聚氨酯——聚丙烯酸酯复合聚合物乳液的研究

本文研究了几种聚氨酯——聚丙烯酸酯乳液复合的方法，制备了新单体N-（4’-甲基3’-二正丁脲基）苯基氨基甲酸内烯酰氧-2-丙酯，使其与丙烯酸酯类单体共聚，显著提高了聚合物的抗张强度，简单介绍了聚合物膜接技法，共混复合法和种子聚合法的实施方法，聚合物膜性能及粒子结构等有关研究内容，实验表明，用几种方法都可以获得综合性能好的复合聚合物乳液。     

In vitro comparisons between Carica papaya and pancreatic lipases during test meal lipolysis: Potential use of CPL in enzyme replacement therapy

High levels of lipase activity are known to occur in Carica papaya latex, and this activity is being used in some biotechnological applications. The lipolytic activity of C. papaya lipase (CPL) on dietary triacylglycerols (TAG) has not yet been studied. Hence, the aim of this study was to characterise the specific activity of CPL on dietary TAG present in a crude preparation. Also, we have determined its stability during the lipolysis of a test meal at various pH values mimicking those occurring in the gastro-intestinal tract, with or without bile, and have compared these properties with those of porcine pancreatic extract (PPE) and human pancreatic lipase (HPL). CPL showed maximum stability at pH 6.0, both with and without bile. Some residual activity was still observed at pH 2 (20%), whereas the pancreatic lipases tested were immediately completely inactivated at this pH. In the absence of bile, the highest specific activities were measured at pH 6 in the case of CPL, PPE and HPL. Adding bile slightly decreased the CPL activity in the 4–6 pH range, thus shifting the optimum CPL activity to pH 7, where the presence of bile had no effect. Lipolysis levels decreased with the pH, but CPL was still more active than PPE at pH 5 on a relative basis. These results suggest that CPL might be a promising candidate for use as a therapeutic tool on patients with pancreatic exocrine insufficiency.     

织物涂层剂研究新进展

纺织品涂层整理剂简称涂层剂,是指一种均匀涂布于织物表面能形成薄膜的高分子类化合物.阐述了近年来新研发的一些织物涂层剂(如新型聚丙烯酸酯类涂层剂、聚氨酯类涂层剂、聚氯乙烯类涂层剂、有机硅类涂层剂)的制备、特性及应用,指出了今后织物涂层剂的研究方向:绿色环保型、特殊功能型、“智能”化、多功能型.     

核壳型马来酸酐改性苯丙乳液纸张湿强剂

采用半连续种子乳液聚合技术结合预乳化工艺,以苯乙烯、丙烯酸乙酯、甲基丙烯酸甲酯为聚合单体,马来酸酐为功能单体进行改性,采用阴/非离子型复配乳化剂(十二烷基硫酸钠SDS/壬基酚聚氧乙烯醚Tx-100)、复配型引发剂(过硫酸钾/亚硫酸氢钠)合成了具有核壳型结构的纸张湿强剂。采用TEM表征证明成功合成了核壳型的苯丙乳液;SDS与Tx-100之比为2:1时反应得到的乳液稳定性好,不产生凝聚物;从纸张成本及纸张物理强度综合考虑,建议选择浓度为3%的浸渍液。     

有机硅交联剂对聚丙烯酸酯性能的影响

以双端丙烯酰胺基丙基聚硅氧烷(diAAp-PDMS)为交联剂,通过细乳液聚合法改性聚丙烯酸酯,并将其用于涂料印花。研究了交联剂diAAp-PDMS用量对改性乳液性能、胶膜结构与性能和印花性能的影响。结果表明:随着diAAp-PDMS用量的增加,聚合单体转化率降低,凝胶率增大,乳液粒径变大;胶膜交联度先增后减,胶膜聚硅氧烷表面富集增加,胶膜耐水性先增后降,胶膜断裂强度降低,断裂延伸率增加,断裂功先增后减;印花织物耐干、湿摩擦色牢度先增后降,柔软性提高。当diAAp-PDMS用量为8%时,胶膜交联度最高,疏水性最强,断裂功最大,印花织物耐干、湿摩擦色牢度可达4~5级,手感柔软。     

聚丙烯酸酯浆料的酯基对混合浆相分离的影响

以初显分离时间和沉降率为量化指标，研究了酯基类型和含量、PVA类型、淀粉含量对混合浆相分离的影响。实验结果表明：酯基类型及数量对淀粉／PVA混合浆液的相分离行为有明显影响，BA链节有利于混合浆液的稳定性，而MA和MMA则能获取相对较低的相分离程度。随着BA含量的增加，混合浆的相分离速度减小，但相分离程度却有所增大。所介绍的几种聚丙烯酸酯浆料有助于降低淀粉与部分醇解型PVA混合浆液的相分离速度，不能改善淀粉与完全醇解型PVA混合浆的相分离速度。     

国际涂布化学品市场的现状与发展

文章从五个方面介绍全球涂布化学品的现状与发展,占造纸原料的8%为颜料和填料,而在占造纸原料1%的合成化学品中,涂布胶乳占到50%,其中又以SBR为主体,随着乳液聚合工艺水平的不断提高,人们已经从单纯的聚合方面来改进SB胶乳的质量,开始进一步考虑控制聚合的分子结构.涂布颜料仍以高岭土为主,但随着中性抄纸比例的不断提高,GCC和PCC的用量在逐年上升;因此,高岭土生产商开发出工程级产品以提高性能.北美市场涂布颜料中高岭土占主导地位,西欧以CaCO3为主.随着涂布纸质量要求及纸机车速的不断提高,在颜料制造商、胶乳生产商、涂布机供应商之间建立技术合作成为一种趋势,再加入油墨制造商和印刷商,这种不同领域、不同行业间的多元合作关系是实现涂布纸技术创新和发展的一个理想的解决问题的方案.     

核壳型聚丙烯酸酯复合乳液的性能研究

采用半连续种子乳液聚合法合成了"硬核软壳"核壳型复合乳液,研究了聚合工艺、乳化剂复配类型对乳液性能、乳胶粒粒径及粒径分布的影响。结果表明:种子聚合采用间歇法、核层及壳层聚合都采用预乳化工艺,乳液聚合稳定且乳胶粒粒径分布窄;乳化剂壬基酚聚氧乙烯醚-2-磺酸基琥珀酸单酯二钠盐(MS-1)分别与十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(SDBS)以及脂肪醇聚氧乙烯醚(OS)复配用于乳液聚合,当m(MS-1):m(SDS)为6:4时所合成乳液的乳胶粒粒径小且分布窄、聚合稳定性好。最后采用红外和透射电镜分别对聚合物分子链结构和乳胶粒形貌进行了表征。     

种子聚合法制备聚丙烯酸酯/苯乙烯复合乳液的研究

采用种子聚合技术,以丙烯酸甲酯和丙烯酸乙酯为核单体,以丙烯酸丁酯和苯乙烯为壳单体,讨论了各种影响因素对复合乳液制备及乳液涂膜性能的影响,合成了水稀释稳定、电解质稳定、机械离心稳定且近似为中性的高分子复合乳液.     

Calibration of transmission electron microscopic mass determination using objects with known mass distribution

An improved calibration procedure is described for dry mass determination methods, that are based on microdensitometry of transmission electron micrographs. Polystyrene latex spheres, that are supposed to have a homogeneous mass distribution, are used for the calibration procedure. By computer fitting of the theoretically expected mass distribution to the distribution measured in a line through the centre of a sphere, a mass calibration factor is obtained. The number of measurements required for a predetermined calibration accuracy can be decreased considerably as compared to other calibration methods. Accurate calibration and reproducible adjustment of the electron optical magnification are required.