PET缩聚催化剂的发展及展望

介绍了PET催化剂的发展及现状,简要比较和评价了各种锑系催化剂及应用,对目前国内外较为关注的各种钛系催化剂及应用概况、合成技术等进行了分析和总结,对新型催化剂的发展趋势进行了展望。     

Ohmic drops in the ion-exchange bed of cationic electrodeionisation cells

The work was aimed at investigating the ohmic drop in ion-exchanging resin beds in EDI cells, by using two techniques. The case of CuSO₄–H₂SO₄ solutions was treated here, using Dowex resins of various degrees of cross-linking. Impedance measurements in a dedicated cell filled with resin packed beds were interpreted by using a model for the conductivity of two-phase media. Secondly, the voltage recorded in a small EDI cell for continuous treatment of copper solutions, led to the bed conductivity, using a model for potential distribution in the cell. The consistency of the two techniques was discussed, and side electrical phenomena in the EDI cell were shown to be the source of an unexpectedly significant increase in the cell voltage.     

聚酯卷材涂料的研制

介绍以高反应活性的聚酯、氨基树脂在高温(1～2)min固化,制成耐候性、加工成型性优异的漆膜。讨论了各种因素对涂膜性能的影响。     

聚酯纤维改性方法的探讨

对聚酯改性进行了讨论,指出了聚酯生产的各个环节改性的方法及在生产实践中的具体应用,主要有共聚改性,共混改性,后加工改性以及纺丝设备上的改性。改性纤维比常规纤维的性能更加优良,可以满足人们的多种要求。     

低温固化酚醛—缩醛—二异氰酸酯胶粘剂的研究

本文研究了一种以线性酚醛树脂和聚乙烯醇的缩醛为底胶，二异氰酸酯为交联联剂，Ｎ—乙基吗啉为固化促进剂，可低温固化的双组份胶粘剂。实验结果表明，该胶粘剂在－１５℃左右仍具有良好的固化性能，对金属、塑料和陶瓷等多种材料都具有较好的粘接性能。     

聚酯短纤维在胶带中的应用

用聚酯短纤维作橡胶制品的填充增强材料，能有效地提高胶体的抗拉伸性能，耐撕裂性能，耐磨性能，耐穿刺性能；通过对短纤维定向工艺处理使复合胶体获得单方向刚性增强和抗拉伸能力增强的特性。     

Intercalation of epoxy resin in organically modified montmorillonite

Various methods of preparation of epoxy resin/clay mixtures, before the addition of the crosslinking agent and curing to form epoxy‐based polymer layered silicate (PLS) nanocomposites, have been investigated to determine their effect on the nanostructure. Organically modified montmorillonite clay was used, and the mixtures were prepared by both simple mixing and solvent‐based methods. X‐ray diffraction shows that intercalation of the resin into the clay galleries occurs for all clay loadings up to 25 wt % and for both preparation methods, but the dispersion of the clay in the resin, observed by optical microscopy, is significantly better for the solvent preparation method. Differential scanning calorimetry (DSC) shows that the intercalated resin has the same molecular mobility as the extra‐gallery resin, but suggests that the intercalated resin does not penetrate completely into the galleries. Prolonged storage of the resin/clay mixtures at room temperature leads to changes in the DSC response, as well as in the response to thermogravimetry, which are interpreted as resulting from homopolymerization of the epoxy resin, catalyzed by the onium ion in the modified clay. This confirms and explains the earlier observation of Benson Tolle and Anderson (J Appl Polym Sci 2004, 91, 89) that “conditioning” of the resin/clay mixtures at ambient temperature has a significant effect when the crosslinking agent is subsequently added, and indicates that the preparation method has important consequences for the nanostructure development in the PLS nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3751–3763, 2006     

Rheology of chemically modified triglycerides

The rheology of chemically modified plant oils was determined to aid in their processing for polymers and other applications. Epoxidized and acrylated triglycerides were derived from various plant oils and model triglycerides. The viscosity of the unmodified oils decreased as the level of oil unsaturation increased. However, the viscosity of the epoxidized oils increased slightly as the level of epoxidation increased. Furthermore, the viscosity of the acrylated oils increased exponentially as the level of acrylation increased because of increased polarity. In addition, the viscosity of the acrylated oils increased as the average distance of the acrylate groups from the fatty acid chain ends decreased. Chemically modified and unmodified oils did not exhibit any shear‐thinning behavior or any memory of shear history. The temperature dependence of the viscosity followed the Arrhenius law, and the activation energy decreased linearly with the level of acrylation. The addition of comonomers, such as styrene, reduced the viscosity of the acrylated oils exponentially as the comonomer concentration increased. However, the glass‐transition temperature and modulus of the triglyceride‐based polymers decreased as the styrene content decreased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 774–783, 2005     

自动电位滴定在大分子量聚酯多元醇羟值测定中的应用

在目前通用的乙酸酐-吡啶法测羟值的基础上,针对低羟值聚酯多元醇建立了准确度更高的分析方法,并采用自动电位滴定法测定聚酯多元醇的羟值。测试结果表明,该法提高了测试的准确度,并可解决深色和浑浊样品无法手动滴定的问题。     

树脂类催化剂在酯化反应中的应用进展

回顾了近年来离子树脂作为酯化催化剂的发展情况。介绍了聚苯乙烯类树脂和Nafion树脂在各类酯化反应中的应用以及发展,对树脂类催化剂的应用前景以及该类催化剂在绿色化学中的重要作用提出展望。