高分子附聚法制备超大粒径聚丁二烯胶乳

以自制丙烯酸胶乳为高分子附聚剂,以粒径300nm聚丁二烯胶乳(PBL-0700)为起始胶乳,采用高分子附聚法制备了500～600nm超大粒径聚丁二烯胶乳(目标胶乳),考察了附聚剂加入量、放置时间、后稳定剂的加入、附聚温度等因素对目标胶乳粒径的影响,确定了高分子附聚法超大粒径聚丁二烯胶乳制备工艺。     

高分子附聚法450nm聚丁二烯胶乳的制备研究

高分子附聚方法是一项独特的技术。特别是在制备超大粒径胶乳方面,可以在较短的时间内制备稳定的胶乳,从而改善产品质量,提高生产效率。作者对制备粒径450nm聚丁二烯胶乳的附聚工艺进行了深入研究,考察了附聚剂胶乳用量、附聚后静置时间、乳化剂用量和搅拌强度等附聚工艺对聚丁二烯胶乳粒径及稳定性的影响,确定了制备450nm聚丁二烯胶乳较为优化的附聚工艺,制备的聚丁二烯胶乳稳定,可用于高性能ABS的制备。     

用NBR胶乳改善NBR/明胶纺织皮辊胶料的混炼工艺及性能

采用ＮＢＲ胶乳与明胶水溶液共沉的方法对ＮＢＲ／明胶纺织皮辊胶料的混炼工艺及性能进行了研究。试验结果表明,采用明胶／ＮＢＲ胶乳并用体系可明显改善明胶与ＮＢＲ的混炼工艺,缩短混炼时间,提高胶料的弹性。在ＮＢＲ胶乳中加入１０ｍＬ水稀释,可改善明胶的分散效果,胶料综合性能较好。明胶／ＮＢＲ胶乳并用体系中填充适量的白炭黑,可弥补拉伸强度和硬度的损失,其用量以６份为宜。加入表面活性剂对甲苯磺酰胺,可降低胶料的体积电阻率,提高皮辊的抗静电性能     

附聚法聚丁二烯胶乳的合成研究

对用于聚丁二烯胶乳合成的附聚胶乳的合成及附聚工艺进行了深入研究，考察了不同单体配比、不同种类电解质及用量、不同反应时间、反应温度及附聚工艺对聚丁二烯胶乳粒径的影响，确定了附聚胶乳的合成工艺及附聚工艺。     

乳胶粒子用附聚剂的制备及应用

采用丙烯酸(AA)、丙烯酸丁酯(BA)混合单体通过乳液聚合方法合成附聚剂,用于聚丁二烯胶乳(PBL)的附聚.研究了附聚时间、附聚剂组成、附聚剂加入量、附聚剂的粒子尺寸等因素对聚丁二烯(PB)胶乳粒径大小的影响.结果表明:附聚时间为40～60 min时,附聚过程基本完成;当BA/AA质量比为80/20时,附聚效果最好;附聚剂在PBL中加入量占PBL总质量的8.3％时,附聚效果明显;PBL平均粒径由原来的96nm附聚到了240～260 nm,粒径得到了明显的增长,合成的附聚剂有良好的附聚效果.     

改善胶乳三腔双囊胃管质量的生产工艺研究

以浓缩天然胶乳并用20份MG49天甲胶乳作胃管基础管身胶料可有效提高管身硬度和撕裂强度,并解决纯天然胶乳管身硬度不足、临床不易插管的难题,而对产品工艺性能及其他性能无不良影响。用"硝酸钙+工业酒精+表面活性剂"代替"硝酸钙+生粉附型剂+表面活性剂"作凝固体系,可改善胃管球囊胶膜厚度的均匀性。对胃管球囊内表面做适度氯化处理,可克服球囊与胃管管身产生的粘连或粘伤。适当改变绑线位置可有效减少胃管球囊胶膜出现的龟裂纹;球囊绑线处涂覆氯仿值二中~三中(见表9注)、总固体25%~35%的胶料3~4次,可获得较好涂胶效果。     

Reinforcement of natural rubber latex film by ultrafine calcium carbonate

Using ultrafine calcium carbonate to reinforce natural rubber latex film, the effect of its content on latex properties such as surface tension, viscosity, mechanical stability, and heat stability and the physical properties of latex film before and after aging such as tear strength, modulus, and tensile strength were investigated. The results showed that the surface tension of natural rubber latex reinforced by ultrafine calcium carbonate only changed slightly; when the content of calcium carbonate was less than 20%, the change of viscosity was not obvious, but when the content was greater than 20%, the viscosity significantly lowered. Ultrafine calcium carbonate could effectively improve the tear strength, tensile strength, and modulus of the natural rubber latex film. The modulus increased with the increment of the calcium carbonate. When the content of calcium carbonate was less than 15%, the tear strength and tensile strength increased with the increments of calcium carbonate, but when the content was greater than 15%, the above‐mentioned properties decreased with the increment of calcium carbonate. By comprehensive consideration, the best reinforcing effect was obtained at a content of 15% ultrafine calcium carbonate. The particle diameters of calcium carbonate and their distribution in the calcium carbonate emulsion and in the rubber film were analyzed with SEM and a laser particle size tester, which showed that the distribution of calcium carbonate in the latex film was even and that it could effectively reinforce natural rubber latex film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 982–985, 2003     

Crosslinking of isocyanate functional acrylic latex with telechelic polybutadiene. I. Synthesis and characterization

An ambient curable isocyanate functional acrylic latex was synthesized by incorporating dimethyl meta-isopropenyl benzyl isocyanate (TMI®), an isocyanate monomer, into styrene/n-butyl acrylate copolymer. An artificial latex of amino-terminated telechelic polybutadiene was prepared and blended with the acrylic latex as a curing agent. The isocyanate content in the blended latex was determined by titration and FTIR measurements. The latex blend properties, in terms of particle size and latex viscosity, and the latex film properties, in terms of stress–strain behavior and solvent swelling behavior, showed no significant change after 30 days' storage of the latex blend at 50°C. The good storage stability was attributed to the stable nature of the latex blend in which there was little chance for the isocyanate-containing particles to come into contact with the curing agent particles, thus preventing premature contact of the acrylic chains with the telechelic chains. The reactivity of different functional groups in the telechelic polymer was studied; the amino group was found to be the most reactive toward the TMI. In addition, a shorter chain telechelic crosslinker was found to result in a higher degree of crosslinking, but this was more intraparticle than interparticle in nature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 965–975, 1998     

大粒径丁苯胶乳的合成：Ⅱ丙烯酸酯系附聚胶乳的合成及附聚工艺

叙述了用于大粒径丁苯胶乳合成的丙烯酸酯系附聚胶乳的合成及附聚工艺,讨论了单体的选择及加料方式对聚合的影响,还考察了附聚胶乳用量与附聚后丁苯胶乳粒径的关系。     

热敏乳液薄膜的制备及性能

本文介绍了一种可以通过三步法制得的具有亲油的核和亲水的壳的高分子微胶粒。首先,通过乳液聚合得到甲基丙烯酸正丁酯与甲基丙酸甲酯的共聚物乳液(p-(BMA-MMA));利用(p-(BMA-MMA)乳液作为种子,用一种氧化还原引发体系引发反应,通过控制反应条件,在乳胶粒表面包覆一层均匀的聚甲基丙烯酸缩水甘油酯(p-GMA)外壳,壳层聚合物的含量为5~15wt.%之间;最后,壳层表面的环氧基团与三乙醇胺盐酸盐反应,环氧基团转变为季铵盐,使外壳成为极性的亲水表面。核-壳型固体微胶粒可以在水中较好地分散并形成稳定的乳液。通过旋涂法将固体乳液颗粒和PVA的混合水溶液涂在铝版基上,室温下干燥,可得到乳液薄膜。实验发现,室温下核-壳乳液薄膜与水的接触角在16.1°-27.5°范围内,可经过150℃短时间的烤版处理后,接触角将超过87,°表明乳液薄膜通过加热后完全由亲水性转为亲油性。同时,该乳液薄膜在烤版前很容易用中性水由版基上冲洗掉,但烤版后不再能够被洗掉。当在乳液薄膜中加入一种红外染料(最大吸收波长在830nm)后,该薄膜变得对830nm的LD激光敏感,并通过LD激光曝光和中性水显影后,得到阴图型图像。     

Strategies for the production of high solids acrylic/methacrylic core‐shell latices

Well‐defined poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core shell particles with a moderately high solid content (49%) and particle diameters of less than 200 nm were prepared via seeded emulsion polymerization with a redox initiator and an anionic surfactant. Low‐viscosity (less than 150 cps at 20 s^?1) latex products were obtained by controlling the particle size distribution to within certain limits. Polymerization conversion and kinetics were followed gravimetrically and were adjusted so as to obtain recipes that could be scaled‐up for industrial production. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

High solids content emulsions. I. A study of the influence of the particle size distribution and polymer concentration on viscosity

An experimental and modeling study was carried out to understand the relationship between the viscosity of a multimodal latex and its particle‐size distribution (PSD) and polymer concentration. This study illustrates the inadequacy of existing models in predicting the viscosity of complex latices. It is shown that the latex viscosity at a fixed shear rate is very sensitive to the polymer concentration at high solids content and to the PSD. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1878–1896, 2002; DOI 10.1002/app.10511     

丁腈橡胶/石墨纳米复合材料的制备、结构及性能研究

采用乳液共混、直接共混及溶液共混等方法制备了丁腈橡胶/石墨复合材料,并用电子显微镜和X-射线进行了观察和衍射测试。结果表明,采用乳液共混可以制备出同时具有插层和剥离结构的纳米复合材料。随着石墨用量的增加,所得复合材料的力学性能(特别是小应变下的应力)逐渐提高,同时动态力学性能也有了显著的改善。另外,该复合材料还表现出多种优异的功能特性,如高气密性、高导电性和高导热性、低的摩擦系数和较好的耐磨损性能。     

密炼机中胶料的混炼工艺与填充因数研究

对不同硬度的三元乙丙橡胶、丁腈橡胶、天然橡胶和氯丁橡胶胶料在密炼机中的混炼工艺与填充因数进行研究。结果表明:胶料的分散过程分为生胶塑炼、添粉/吃粉、分散后结团、形成团聚体、软化、配合剂分散和细分散、配合剂分布以及形成复合结构8个阶段;影响混炼填充因数的因素主要为胶料粘度和硬度;胶料的粘度和硬度越高,混炼填充因数越小;混炼工艺确定后,以胶料最佳分散为目标,可确定适合的混炼填充因数。     

Agglomeration of polybutadiene latex by highly carboxylated functional microspheres

Polybutadiene latex (PBL) was agglomerated by highly carboxylated core-shell agglomerating agents, which contained carboxyl groups in the shell polymer [core monomers (methyl methacrylate, n-butyl acrylate, and ethyl acrylate)/shell monomer (acrylic acid)]. The effects of different parameters upon the particle size of agglomerated PBL were investigated, namely, agglomeration time, amount of agglomerating agent, pH of dispersion medium, amount of acrylic acid and combination of core monomers. The particle growth mechanism was also examined. © 1999 Society of Chemical Industry     

Core–shell latex containing fluorinated polymer rich in shell

Core–shell latex with polyacrylate rich in core and fluoropolymer rich in shell was prepared by semicontinuous emulsion polymerization in the presence of mixed emulsifiers. The solids content of the latex was about 25 wt %. The polymerization conditions for the latex were discussed. The morphology of latex particles was characterized by transmission electron microscopy and the surface properties were determined by the Wilhelmy method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1147–1153, 2002     

Hydrogenation of acrylonitrile–butadiene rubber latexes

The hydrogenation of acrylonitrile–butadiene rubber (NBR) latex was carried out by a system consisting of hydrazine hydrate and hydrogen peroxide, with boric acid as catalyst. Highly saturated hydrogenated NBR (HNBR) latex was obtained through the optimization of the reaction conditions. The dried HNBR was found to be heavily gelled. The cause for the crosslink of dried hydrogenated NBR products was investigated. With the improvement of the hydrogenation system, that is, by adding gel inhibitor to the system, the crosslinking was controlled to a large extent, and dried HNBR with gel content of about 3% was prepared by the improved system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2072–2078, 2004     

附聚法制备高抗冲ABS树脂研究

以较大粒径和小粒径聚丁二烯(PB)胶乳为待附聚胶乳,用高分子附聚剂进行粒径放大,合成大粒径PB胶乳,再进行接枝共聚反应,用所得的丙烯腈-丁二烯-苯乙烯(ABS)接枝粉料掺混造粒,进而制备出高抗冲ABS树脂,获得了附聚法制备高抗冲ABS树脂的最佳条件.     

Control of rheology of water-borne paints using associative thickeners

Water-borne decorative topcoats generally show inferior leveling and open time compared to solvent-based paints. Basically, this behavior is caused by the divergent viscosity–solid content relationship for dispersions and emulsions and by the relatively high evaporation rate of water. Employment of associative thickeners may improve leveling and open time of latex paints only if they introduce a substantial amount of ‘network viscosity,' characterized by a short relaxation time and little dependence on solid content. This network viscosity enables one to formulate a paint with sufficient high-shear viscosity at a particle-packing density far below the value where low-shear viscosity starts to diverge. Addition of an associative thickener not only affects rheology, but also the interaction between latex particles: Associative HEUR thickeners may induce undesired phase separation by strong bridging between the latex particles. The influence of HEUR thickeners on latex particle interaction has been studied by turbidity measurements. The experimental results could qualitatively be interpreted very well by two-particle interaction potentials computed using the Self-Consistent-Field theory of Scheutjens and Fleer. It is demonstrated how viscosity, created by the addition of an associative thickener to a highly concentrated latex, can be split up into a polymer network viscosity and a contribution to (relative) dispersion viscosity. According to these analyses, reduction of the molecular weight of tri-block HEUR thickeners yields an increase of the favorable network viscosity and a reduction of the unfavorable dispersion viscosity. However, reduction of the molecular weight of the HEUR thickener is limited by the introduction of undesired phase separation (bridging flocculation) below a certain molecular weight.     

Toughness enhancement of high‐impact polystyrene based on γ‐radiation vulcanized natural rubber latex by using block copolymer

Polyisoprene‐block‐polystyrene‐block‐polyisoprene (ISI) was synthesized by the iniferter route and its use, as compared to a commercial polystyrene‐block‐polyisoprene‐block‐polystyrene (SIS), in the enhancement of the toughness of high‐impact polystyrene (HIPS), prepared by the γ‐radiation vulcanized natural rubber (RVNR) latex/phase transfer/bulk polymerization technique, was investigated. Addition of 5% SIS was adequate as an interfacial agent, which effectively increased the unnotched Izod impact energy of HIPS, whereas use of 10% of ISI was required. A long polyisoprene block with two polystyrene segments of SIS was favorable for compatibilization of HIPS. Transmission electron micrographs revealed the uniform distribution of the block copolymer at the shell region of the rubber particle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1307–1316, 2002