Effect of ionic content,solid content,degree of neutralization,and chain extension on aqueous polyurethane dispersions prepared by prepolymer method

There are many variables in the preparation of aqueous polyurethane (PU) dispersions. Carboxylic acid content, solid content, degree of pre/postneutralization of the carboxylic acids, and chain extension all impact dispersion particle size, viscosity, pH, molecular weights, and glass transition temperature. This study evaluated the impact of these variables on a given PU dispersion formulation prepared from isophorone diisocyanate, an aliphatic polyester polyol, dimethylol propionic acid, and hexamethylene diamine with triethyl amine as the neutralizing base and N‐methyl pyrrolidone as the cosolvent. Changes in carboxylic acid content, degree of preneutralization, and chain extension were found to have the expected impacts on dispersions properties. Increased ionic content in the dispersion step led to lower particle size and higher viscosity, increased chain extension with its concurrent increase in molecular improved subsequent film properties. Surprising results were obtained by varying the amount of postneutralization and from increased solids content at the time of dispersion. Unexpectedly, both of these variations led to much higher dispersion viscosities and particle size in solution. To have these changes take place, it is theorized that there is a major change in solution morphology caused by these modifications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2514–2520, 2005     

服装低密度聚乙烯热熔胶化学粉碎的研究

服装粘合衬布的生产需要低密度聚乙烯热熔胶的微细粉末,介绍了对该热熔胶的化学粉碎技术所进行的实验研究,表明采用适当的助剂种类和用量以及适宜的工艺过程,通过化学粉碎可以得到合格的粉末产品。     

Finite-element analysis and experimental study on tensile fatigue behaviour of bitumen–stone adhesion

Tensile fatigue behaviours of bitumen–stone adhesion were investigated using a dynamic mechanics analyser under stress‐controlled mode at two temperatures of 5 and 25°C and various controlled‐stress levels. Failure characteristics including interfacial failure and cohesive failure were examined using image analysis of fracture surfaces. Finite‐element analysis on stress distributions was conducted under different temperatures, film thickness and interfacial bonding conditions. A Coulomb–Mohr like criterion in combination with shear and normal stresses is proposed to deal with the extreme thin adhesive layer, which can be further simplified into an adhesive zone without significant loss of accuracy for stress analysis.     

PMMA／PBA乳胶IPN阻尼材料的研究

用乳液聚合方法合成了一系列的互穿聚合物网络，其中包括：ＰＭＭＡ／ＰＢＡ和Ｐ（ＭＭＡ－ｃｏ－ＰＭＡ）／ＰＢＡ乳胶互穿聚合物网络（ＬＩＰＮ），ＰＭＭＡ／ＰＢＡ乳胶双向互穿聚合物网络（ＬＢＩＰＮ）以及ＰＭＭＡ／ＰＢＡ界面交联互穿聚合物网络（ＩＣＬＩＰＮ）。动态力学谱和拉伸试验结果表明：（１）ＰＭＭＡ／ＰＢＡ互穿聚合物网络的两组分相容性和阻尼性能可通过ＭＭＡ和ＰＭＡ共聚来改善；（２）双向互穿技术是一种行之     

皮革服装生产中胶粘剂对人体的危害及防护措施

本文主要讨论皮革服装生产用胶粘剂中溶剂对人体的危害及建议采取的安全防护措施     

红外研究丁羟二异氰酸酯的固化反应动力学

用红外分光光度计研究了端羟基聚丁二烯(HTPBD)与二异氰酸酯的反应动力学,结果表明,NCO与OH的反应为二级动力学反应,由于位阻效应和共轭效应,MDI比TDI的反应活性大得多,前者的反应速率常数大约是后者的10～20倍。反应速率常数及活化能随NCO的过量而有所变化。在NCO过量体系中。TDI-HTPBD体系中有次级反应发生,由于氢键的作用,次级反应为对于氨基甲酸酯基为二级、NCO为一级的三级反应动力学.由于位阻效应,MDI体系很难发生次级反应。     

聚四氢呋喃及其下游产品的开发应用

本文论述了聚四氢呋喃技术进展、氨纶弹性纤维发展现状和国内外聚四氢呋喃产能和需求。     

聚氨酯IPN的研究——制备方法与性能的关系

介绍了聚氨酯 IPN合成技术的主要特征 ,PU预聚体分子量大小、NCO/ OH的比值 ,互穿网络的方式及反应温度、速率对性能的影响     

制革用水乳型聚氨酯涂饰剂行业标准的制定

本文概述了制定该标准的背景，对标准的主要内容加以科学的阐述。     

含聚二甲基硅氧烷的聚醚聚氨酯膜透气性及表面性质研究

以聚二甲基硅氧烷（ＰＤＭＳ）／聚四氢呋喃（ＰＴＭＯ）为软段，４，４＇－二环己基甲烷二异氰酸酯（ＨＭＤＩ）为硬段（丁二醇ＢＤ为扩链剂）制成的多相嵌段共聚物作为基质材料，进行了气体（Ｏ２和Ｎ２）透过性试验，同时对膜材料进行了ＥＳＣＡ表面分析。结果表明，共聚物膜的透气性能取决于材料中连续相组分，随着软段中ＰＤＭＳ含量的改变而变化。当ＰＤＭＳ含量较高时，共聚物膜显示出ＰＤＭＳ均聚物的特性，具有较高的气体秀