含磷化合物对尼龙66的扩链研究

采用磷化合物ＰＴＬ、ＳＨＰ和ＴＰＰ作为尼龙６６的扩链剂,在抽真空或充氮条件下进行熔融扩链反应。研究了尼龙６６样品的特性粘度随扩链剂用量的变化规律,测定了扩链前后端羧基、端氨基含量的变化。结果表明,三种含磷化合物均是尼龙６６的有效扩链剂。其中,单独使用ＰＴＬ的扩链效果最好,用０６％ＰＴＬ扩链,尼龙６６最高特性粘度可达１８４ｄｌ／ｇ,大大超过了吹塑加工对尼龙６６的粘度要求     

先醇后碱双解聚PET新工艺

研究采用了一种常压、较低温、无污染的先醇后碱双解聚PET回收新工艺。首先通过EG使PET醇解为低聚物和小分子,再通过氢氧化钠的碱解与浓硫酸的酸化等作用回收TPA和EG。简化工艺条件的同时,也较单纯的醇解或碱解等其他工艺更加符合PET解聚的反应机理。研究结果表明：194℃为最佳分解温度,105%的氢氧化钠用量为最佳碱解用量,对苯二甲酸的回收率为92%,酸度值为617 mg KOH/g。     

Poly(ethylene terephthalate) Recycling and Recovery of Pure Terephthalic Acid. Kinetics of a Phase Transfer Catalyzed Alkaline Hydrolysis

Poly(ethylene terephthalate) (PET) taken from post‐consumer soft‐drink bottles was subjected to alkaline hydrolysis with aqueous sodium hydroxide after cutting it into small pieces (flakes). A phase transfer catalyst (trioctylmethylammonium bromide) was used in order the reaction to take place in atmospheric pressure and mild experimental conditions. Several different reaction kinetics parameters were studied, including temperature (70–95°C), NaOH concentration (5–15 wt.‐%), PET average particle size, catalyst to PET ratio and PET concentration. The disodium terephthalate received was treated with sulfuric acid and terephthalic acid (TPA) of high purity was separated. The ¹H NMR spectrum of the TPA revealed an about 2% admixture of isophthalic acid together with the pure 98% terephthalic acid. The purity of the TPA obtained was tested by determining its acidity and by polymerizing it with ethylene glycol using tetrabutyl titanate as catalyst. A simple theoretical model was developed to describe the hydrolysis rate. The apparent rate constant was inversely proportional to particle size and proportional to NaOH concentration and to the square root of the catalyst amount. The activation energy calculated was 83 kJ/mol. The method is very useful in recycling of PET bottles and other containers because nowadays, terephthalic acid is replacing dimethyl terephthalate (the traditional monomer) as the main monomer in the industrial production of PET.     

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.     

Recycling Nylon 6 Carpet to Caprolactam

The recycling of nylon 6 carpet via depolymerization provides the potential for an environmentally benign new process to produce world-class caprolactam. This article describes the depolymerization of nylon 6 carpet in the presence of steam under medium pressure (800-1500 kPa, 100-200 psig). A small laboratory apparatus was set up to demonstrate the feasibility of the scheme. A total of eight runs were carried out using ～180 g of pellitized carpet and 2-6 g/min steam (at 101-1500 kPa, 0-200 psig, and 300-340°C). In our best run at 340°C, 6 g/min of steam, and 1500 kPa (200 psig) for 3 h, we obtained a 95% yield of crude caprolactam. The lactam purity was 94.4%, resulting in an overall 89.7% yield of caprolactam. The laboratory data were used to construct a computer model of the process for both batch and continuous-flow stirred reactors.     

尼龙66基复合材料的研究进展

综述了近年来尼龙66(PA66)复合材料的研究状况和技术进展,重点讨论了PA66合金、PA66无机纳米复合材料和PA66填充增强改性,并对PA66复合材料的制备方法进行了介绍。同时对PA66复合材料的发展趋势及应用前景进行了分析和展望。     

玻纤增强尼龙材料熔接痕强度初探

制备了不同黏度的尼龙6或尼龙66与不同直径的玻纤的共混物,对玻纤增强尼龙材料的熔接痕强度进行了研究。结果表明:使用相对黏度为2.4的尼龙6或2.4的尼龙66,其熔接痕都要比相对黏度为2.7的尼龙6或2.7的尼龙66高;在相同黏度尼龙6或尼龙66体系中,使用10μm直径玻纤要比使用13μm直径玻纤的熔接痕强度高。同时从扫描电镜可知:尼龙树脂对直径为10μm玻纤的包覆,要优于对直径为13μm玻纤的包覆。     

Heat Transfer Studies in an Agitated Vessel During Aqueous Alkaline Depolymerization of Poly(Ethylene Terephthalate) (PET) Waste

Depolymerization reactions of poly(ethylene terephthalate) (PET) waste in aqueous sodium hydroxide solution were carried out in a batch reactor at 150°C at atmospheric pressure. Disodium terephthalate (terephthalic acid salt) and ethylene glycol (EG) remain in the liquid phase. Terephthalic acid (TPA) salt was converted into TPA. The produced monomeric products (TPA and EG) were recovered. Various design parameters were estimated. Design of a batch reactor was undertaken for depolymerization of PET waste in aqueous sodium hydroxide solution. As expected, the Reynolds numbers, Prandtl numbers, Nusselt numbers, coil-side heat transfer coefficients, and overall heat transfer coefficients were consistent with the fluid velocities. It shows excellent potential for commercialization of the depolymerization of PET waste.     

邻甲酚、间甲酚的常压合成研究

以二甲苯为溶剂,邻氯甲苯、氢氧化铯为原料常压条件下合成邻甲酚和间甲酚。其优化工艺为投料比n（氢氧化铯）：n（邻氯甲苯）=1．8：1．18-冠-6为相转移催化剂,回流反应8h,此工艺条件下产品的总收率可达64％,生成的间甲酚和邻甲酚的比例为1．2：1,无副产物。     

红磷阻燃剂在尼龙—66工程塑料中的应用

简介含红磷阻燃剂在尼龙－６６中的应用,含磷高的红磷阻燃剂用于加工温度较高的尼龙－６６具有较平衡的阻燃和耐漏电性。     

Investigation of alkaline hydrolysis of polyethylene terephthalate by differential scanning calorimetry and thermogravimetric analysis

The hydrolytic depolymerization of polyethylene terephthalate (PET) with alkaline hydroxides was investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The reactions of the mixtures were conducted in their solid states under nitrogen atmosphere. The experimental results showed that potassium hydroxide possessed the hydrolytic activity of depolymerizing PET into small molecules such as ethylene glycol; in contrast, sodium hydroxide did not. The production rate of ethylene glycol was enhanced by increasing charge ratio of potassium hydroxide to PET. The presence of water facilitated the alkaline hydrolysis of PET; however, the presence of metal acetates decreased the hydrolysis rate. The activation energy for alkaline hydrolysis of PET determined by the thermograms was in good agreement with the value obtained from the experiments in a batch reactor. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1939–1945, 1998     

Deformation of doubly oriented polyethylene,nylon 66 and poly(ethylene terephthalate)

Doubly oriented specimens of high density polyethylene (HDPE), nylon 66 and poly(ethylene terephthalate) (PET) were re-stretched along a direction perpendicular to the molecular chain axis at temperatures ranging between room temperature and the respective polymer melting points. Brittle failure was observed for PE samples at all the test temperatures with no significant amount of plastic deformation; whereas, for both PET and nylon 66 samples, ductile deformation was observed at elevated temperatures with plastic strain of >400%. The ductile deformation of nylon 66 and PET occurred with an anisotropic change in the cross-sectional dimensions of the specimen, the reduction taking place predominantly in only one lateral direction. The morphological change accompanying the drawing of the doubly oriented PET and nylon 66 material was examined by using X-ray and optical methods. The implications of the difference in deformation behaviour with respect to the morphological differences among oriented PE, PET and nylon 66 materials are discussed.     

Hydrolytic Depolymerization of PET in a Microwave Reactor

Recycling of PET was examined using hydrolytic depolymerization in an alkaline solution under microwave irradiation. The reaction was carried out in a sealed microwave reactor in which the pressure and temperature were controlled and recorded. The main products were the monomers TPA and EG. The effect of reaction temperature, time, amount of PET and alkaline concentration on the degree of PET depolymerization and TPA recovery was investigated. Microwave irradiation was found to reduce the time needed to achieve a specific degradation of PET significantly, with almost complete depolymerization occurring in 30 min at 180 °C and only 46 W of microwave power. Using a phase transfer catalyst (TOMAB) resulted in the same amount of unreacted PET but at significantly lower depolymerization temperatures.

     

Kinetics of formation of diphenoxymethane from phenol and dichloromethane using phase-transfer catalysis

The reactions of phenol with dichloromethane using quaternary ammonium salts as a liquid–liquid phase-transfer catalyst in an organic solvent/alkaline solution were investigated. The technique of phase-transfer catalysis had a dramatic accelerating effect on the reaction and increased the yield of diphenoxymethane by more than 95%. The effects of catalysts, temperature, and basic concentration on reaction rate were studied in order to find the optimum operating conditions for this reaction. Experimental results indicated that a potassium hydroxide was preferred over sodium hydroxide in order to enhance the reactivity of the reaction. The reaction rate constant and the distribution coefficient of the intermediate product were obtained. During the reaction, the concentration of the intermediate product was also measured in order to study its behavior in the liquid–liquid system.     

抗氧化尼龙66的制备与性能研究

通过在尼龙66聚合过程中加入含磷抗氧剂，制备了抗氧化尼龙66树脂；并对其抗热氧能力、力学性能、热变形温度和流变性能进行了表征。结果表明：抗氧剂的加入使尼龙66的黄色指数显著降低，抗热氧能力提高；拉伸性能、弯曲性能及热变形温度均有增加，且非牛顿指数减小，粘流活性能降低。     

Catalyzed hydrolysis of polyethylene terephthalate melts

The effect of zinc catalysts on the hydrolytic depolymerization of polyethylene terephthalate (PET) melts in excess water was studied using a 2-L stirred pressure reactor at temperatures of 250, 265, and 280°C. The main products of the reaction were found to be terephthalic acid, ethylene glycol, and diethylene glycol. Rate constants were calculated from initial rate data at each temperature and found to be about 20% greater than the corresponding rate constants for uncatalyzed hydrolysis. The catalytic effect of zinc, as well as sodium, salts is attributed to the electrolytic destabilization of the polymer-water interface during hydrolysis. The depolymerization rate data at 265°C were found to fit a kinetic model proposed earlier for the uncatalysed hydrolysis of PET. The effect of zinc and sodium salts on the activation energy of hydrolysis, or on the formation of ethylene glycol monomer is unclear. © 1994 John Wiley & Sons, Inc.     

铸型尼龙制备与改性研究

铸型尼龙是以己内酰胺为单体，强碱性物质为催化剂，与助催化剂等助剂一起，经过真空脱水后直接注入到已预热至一定温度的模具中，聚合成固体坯料。根据阴离子聚合反应的机理，考察了催化剂、助催化剂、改性剂等因素对材料拉伸强度、断裂伸长率、硬度和冲击强度等指标的影响，分析了各指标的变化规律及联系。实验结果表明，真空度为1.333kPa，氢氧化钠一般是己内酰胺的0.4%~0.5%·mol-1，列克纳胶用量为4mL，材料的综合性能较佳。     

Effective aminolytic depolymerization of poly(ethylene terephthalate) waste and synthesis of bisoxazoline therefrom

Aminolytic depolymerization of postconsumer poly(ethylene terephthalate) (PET) bottle waste with 2-amino-2-methyl-1-propanol and 1-amino-2-propanol under atmospheric condition was investigated in the presence of catalysts zinc acetate or sodium acetate. The virtual products obtained in pure form were, respectively, bis(1-hydroxy-2-methylpropan-2-yl)terephthalamide and bis(2-hydroxypropyl)terephthalamide. The latter was taken for further studies because of its higher yield and subjected to cyclization using thionyl chloride under low-temperature conditions to get 1,4-bis(5-methyl-4,5-dihydrooxazol-2-yl)benzene, which is used as chain extender in polyester and nylon compositions and as a crosslinking agent in powder paint compositions. The products obtained from depolymerization were characterized by TLC, melting point, IR spectroscopy, ¹H-NMR, ¹³C-NMR, and DSC. We have shown that it is possible to synthesize new utility products by recycling of PET waste. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

高纤维含量的短切碳纤维增强尼龙流变行为研究

以40%高纤维含量的短切碳纤维增强尼龙(PA66/SCF(40%))复合材料为研究对象,采用高压毛细管流变仪对其挤出料粒进行稳态流变试验,并采用扫描电子显微镜(SEM)观察其注塑试样拉伸断面表观形貌,深入研究了高纤维含量下短切碳纤维增强尼龙的流变行为。结果表明,随着表观剪切速率增加,材料挤出过程中总压力降不断增加;随着温度增加,总压力降逐渐减小;PA66/SCF(40%)复合材料为假塑性流体,存在剪切变稀行为,在较高剪切速率下,纤维沿流动方向发生取向;材料挤出胀大比与弹性回复有关,挤出胀大比随剪切速率增加而增加,随温度增加而减小。     

尼龙66高铁专用材料的研究

采用双螺杆挤出加工工艺,对尼龙66材料增强增韧进行了研究,深入探讨了玻璃纤维、增韧剂及助剂等材料对尼龙66的性能影响,确定了合金复合尼龙材料的最佳工艺参数和配方,所制备的尼龙复合材料可以达到高铁用尼龙材料的性能要求.