0.7 phr时,R-ABS的综合力学性能最佳,缺口冲击强度达到6.33 k J/m2;熔体流动速率测试表明,R-ABS的熔融指数随着ADR-4370S含量的增加而降低;凝胶渗透色谱测试表明,ADR-4370S的加入使R-ABS的相对分子质量提高,相对分子质量分布变窄。     

聚乳酸扩链及其超临界二氧化碳微孔发泡

采用环氧类扩链剂对聚乳酸进行反应挤出扩链,通过超临界CO2快速降压法对扩链聚乳酸进行发泡。采用凝胶渗透色谱仪、高级动态流变仪、差示扫描量热仪、动态热机械分析仪研究了扩链聚乳酸的动态流变行为、结晶性能及粘弹性;并采用密度仪及扫描电镜研究了发泡温度对聚乳酸泡沫发泡倍率及泡孔形态的影响。研究结果表明,扩链后聚乳酸的相对分子质量增大,熔体的复数黏度和储能模量增加。与聚乳酸相比,扩链聚乳酸的冷结晶现象比较显著,冷结晶温度明显下降,冷结晶热焓明显增大。冷结晶导致扩链聚乳酸在100~120℃温度区间内的储能模量较高,从而有利于泡孔的生长。通过对聚乳酸的扩链改性,采用超临界CO2发泡技术,成功制备出了聚乳酸微孔泡沫材料,发泡倍率可达20倍,泡孔规整,平均孔径43μm,孔径分布较窄。     

增容型聚甲基乙撑碳酸酯/聚丁二酸丁二醇酯共混材料的制备与性能

在聚甲基乙撑碳酸酯(PPC)/聚丁二酸丁二醇酯(PBS)共混体系中加入4,4′,4″-三苯基甲烷三异氰酸酯(TTI)作为增容剂,与PPC和PBS的端羟基反应形成扩链产物,原位生成PPC和PBS的相容剂,从而提高材料的相容性。文中采用熔体流动速率分析、微卡软化温度测定、拉伸性能和冲击强度测试来表征材料的性能。共混物制备过程扭矩的提高和共混物熔体流动速率的降低表明了扩链反应的进行,材料断裂伸长率和冲击强度的提高表明,TTI的加入能促进两组分相容性的明显改善,扩链反应的进行和体系相容性的提高也使共混材料的热性能得到显著提高。当TTI加入量由0 phr增加到0.36 phr时,共混物的断裂伸长率由46.3%增加到了212.0%,缺口冲击强度由4.5kJ/m2增加至9.0 kJ/m2,维卡软化点由57.6℃提高到了68.7℃。     

长支链化聚乳酸/聚丁二酸丁二醇酯的流变特性与发泡性能

为提高熔体强度,以均苯四甲酸酐(PMDA)、异氰尿酸三缩水甘油酯(TGIC)为扩链剂,对聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)共混体系进行长支链化改性,通过挤出发泡制备PLA/PBS发泡材料。采用转矩流变仪、旋转流变仪、扫描电镜研究了扩链剂用量对PLA/PBS体系流变性能和发泡性能的影响。结果表明,扩链剂PMDA和TGIC联合使用能有效对PLA/PBS体系进行长支链化改性,得到具有一定长支链结构的体系,提高了其熔体强度、弹性和拉伸黏度,改善了PLA/PBS体系的发泡性能。当扩链剂质量分数为0.8%时,发泡材料的泡孔密度达到4.96×107cm-3,平均孔径为60μm,泡孔规整且分布均匀。     

酮肟基硅烷扩链/交联低模量有机硅密封胶的制备及性能

以酮肟基硅烷为扩链/交联体系,以自制的含氰基和仲胺基的新型硅烷偶联剂为增粘剂,制备挤出流动性良好、表干时间短、粘接性好、模量低(100%定伸应力<0.4 MPa)、断裂伸长率高(>800%)的有机硅密封胶。讨论了扩链/交联体系、增粘剂类型及用量对有机硅密封胶表干时间、力学性能和粘接性能的影响。发现随扩链剂用量的增大,密封胶的断裂伸长率提高,但强度降低,表干时间延长。只有合理选用交联剂的用量,才能使密封胶固化交联。相对于传统的增粘剂而言,自制的增粘剂可显著提高密封胶的力学性能和粘接强度,缩短表干时间。     

正确理解供应链与价值链的关系

首先较系统地概述了供应链和价值链的涵义,发展和研究状况,在此基础上深入地探讨了两者的本质区别与联系。两者有不尽相同的地方,如价值链思想是面向效益,着眼点是企业的价值增值过程;供应链思想是面向效率,主要是围绕物流、降低成本和提高生产率方面。但两者也有许多交叉的地方,如价值链研究把成本优势作为重要方面之一,供应链的发展也逐渐强调联系的重要性等。正确理解供应链与价值链的关系可以为实现两者的有效管理提供一     

Leagile supply chain: design drivers and business performance implications

In the context of a dynamic and hypercompetitive business environment, effective supply chain design helps organisations to align resources for improved flow of products and services and satisfy customers’ diverse needs. Scholars have proposed several mutually exclusive supply chain designs such as efficient versus responsive, and lean versus agile. Quantitative testing has revealed that supply chain designs of many firms do not match with what was conceptually expected. To address this mismatch, in this study, a new approach to supply chain leagility is introduced and the impact of uncertainty as the key design driver of supply chains on leagility is investigated. The partial least squares (PLS) was employed to analyse data collected from 299 Australian firms by administering a structured questionnaire. Results indicate that higher performance is achievable on minimising the deviation from a balanced supply chain in which aspects of both leanness and agility are equally embedded. Further, the level of uncertainty directly and positively affects the Deviation from Leagility (DFL) index.     

Literature review on disruption recovery in the supply chain*

Recent research underlines the crucial role of disruption events and recovery policies in supply chains. Despite a wealth of literature on supply chain design with disruption considerations, to the best of our knowledge there is no survey on supply chain with disruptions and recovery considerations. We analyse state-of-the-art research streams on supply chain design and planning with both disruptions and recovery considerations with the aim of relating the existing quantitative methods to empirical research. The paper structures and classifies existing research streams and application areas of different quantitative methods subject to different disruption risks and recovery measures. We identify gaps in current research and delineate future research avenues. The results of this study are twofold: operations and supply chain managers can observe which quantitative tools are available for different application areas; on the other hand, limitations and future research needs for decision-support methods in supply chain risk management domains can be identified.     

Revealing interfaces of supply chain resilience and sustainability: a simulation study

Dynamics of structures and processes is one of the underlying challenges in supply chain management, where multiple dimensions of economic efficiency, risk management and sustainability are interconnected. One of the substantiated issues in supply chain dynamics is resilience. Resilience has a number of intersections with supply chain sustainability. This paper aims at analysing disruption propagation in the supply chain with consideration of sustainability factors in order to design resilient supply chain structure in regard to ripple effect mitigation and sustainability increase. Ripple effect in the supply chain occurs if a disruption at a supplier cannot be localised and cascades downstream impacting supply chain performance. This simulation-based study helps to identify what sustainability factors mitigate the ripple effect in the supply chain and what sustainability factors enhance this effect. The results indicate that (i) sustainable single sourcing enhances the ripple effect; (ii) facility fortification at major employers in regions mitigates the ripple effect and enhances sustainability; and (iii) a reduction in storage facilities in the supply chain downstream of a disruption-risky facility increases sustainability but causes the ripple effect.     

Emerging trends in supply chain architecture

This paper traces significant developments in technology, quality, measurement, and relationships that have led to the study of supply chain networks. The paper introduces five principles of supply chain networks—velocity, variability, vocalize, visualize, and value—that have moved supply chain architecture from an art to a science. Finally, the paper uses each principle to point to an important, emerging trend in supply chain architecture.     

A graph-based model to measure structural redundancy for supply chain resilience

Globalisation and lean initiatives increase the vulnerabilities of the supply chains (SC), where disruptions in any plant in a supply chain network (SCN) can propagate throughout the whole SCN. Redundancy is part of the SC re-engineering to improve supply chain resilience (SCRES). This paper presents a conceptual model of an SCN using graph theory, considering the relationships between plants and materials. Based on the model, the structural redundancy of the SCN is measured, which is used to assess SCRES. This assessment approach focuses on the resilience of the SCN against disruptions. Case studies are discussed to illustrate the applicability of this model and show that increasing structural redundancy of the SCN improves SCRES against disruptions.     

制造企业转型电子商务的价值链研究

本文的研究将依据两条线索展开,一条是迈克尔．波特的企业价值链一电子商务下的企业价值链一虚拟价值链,即企业价值链线索;另一条是迈克尔,波特的行业价值链一电子商务下的行业价值链一价值网,即行业价值链线索。通过以上两条线索分析制造企业价值链的演化过程,指出在电子商务时代,制造企业应该注意到物理价值链和虚拟价值链的理论正在发展,分工的高度专业化和对合作的强调,又导致企业之间虚拟价值链寻求整合,演变为价值网,而价值网随着合作的动态变化而改变,企业必须高度关注这些变化并运用新的价值链理论指导企业实践,才能赢得竞争优势。     

供应链设计、供应链整合、信息共享与供应链绩效的关系研究

构建了供应链设计、供应链整合、信息共享及供应链绩效之间关系的理论模型,并以广东省珠三角地区162家制造企业为调查对象,对供应链设计、供应链整合、信息共享及供应链绩效之间的关系进行实证研究。研究结果表明,供应链设计对供应链整合、供应链绩效均有显著的正向影响;供应链设计对信息共享的直接影响并不显著,却会以供应链整合为中介对信息共享产生间接影响;供应链整合对信息共享、供应链绩效有显著的正向影响;而低层次的信息共享对供应链绩效并无显著影响。根据上述实证研究结果,本研究结合中国情境给出了相关管理启示。     

过渡金属催化烯烃聚合

论述了烯烃聚合催化剂的发展更新过程,催化聚合的过程。涉及配位聚合的链增长机理、单体几种可能的插入模式及聚合的立构控制方式、链转移或链终止机理以及可能存在的催化活性中心的失活过程。对于过渡金属催化烯烃聚合的理解有助于催化剂设计的理性化。     

基于分形理论的供应链管理模型分析

为了克服日益复杂的供应链问题,在分形理论的基础上介绍了分形供应链的概念和特点,认为分形供应链所具有的自相似、自组织、自优化等特点可以很好地提高供应链的灵活性,增强适应环境的能力.在此基础上进一步研究了分形供应链的结构模型和运作模型,探讨了其现实意义.