Study on soap‐free P(MMA‐EA‐AA or MAA) latex particles with narrow size distribution

Soap‐free poly(methyl methacrylate‐ethyl acrylate‐acrylic acid or methacrylic acid) [P(MMA‐EA‐AA or MAA)] particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and acrylic acid (AA) or methacrylic acid (MAA), and the influences of the mass ratio of core/shell monomers used in the two stages of polymerization ([C/S]_w) and initiator amount on polymerization, particle size and its distribution were investigated by using different monomer addition modes. Results showed that when the batch swelling method was used, the monomer conversion was more than 96.0% and particle size distribution was narrow, and the particle size increased first and then remained almost unchanged at around 600 nm with the [C/S]_w decreased. When the drop‐wise addition method was used, the monomer conversion decreased slightly with [C/S]_w decreased, and large particles more than 750 nm in diameter can be obtained; with the initiator amount increased, the particle size decreased and the monomer conversion had a trend to increase; the particle size distribution was broader and the number of new particles was more in the AA system than in the MAA system; but the AA system was more stable than the MAA system at both low and high initiator amount. Copyright © 2006 John Wiley & Sons, Ltd.     

The effect of cosurfactants and the initiator concentration on the polymer to surfactant concentration in nanolatexes

The effect of cosurfactant and initiator concentration on the ab initio production of nanolatexes using low surfactant levels was investigated. While the use of cosurfactants (acrylic acid and pentanol) increased the amount of monomer that can be used in styrene‐SDS microemulsion formulations to 13 wt %, high surfactant concentrations are still required, resulting in polymer‐to‐surfactant ratios (Pol/Surf) <1. Latexes with particle size of 30 ± 5 nm were produced upon polymerization of these microemulsions. The Pol/Surf can be significantly increased by increasing the initiator concentration of emulsion polymerization recipes. Particle sizes are comparable with microemulsion latexes, however, less surfactant is required. The reduction in the particle size with higher initiator concentration is attributed to a higher efficiency of particle nucleation and to a higher nucleation rate relative to the rate of monomer transfer. Nanolatexes (particle size < 30 nm) were obtained with 19 wt % solids content and Pol/Surf of 3.6 in ab initio. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Properties of single-component acrylic pressure-sensitive adhesives synthesized using <Emphasis Type="Italic">tert</Emphasis>-butyl peroxypivalate initiator

In this work, tert-butyl peroxypivalate initiator was newly used in the solution polymerization of acrylic copolymers with 2-ethylhexyl acrylate, butyl acrylate, methyl methacrylate and acrylic acid monomers for application of pressure-sensitive adhesives (PSAs). Its proper dosage was determined to vary from 0.6 to 1.2 wt % when a high monomer conversion (>99%) was ensured. In this amount range, polymer properties and adhesive performance of the PSAs were investigated. The results indicated that with the amount of tert-butyl peroxypivalate increased, the molecular weights of the polymer decreased and the molecular weight distribution became wider. It was also observed that the synthesized PSAs had high interfacial adhesion and low cohesion strength, and thus exhibited cohesive failure during the peel test. So cross-linking agent was employed to improve the shear strength of the PSAs and to eliminate the adhesive residue while at the sacrifice of loop tack and peel strength. As a whole, the optimal performance was obtained by using 1.2 wt % amount of initiator and 0.5 wt % concentration of cross-linker. In this case, the peel and shear strength have achieved the best balance. In addition, for the cross-linked PSA tapes, the peel strength slightly decreased with the dwell time.     

聚乙烯与丙烯酸的溶液接枝聚合

以过氧化苯甲酰为引发剂，二甲苯为溶剂，进行了丙烯酸与低密度聚乙烯的溶液接枝聚合，研究了ＢＰＯ用量、溶液浓度以及丙烯酸用量对接枝率的影响。聚乙烯接枝了丙烯酸后与铝的粘结强度显著增大，当接枝率为７．２％时，剥离强度由未接枝时的１９３Ｎ／ｍ，提高到９８４Ｎ／ｍ。     

Radiation polymerization of acrolein at low temperatures

Radiation polymerization of acrolein in the presence of the additives such as 2-hydroxyethyl methacrylate, acrylic acid, and water at low temperatures (0–78°C) was studied. The polyacrolein resulting from the polymerization gave a small particlelike microsphere (0.5–5 μm in diameter). The rate of the polymerization reaction of acrolein appeared to be accelerated by the addition of a small amount of 2-hydroxyethyl methacrylate or acrylic acid. The particle size of the polyacrolein particle varied with the condition of the polymerization and increased or decreased with an increase in the addition concentration of 2-hydroxyethyl methacrylate or acrylic acid.     

Synthesis and Demulsibility of the Terpolymer Demulsifier of Acryl Resin

Terpolymer demulsifier of acryl resin has been synthesized through solution polymerization with water as a dissolvent, potassium persulfate as an initiator and the monomers of methyl methacrylate, butyl acrylate and acrylic acid as starting materials. The effects of the reaction temperature, dripping time, the amount of monomers and initiator on the dehydration rate of the demulsifier were investigated by an orthogonal experiment. It shows that the stronger influence on the dehydration rate among six factors is reaction temperature, dripping time, and amount of catalyst, while monomer has weak influence. The performance of the demulsifier was evaluated under different demulsification time, temperatures and concentrations of the screened demulsifiers. The result shows that the dehydration rate of the demulsifier can reach over 67%, which is better than that by the emulsion polymerization way.     

Preparation and properties of diatomite composite superabsorbent

A novel diatomite composite superabsorbent was synthesized by solution polymerization of partially neutralized acrylic acid and diatomite, using N,N′-methylenebisacrylamide as a crosslinking agent and hydrogen peroxide and L -ascorbic acid as a redox initial system. The influences of some reaction conditions, such as diatomite content, neutralization degree of acrylic acid, amount of initiator, amount of crosslinking agent, monomer concentration, and the reaction temperature on swelling characteristic were investigated. The water absorbency of the sample prepared at optimum conditions was 99 g/g in 0.9 wt% NaCl solution. The results of swelling rate measurement showed that diatomite composite superabsorbent had better swelling rate than that of poly(sodium acrylate) prepared in the same conditions. Other properties, i.e. water retention, reswelling ability and resistance to salt, were also examined. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,characterization and water absorbency properties of poly(acrylic acid)/sodium humate superabsorbent composite

A novel poly(acrylic acid)/sodium humate superabsorbent composite was synthesized by aqueous solution polymerization of acrylic acid using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator in the presence of sodium humate. The effects on water absorbency such as initial monomer concentration, degree of neutralization of acrylic acid, amount of crosslinker, initiator and sodium humate, etc. were investigated. The water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with a sodium humate content of 20% exhibited an absorption of 1268 g H₂O/g sample and 93 g H₂O/g sample in distilled water and in 0.9 wt% NaCl solution, respectively. Swelling rate and water retention tests were also carried out. The results show that sodium humate, as a kind of functional filler, can enhance comprehensive properties of superabsorbent composite and reduce the product cost significantly. Copyright © 2005 John Wiley & Sons, Ltd.     

MMA-EA-AA无皂共聚胶乳中羧基分布的研究

用无皂乳液聚合法合成了粒径窄分布的MMA EA AA三元共聚胶乳 ,用电导滴定法测定了羧基在胶乳中的分布 ,系统研究了聚合体系中各组分对胶乳中羧基分布的影响 .结果表明随着NH4 HCO3用量的增加 ,表面羧基含量 (Sa)、表面羧基密度 (Sd)和水相羧基含量 (Fa)逐渐增大 ,包埋羧基含量 (Ea)明显降低 ;随着AA用量的增加 ,Sa、Sd 、Fa 和Ea 均逐渐增大 ,但包埋羧基百分比也呈增大趋势 ;随着引发剂用量的增加 ,Sd 和Ea 逐渐减小 ,而Fa 先增大然后趋于恒定 .     

水溶液中单电子转移活性自由基聚合法制备新型阳离子共聚丙烯酰胺/丙烯酸酯

以咪唑、丙烯腈和溴辛烷等为原料,合成了新型阳离子型可聚合离子液体表面活性剂单体：氯化-1-正辛基-3-（4-丙烯酸丁酯基）咪唑（PMOIH8）。 以2-氯丙酰胺为引发剂,Cu0粉/三-（2-二甲氨基乙基）-Me-6-TREN为催化体系,采用单电子转移活性自由基聚合法对丙烯酰胺（AM）、PMOIH8进行了二元共聚合反应,合成了一种新型阳离子共聚丙烯酰胺/丙烯酸酯P（AM/PMOIH）。 FT-IR、MS和1H NMR分析表明,所得聚合物为目标产物,采用GPC测得聚合物的相对分子质量为2×103~14×103,相对分子质量分布Mw/Mn在1.21~1.75之间。 考察了催化剂、引发剂等因素对聚合的影响。 结果表明,降低催化剂用量,聚合反应速率变慢,链增长速率常数kappp由0.0168 min-1降低至0.0065 min-1,Mw/Mn由1.25~1.71增加至1.32~1.75,引发效率Ieff=90.24%;增加引发剂用量,Mw/Mn由1.25~1.71减小至1.21~1.68,kappp由0.0168 min-1增加至0.0201 min-1,Ieff增加至93.17%。     

表面交联的三元共聚高吸水树脂的合成及其性能研究

以丙烯酸、丙烯酰胺及丙烯磺酸钠为单体,采用水溶液聚合法制得三元共聚高吸水树脂(SAP1),用乙二醇二环氧甘油醚与氯化铝作交联剂,对SAP1进行表面交联处理得高吸水树脂SAP2。SAP2在加压下吸盐水率高,凝胶颗粒表面干爽且易分散。考察了引发温度、丙烯酸中和度、交联剂、引发剂、丙烯酰胺及丙烯磺酸钠的用量对常压下吸盐水率的影响。同时还考察了乙二醇二环氧甘油醚与无机盐用量对常压及加压下吸盐水率的影响。     

Synthesis of Acrylic Acid／Kaoline Powder Superabsorbent Composite by Inverse-suspending Polymerization

An acrylic acid/kaoline powder superabsorbent composite with a water absorbency of the superabsorbentcomposite about 1/800 was synthesized by inverse-suspending polymerization reaction between acrylic acidmonomer and kaoline ultrafine powder. The influence of the dispersant agent on the configuration of theproducts in the inverse suspension polymerization is investigated. The influences of the kaoline powder.cross-linker, initiator, neutralization degree and the volume ratio of oil to water phase on the water absorben-cy of the superabsorbent composites are discussed in the paper.     

Graft Copolymerization of Artemisia Seed Gum with Acrylic Acid under Microwave and its Water Absorbency

A super‐absorbent polymer was prepared by grafting copolymerization of acrylic acid onto Artemisia seed gum, using microwave irradiation and ammonium persulfate as an initiator. The effect of various preparation conditions on its water absorbency, such as the ratio of acrylic acid to Artemisia seed gum, degree of acrylic acid neutralization, amount of initiator and microwave irradiation time, was investigated by orthogonal tests. The optimal reaction conditions were 3 min (irradiation time), 70% neutralization degree of acrylic acid and 2% initiator on the basis of the mass of acrylic acid used. When the mass ratio of acrylic acid to Artemisia seed gum is 5:0.5, the product has a water absorbency close to 400 times at room temperature in distilled water, this indicated that is has a high water absorbency. The structure of the graft copolymer was confirmed by Fourier transform infrared spectrometer (FT‐IR) and thermogravimetric analysis (TGA). Further more, this microwave irradiation processing method to prepare water absorbent materials has no industrial cast off produced, that is to say, this method is environmentally friendly.     

MMA-EA-AA无皂乳液聚合中粒径及粒径分布的控制

系统研究了MMA EA AA三元无皂乳液聚合体系中各种因素对乳胶粒大小及分布的影响 ,制得了单分散、粒径在 30 0～ 6 0 0nm可控聚合物乳胶粒 .结果表明 ,在过硫酸铵用量一定的条件下 ,聚合初期加入大量引发剂可同时提高单体转化率和乳胶粒的单分散性 ;随着引发剂和AA用量的增加以及聚合温度的升高 ,胶粒粒径逐渐减小 ,转化率逐渐升高 ;随着NH4 HCO3用量的增加 ,粒径逐渐增大 ,当NH4 HCO3用量达到 0 5g以后 ,转化率逐渐降低 ;搅拌速率为 30 0r min左右时 ,单体转化率最高 ,所得乳胶粒粒径最均一 .     

Frontal copolymerization synthesis and property characterization of starch-graft-poly(acrylic acid) hydrogels

Recently, a considerable amount of research has centered on uniquely structured polymers synthesized through self-propagating frontal polymerization. The obtained polymer materials have better features than those obtained by using the classical batch route. The additional advantages are short reaction times and low cost. This work describes the first frontal polymerization synthesis of a graft copolymer superabsorbent hydrogel of acrylic acid onto starch at high monomer and initiator concentration. The effects of varying the relative amounts of the reaction components on the most relevant parameters relating to frontal polymerization were explored. The front velocity dependence on initiator concentration could be fit to a power function. The temperature profiles were found to be very sharp with a maximum temperature below 150 degrees C, which was responsible for high monomer conversion. The ultimate properties of the product appear to depend on the polymerization front velocity and the temperature. The high-temperature and rapid temperature increase at the polymerization front led to products with interconnected porous structures caused by the evaporation of water. So, a fast-swelling, highly absorbing hydrogel with respect to batch polymerization was obtained.     

Preparation and characterization of pure polyacrylate polymer colloid through emulsion polymerization using a novel initiator

A series of acrylic polymer colloids were prepared via semi-continuous seeded emulsion polymerization of BA and MMA in water phase when OP-10 and AIBI is used to be emulsifier and initiator, respectively. FTIR spectrum identifies the formation of copolymers of P (MMA-co-BA). DSC confirms that the colloid is a kind of random copolymer and the consistency among the chain segment is fairly good. The emulsion polymerization conditions of preparing acrylic polymer colloid are optimized. Results show that the conversion rate is high and the coagulum is low and the particle size of the acrylic polymer colloids is small when the amount of AIBI is 0.75 g. The polymerization temperature is 70 °C, which is lower than the one that the emulsion polymerization is initiated with the persulfate.     

丙烯腈的悬浮聚合

<正> 适用于普通溶液纺丝加工成形的聚丙烯腈(PAN)的分子量一般在5—8万范围内,近年来发展起来的冻胶纺丝方法使得(?)>4.0×10~5的超高分子量PAN也可以纺丝成形,成为制备高强高模PAN纤缎的有效方法之一。随着PAN材料应用领域的开拓,合成超高分子量的PAN是一个首要解决的问题。     

反相乳液聚合法制备丙烯酰胺-丙烯酸铵共聚物

以煤油为连续相,水为分散相,Span-80/Tween-80为复配乳化剂,过硫酸铵为引发剂,丙烯酰胺、丙烯酸和氨水为原料,采用反相乳液聚合法合成了丙烯酰胺-丙烯酸铵共聚物絮凝剂.考察了乳化剂种类及用量、引发剂浓度、单体浓度、EDTA用量、聚合温度等对共聚物特性黏数的影响.确定了最佳实验条件,利用FTIR对样品进行了表征.     

ATRP法合成聚去氢枞酸丙烯酸乙二醇酯的研究

本研究从歧化松香中提取的去氢枞酸(DHA)出发,经酰氯化后与丙烯酸(2-羟基)乙酯反应,合成了去氢枞酸丙烯酸乙二醇酯(DHAAGE);并以此为单体,2-溴-异丁酸乙酯(EBr-iB)为引发剂,CuBr/2,2'-联吡啶(2,2'-bipyridine)为催化体系,在90 oC下,利用原子转移聚合(ATRP)法制备了聚去氢枞酸丙烯酸乙二醇酯(PDHAAGE).利用FT-IR、1H-NMR和GPC对所制备的单体和聚合物进行了表征,同时考察了单体转化率随聚合反应时间的变化.结果表明,聚合反应动力学曲线呈良好线性关系,表观聚合速率常数kp′为3.6 ×10-7 s-1;所得聚合物的分子量分布很窄.     

Nonswellable and swellable ethylene glycol dimethacrylate-acrylic acid copolymer microspheres

In this study, nonswellable and swellable poly(ethylene glycol dimethacrylate/acrylic acid) copolymer microspheres, in the size range of 50–150 μm, were produced by conventional and modified suspension copolymerizations of the respective monomers, i.e., ethyleneglycol dimethacrylate (EGDMA) and acrylic acid (AA) in aqueous media. Poly(vinyl alcohol) and benzoyl peroxide were used as the stabilizer and the initiator. The diluent, i.e., toluene was included in the polymerization recipe of the modified suspension polymerization. The microspheres were characterized by optical microscopy, FTIR, and FTIR-DRS, and potentiometric titrations. Highly crosslinked, transparent, and nonswellable poly(EGDMA/AA) microspheres were obtained with the conventional suspension polymerization procedure. The modified suspension polymerization provided swellable, opaque, and crosslinked copolymer microspheres. Acrylic acid incorporation into the copolymeric microspheres were significantly higher in the modified procedure, relative to the conventional procedure. © 1996 John Wiley & Sons, Inc.