聚硅氧烷／丙烯酸酯乳液的研究现状

详细介绍了聚硅氧烷／丙烯酸酯混乳液，共聚乳液及复合乳液。阐述了各种乳液的制备方法，对各种乳液的性能及应用进行了综合评价。     

聚硅氧烷-g-聚丙烯酸酯乳液接枝共聚的研究

以含活性点的聚硅氧烷为主链,以丙烯醚丁酯（ＢＡ）、甲基丙烯酸甲醌（ＭＭＡ）为接枝单体,通过乳液接枝共聚合合成了聚硅氧烷－ｇ－聚丙烯酸酯接枝共聚物,通过对产物的分离过程,红外光谱和核磁共振谱分析,对接枝物进行了表征,研究了加料方式、乳化剂用量、引发剂用量、反应温度和用配比等对单体转化率、接枝效率和交联度的影响;研究了部分工艺的乳液的粒子形态。     

高分子量聚醋酸乙烯酯乳液和醋酸乙烯酯-乙烯共聚物乳液的合成及力学性能

对比研究了保护胶体聚乙烯醇(PVA)、阴离子乳化剂十二烷基硫酸钠(SDS)加料量和引发剂加料速率对聚醋酸乙烯酯(PVAc)和醋酸乙烯酯-乙烯共聚物(VAE)乳液聚合过程中乳胶粒粒径和相对分子质量演化的影响。乳胶粒成核后明显的团聚特性决定了增加保护胶体PVA和阴离子乳化剂SDS加料量对提高PVAc相对分子质量作用不明显。该聚合体系中由于成核乳胶粒强烈的团聚倾向,同一乳胶粒中可同时存在多个自由基,减小引发剂加料速率可降低双基终止几率,明显提高PVAc相对分子质量。进一步利用该技术合成了不同相对分子质量的VAE乳液,力学性能对比测试表明,高分子量VAE乳液成膜具有更优异的力学性能,在聚合物水泥防水复合材料领域具有明显的性能优势。     

丁苯胶乳接枝醋酸乙烯酯共聚改性的研究

为了改善丁苯胶乳(SB)与水泥的相容性,采用醋酸乙烯酯(VAc)单体与SB进行乳液接枝共聚。研究了单体浓度、引发剂和乳化剂的用量、反应温度、反应时间等对接枝率的影响,确定了最佳的接枝反应条件为:[VAc]=5.0mol/L;[(NH4)2SO3]=9.4×10-3mol/L;乳化剂C12H25SO3Na含量为4%(按单体质量计),温度80℃,时间3h。以IR测定了未接枝的的SB和接枝物的结构,比较二者的IR谱图,在1815.44cm-1、1753.91cm-1处有强吸收峰,表明接枝物含有羰基,从而证明VAc接枝到SB上。以SEM观察了胶乳的成膜性,接枝聚合物的成膜性远优于未接枝的SB膜;其拉伸强度显著提高。     

丙烯酸酯共聚乳液胶粘剂配方的优化

目的提高丙烯酸酯共聚乳液胶粘剂的粘接强度,运用响应面法对丙烯酸酯共聚乳液胶粘剂的配方进行优化。方法将硬单体和软单体的质量比、乳化剂质量分数、引发剂质量分数、丙烯酸质量分数作为考察因素,以丙烯酸酯共聚乳液胶粘剂在PE板上的剥离强度作为因变量,利用Design-Expert软件对2个自变量进行多次拟合,建立相应的数学模型和三维曲面,得到最优的丙烯酸酯共聚乳液胶粘剂配方,最后加以实验验证。结果二项式是描述因变量和自变量之间的最佳模型,当硬单体和软单体的质量比值为2.09、乳化剂质量分数为1.56%、引发剂质量分数为0.54%、丙烯酸质量分数为6.16%时,能够获得最大的剥离强度。剥离强度为5.36 k N/m时,混合制成的丙烯酸酯共聚乳液胶粘剂在PE板上的剥离强度最优,即得到最优的丙烯酸酯共聚乳液胶粘剂配方。结论将响应面实验设计方法应用于优化丙烯酸酯共聚乳液胶粘剂配方,可减少实验次数,且对丙烯酸酯共聚乳液胶粘剂在PE板上的剥离强度具有较好的预测效果。     

聚醋酸乙烯酯共聚胶液的改性研究

聚醋酸乙烯酯作为常用的胶粘剂之一,有明显的优点,但随着环保和绿色生活的要求,其有毒和耐水性等缺陷影响了其更好发展.本研究利用醋酸乙烯酯与其它烯类单体的共聚,制备出了无毒、快干、胶接强度高、耐水性好的高性能聚醋酸乙烯酯共聚改性胶液,并对其相关影响因素及工艺条件的确定进行了讨论.     

乳液法合成氨基聚硅氧烷的研究

在碱性催化剂作用下,采用八甲基环四硅氧烷(D4)与硅烷偶联剂γ-氨丙基三乙氧基硅烷(KH-550)乳液共聚制得了氨基聚硅氧烷乳液.考察了八甲基环四硅氧烷(D4)在碱性条件下的温度、pH值、反应时间以及乳化剂复配和用量、偶联剂用量等影响单体转化率、乳液稳定性及聚合物分子量的因素.实验结果表明:当乳化剂总用量为15%～25%,反应温度在75～85℃,反应pH值为11～13,反应时间为6～8h的条件下,可以得到稳定的有机硅聚合物乳液.     

聚醋酸乙烯酯纳米乳液的稳定性

采用扩散过程控制的乳液聚合方法,合成聚醋酸乙烯酯纳米乳液,研究乳化剂的种类和配比及缓冲溶液、助乳化剂、聚合物等对聚醋酸乙烯酯纳米乳液稳定性的影响.研究结果表明,使用十二烷基硫酸钠(SDS)/辛基苯基聚氧乙烯基醚(OP-10)复合乳化剂体系、碳酸氢钠缓冲溶液、十六烷等助乳化剂和聚苯乙烯等能有效提高醋酸乙烯酯纳米乳液的贮存...     

D4/D4Vi阴离子开环乳液共聚动力学及乳胶粒径

采用阴离子开环乳液聚合法制备了聚硅氧烷共聚乳液,研究了反应条件对共聚动力学及乳胶粒径的影响。结果表明,初始恒速阶段的表观动力学方程为Rp=k[E]0.18[KOH]0.59[M]0.75,表观活化能为52.77 kJ/mol。乳胶粒径随反应温度升高而变小,粒径分布在80℃出现最小值。随[KOH]的增大,乳胶粒径变大,粒径分布变宽。复合乳化剂质量浓度[E]在不同范围内对乳胶粒径及其分布的影响不同,当[E]<0.0572 g/mL时,随[E]增大,乳胶粒径变小,粒径分布变窄;当[E]>0.0572 g/mL时,乳胶粒径反而变大。     

淀粉与乙酸乙烯酯-丙烯酸乙酯的合成与应用研究

以玉米淀粉为接枝骨架,过硫酸铵为引发剂,丙烯酸乙酯(EA)和乙酸乙烯酯(VAc)为接枝单体,进行接枝共聚,制备淀粉基木材胶粘剂.研究了反应时间、反应温度、引发剂用量以及两单体配比对淀粉与丙烯酸乙酯-乙酸乙烯酯接枝共聚反应的影响.结果表明,当引发荆浓度9.7×10-3mol/L、反应温度65℃、反应时间3h、VAc和EA体积比为6:4时,可得到较高的接枝效率和接枝率.     

Thermal conductivity of ethylene vinyl acetate copolymer/nanofiller blends

To reduce weight and increase mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. As an approach to raise thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax^™ 260), it was compounded with carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG) as well as metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum. Ribbons and tubing of the nanocomposites, in which the nanofillers were aligned in the direction of flow, were extruded. Compression molding was used to fabricate nanocomposites in which the nanofillers were randomly oriented. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction and significant improvement in TC (up to 24-fold) was observed when measurements were made in the direction of alignment.     

Hydroxyapatite precipitation on a carboxylated vinyl chloride-vinyl acetate copolymer

The kinetics of crystal growth of hydroxyapatite [Ca₅(PO₄)₃OH, HAP], the thermodynamically most stable calcium phosphate phase, on a commercially available carboxylated (1%) vinylchloride (83%) vinyl acetate (13%) copolymer was investigated at relatively low ionic strength, at 37 °C and pH 7.4. Stable supersaturated solutions were seeded with HAP seed crystals as reference and with the polymer in powder form. Well defined induction times preceded the growth of HAP on the polymeric substrate. The induction times measured were inversely proportional to the solution supersaturation. The rates of crystallization both on HAP and on the polymer were measured at conditions of constant supersaturation. HAP growth took place on both substrates and the parabolic dependence of the rates of crystal growth on the relative solution supersaturation suggested a surface diffusion controlled mechanism. The rates of HAP crystal growth on the polymeric substrate were found to depend on the amount of the seed material suggesting selective overgrowth of HAP. A possible explanation for this selectivity is the development of active growth sites through the formation of surface complexes of the calcium ions with the dissociated carboxyl groups.     

氧化木薯淀粉与丙烯酸丁酯/醋酸乙烯酯的接枝共聚反应研究

以过硫酸铵为引发剂,以氧化后的木薯淀粉为接枝骨架,制备了氧化淀粉-丙烯酸丁酯-醋酸乙烯酯接枝共聚物.考察了氧化剂浓度对黏度及引发剂浓度、单体浓度、反应温度和反应时间对接枝率、接枝效率的影响.实验结果表明,在氧化剂浓度为0.04mol/L,引发剂浓度为9×10-3mol/L,单体浓度为1.0mol/L,反应温度为65℃,反应3h时,反应体系的接枝率和接枝效率较高.通过红外光谱对接枝共聚物进行了结构表征.     

Studies of casting and LB films of ferroelectric liquid crystalline polysiloxane

Monolayers of side chain ferroelectric liquid crystalline polysiloxane have been successively transferred onto appropriate substrates by vertical dipping method to study the morphology and the orientation of the mesogens and the side chains by UV spectra and polarized FT-IR spectra and X-ray diffraction. The spectra for casting film and LB film are compared. The molecules in LB films are found to be more orientated along the normal of the substrate at an angle of 37° for the mesogens as the side chain as found by polarized FT-IR spectra and transmitting FT-IR spectra than casting film. Layer structure is also confirmed by X-ray diffraction results. The mesogens are found to form H-aggregates structure in bulk phase and LB films from UV spectra. Temperature-dependent UV spectra have revealed the change of the tilt angle of the mesogens inside the layer of both bulk phase and LB films.     

含氟丙烯酸酯共聚物乳液的制备及复配研究

溶液型含氟丙烯酸酯共聚物在使用中会产生环境污染。近年来人们更加重视乳液型含氟丙烯酸酯共聚物的开发和应用,常采用的方法有2种:通过乳液聚合将含氟丙烯酸酯单体和其他烯类单体共聚,以及将含氟丙烯酸酯聚合物乳液和其他乳液通过共混和偶联进行复配。本文对这2 种方法进行了综述。     

LDPE/EVA/蒙脱土熔融插层纳米复合体系稳态剪切流变行为

用平行板和毛细管流变仪测定并研究了具有剥离结构的低密度聚乙烯(LDPE)／乙烯-醋酸乙烯共聚物(EVA)／蒙脱土纳米复合材料熔体的稳态剪切流变行为。研究结果表明,蒙脱土含量较低的复合物熔体,在低剪切速率下,即出现剪切变稀现象；而在较高剪切速率下,填充物浓度对体系熔体的剪切粘度影响较小；与基体树脂相比较,蒙脱土的加入,使其熔体的非牛顿指数降低,粘流活化能略有增加。     

可紫外光/湿气双重固化聚硅氧烷丙烯酸酯树脂的合成与表征

分别以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)、端羟基聚二甲基硅氧烷(107)为原料,采用脱醇缩合的方法合成了含不饱和C=C双键和Si-OCH3的聚硅氧烷丙烯酸酯(PSA).用FTIR,NMR表征其结构,并对双重固化行为进行了研究.结果表明:预聚物在3％光引发剂下进行紫外光固化,其双键的最终转化率可达100％;...