聚酯废料乙二醇解聚反应的研究

在选定的条件下,使聚酯废料乙二醇解聚,反应产物中BHET含量高,易精制,对乙二醇醚化反应也有所抑制。BHET缩聚后得到的聚酯的各顷指标达到了纺丝要求,可纺性能良好。     

ABA／PET液晶共聚酯酰胺的结构与性能

研究了对象基苯甲酸（ＡＢＡ）／聚对苯二甲酸乙二酯（ＰＥＴ）液晶共聚酯酰胺的晶体结构，以及热性能、流变学和力学性质。广角Ｘ射线衍射研究结果表明ＡＢＡ链节的引入使ＰＥＴ的晶态结构发生畸变，但大部分结晶衍射峰仍然存在。随着ＡＢＡ含量的增加，各晶面间距基本不变，微晶尺寸显著增大，结晶度急剧降低。差示扫描量热分析和热失重结果表明共聚酯胺具有优良的热稳定性，并且随着ＡＢＡ含量的增加，共聚物的热稳定性提高，共聚     

改性PHB/PET液晶共聚酯的合成

精选八种具有不同结构特征的第三单体,以熔融缩聚法合成了八种改性PHB/PET共聚酯。发现含香草酸第三单体的PHB/PET/VA三元共聚酯具有较快共聚反应速率、较低熔融温度、典型热致液晶行为和良好成纤性。香草酸是最适合于PHB/PET体系共聚改性的第三单体。     

三元共聚液晶聚酯酰亚胺/PET共混体系结构与性能研究

通过熔融共混的方式,将实验室自行设计合成的三元共聚热致液晶聚酯酰亚胺(PPDI)与聚对苯二甲酸乙二酯(PET)进行共混,制备一系列不同液晶聚合物含量的共混体系.采用示差扫描量热仪(DSC)、广角X-射线衍射仪(WAXD)和动态力学性能分析仪(DMA)对共混体系的结构与性能进行表征.结果表明,共混体系中两组份之间具有良好...     

聚酯酰胺的合成及表征

 用两种方法合成了聚酯酰胺（ＰＥＡ）共聚物．一种是两步法，即先合成对苯二甲酸乙醇酰胺（ＢＡＥＴ）单体，然后与对苯二甲酸乙二酯（ＢＨＥＴ）共缩聚；另一种是一步法．即在酯交换反应中直接添加乙醇胺（ＥＡ）．两种方法制得的聚酯酰胺（ＰＥＡ）共聚物测试证明了为产物，并分析了合成中的化学反应．     

一维取向聚酯材料的研究进展

回顾了近年来在一维取向聚对苯二甲酸乙二酯材料的形态结构，特别是其非晶区结构和力学变形机理方面的研究进展。着重对制备高取向纤维的几种新技术及所得材料的力学性能进行了介绍。     

热致液晶共聚酯酰胺／PET共混物的流变性能和原位增强特性

采用Ｉｎｓｔｒｏｎ３２１１型毛细管流变仪研究了ＰＥＡ／ＰＥＴ共混物的流变性能，据此探讨共混物熔体的可纺性，讨论了共混物配比与复合纤维力学性能的关系，并且偏光显微镜，扫描电镜研究纤维的结构。结果表明，共混物的表观粘度低于ＰＥＴ的粘度，当ＰＥＡ为１０％，共混物的表观粘度达到最小值；且ＰＥＡ含量低于１０％时，共混物的可纺性即，表现出良好的原位增强效果。     

降解PET聚酯瓶实验条件的研究——综合研究型实验设计

为了从废PET聚酯瓶中回收对苯二甲酸(TPA),分别对比研究了酸性水解法、肼解法和醇碱联合法降解PET聚酯瓶的反应收率及环境友好性、经济性等.通过正交实验,探索了醇碱联合解聚法的最佳反应条件.采用红外光谱对回收的对苯二甲酸进行了表征,结合量子化学计算对振动光谱和分子间氢键进行了研究.     

Calorimetric study of Diepoxide Chain-Extended Poly(Ethylene Terephthalate)

A series of chain-extended PET samples were obtained by the use of different amounts of a diepoxide as chain extender, which was prepared for this purpose. These samples exhibited different intrinsic viscosities and degrees of branching or cross-linking. The effects of this differentiation on the thermal properties were studied by differential scanning calorimetry. The thermal parameters studied were the glass transition temperature (T_g), the cold-crystallization temperature (T_cc), the melting temperature (T_m), the enthalpy (ΔH_m) and the degree of crystallinity. The data revealed that, the higher the quantity of chain extender or the chain extension time, the higher T_gand T_cc, but the lower T_mand ΔH_m, i.e. the more amorphous the chain-extended samples, as also shown by density measurements. This revised version was published online in July 2006 with corrections to the Cover Date.     

Optical Transmittance Thermal Analysis of the Poly(Ethylene Terephthalate) Foils

The optical transmittance of poly(ethylene terephthalate) foils has been investigated using the linear heating as well as the isothermal heating. It was found out that transmittance records obtained at linear heating show the crystallisation and melting processes distinctly. These results are in accordance with those achieved by DSC measurements. The isothermal heating was especially applied to investigate PET cold crystallisation. In its course the optical transmittance first decreases to a certain minimal value, regaining some of the transmittance in the final period of crystallisation (crystal growth). The used method is suitable for investigating crystallisation processes of polymers accomplished at very slow rates.This revised version was published online in November 2005 with corrections to the Cover Date.     

A Study on Improving the Crystallization Rate of Poly (Ethylene Terephthalate)

In this study, sodium benzoate was selected as the nucleating agent to improve the crystallization rate of Poly (Ethylene Terephthalate) (PET). A new polyester, PEAT, which was systhesized from Bis Hydroxy-Ethyl Terephthalate (BHET) and adipic acid, was blended with PET to improve the (crystallization) rate of PET at lower temperatures. The crystallization rate of the PET blends was measured with a DSC and the kinetics of crystallization were studied. It was found that the range of the crystallization temperatures for the PET/sodium benzoate blends was wider than that for the PET/PEAT blends which shifted to a lower temperature region. PEAT showed a pronounced effect on the crystallization rate at lower temperatures, while sodium benzoate effected the crystallization rate within the entire range of crystallization temperatures.     

红外光谱在聚对苯二甲酸乙二醇酯纤维结构研究中的应用

回顾了近年来红外光谱在聚对苯二甲酸乙二醇酯(PET)纤维结构研究中的应用,介绍了纤维制样技术,归纳了构象含量、取向、折叠链含量等结构参数的表征方法及其应用,以及这些结构参数与纤维性能间的联系。     

Modification of Poly(Ethylene Terephthalate) Track Membranes by Sorption of Poly(Ethylene Glycol)

Sorption of poly(ethylene glycol) on poly(ethylene terephthalate) track membranes was studied at different pH. The hydrophilic-hydrophobic properties of the intact membranes and those modified with poly(ethylene glycol) are compared. The membrane-aqueous human serum albumin and membrane-aqueous insulin adhesive tensions were determined for modified membranes. The competitive sorption of human serum albumin and poly(ethylene glycol) from aqueous solution on the track membranes is analyzed.     

Chemical Recycling of End-of-Life Poly(lactide) via Zinc-Catalyzed Depolymerization and Polymerization

The chemical recycling of poly(lactide) was investigated based on depolymerization and polymerization processes. Using methanol as depolymerization reagent and zinc salts as catalyst, poly(lactide) was depolymerized to methyl lactate applying microwave heating. An excellent performance was observed for zinc(II) acetate with turnover frequencies of up to 45000 h⁻¹. In a second step the monomer methyl lactate was converted to (pre)poly(lactide) in the presence of catalytic amounts of zinc salts. Here zinc(II) triflate revealed excellent performance for the polymerization process (yield: 91 %, M_n ∼8970 g/mol). Moreover, the (pre)poly(lactide) was depolymerized to lactide, the industrial relevant molecule for accessing high molecular weight poly(lactide), using zinc(II) acetate as catalyst.     

Aspects of the Chemistry of Poly (Ethylene Terephthalate). IV. Hydrolysis of Poly(Ethylene Terephthalate) in the Melt Phase

The effect of water vapor pressure on the molecular weight of molten poly (ethylene terephthalate) has been followed by measurement of the changes which occur in the intrinsic viscosity and the end-group concentrations upon hydrolysis. It was found that phosphoric acid is highly effective as a stabilizer; the hydrolysis rate constant (K_h) decreasing from 7.6 × 10^?7 mol^?1s^?1 for nonstabilized to 2.5 × 10^?7 mol^?1s^?1 for the stabilized polyester at 290°C and water vapor pressure of 20 mmHg.     

Micellization and Adsorption Parameters of Nonionic Polymeric Surfactants from Poly(ethylene terephthalate) Waste

Poly (ethylene terephthalate), PET, waste was recycled to oligomers in the presence of triethanolamine and manganese acetate as a catalyst. The produced oligomers were reacted with stearic acid and polyethylene glycol having different molecular weights 400, 1000, and 4000 to produce nonionic polymeric surfactants having different hydrophile‐hydrophobe balances (HLB). The surface tension, critical micelle concentration (CMC) and surface activities were determined at different temperatures. Surface parameters such as, surface excess concentration Γ_max, the area per molecule at interface A_min and the effectiveness of surface tension reduction (Π_CMC) were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption process are calculated and discussed.     

Base Hydrolysis of Poly(Ethylene Terephthalate) in Methanolic and Aqueous Solutions

Abstract

Hydrolysis of poly(ethylene terephthalate) fibers (intrinsic viscosity: 0.819 dL/g) using methanolic sodium methoxide was compared to that using aqueous sodium hydroxide. Weight and tenacity loss occurred more rapidly with methanolic NaOCH₃. After the methanolic NaOCH₃ treatment, the surface appeared far rougher, much of which was due to low molecular weight material present on the fibers. Intrinsic viscosity measurements indicated virtually no difference between the two treatments in the small amount of chain cleavage obtained at a given weight loss. Fiber density increased after the reaction with methanolic NaOCH₃, probably due to the presence of the methyl ester end groups formed during the ester interchange reaction, while fiber density was essentially unaffected by treatment in aqueous NaOH. Density decreased after the methanolic NaOCH₃-treated fiber was hydrolyzed with aqueous NaOH. Thermal analysis revealed a small increase in the melting temperature after methanolic NaOCH₃ treatment. The shoulder present in the melting region of this sample was markedly affected by chloroform extraction of low molecular weight products resulting from the reaction. While hydrolysis using methanolic NaOCH₃ was more severe than that using aqueous NaOH, both reactions appeared to be confined to the fiber surface.