Comparative Study on Properties of PBAT/PBSA Film Modified by a Multi-Functional Epoxide Chain Extender or Benzoyl Peroxide

Poly(butylene adipate-co-terephthalate)(PBAT)and poly(butylene succinate-co-adipate)(PBSA)blend films were prepared with different contents of a multifunctional epoxide chain extender Joncryl ADR-4468(ADR)or benzoyl peroxide(BPO).The long-chain-branching(LCB)introduced by ADR and branched/crosslinked entanglement induced by BPO increased melt elasticity,viscosity and compatibility,as indicated by thermal properties,rheological and morphological analyses.It was found that the elongation at break and the tensile strength were significantly improved,due to the enhancement of compatibility and the interfacial adhesion by the incorporation of ADR or BPO.The best mechanical properties were obtained in PBAT/PBSA/ADR(60/40/0.3)(A4T6A_(0.3))and PBAT/PBSA/BPO(60/40/0.9)(A4T6B_(0.9))films,respectively.With the rapid initiation of chain growth by BPO,it has significantly improved the transparency of the film.ADR and BPO can be used interchangeably in improving the comprehensive properties of PBAT/PBSA films,and it would provide more strategies for developing biodegradable materials for various applications.

Silicone Chain Extender for Recycled Polyethylene-terephthalate with Higher Flexibility

To decrease the modulus and increase the mechanical properties of recycled PET by introducing the flexible segments, the recycled polyethylene-terephthalate(PET) was modified by the chain extender produced with 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetra(2, 3-epoxypropoxy) propylcyclotetrasiloxane by the hydrosilylation reaction. Different percentages of chain extender were used in order to investigate the effect of chain extender content on the modulus of PET. The dynamic mechanical analysis was performed on PET samples, which showed that Tg of PET was firstly raised by the addition of chain extender and then decreased. Small amplitude shearing test performed on PET samples confirmed that the addition of the flexible segments could remarkably decrease the modulus of PET, which would be helpful for the extrusion process. The entanglements from branches were also influenced by the addition of extender.

Model-driven full system dynamics estimation of PMSM-driven chain shell magazine

Based on the system dynamic model, a full system dynamics estimation method is proposed for a chain shell magazine driven by a permanent magnet synchronous motor(PMSM). An adaptive extended state observer(AESO) is proposed to estimate the unmeasured states and disturbance, in which the model parameters are adjusted in real time. Theoretical analysis shows that the estimation errors of the disturbances and unmeasured states converge exponentially to zero, and the parameter estimation error can be obtained from the extended state. Then, based on the extended state of the AESO, a novel parameter estimation law is designed. Due to the convergence of AESO, the novel parameter estimation law is insensitive to controllers and excitation signal. Under persistent excitation(PE) condition, the estimated parameters will converge to a compact set around the actual parameter value. Without PE signal, the estimated parameters will converge to zero for the extended state. Simulation and experimental results show that the proposed method can accurately estimate the unmeasured states and disturbance of the chain shell magazine, and the estimated parameters will converge to the actual value without strictly continuous PE signals.

Effects of Bifunctional Chain Extender on the Crystallinity and Thermal Stability of PET

Effects of bifunctional chain extender on the crystallinity and the thermal stability of PET were studied in this work. Results of Infrared substractive spectrum indicated that one oxazoline ring of 2,2’-bis(2-oxazoline) (BOZ) reacted with one carboxyl in PET to generate a blocked PET chain with an oxazoline ring, which then reacted with one carboxyl in second PET to form an extended chain. The intrinsic viscosity (IV) of extended PET would increase from 0.61 of initial PET to 0.80 when the addition of BOZ was 0.52 wt%. Furthermore, when BOZ was used with hydroxyl-addition-type chain extender 2,2’-(1,4-phenyl)bis(4H-3,1-benzoxazin-4-one) (BNZ) or chain end modifier phthalic anhydride (PA), IV of chain extended PET would be 0.83 and 0.97 respectively. DSC results showed that chain extending would result in a decrease in crystallinity of PET. Comparing with initial PET, the intrinsic viscosity loss of the chain extended products would be smaller after multi-melting processing.

Chain Extender-induced Hydrogen Bonding Organization Determines the Morphology and Properties of Thermoplastic Polycarbonate Polyurethane

Thermoplastic polycarbonate polyurethanes(PCUs) are multiblock copolymers that have been applied for medical devices for long time. Aliphatic diols are common chain extenders(CE) involved in the composition of the hard segments of PCU. However, limited knowledge was discovered about how the chemical structure of CE affects the hydrogen bonding organization within PCUs and their mechanical properties.To investigate this problem, a group of PCUs were synthesized respectively by extending the polymer chain with 1,4-butanediol(BDO),aminoethanol(MEA), ethanediol(EO) as three kinds of chain extenders. Tiny differences in the CE chemical structure results in remarkable variations in phase separation, condensed morphologies, thermal and mechanical properties, which are characterized by Fourier transform infrared spectrometer, atomic force microscopy, small-angle X-ray scattering, differential scanning calorimetry, and tensile tests. The microstructural evolution during unilateral deformation and the different mechanism induced by the different CEs was probed and unveil by in situ wide-and small-angle X-ray diffraction. Symmetry of CE can improve the organization of the hydrogen bonding. The coherence strength of the urethane/urea group also plays a key role by comparing the two PCUs with ethanediol and aminoethanol.

Testing and Evaluation for Web Usability Based on Extended Markov Chain Model

As the increasing popularity and complexity of Web applications and the emergence of their new characteristics, the testing and maintenance of large, complex Web applications are becoming more complex and difficult. Web applications generally contain lots of pages and are used by enormous users. Statistical testing is an effective way of ensuring their quality. Web usage can be accurately described by Markov chain which has been proved to be an ideal model for software statistical testing. The results of unit testing can be utilized in the latter stages, which is an important strategy for bottom-to-top integration testing, and the other improvement of extended Markov chain model (EMM) is to present the error type vector which is treated as a part of page node. this paper also proposes the algorithm for generating test cases of usage paths. Finally, optional usage reliability evaluation methods and an incremental usability regression testing model for testing and evaluation are presented. Key words statistical testing - evaluation for Web usability - extended Markov chain model (EMM) - Web log mining - reliability evaluation CLC number TP311. 5 Foundation item: Supported by the National Defence Research Project (No. 41315. 9. 2) and National Science and Technology Plan (2001BA102A04-02-03)Biography: MAO Cheng-ying (1978-), male, Ph.D. candidate, research direction: software testing. Research direction: advanced database system, software testing, component technology and data mining.

A novel chain-extended urea containing hyperbranched polymer used as toughening modifier for epoxy resin

A new kind of reactive toughening accelerator for epoxy resin, amine-teminated hyperbranched polymer (H2O-NMe2) was synthesized and characterized by FT-IR spectroscopy. Dynamic mechanical analysis (DMA) was used to study the glass transition temperature (Tg), loss factor (tanδ) and activation energy (Ea) by using multiplexing frequency. The results show that the Ea at glassy relaxation process of modified system is about 70-80 kJ/mol higher than that of unmodified system, and the high modulus and good thermal properties are still maintained.

STUDY ON THE CHAIN-EXTENDING REACTION OF POLY (ETHYLENE TEREPHTHALATE) WITH 2, 2′-BIS (4H-3, 1-BENZOXAZIN-4-ONE)

2,2'-Bis (4H-3,1-benaoxazin-4-one) (BBON) has been proved to be an effective chain extender for poly (ethylene terephthalate) (PET). In order to study the reaction mechanism and kinetics of chain-extending reaction, beta-bishydroxyethylene terephthalate (BHET) was selected as model compound. The NMR data, IR spectra and number average molecular weight (<(M)over bar (n)>) of the products obtained from the reaction of BBON and BHET verify that BBON is a hydroxyl-reactive extender. The mechanism was discussed. Kinetics data indicate that extending reaction is a second order reaction, and BBON has high reactivity. The activation energy (E(a)) was measured.

数字化转型、创新发展与制造业价值链高质量发展

创新驱动发展战略背景下,企业数字化转型对制造业价值链高质量发展具有重要意义。采用2007—2021年沪深A股制造业上市企业数据,从价值链上游度即“强链”和价值链长度即“延链”双重视角,探析企业数字化转型对制造业价值链高质量发展的影响效果、作用机制与异质性特征。研究结果表明:企业数字化转型从“强链”和“延链”两方面推动了制造业价值链高质量发展,且该结论通过了稳健性检验。作用机制检验表明,企业创新发展在此过程中具有显著的正向传导作用。异质性分析表明,在非国有制企业、技术密集型行业、劳动密集型行业和创新引领型城市,企业数字化转型通过“强链”和“延链”推动制造业价值链高质量发展的效果更为显著。为此,在城市层面应健全数字化转型治理体系,在行业层面应加快“新基建”建设进程,促进数字化均衡发展,在企业层面应鼓励以强带弱、协同发展,为企业数字化转型提速增质。

考虑渠道结构的竞争性网购供应链产品-延保联合定价策略

本文考虑网络商店销售由两个竞争性制造商生产的同类但具有差异化的替代性产品,在网络商店提供延保的服务模式下分别针对RO/MO/PO三种典型渠道结构构建产品-延保决策模型,分析了制造商之间,以及制造商与网络商店之间的互动决策。研究结果表明,各渠道结构下供应链均存在唯一的均衡,使供应链系统中各参与者的利润同时实现最大化;当制造商之间的竞争强度处于中等及以下水平时,RO渠道结构有利于系统各参与者;当竞争强度处于中高水平区间时,采用MO渠道结构会拉大制造商之间的绩效差距;当竞争强度较高时,采用RO渠道结构有助于提升两个制造商的利润,但更高的竞争强度更有利于网络商店且在高强度区间内的竞争波动对零售商和制造商的影响并非线性,即存在具有区间依赖和强度差异特性的影响。此外,较高的平台佣金率并非总有利于网络商店,反而可能影响其销售渠道选择;消费群体延保服务质量敏感性存在差异,该差异决定相应消费群体的延保购买率上限且延保服务质量成为影响高端群体延保购买率的重要因素。

海水条件下延展型表面活性剂降低界面张力性能研究

为系统探究海水条件下延展型表面活性剂降低界面张力的结构-性能关系,本研究选取不同结构的延展型表面活性剂进行了界面张力测试,并分别考察了疏水烷基链长、烷基支链化、氧丙烯(PO)基团数、氧乙烯(EO)基团数对降低界面张力能力的影响。结果表明,通过增加烷基链长和疏水基支链化,对界面张力降低能力影响幅度小,不能达到超低数值(<10^(-2)m N/m)。PO数是影响延展型表面活性剂降低界面张力能力的关键因素,通过长PO链段螺旋卷曲,增大疏水基尺寸,在适宜的亲水亲油平衡条件下,可以将界面张力降至10^(-3)m N/m数量级。EO基团增加不利于分子在界面上紧密排列,造成界面张力升高。原油组分在界面上的竞争吸附不利于界面张力降低,PO数增加,与原油的界面张力逐渐降低。该类表面活性剂在海水条件下依然具有高界面活性,适用于海上油藏化学驱提高采收率。

聚乳酸基水性聚氨酯的制备及其在合成革中的应用研究

以聚乳酸二元醇(PLA⁃OH)和六亚甲基二异氰酸酯(HDI)为原料,2,2⁃二羟甲基丁酸(DMBA)为亲水扩链剂合成了亲水扩链剂含量不同的聚乳酸(PLA)基水性聚氨酯(PLA⁃WPU)乳液,制备了PLA⁃WPU胶膜和超细纤维合成革。结果表明,随DMBA含量的增加,PLA⁃WPU乳液粒径减小、固含量增大,PLA⁃WPU超细纤维合成革拉伸强度和最大负荷增大,水接触角减小。当DMBA含量为5.5%时,PLA⁃WPU乳液固含量达到35.4%,粒径为196.37 nm,PLA⁃WPU超细纤维合成革的拉伸强度提高到29.9 MPa,约为超细纤维基布的1.7倍,水接触角降低到73°。

聚乙醇酸高温降解性能研究及其调控方法

评价聚乙醇酸(PGA)在不同温度和不同pH环境下的降解性能,研究降解过程中PGA的结晶性能、热稳定性的变化,并通过液相色谱-质谱联用分析PGA的降解产物。随后,分别使用聚碳化二胺类抗水解剂HyMax@210和环氧类扩链剂ADR-6488熔融共混改性PGA,研究2种助剂对PGA的熔体流动性、热稳定性、力学性能和降解性能的影响。结果表明:PGA在高温水溶液中的降解性能远优于传统可降解材料,130℃水中10 h降解完全,降解产物主要为乙醇酸三聚体,提高pH值可促进PGA的降解。扩链剂和抗水解剂的存在提高了PGA的热稳定性和力学性能,延缓了PGA的降解速率。

基于废弃PET的环氧超支化聚酯扩链剂应用性能

以废弃聚对苯二甲酸乙二酯(PET)的降解产物为核心,制备了环氧超支化聚酯扩链剂(EHBP),探究了该扩链剂对聚对苯二甲酸-己二酸丁二酯/聚乳酸/碳酸钙(PBAT/PLA/CaCO_(3))三元复合材料微观结构、热性能、力学性能的影响。结果表明,以PET降解产物制备的EHBP对复合材料有明显的增容作用。扩链剂中的高活性环氧基团能够与PBAT和PLA上的端羧基、端羟基发生开环加成反应,形成扩链大分子以增强PBAT和PLA之间的界面相互作用。当EHBP添加量达到0.6份时,可以明显观察到两相间变得模糊、孔洞减少。缺口冲击强度由6.48 kJ/m^(2)增加到43.02 kJ/m^(2),拉伸强度由10.15 MPa增加到24.59 MPa,断裂伸长率由11.8%增加到56.72%。

成核剂ST-NAB3改性扩链聚乳酸的微观结构与性能研究

使用转矩流变仪将扩链剂CEAX8840、成核剂ST-NAB3与PLA熔融共混制备改性PLA,采用扫描电子显微镜、偏光热台显微镜、差示扫描量热仪、热变形仪、万能试验机以及冲击测试仪对改性PLA微观结构、结晶性能以及力学性能和耐热性进行了表征与测试。结果表明,CEAX8840和ST-NAB3的含量分别为6%(质量分数,下同)和1%时,PLA的晶体最小,密度最大,结晶温度提高到123.9°C,结晶度达到44.9%;此外,其冲击强度和热变形温度分别提高到了64.7 kJ/m2和84.9℃。

环保型仲胺扩链剂在双组分聚脲防水涂料中的应用

仲胺扩链剂是双组分聚脲防水涂料配方体系中的关键原材料,其分子结构中的位阻基团可有效降低反应活性、改善操作性,提高配方容忍度,同时改善材料性能。本文重点介绍了3类环保型液体仲胺扩链剂在双组分喷涂聚脲防水涂料(芳香族、脂肪族)、双组分涂刷聚脲防水涂料(天冬聚脲、新型、黏弹型)共5个不同配方体系中的应用。

基于扩展状态观测器的链式自动弹仓广义预测控制

为了实现链式自动弹仓的位置跟踪问题,设计了一种将扩展状态观测器和广义预测控制相结合的新的控制策略。在连续时间广义预测控制算法的基础上,设计了广义预测位置控制器;通过扩展状态观测器对弹仓系统的多源扰动进行了估计,利用估计值对广义预测控制器进行了前馈校正,增强了控制器的抗干扰能力,确保了控制系统的稳定。分别在空载、半载和满载3种不同负载工况下对链式自动弹仓进行控制仿真和分析。结果表明:与PID控制相比,提出的控制策略对扰动力矩不敏感,具有更好的鲁棒性,且稳态误差更小,位置控制精度更高。

信息不对称下绿色供应链延保服务策略研究

为了探讨延保服务对绿色供应链成员决策及信息共享的影响,分别构建了零售商不提供延保、零售商提供延保及零售商与第三方企业合作提供延保的三种模型。通过对比不同延保模型得出以下结论:(1)企业的延保服务能够有效提升产品绿色度和渠道成员利润,且零售商单独提供延保服务能够最有效的改善绿色供应链绩效;(2)延保服务对零售商信息共享的影响取决于制造商对市场需求预测值的大小,即当制造商对市场需求的预测值较小时,延保服务有利于零售商信息共享,反之则不利;(3)零售商进行信息共享总是对制造商和第三方企业有利,但不一定有助于提升自身利润和产品绿色度。

扩链剂对PLA/PBAT复合材料结构与性能的影响

通过混合熔融挤出方法制备聚乳酸(PLA)/聚对苯二甲酸-己二酸丁二酯(PBAT)复合材料,采用差式扫描量热仪(DSC)、凝胶渗透色谱仪(GPC)、高压毛细管流变仪、偏光显微镜等分析手段,研究扩链剂对PLA/PBAT复合材料熔体流动速率、拉伸性能、热性能、相容性、相对分子质量、流变行为、成膜性以及薄膜制品力学性能等的影响。结果表明:扩链剂的加入,能够有效改善PLA/PBAT复合材料的相容性,提高PLA/PBAT复合材料的流动性、拉伸性能、热稳定性、熔体强度以及临界剪切速率等性能。同时,扩链剂的加入,提高了PLA/PBAT复合材料的加工成膜性能,制备的薄膜制品具有较好的力学性能。

改性淀粉絮凝剂链结构形态对石材废水絮凝性能的影响

石材废水具有高浊度特征,混凝/絮凝工艺是降浊净水的有效手段.本研究以绿色环保且价格低廉的天然高分子材料淀粉为原材,分别通过醚化和接枝共聚技术,合成了两种电荷密度相近,但链结构形态与电荷分布不同的阳离子改性淀粉絮凝剂:3-氯-2-羟丙基三甲基氯化铵改性淀粉(St-CTA,直链型)和淀粉接枝共聚丙烯酰胺-聚甲基丙烯酰氧乙基三甲基氯化铵(St-g-PAM-co-PDMC,接枝型).以泉州某石材加工厂废水为研究对象,详细考察并比较了两种阳离子改性淀粉絮凝剂对石材废水的絮凝性能,同时结合絮凝后上清液zeta电位、絮体结构的动态监测结果以及扩展DLVO理论等,探究其絮凝机理.研究结果表明,两种改性淀粉絮凝剂均表现出优于传统无机混凝剂聚合氯化铝的絮凝性能;除高效降低水体浊度,其对COD、氨氮、总磷及总氮均具有一定去除效果;改性淀粉絮凝剂絮凝过程主要是电中和与黏结架桥作用协同作用的结果.此外,St-g-PAM-co-PDMC由于具有丰富的接枝链结构,且阳离子基团随机分布在接枝链上,具有较高的阳离子基团利用效率及电中和混凝效果,表现出优于直链型St-CTA的除浊效果,具有较低的絮凝剂投加量、较大的絮体尺寸、较快的絮体生长速度、较高的絮体强度及更佳的破碎后絮体恢复性能.扩展DLVO理论结果也表明,St-g-PAM-co-PDMC的总相互作用低于St-CTA,有着更为高效的电中和混凝作用及降浊效果.两种电荷密度相近的改性淀粉絮凝剂絮凝性能的差异主要是由于其不同的链结构与电荷分布造成的,但其均具有优良的降浊净水效果及绿色环保等显著特征,其在石材废水等行业废水处理中应有着良好的应用前景.