二氧化碳／环氧氯丙烷共聚物的热降解动力学研究

二氧化碳（ＣＯ２）和环氧氯丙烷（ＥＣＨ）在稀土络合催化体系作用下共聚反应,合成出脂肪族聚碳酸酯（ＥＣＨＣＯ２）。采用热重分析法研究了共聚物ＥＣＨＣＯ２热降解反应的动力学,测定了不同升温速率下共聚物的热降解过程,并计算出其降解反应级数和活化能。     

堆肥条件下多价态金属有机化合物对聚乙烯促降解规律的研究

造反爽价金属的有机化合物为降解剂,研究了基人民环境中对ＰＥ的促降解规律。通过对试样的力学性能、相对分子质量和氢过氧化物浓度进行了跟踪测试,对部分试样进行的ＦＴ－ＩＲ分析和ＴＧＡ、ＤＳＣ热分析,表征了体系的降解。实验结果表明,多价金属有机化合物降解剂在堆肥温度下对ＰＥ有明显的促降解作用,ＰＥ具体的降解程度速度又与降解剂中心离种类、含量以及配位体等因素有关。所测「ＰＯＯＨ」结果与相对分子质量变化趋势基     

固相法合成涂料用高氯含量氯化聚乙烯

研究了固相合成高氯含量氯化聚乙烯过程中氯取代基，氯化温度、引发方式等对氯化速度的影响，及ＨＣＰＥ的降解。结果表明，大分子链上的氯取代代基对分子链进一步氯化起阻碍作用；氯化前期使用较高的温度或引发剂将使后面的氯化速度减慢；增大前期引发剂用量时，将会再次降低后期的氯化速度；通过机械剪切作用可使具有较高相对分子质量的ＨＣＰＥ大幅度降解。     

醇乙氧基化物的高温稳定性

我们所要研究的是醇乙氧基化物在贮存和装运过程中氧化的稳定性，通过在静态空气中加热来模拟实际情况，通过用质量光谱检测的热重量分析法和汽相取样的微分扫描热法来模拟更严格，广泛的通风情况。在静态的空气中，醇化物乙基即Ｃ１２（ＥＯ）７加热至２０４℃时变色，并产生更多的醛类，但是，样品ＥＯ的分布没有变化，在强烈的通风条件下，温度高于１５０℃，氧化作用会加强，随着ＥＯ单元的损失，从样品中产生的ＣＯ和ＣＯ２会增     

低分子量聚环氧乙烷的结晶特性

综述了低分子量聚环氧乙烷（ＰＥＯ,ＣＨ２ＣＨ２Ｏｎ）的结晶特性。ＰＥＯ结晶受结晶温度的影响较大,ＰＥＯ的分子量和端基对结晶特性也有影响,在ＰＥＯ结晶中既有规整链折叠结晶也有非规整链折叠结晶存在。这些结晶会以恒温增厚或恒温变薄的方式相互转化,它们的存在和相互转化不但依赖于结晶热力学作用也与结晶动力学条件密切相关。     

CeO2纳米粒子形成过程中Ce的价态变化

用溶胶－凝胶法制备了ＣｅＯ２纳米粒子，ＸＲＤ分析表明，所合成的ＣｅＯ２纳米粒子均为立方晶系，空间群为Ｏ＾５ｈ－Ｆｍ３ｍ。ＴＥＭ分析表明，ＣｅＯ２粒子球形。研究了ＣｅＯ２纳米粒子形成过程中Ｃｅ价态的变化与性质，发现干凝胶中Ｃｅ＾３＋和Ｃｅ４＋共存；当焙烧温度低于２３０℃时，随焙烧温度的升高，     

ALC-CH系统在水热处理过程中的物理化学变化Ⅰ水热处理温度的影响

采用ＴＧ－ＤＴＡ，ＩＲ，ＸＲＤ和ＮＭＲ对ＡＬＣ（压蒸轻质混凝土）废渣中添加氢氧化钙后的ＡＬＣ－ＣＨ系统，在水热处理过程中的物理化学变化进行了分析，同时用ＢＥＴ方法测定了不同温度水热处理物的比表面积。结果表明，ＡＬＣ渣添加适量氢氧化钙，经１４０～２００℃下水热处理３ｈ的水热处理物理中形成了新的水化硅酸钙α－Ｃ２ＳＨ．α－Ｃ２ＳＨ的形成量随水热处理温度的提高而增加。水热处理物的比表面积波动于１２～２２     

三乙烯四胺吸收CO2的初探

在常压下，采用搅拌式反应器对ＴＥＴＡ（三乙烯四胺）水溶液吸收ＣＯ２进行了研究，测定了不同温度下，不同浓度的ＴＥＴＡ的ＣＯ２吸收情况，并与常用醇胺吸收剂ＭＥＡ（一乙醇胺）、ＤＥＡ（二乙醇胺）、ＴＥＡ（三乙醇胺）的吸收效果作了比较，同时观察了ＴＥＴＡ－胺－水多元体系对ＣＯ２的吸收情况，得出最佳配比。有关ＴＥＴＡ吸收ＣＯ２研究尚无报道。     

PET缩聚过程反应与传质Ⅰ反应动力学研究

聚对苯二甲酸乙二醇酯缩聚过程是反应－传质耦合过程,本文利用静止膜实验在排除传质影响情况下研究了ＰＥＴ缩聚过程反应规律,建立了链增长,链降解反应动力学模型,并利用可逆反应极限的概念确定了小分子界面浓度。     

复合晶核剂（MoO3＋CaF2）对铝硅酸盐玻璃析晶行为的影响作用研究

采用ＤＴＡ，ＳＥＭ，ＥＤＡＸ，ＳＡＤＰ和ＸＲＤ等测试方法研究了含复合晶核剂（ＭｏＯ３＋ＣａＦ２）的铝硅酸盐玻璃的分相与析晶行为。实验结果表明，含单一晶核剂ＣａＦ２或ＭｏＯ３的玻璃仪产生表面析晶，而ＣａＦ２和ＭｏＯ３共同引入时能诱导玻璃的体内核化，ＣａＦ２和ＭｏＯ３均能降低基玻璃的析晶温度，整体析晶的机理是ＣａＦ２促进了玻璃的分相，ＭｏＯ３富集子分相玻璃的富钙相中，热处理过程中优先析出了ＣａＭｏＯ４     

Kinetics of the thermal degradation of poly(1,4-cyclohexylenedimethylene terephthalate)

The kinetics for the thermal degradation of poly (1,4-cyclohexylenedimethylene terephthalate) (PCHDT) were evaluated by means of a melt extruder. The effects of temperature, residence time, and oxygen content of the gas blanketing the polymer during storage on degradation of PCHDT were determined. The rate of thermal degradation was measured in terms of the rate of decrease of inherent viscosity and the rate of increase of carboxyl end group concentration. Residence time, temperature, and their interaction all contributed significantly to the degradation. For the conditions investigated, the oxygen content of the blanketing gas had no measurable effect on degradation. Analysis of the kinetic data yielded equations based on a random chain scission mechanism. These equations enabled the prediction of inherent viscosity and carboxyl end group concentration as functions of temperature and residence time and the inherent viscosity and carboxyl end group concentration of the original polymer. The activation energies for decrease in inherent viscosity and increase in carboxyl end group concentration of poly (1,4-cyclohexylenedimethylene terephthalate) were determined as 38.7 kcal/mole, respectively.     

Effect of Ultrasound on Molecular Structure Development of Polylactide

In this work, effect of ultrasound on molecular structure development of Polylactide (PLA) was studied. It was found that the intrinsic viscosity of PLA decreased with increasing treating time, temperature and ultrasound time. Different from traditional thermal degradation of PLA, the degradation of PLA under ultrasound treatment showed that chain scission and chain combination of PLA competed with each other in the degradation process, which could be divided into two steps. The mechanism of ultrasound degradation of PLA was proposed. Furthermore, Thermal properties were characterized by DSC to show heat and ultrasound effects on molecular structure development of PLA.     

Thermal stabilization of poly(3‐hydroxybutyrate) by poly(glycidyl methacrylate)

Poly(3‐hydroxybutyrate) (PHB)/poly(glycidyl methacrylate) (PGMA) blends with the PGMA content up to 30 wt % were prepared by a solution‐precipitation procedure. The thermal decomposition of PHB/PGMA blends was studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). The thermograms of PHB/PGMA blends contained a two‐step degradation process, while that of pure PHB sample exhibited only one‐step degradation process. This degradation behavior of PHB/PGMA blends, which have a higher thermal stability as measured by maximum decomposition temperature or residual weight after isothermal degradation for 1 h, is probably due to crosslinking reactions of the epoxide groups in the PGMA component with the carboxyl chain ends of PHB fragments during the degradation process, and the occurrence of such reactions can be assigned to the exothermic peaks in their DTA thermograms. An isothermal study of these blends at 200–250°C for 1 h indicated that the residual weight was directly correlated with the amount of epoxide groups in the PHB/PGMA blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2945–2952, 2002; DOI 10.1002/app.10318     

山梨醇醚存在下聚乙烯的光氧化降解特性研究

通过特性粘度、凝胶含量、羧基含量及红外光谱测试,分析了山梨醇醚含量为0%、0.1%、0.3%、0.5%、l%、5%、8%的7种聚乙烯膜样品在人工加速老化实验下的光氧降解特性研究,并通过扫描电镜对山梨醇醚含量为1%的聚乙烯膜表面形貌进行了分析.结果表明,光照过程中,山梨醇醚在7种膜中引发自由基反应,致使聚乙烯分子交联、断...     

反应挤出过程中PET扩链反应的研究

分别加入羧基加成型的双噁唑啉(BOZ)和羟基加成型的均苯四甲酸酐(PMDA)为扩链剂,考察了反应挤出前后PET特性黏度([η])和羧基值的变化情况。实验结果表明:BOZ的扩链效果不明显;PMDA能较大程度地提高PET的[η],但产品羧基值较高;BOZ和PMDA联用可得到高[η]低羧基值的产品,扩链效果最佳。当挤出机工艺条件为:反应段温度260℃、螺杆转速45 r/min、反应段压力1 kPa、BOZ和PMDA质量分数均为0.2%时,可得到[η]为0.90 dL/g,羧基值为25 mol/t的PET产品。     

PET液相增黏熔体可纺性探究

研究了液相增黏熔体直纺技术中,高黏聚酯熔体可纺性能。研究表明,对于降膜式液相增黏反应器,传质的速率、传热的均匀性以及熔体热历史的一致性是影响聚酯可纺性以及物性指标的重要因素。分子量的增大使得聚酯分子链难以展开和伸直,甚至不完全取向,运动黏度剧增,熔体输送困难,在经过管道时的温升、降解严重。聚酯分子的分子量分布越窄,低相对分子量组分含量越低,越有利于纺丝。在降膜式液相增黏反应器中,由于成膜表面更新速率,以及熔体沿管壁下降的速率分布不均,导致PET分子量分布变宽,端羧基含量增大。液相增黏熔体直纺过程,是PET熔体在热量和应力的作用下,结晶和取向的过程。取向使聚酯分子产生强度,而结晶则使已取向的分子更稳定,降低体系的熵值。     

Processing characteristics of poly(ethylene terephthalate): hydrolytic and thermal degradation

The effects of poly(ethylene terephthalate) (PET) resin moisture content and temperature exposure have been investigated in terms of material changes resulting from the injection moulding process. Two resins with initial carboxyl contents of 10 µeq/g PET and 20 µeq/g PET have been analysed. Preforms processed at different resin moisture contents and processing temperatures of 280, 290 and 300 °C were evaluated in terms of carboxyl end‐group concentration using a titration method. Intrinsic viscosities of the performs were also measured by solution viscosity. Mathematical models describing the relationships of carboxyl end‐group concentration and intrinsic viscosity to the processing conditions were generated from the experimental data. Carboxyl end‐groups formed were compared for both resins and shown to be dependent on initial carboxyl content in the resin. Reducing the initial carboxyl content in the resin has been shown to increase its hydrolytic stability. The hydrolytic effect on the overall molecular weight drop was separated from the thermal/thermal‐oxidative degradation and shown to be dependent on both the processing temperature and the resin moisture content. © 2002 Society of Chemical Industry     

多元环氧扩链剂（ADR）对PBAT的扩链改性及其耐老化性能的影响

将多元环氧扩链剂（ADR）在双螺杆中对聚对苯二甲酸?己二酸丁二酯（PBAT）进行挤出扩链反应改性,研究了添加不同含量ADR对PBAT端羧基含量、相对分子质量、力学性能、结晶度及色度的影响,并采用氙灯老化实验研究了老化时间对添加不同含量ADR的PBAT力学性能与相对分子质量的影响。结果表明,经ADR扩链后,PBAT的端羧基含量下降,力学性能和相对分子质量提高;当ADR添加量为1 %时,PBAT的端羧基含量下降尤为显著,从23.3 mol/t下降至13.8 mol/t,相对分子质量、结晶温度和力学性能有所提高;当ADR添加量为1 %时,样品的力学性能最优,在老化期间断裂伸长率高于其他样品,并且化学结构和相对分子质量体现出的耐老化性能较优,老化期间的相对分子质量始终高于其他样品。     

Thermal and hydrolytic degradation of poly(1,4-cyclohexylenedimethylene terephthalate)

The kinetics of simultaneous thermal and hydrolytic degradation of poly(1,4-cyclohexylenedimethylene terephthalate) (PCHDT) were evaluated by using a 1.5-in.-diam. melt extruder (≈20/1 length/diameter ratio) as a reactor. The effects of extrusion temperature (295°-330°C), residence time (2.6–17.5 min), and moisture content (<0.001% to 0.2%) of the supply polymer on degradation were determined. The rate of degradation was measured in terms of the rate at which inherent viscosity (I.V.) decreased and the rate at which carboxyl endgroup concentration increased. The contributions of both thermal and hydrolytic degradation to the total degradation of PCHDT could be separated because the hydrolysis was rapid enough that it could be considered as occurring prior to thermal degradation. Thus, the hydrolysis merely adjusted the initial properties of the supply polymer, which was then subjected to thermal degradation. Equations were developed from an analysis of the kinetic data based on a random chain scission mechanism. The activation energies for decrease in I.V. and increase in carboxyl endgroup concentration of PCHDT from thermal degradation were determined as 33.5 and 41 kcal/mole, respectively.     

Reactive Extrusion of Polyamide 6 Using a Novel Chain Extender

Polyamide 6 (PA6) is an important engineering thermoplastic, very widely used but prone to thermal degradation during extrusion at temperature not far from its melt temperature (220°C). Typically, and as measured in this study, PA6 extruded at temperature of 300°C shows a 40% decrease in tensile modulus compared with non‐extruded PA6. To rebuild PA6 molecular weight, the easiest and cheapest method is to use an appropriate chain extender. Many chain extenders have been used in the past but they are essentially suited to nucleophile induced degradation, targeting split PA6 chains carboxyl COOH and amine NH₂ end groups. What have been lacking are effective chain extenders for thermally only induced degradation, i.e. for the practical cases where the PA6 is thoroughly dried before extrusion. For such a case, the degradation reaction mechanism dictates that the solution is to develop chain extenders that target the split PA6 chains amide CONH₂ groups not the carboxyl COOH and amine NH₂ end groups. As amide groups strongly react with anhydride functionalities, we test the effectiveness of a novel chain extender, Joncryl® ADR 3400, a styrene maleic anhydride copolymer with multiple, repeating anhydride functionality. Assessment of chain extension in this study is done as with previous work, using rheology, mechanical and thermal properties of PA6 extruded on its own and with the chain extender. The viscoelastic data conclusively show the efficacy of such chain extender with more than 10‐fold changes in the comparative values of the extruded sample storage modulus G’ and as much as an 85% increase in the tensile modulus. POLYM. ENG. SCI., 59:E25–E31, 2019. © 2018 Society of Plastics Engineers