BEHAVIOUR OF INHIBITORS IN EMULSION POLYMERIZATION(Ⅰ)CaseⅡKinetics

The behaviour of water soluble and monomer soluble inhibitors in emulsion polymerization of monomersfollowing Case Ⅱ kinetics(e.g.styrene)has been investigated.Experimental studies reveal that inhibitors canhave an appreciable effect on both polymer particle nucleation and growth.A mathematical model showingthese effects has been developed and simulation studies have been done.The simulation results imply that theconsequences of these effects of monomer soluble inhibitors for industrial emulsion polymerization may be quiteserious.

BEHAVIOUR OF INHIBITORS IN EMULSION POLYMERIZATION(Ⅱ)CaseⅠKinetics

The behaviour of water soluble and monomer soluble inhibitors in the emulsion polymerization for CaseI system(e.g.vinyl acetate and vinyl chloride)has been studied.The behaviour of monomer soluble inhibitorsis shown to be quite different from that observed in Case Ⅱ emulsion polymerization system.Model predictionsof the effect of these inhibitors on polymer particle nucleation and growth rate are shown to be in satisfactoryagreement with experimental results.

Effect of Polymerization Temperature on Cationic Emulsion Properties

The objective of this work was to analyze the effects of the polymerization temperature on the kinetic features(instantaneous and overall conversions)and colloidal characteristics[mean particle diameter,stabilities]in the semicontinuous seeded cationic emulsion polymerization of styrene and butyl acrylate.Azobis is obutyl amidine hydrochloride was used as an initiator.The surfactants wascetyl trimethyl ammonium chloride.The results showed that the final instant when the polymerization temperature of 85℃emulsion highest conversion rate,and the temperature of the emulsion particle size,centrifugal stability is the best,85℃emulsion in the emulsion anti-dilution and acid salt stability also showed excellent stability.

PREPARATION AND FLUORESCENT PROPERTIES OF Eu^(3+)-CONTAINING CORE-SHELL NANOPARTICLES

By using a two-stage soapless emulsion polymerization, four kinds of core-shell nanoparticles have been prepared,which are composed of a polystyrene core having an average diameter of 256 nm and a poly(methyl methacrylate-co-acrylicacid) shell. The transmission electron microscopy (TEM) micrographs and the atomic force microscopy (AFM) imagesevidenced the presence of a core-shell structure. In the infrared spectra, the shift of v_(COOH) to lower wavenumber withincreasing Eu^(3+) ion content indicates that coordination between the oxygen of the carboxylic group and Eu^(3+) has occurred.The fluorescence intensity of ~5D_0-~7F_2 transition was observed to reach its maximum with a carboxyl group molar percentageof 40% in the shell and an Eu^(3+)/--COO^- molar ratio of 1:3. The fluorescence intensity ratio of ~5D_0-~7F_2 to ~5D_0-~7F_1 transition reached its maximum with an Eu^(3+)/--COO^- molar ratio of 1:3 for all the four series.

Effects of water phase concentration on the emulsion polymerization of polyaniline

The emulsion polymerization of aniline in three phase system of xylene functionalized protonic acid water was carried out using (NH 4) 2S 2O 4 as oxidant. The influences of water phase concentration on the viscosity, conductivity, transmittance of polyaniline(PAN) latex and its powders were studied. The results show that the properties of PAN prepared through the emulsion polymerization are influenced by the amount of water used in the polymerization. The morphology of PAN varies with the water phase concentration used in the polymerization, which may result in the change of properties of PAN latex and its powders. When the volume fraction of water (φ) is about 20% 30%, the prepared PAN powder has higher conductivity, and the PAN latex has appropriate viscosity and particle size. The consumption of xylene was reduced at high φ value.

Effect of cationic monomer on properties of fluorinated acrylate latex

Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers. The resultant latex and its film were characterized with dynamic light scattering detector and contact angle meter. Influences of amount of DMDAAC on the properties of resultant latex and its film were investigated in detail. Results show that the particle size of the latex has the minimum value knd the zeta potential of the latex is increased when the amount of DMDAAC is increased. In addition, the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%. However, the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%. The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%. Nevertheless, the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 2.5%.

FT-IR Study on Crosslin king Reaction of Acrylates Copolymer Emulsions

Introduction The emulsion of acrylate copolymers with actively functional groups have been widely developed and used as coating, adhesive and handling agent in spinning and weaving industry. Bessett, D. R. et al. studied the thermoset of N-(isobutoxymethyl) acrylamide by thermal evolution analysis and thermal gas chromatogram. Krejcar,

衰减全反射红外光谱法分析本体聚合ABS相转变过程

本体法合成丙烯腈-丁二烯-苯乙烯共聚物(ABS)树脂具有环境友好的优势,然而引发体系以及本体法中的相转变和接枝过程会对ABS成品性能产生影响。采用本体法合成ABS树脂,研究了不同引发剂(偶氮二异丁腈)、链转移剂(叔十二烷基硫醇)、溶剂(乙苯)用量对本体聚合相转变动力学过程和相转变过程的影响。通过衰减全反射-傅里叶变换红外光谱(ATR-FTIR)分析了本体聚合相转变过程中的ABS树脂结构,对比力学性能。结果表明,相转变中的接枝行为会影响聚合速率,适量的引发剂、链转移剂和溶剂(质量分数分别为0.06%,0.30%和20%)有利于相转变过程中的接枝过程,ATR-FTIR分析相转变过程接枝相的苯乙烯的苯环和丙烯腈的腈基峰强度明显增加,同时获得综合性能最佳的ABS树脂。然而链转移剂过量时,ABS中的丙烯腈单体会受到影响。

疏水改性微球的制备及其膨胀性能与应用研究

通过反相乳液聚合法制备了一种疏水改性P(AM-N)微球.采用傅里叶变换红外光谱(FTIR)、热重分析仪(TGA)、扫描电镜(SEM)、流变及岩心驱替实验对所合成微球的结构、形貌、性能以及封堵效果进行了表征与测试,并考察了溶胀时长、温度和不同盐溶液浓度对P(AM-N)微球性能的影响.测试结果表明,P(AM-N)微球的平均粒径为76.42 nm,溶胀5 d后P(AM-N)微球的膨胀率高达17.21倍;在70℃下,P(AM-N)微球老化2 d后溶胀率高达17.14倍,在20000 mg/L NaCl溶液和2000 mg/L CaCl_(2)溶液中分别溶胀3 d后膨胀率高达5.31倍和6.03倍,说明其具有较好的耐温性和抗盐性;在注入量为0.5%的条件下,P(AM-N)微球封堵率可达到97.98%,与P(AM)微球相比具有更好的封堵性且弹性增强.

反相乳液聚合法制备缔合型耐盐聚合物及其流变性能

以丙烯酰胺(AM)、2-丙烯酰胺-十二烷基磺酸钠(AMC_(12)S)、疏水单体29-(4-辛基苯氧基)-3,6,9,12,15,18,21,24,27-壬氧烷酮基甲基丙烯酸酯(GTE-10)为原料,通过反相乳液聚合法制备了一种缔合型耐盐聚合物p(AM/AMC_(12)S/GTE-10)。通过FTIR、~1HNMR、SEM、TEM及激光粒度分析仪对其结构和形貌进行了表征,并对其流变性能、触变性能和黏弹性进行了评价。结果表明,疏水单体GTE-10成功引入聚合物中,聚合完成后的乳液粒径分布集中且均一,盐(NaCl、CaCl_(2))的加入使p(AM/AMC_(12)S/GTE-10)分子聚集态更紧密,形成的空间网络结构更稳定。质量分数为0.7%的p(AM/AMC12S/GTE-10)聚合物水溶液在140℃时表现出较好的耐温性能;在120℃、170s^(–1)条件下剪切1 h,在质量浓度为20000 mg/L的NaCl和CaCl_(2)水溶液中分别配制质量分数0.7%的聚合物溶液,其表观黏度分别为64.8和54.1m Pa·s;聚合物具有较好的剪切恢复性能;盐水条件下储能模量大于损耗模量,金属离子与苯氧乙烯基发生络合反应,使分子间作用力增强,形成的空间结构更稳定且难被破坏,黏弹性更高。

流变学方法评价水包油乳液稳定性

在50℃下分别制备了稳定和不稳定的水包油(O/W)乳液体系,考察了2类乳化体系的稳态黏度曲线、流动曲线、线性黏弹性、黏弹性模量随温度变化曲线和大振幅振荡剪切(LAOS)流变性。通过三参数流变动力学新方程、Carreau-Yasuda修正方程,四参数流变动力学方程较好地拟合了相应的稳态黏度曲线、样品的流动曲线以及黏弹性模量曲线。通过主成分回归分析方法,建立了50℃下水包油乳液流变指标与稳定性的经验关系,获得了流变学评价水包油乳液稳定性的新方法,为应用流变学性质指导制备稳定乳液奠定良好基础。

碳/碳边角料对天然橡胶复合材料性能的影响

通过使用球磨机对碳/碳边角料进行研磨,得到其粒径均匀分布。采用乳液聚合法将碳/碳边角料填充到天然橡胶中,制备出天然橡胶复合材料,对复合材料的性能进行了研究。实验结果表明:碳/碳边角料的加入能明显提高橡胶复合材料的耐磨、导电和导热性能,但硫化时间随用量增多呈现缓慢上升的趋势;当碳/碳边角料的用量为5份时,通过SEM观察可知,碳/碳边角料中的碳纤维在橡胶中分散程度和界面结合力达到最佳,测试表明此时复合材料的整体力学性能最优。

乳化性能对乳液聚合体系稳定性及反应过程的影响

反相乳液聚合是合成聚丙烯酰胺一种重要的聚合方式,乳液体系由聚合单体水溶液、溶剂及乳化剂组成,体系的乳化性能对乳液的稳定性、聚合反应过程及产品粒径分布具有重要影响。本文通过研究体系中亲水乳化剂含量、总乳化剂含量、亲油/亲水乳化剂配比对乳液稳定性及聚合过程的影响,精确计算每组实验乳液体系的乳化性能,确定了水油比例为1.5时,粒径200~450 nm产品乳化体系稳定、反应过程较好的乳化性能区间,为后续同类反应研究提供参考。

辐射乳液聚合羧基型丙烯酸酯橡胶的性能评价

评价了辐射乳液聚合羧基丙烯酸酯橡胶的加工性能、力学性能、耐热空气老化性能、压缩永久变形以及耐油性能,并与国外牌号的丙烯酸酯橡胶进行性能对比。结果表明,辐射法丙烯酸酯橡胶加工性能优异,焦烧时间合适,硫化速度快,相对分子质量大,交联网络完整,其硫化胶力学性能和耐油性能优异;其热空气老化性能和压缩永久变形能与国外品牌丙烯酸酯橡胶媲美。

Synthesis of nano-CaCO_3 composite particles and their application

Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.

反相乳液五元体系淀粉接枝共聚反应动力学

研究了在淀粉/单体/乳化剂/油/水五元反相乳液体系中引发淀粉和丙烯酰胺接枝共聚反应的动力学,考察了引发剂和乳化剂浓度、单体和淀粉浓度、反应温度等因素对表观聚合速率的影响.结果表明:在本实验考察范围内单体浓度和淀粉浓度对聚合速率影响明显,聚合过程中快速链终止和慢速链终止反应同时存在,动力学关系式为:Rp∝[I]0.93[M]1.28[St]1.47[E]0.61,聚合速率随体系温度的升高而加快,在35～55℃范围内,聚合反应的表观活化能为82.01kJ·mol-1.

丙烯酰胺和阳离子型单体反相乳液共聚合的研究

以油酸失水山梨醇酯（ＳＰＡＮ８０）作为乳化剂，偶氮二异丁基脒盐酸盐（ＡＩＢＡ）作为引发剂，进行丙烯酰胺———Ｎ，Ｎ二甲基，Ｎ丁基，Ｎ（３甲基丙烯酰胺基）丙基溴化铵（ＤＢＭＰＡ）反相乳液共聚合反应，研究了单体配比、乳化剂用量、引发剂用量及反应条件等对聚合反应动力学的影响。

丙烯酸钠反相乳液聚合

以阴离子乳化剂制备丙烯酸钠反相乳液，用γ射线引发其聚合，用扫描电镜观测了聚合前后粒径的变化；并在聚合过程中改变剂量率观测了聚合速率的变化．这两个实验结果都显示聚合以液滴成核为主，即聚合机理类似于悬浮聚合．与以司盘８０为乳化剂的丙烯酸钠反相乳液聚合相比，体系与司盘体系的聚合动力学基本相似；但是体系中的分散液滴比司盘体系要大，结果使得在动力学上体系更类似于悬浮聚合的动力学．从聚合机理看，反相乳液聚合实际上就是粒子分散得比较小的反相悬浮聚合．

两亲聚合物溶液性质及其乳液聚合的研究进展

综述了两亲聚合物溶液性质以及作为乳化剂的乳液聚合研究进展和现状，介绍了两亲聚合物溶液的特殊性质，阐述了作为乳化剂的独特作用。

机械活化淀粉反相乳液聚合动力学及机理探讨

以过硫酸铵为引发剂,研究了经机械活化预处理的玉米淀粉与丙烯酰胺在反相乳液体系中的接枝共聚反应动力学,分别考察了引发剂浓度、单体浓度、淀粉乳浓度和乳化剂浓度等对表观聚合速率的影响。结果表明,在本实验考察范围内的动力学关系式为Rp∞[I]0.84[M]1.12[St]1.07[E]0.54。推导并验证了该反应的表观动力学方程和反应机理,双基终止与单基终止过程同时存在,实验结果与理论推导基本符合。