聚(对苯二甲酸乙二醇酯-co-对苯二甲酸异山梨醇酯)等温结晶行为研究

以对苯二甲酸(PTA)、乙二醇(EG)、异山梨醇(ISB)为原料,通过直接熔融缩聚法合成聚(对苯二甲酸乙二醇酯-co-对苯二甲酸异山梨醇酯)(PEIT)共聚酯。利用差示扫描量热法(DSC)研究了共聚酯的结晶行为,采用Avrami方程分析了共聚酯的等温结晶动力学。结果表明,PEIT共聚酯结晶行为受共聚组成和结晶温度影响。随着ISB用量的增加或结晶温度的降低,共聚酯半结晶周期t1/2增加、结晶速率变慢;ISB摩尔分数超过20%,共聚酯无法结晶。     

聚对苯二甲酸乙二醇酯特性的研究进展(英文)

简述了近年来聚对苯二甲酸乙二醇酯,关于热降解、扩链、结晶完整性、双冷结晶峰,以及溶剂诱导结晶等方面的研究进展     

聚对苯二甲酸乙二醇异山梨醇酯的结构和性能

以异山梨醇、乙二醇、对苯二甲酸(PTA)为原料,采用PTA法制备了异山梨醇质量分数为20%的对苯二甲酸/乙二醇/异山梨醇的无规共聚酯(PESIT)。PESIT的氢核磁共振谱和红外光谱分析表明,异山梨醇参与了对苯二甲酸与乙二醇的聚合反应。差热和热失重分析表明:PESIT具有较好的热稳定性,玻璃化转变温度和热分解温度较聚对苯二甲酸乙二酯(PET)高。纺丝速度3150 m/min的POY纺丝实验表明:PESIT与PET一样具有好的可纺性,制得的POY断裂强度为1.72 cN/dtex,断裂伸长为175%。     

聚对苯二甲酸乙二醇酯发泡材料开发及应用进展

概述了聚对苯二甲酸乙二醇酯(PET)发泡材料的性能优势,对比了国内外开发进展,PET连续挤出发泡技术主要掌握在欧美发达国家企业中;介绍了PET发泡材料的应用领域,包括风电、交通运输、包装和保温隔热、建筑、光学器件等领域.国内PET泡沫生产厂家通过与高校合作开发,正逐渐缩小与发达国家的技术差距.认为PET挤出发泡专用装备...     

聚对苯二甲酸丙二醇酯的热性能研究

研究了聚对苯二甲酸丙二醇酯 (PTT) ,PET ,CDP在不同温度和时间下的特性粘数和端羧基含量的变化。结果表明 ,一定温度下 ,PTT熔体特性粘数随熔融时间的延长而下降 ,一定时间下 ,随温度的升高而下降。PTT端羧基含量随温度升高而增大 ,PTT的热稳定性较PET明显下降。     

聚对苯二甲酸乙二醇酯无预干燥挤出

传统的PET膜挤出加工要求预干燥。预干燥技术方案能耗高，投资大，很不合算，而且生产灵活性受限制。本文介绍一种新的排气式挤出技术方案，即单螺杆挤出机结合有料斗排气和熔体排气的技术方案。本文还介绍了挤出参数、排气参数、螺杆设计、水含量对特性粘度，熔体粘度的影响，及有关试验。     

3D打印用聚对苯二甲酸乙二醇酯的研究

选用聚对苯二甲酸乙二醇酯(PET)作为基体材料,通过添加聚对苯二甲酸丁二醇酯(PBT)、相容剂、增韧剂和成核剂制得适用于熔融沉积技术的PET丝材.结果表明,当PET:PBT为7:3时,熔体流动速率最低;过多相容剂在螺杆进料口架桥,不利于螺杆挤出;当增韧剂含量为15份(质量份,下同)时,材料能够正常打印,样条无翘曲且表面...     

快速结晶聚对苯二甲酸乙二醇酯复合物

本发明提供了一种快速结晶聚对苯二甲酸乙二醇酯复合物及其制备方法。该复合物由30—80份(重量份数，下同)聚对苯二甲酸乙二醇酯、012—8份复合结晶成核剂、10—25份复合阻燃剂、10—60份填充增强剂、0．1—5份其它加工助剂经熔融挤出而成。本发明采用快速结晶技术，解决了聚对苯二甲酸乙二醇酯作为工程塑料使用时成型加工过程中结晶速率慢、注模温度高、模塑周期长的缺点，可广泛用于制造电子电器、机器机械、家电等的零部件。     

聚对苯二甲酸丙二醇酯的结晶性能研究

采用热台偏光显微镜和DSC差示扫描量热仪对PET、PTT和PBT的结晶性能进行了研究。实验得到的结果是:PBT具有极强的结晶能力。在相同的△T下,PTT的结晶诱导期和球晶出现的时间比PET短,球晶的生长速率也比PET快;同时,在相同的△T下,PTT的总结晶速率大于PET。PET和PTT在较高的温度下等温结晶时倾向于异相成核,而随着等温结晶温度的降低,开始倾向于均相成核。     

聚对苯二甲酸乙二醇酯合成基本原理Ⅱ.聚对苯二甲酸乙二醇酯的合成

概述了聚对苯二甲酸乙二醇酯(PET)合成的基本原理,以及由对苯二甲酸乙二醇酯(BHET)单体经缩聚反应合成PET的反应机理、合成过程中的主要化学反应,详述了BHET缩聚合成PET的主要影响因素。由BHET缩聚合成PET属于逐步缩合聚合过程,缩聚过程中存在多个化学反应,包括链增长反应、链降解反应及网状结构凝胶物生成的副反应。BHET缩聚合成PET的影响因素主要有催化剂种类及其用量、稳定剂种类及其用量、反应温度、反应釜余压及物料的液层厚度等。今后,在PET及其共聚酯的合成中,应加大无毒催化剂的使用与推广、非石油基原料的开发及化学改性共聚酯的开发,以及废旧聚酯的化学法回收再生利用。     

聚酯固相缩聚等温结晶特性的研究

聚酯(PET)固相缩聚(SSP)中切片的结晶性能及其演变影响固相缩聚反应,采用差示扫描量热仪(DSC)和热台偏光显微镜研究了固相缩聚反应前后PET切片的等温结晶特性。结果表明:PET切片在DSC中的等温结晶符合Avrami 方程,等温结晶温度升高,结晶速率常数K值减小,即结晶速率降低;热台偏光显微镜中不同等温结晶温度下形成了不同的球晶形态:黑十字消光图以及环形消光图;随着PET特性粘数(平均分子质量)增大,结晶速率常数K值减小,球晶生长速率减小,Avrami指数n值增大,形成更加复杂的消光图。对于固相缩聚前PET基础切片,球晶最大结晶速率在190℃左右。     

Kinetics of thermally induced solid state polycondensation of poly(ethylene terephthalate)

A diffusional model was established to study the kinetics of thermally-induced solid state polycondensation of poly(ethylene terephthalate). Diffusion through solid polymer is the rate controlling step when temperature is higher than 210°C and particle size is no smaller than 100 mesh. The activation energy is 30 Kcal/g mole. In polymerizing powders (20-200 mesh), the crystallinity of prepolymer and its changes during the polymerization affect the diffusivity and thus the polymerization rate. The diffusivity was found to be linearly proportional to the mass fraction of the amorphous phase in PET polymer.     

Solid state polycondensation of poly(butylene terephthalate)

Solid state polycondensation of poly(butylene terephthalate) has been studied under vacuum at 200°C for various particle sizes. The effect of the process on intrinsic viscosity and number of end groups has been examined. The results suggest that the increasing of the number average molecular weight can be explained by a mechanism involving hydroxyl groups, which approach each other by diffusion until a limiting value of their concentration is attained.     

Modeling of poly(ethylene terephthalate) reactors. IX. Solid state polycondensation process

A mathematical model for simulation of industrial process of solid state polycondensation of poly(ethylene terephthalate) (PET) has been developed. The model eliminates errors evident in the earlier models by proper formulation. The model results have been validated by experimental data in the literature. It enables prediction of the influence of particle shape, size, temperature, etc. on the polycondensation process correctly in all different regimes of operation, apart from bringing out the importance of gas-side resistance, influence of carrier gas, etc. for the first time.     

Solid-state polycondensation of poly(ethylene terephthalate): Kinetics and mechanism

A numerical method to seek a solution for the solid-state polycondensation (SSP) proces has been proposed to analyze the mechanism of SSP. Results expound that, for the industrial SSP process of PET, the overall reaction rate in a single pellet is appropriately simulated by the diffusion and reaction rate jointly controlling the model. From the core to the surface the SSP rate increase monotonically due to a gradual reduction of the concentration of such by-products as ethylene glycol and water. However, the SSP rate at any location within the pellet is constrained between two purely reaction rate controlling cases. © 1995 John Wiley & Sons, Inc.     

Effect of antimony catalyst on solid-state polycondensation of poly(ethylene terephthalate)

The effect of antimony trioxide (Sb₂O₃) catalyst on the solid-state polycondensation (SSP) of poly(ethylene terephthalate) (PET) has been rigorously studied. It has been determined that the rate constant increases, while the activation energy decreases, linearly with increasing catalyst concentration within the range of 0-100 ppm Sb. The SSP rate reaches its maximum value at about 150 ppm Sb. The activation energies are 30.7 and 23.3 kcal/mol respectively for the uncatalyzed and fully catalyzed SSP. The frequency factor decreases with increasing catalyst concentration due to the decreased mobility of catalyzed end groups. A mechanism of Sb catalysis has been proposed to explain these observations.     

Optimization of the polycondensation stage of poly(ethylene terephthalate) reactors

A general kinetic scheme for the polycondensation step of the PET formation has been used to establish the mole balance equations of various functional groups in batch reactors. An objective function has been defined which aims to attain a desired degree of polymerization in the shortest time, has a specified level of diethylene glycol group content, and minimizes the other side products. Using the control vector iteration procedure, an optimum temperature profile has been calculated. The computations suggest that a high temperature should be used initially which must be lowered as the time of reaction increases for limiting the formation of side products.     

Melt polycondensation of poly(ethylene terephthalate) in a rotating disk reactor

A multicompartment model is proposed for a semibatch melt polycondensation of poly(ethylene terephthalate) in a rotating disk polymerization reactor and compared with laboratory experimental data. The reactor is a horizontal cylindrical vessel with a horizontal shaft on which multiple disks are mounted. The reactor is assumed to comprise N equal sized compartments and each compartment consists of a film phase on the rotating disk and a bulk phase in which disks are partially immersed. The effects of disk rotating speed, number of disks, reaction temperature, and pressure were investigated. It was observed that ethylene glycol is predominantly removed from thin polymer layers on the rotating disks and the enhanced interfacial area exerted by ethylene glycol bubbles accounts for about 30–50% of the total available interfacial mass transfer area. Although the rate of polymerization increases as more disks are used, the maximum number of disks in a reactor must be determined properly in order to prevent the formation of thick polymer films that result in a reduced specific interfacial area and reduced polymerization efficiency. At a fixed reaction pressure, the equilibrium conversion is reached but the rate of reaction can be further increased by increasing the reaction temperature. The results of the proposed multicompartment model are also compared with those predicted by a simple one-parameter model. © 1995 John Wiley & Sons, Inc.     

Dispersion of nanoclays with poly(ethylene terephthalate) by melt blending and solid state polymerization

Melt intercalation of clay with poly(ethylene terephthalate; PET) was investigated in terms of PET chain mobilities, natures of clay modifiers, their affinities with PET, and nanocomposite solid state polymerization (SSP). Twin screw extrusion was used to melt blend PET resins with intrinsic viscosities of 0.48, 0.63, and 0.74 dL/g with organically modified Cloisite 10A, 15A, and 30B montmorillonite clays. Clay addition caused significant molecular weight reductions in the extruded PET nanocomposites. Rates of SSP decreased and crystallization rates increased in the presence of clay particles. Cloisite 15A blends showed no basal spacing changes, whereas the basal spacings of Cloisite 10A and Cloisite 30B nanocomposites increased after melt extrusion, indicating the presence of intercalated nanostructures. After SSP these nanocomposites also exhibited new lower angle X‐ray diffraction peaks, indicating further expansion of their basal spacings. Greatest changes were seen for nanocomposites prepared from the lowest molecular weight PET and Cloisite 30B, indicating its greater affinity with PET and that shorter more mobile PET chains were better able to enter its galleries and increase basal spacing. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013