PET／蒙脱土纳米复合材料的制备及其性能研究

将十六烷基三甲基溴化铵／聚乙二醇混合物处理的蒙脱土与聚对苯二甲酸乙二醇酯在哈克流变仪上进行熔融复合，制备了聚对苯二甲酸乙二醇酯(PET)/蒙脱土纳米复合材料。X射线衍射以及透射电镜分析表明，蒙脱土层间距明显增大，部分剥离并分散于PET基体中。对其力学性能和热性能的分析发现，当有机化蒙脱土用量为5％(质量含量，下同)时，材料的热变形温度及弯曲模量分别达到154℃和3．335GPa。     

PET/ZnO纳米复合材料的制备及结晶性能

通过纳米ZnO存在下的对苯二甲酸／乙二醇(TPA／EG)酯化和缩聚反应制备聚对苯二甲酸乙二醇酯(PET)／ZnO纳米复合材料，研究了纳米ZnO用量及其分散方式对PET粘均摩尔质量、纳米ZnO在复合物中的分散及聚乙二醇(PEG)结晶性能的影响。发现纳米ZnO及分散改性剂(PEG)的加入，对合成PET的粘均摩尔质量均有一定影响；纳米ZnO在EG中直接分散再缩聚形成的复合物中，纳米ZnO团聚严重、分散性差，PET的结晶度和结晶速率降低；在纳米ZnO分散过程中加入PEG可以降低纳米ZnO在复合物中的团聚，提高分散性，PET的结晶度和结晶速率提高。     

蒙脱土对PET结晶性能、热稳定性和力学性能的影响

通过熔融共混法制备了聚对苯二甲酸乙二醇酯(PET)／蒙脱土复合材料，用X-射线衍射和透射电镜对蒙脱土在基体中的分散情况进行了表征。研究了蒙脱土对PET结晶性能、热稳定性和力学性能的影响。结果表明，蒙脱土在PET结晶过程中起异相成核作用，明显提高了PET的结晶速率；基体中分散的蒙脱土片层结构可显著改善其热稳定性，加入3％(质量含量，下同)蒙脱土时，起始热分解温度提高22℃，热变形温度提高41℃；加入1％时，材料拉伸强度提高25％，缺口冲击韧性略有下降，此时材料有较好的综合力学性能。     

PET/PTT/MMT复合材料的制备及其非等温结晶行为

采用双螺杆挤出机制备了聚对苯二甲酸乙二醇酯/聚对苯二甲酸丙二醇酯(PET/PTT)合金以及该聚酯合金基蒙脱土(MMT)复合材料。采用扫描电镜(SEM)观察了聚酯合金以及聚酯合金基蒙脱土复合材料的结构,通过差示扫描量热仪(DSC)对其非等温结晶行为进行了研究。结果表明:PET/PTT/MMT复合材料结构比聚酯合金致密,并且MMT的分散比较均匀;相同的降温速率下,随着蒙脱土含量的增加,PET/PTT/MMT复合材料的结晶温度向高温方向移动。随着降温速率增大,聚酯合金与聚酯合金基复合材料的结晶峰温度都向低温方向移动。     

阻隔性聚合物/蒙脱土纳米复合材料的开发

介绍了聚合物／蒙脱土纳米复合材料的制备方法和主要特性，重点综述了阻隔性聚合物／蒙脱土纳米复合材料的开发进展，包括聚酰胺(PA)／蒙脱土纳米复合材料、聚对苯二甲酸乙二醇酯(PET)／蒙脱土纳米复合材料、聚苯乙烯(PS)／蒙脱土纳米复合材料、超高相对分子质量聚乙烯(UHMWPE)／蒙脱土纳米复合材料。     

PET/MMT纳米复合材料的研究进展

综述了聚对苯二甲酸乙二酯(PET）/蒙脱土(MMT)纳米复合材料的2种制备方法、性能及其表征方法。MMT对PET的改性可以提高PET的阻隔性和结晶速率．并使PET拉伸模量和热变形温度大幅度提高,是目前PET改性的新方向。     

PET／无机纳米粒子复合物的制备及性能

将分散处理后的纳米二氧化硅和纳米二氧化钛分别加入对苯二甲酸乙二醇酯的熔体中缩聚,制得聚对苯二甲酸乙二醇酯(PET)／无机纳米粒子复合物,对其结晶性能、热性能和抗紫外性能进行了分析。结果表明:与PET比较,PET／无机纳米粒子复合物的结晶度提高,熔点略有降低,冷结晶温度下降,热结晶温度升高,热稳定性能变化不大;抗紫外性能优良。     

PTT/MMT纳米复合材料的研究

采用熔融共混的方法制备了聚对苯二甲酸丙二醇酯/有机蒙脱土（PTT/MMT）纳米复合材料,通过DSC、热台偏光显微镜等研究了PTT/MMT纳米复合材料的结晶行为,测定了纳米复合材料的力学性能,并用熔体流变仪研究了PTT/MMT纳米复合材料熔体流变性能。结果表明：随着PTT/MMT纳米复合材料中蒙脱上含量的增加,PTT/MMT纳米复合材料的熔融结晶温度增高,纳米复合材料的力学性能有一定的提高;PTT-蒙脱土纳米复合材料熔体的流变性能随MMT含量的增加非牛顿性减弱,熔体的粘流活化能减小。     

PET/MMT纳米复合材料的制备及其在液体包装中的应用

针对聚对苯二甲酸乙二酯(PET)熔体强度差、结晶速率慢、尺寸稳定性差等缺点,利用蒙脱土(MMT)的可膨润性和层间的阳离子可交换性,采用有机处理的MMT对PET进行改性,采用熔融插层共聚法制得PET／MMT纳米复合材料。该复合材料的结晶速率快,对气体、液体的阻隔性好,强度、模量、热变形温度高,且透明、无毒、无味,不易破碎,完全可应用于茶饮料、油品及碳酸类饮料等液体的包装。     

纳米PET树脂及其工程塑料应用

通过双螺杆挤出机熔融共混技术，将蒙脱土以纳米尺度分散在聚对苯二甲酸乙二醇酯(PET)基体树脂中制得纳米复合PET树脂。蒙脱土在与PET树脂结合前，先经过了有机化处理。X-射线衍射结构分析表明，蒙脱土层间距依次按照纯蒙脱土、有机化蒙脱土、PET复合蒙脱土的顺序从1．3nm增大到2．3nm。直至3．1nm。透射电子显微镜图象显示，纳米分散的层状硅酸盐的片层厚度平均在30nm左右。纳米复合PET具有良好的熔体强度、快速结晶、良好机械强度等性能，是开发耐热、增强、阻燃工程塑料的良好基础树脂。     

Depolymerization of poly(ethylene terephthalate) resin under pressure

The process of depolymerization of PET resin by EG glycolysis under pressure is investigated. The kinetics of this pressurized depolymerization of PET resin is discussed. It was found that the rate of depolymerization is dependent of temperature, pressure, and concentration ratio of EG to PET. The rate of depolymerization is proportional to the square of EG concentration and faster than that under atmospheric pressure. Glycolyzed products under pressure consist of the PET monomer, BHET, and oligomers, mostly dimer and trimer. An equilibrium between BHET and oligomers is attained quickly soon after the depolymerization step is completed in the case of a higher ratio of EG/PET used. In the case of lower ratio of EG/PET, the final product now consists of higher molecular weight of oligomers rather than monomer, dimer, and trimer.     

Kinetics of glycolysis of poly(ethylene terephthalate) under microwave irradiation

The glycolysis of poly(ethylene terephthalate) (PET) was carried out using excess ethylene glycol (EG) in the presence of zinc acetate as catalysts under microwave irradiation. The effects of particle size, microwave power, the weight ratio of EG to PET, the weight ratio of catalyst to PET, reaction temperature and stirring speed on the yield of bis(hydroxyethyl terephthalate)(BHET) were investigated. The experimental results indicated that the glycolysis rate was significantly influenced by stirring speed and initial particle size. The optimal parameters of glycolysis reactions were the weight ratio of catalyst to PET of 1%, the weight ratio of EG to PET of 5, 500 W and 196°C, the yield of BHET reached to 78% at only 35 min. The glycolysis products were analyzed and identified by FTIR, differential scanning calorimetry, and elemental analysis. The kinetics of glycolysis of PET under microwave irradiation could be interpreted by the shrinking core model of the film diffusion control. The apparent activation energy was evaluated using the Arrhenius equation and it was found to be 36.5 KJ/mol, which was lower compared to the same process using conventional heating. The experimental results also showed that the reaction time was significantly decreased under microwave irradiation as compared with it by conventional heating. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of γ‐irradiation on glycolysis of PET waste and preparation of ecofriendly coatings using bio‐based and recycled materials

Recycling of postconsumer poly (ethylene terephthalate) (PET) is a worldwide concern due to large increasing volume of these materials produced by society. In the present study, we report the effect of gamma irradiation on degradation of PET and its subsequent effect on glycolysis by using excess ethylene glycol (EG). The results as analyzed by molecular weight determination showed that extent of depolymerization of PET were dose dependent. The doses of 30, 50, 70, and 100 kGy resulted in decrease in the molecular weight by about 15%, 25%, 30%, and 40% respectively. The irradiated waste PET samples were further subjected to glycolysis using EG by conventional and microwave method which resulted in increased yield of monomeric product, bis (2‐hydroxyethylterephthalate) (BHET). The recycled material, BHET, was then used in combination with bio‐based monomers to prepare a new eco‐friendly polyester polyol which was analyzed for hydroxyl, saponification, acid value and further characterized by FTIR, ¹HNMR, and GPC techniques for molecular weight determination. Polyurethane coatings were prepared from the polyester polyol and various commercial polyisocyanate curing agents. The coated films were evaluated for their performance properties. Thermal properties of coatings were investigated by differential scanning calorimetry and thermogravimetric analysis. POLYM. ENG. SCI., 55:2653–2660, 2015. © 2015 Society of Plastics Engineers     

聚酯废丝的化学回收研究

使用乙二醇(EG)对有色聚酯(PET)废料解聚,经分离提纯,得到对苯二甲酸二乙二醇酯(BHET)。研究了物料比、反应温度、反应时间、催化剂对醇解率的影响。结果表明,在m(乙二醇)∶m(PET)=2∶1,反应温度196℃,反应时间3 h,催化剂用量为PET质量的0.5%条件下,聚酯解聚很彻底,产物羟值可达434 mg/g以上,主要成分是BHET单体及其低聚物。并通过IR,DSC,HPLC验证了产物的组成,BHET单体纯度可达96.457%。     

Study on PET fiber modified by nanomaterials: Improvement of dimensional thermal stability of PET fiber by forming PET/MMT nanocomposites

Poly(ethylene terephthalate) (PET) and PET/montmorillonite(MMT) (2.5 wt %) nanocomposites with high molecular weight were prepared by solid‐state polycondensation and their fiber was spun and drawn under various conditions. The influence of MMT nanomaterials on the thermal shrinkage of PET fiber was investigated and the structure was studied using the methods of WAXD, DSC, fiber orientation measurement, etc. The results showed that the MMT nanomaterials improved the thermal stability of microstructure of PET fiber. The fusion heat of PET/MMT was higher than that of PET, which generally implied the high orientation or high crystallinity. However, the degree of orientation and the crystallinity of PET/MMT fiber measured by WAXD were lower than that of pure PET fiber. It is suggested that the strong interaction between MMT layer and PET restricted the motions of PET molecular chains, which developed “a special continuous network structure” and prohibited the thermal shrinkage of PET fiber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2247–2252, 2005     

聚对苯二甲酸乙二酯/蒙脱土纳米复合材料的制备及性能研究

研究了聚酯(PET)/蒙脱土(MMT)纳米复合材料的制备方法,测试了复合材料的各种性能。结果发现酯化时间和缩聚时间均随MMT加入量的增加而缩短;PET/MMT纳米复合材料的特性粘度则随MMT添加量的增加而减小;与纯PET相比,PET/MMT纳米复合材料的冷结晶温度tcc变化不大,热结晶温度tmc有较大提高;PET/MMT纳米复合材料比PET有更快的结晶速度;TG测试表明PET/MMT有更好的热稳定性;PET/MMT纳米复合材料和PET均为假塑性流体。     

The onset of orientational crystallization in poly(ethylene terephthalate) during low temperature drawing

It is well known that crystallization can be induced in amorphous poly(ethylene terephthalate) (PET) by orientation below the isotropic crystallization temperature. The magnitude of the strain necessary for crystallization varies inversely with molecular weight because of relaxation. However, lower molecular weight PET might be expected to, crystallize at a lower extent of molecular orientation, since the crystallization rate also varies inversely with molecular weight. Chain conformations were measured during low temperature drawing of PET of various molecular weights. The molecular configuration associated with strain induced crystallization was found to be independent of chain length. The onset of orientational crystallization was associated with a particular conformation, and this critical trans/gauche ratio was equivalent for PETs of various molecular weights. The drawing behavior is thus in accord with theory concerning the transition of flexible chain polymes from isotropy to an ordered state. This result is congruent with previous studies suggesting the presence of extended chain crystallinity in amorphous PET after low temperature drawing.     

Poly(ethylene-2,6-naphthalenedicarboxylate) fiber for industrial applications

Poly(ethylene-2,6-naphthalenedicarboxylate) (PEN) has been prepared from commercial dimethyl-2,6-naphthalenedicarboxylate (DM-2,6-NDC) and ethylene glycol (EG) according to the well-known transesterification/polycondensation route. PEN fibers, intended for industrial yarn applications, were obtained by melt spinning and drawing high molecular weight PEN. The properties of these yarns were measured in detail and compared with those of PET industrial yarns. The development of molecular orientation in the spinline is more pronounced for PEN than for PET. Because the yield stress is lower, PEN yarns can more easily be drawn. Breaking tenacities of PEN yarns are comparable with those of PET yarns, but the modulus is much higher and the thermal shrinkage is lower. Therefore, PEN yarns have a better dimensional stability than PET yarns. In addition, it was demonstrated that the thermal resistance of PEN yarns is better. © 1995 John Wiley & Sons, Inc.