高吸水树脂的等离子体引发聚合反应制备研究进展

介绍了等离子体引发聚合反应的特点;综述了等离子体引发聚合反应在制备高吸水树脂领域的研究进展,包括等离子体引发乙烯基系列单体聚合制备高吸水树脂、等离子体引发乙烯基系列单体接枝共聚制备高吸水树脂、等离子体引发制备有机-无机复合高吸水树脂等;最后指出了等离子体引发制备高吸水树脂研究需要加强的几个方向:即加强对等离子体引发聚合制备高吸水树脂反应机理的研究;加强天然产物接枝系列、有机-无机复合系列高吸水树脂以及多功能高吸水树脂的等离子体引发聚合制备研究等。     

均匀设计法优化一种高吸水性树脂的制备工艺

采用水溶液聚合的方法制备了黄原胶接枝丙烯酸/2-丙烯酰胺基-2-甲基丙磺酸[XG/P（AA-AMPS）]高吸水树脂。采用U10*（104）均匀设计对合成工艺进行优化,得出最佳合成条件为丙烯酸用量12 g、引发剂用量为单体总量的0.5%、丙烯酸的中和度为80%、聚合反应温度60 ℃。最佳合成条件下制备的高吸水性树脂吸水倍率达997.1 g/g,吸生理盐水倍率为176.2 g/g。采用傅里叶红外光谱（FTIR）、扫描电镜（SEM）和综合热分析仪对高吸水树脂进行表征。红外光谱分析结果显示丙烯酸（AA）和2-丙烯酰胺基-2-甲基丙磺酸（AMPS）已接枝到黄原胶分子链上,扫描电镜观察结果显示树脂形成一种多孔性网络结构,热性能分析结果显示树脂在高温下具有良好的热稳定性。     

微波辐射制备合成聚合物系列高吸水树脂研究进展

首先介绍了微波辐射聚合反应及其特点,对传统加热条件下和微波辐射条件下的自由基聚合反应进行了比较。然后就微波辐射乙烯基单体溶液聚合制备合成聚合物系列高吸水树脂的研究进展进行了综述。最后指出了微波辐射乙烯基单体聚合制备高吸水树脂研究需要关注的几个方向,即加强理论对实践的指导研究,尝试引入更多的功能性单体来改善高吸水树脂的性能,尝试采用乳液聚合、悬浮聚合等多种聚合方式等。     

微波辐射制备淀粉接枝共聚高吸水树脂研究进展？

综述了微波辐射下五种淀粉接枝共聚高吸水树脂的制备研究进展,包括淀粉接枝丙烯腈类高吸水树脂、淀粉接枝丙烯酸类高吸水树脂、淀粉接枝多元单体类高吸水树脂、淀粉系列互穿网络高吸水树脂、无机复合淀粉接枝高吸水树脂等;指出了微波辐射制备淀粉接枝共聚高吸水树脂的研究中,几个需要加强的研究方向：加强理论研究与实践研究的相互促进,开发新型无机矿物复合淀粉接枝共聚高吸水树脂等。     

TAAB交联的聚丙烯酸-丙烯酰胺吸水树脂的高温耐水解性能

针对现有吸水树脂高温易水解的缺陷,以四烯丙基溴化铵为交联剂,偶氮二异丁咪唑啉盐酸盐为引发剂,丙烯酸和丙烯酰胺为共聚单体,采用水溶液聚合法制备了一种高温耐水解型吸水树脂,并通过单因素实验法对聚合条件进行优化。结果表明:交联剂用量、引发剂用量、丙烯酰胺用量分别占丙烯酸质量的0.16%,0.12%,20.00%,中和度为75%时,吸水树脂在180℃条件下表现出良好的耐水解性能,吸水倍率可达362 g/g;吸水树脂在pH值为5~9的溶液中表现出良好的耐酸碱性能。     

马铃薯淀粉接枝丙烯酸/腐植酸钠复合高吸水树脂的合成工艺

采用不除去丙烯酸中阻聚剂及无氮气保护的新工艺,通过接枝聚合反应合成了马铃薯淀粉接枝丙烯酸/腐植酸钠复合高吸水树脂。实验研究表明,该复合高吸水树脂最高吸水率为1280g/g。该研究采用的新工艺,简化了生产工艺,降低了生产条件要求,同时也节约了生产成本。     

苹果渣基高吸水树脂的制备

以苹果渣为主要材料,过氧化氢为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,采用微波辐射法制备苹果渣基高吸水性树脂,并得到高吸水性树脂的最佳制备条件为:丙烯酸中和度为70%,苹果渣为单体的50%,交联剂为单体的0.5%,引发剂与丙烯酸摩尔比为0.075∶1,以此条件制备得到的苹果渣基高吸水树脂的吸水倍率可达到298 g/g。     

高固含量羟基丙烯酸涂料树脂的制备及性能研究

以溶液聚合法合成了2种不同组成的羟基丙烯酸树脂,研究了引发剂、反应温度与共聚物组成对共聚物相对分子质量、羟值和聚合体系黏度的影响.采用六亚甲基二异氰酸酯(HDI)三聚体分别与2种羟基丙烯酸树脂进行交联固化,并表征了树脂及其交联固化涂膜的机械性能、耐化学试剂性能和热稳定性.结果表明:共聚物组成中苯乙烯的加入明显降低了聚合体系的黏度,提高了树脂固含量,改善了涂膜物理性能.通过对引发剂用量、聚合反应温度、反应单体配比的控制,成功地制备出固含量为70％,综合性能优良的羟基丙烯酸树脂.     

微波辐射下耐盐性高吸水树脂的制备

对微波辐射下丙烯酸(AA)、丙烯酰胺(AM)和凹凸棒的水溶液聚合反应进行研究,合成凹凸棒复合P(AAAM)高吸水树脂,探讨微波功率、辐射时间、单体配比、中和度、引发剂用量、交联剂用量等对高吸水性树脂吸液倍率的影响,并用红外光谱对产物的结构进行表征.合成的高吸水树脂吸水倍率迭1 580 g/g,在质量分数为0.9%的食盐水中的吸液倍率达170 g/g.     

三烯丙基溴化铵交联的P(AA-AMPS)吸水树脂耐水解性能的研究

针对现有吸水树脂在酸、碱、高温环境中使用易水解的问题,以三烯丙基溴化铵(TAAB)为交联剂,过硫酸铵(APS)为引发剂,丙烯酸(AA)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)为共聚单体,制备了一种耐水解型吸水树脂。通过单因素实验法得到最佳聚合条件为:AMPS、TAAB和APS占AA的质量分数分别为18%、0. 20%、0. 16%,中和度为77%。此条件下制备的吸水树脂150℃下在蒸馏水与1%NaCl盐水中的吸水倍率分别为456、85 g/g,高温耐水解性能良好。此外,还对吸水树脂在不同盐、不同pH值溶液中的耐水解性能进行了测定。     

纤维素非均相接枝丙烯酸制备吸水材料

研究了经过氧化氢(H2O2)处理过的纤维素与丙烯酸在非均相体系中进行的接枝共聚,主要考察了聚合温度、聚合时间、预处理温度和纤维素状态对接枝聚合物的接枝参数的影响,以及交联剂对吸水倍率的影响,发现了H2O2-Cellulose先形成氧化还原体系,再引发丙烯酸与纤维素接枝的聚合机理。     

Alkyd-acrylic hybrid systems for use as binders in waterborne paints

Alkyd-acrylic hybrids were prepared by polymerizing acrylic monomers in the presence of colloidal alkyd droplets. Polymerization in the presence of alkyd caused a retardation of the polymerization through radical delocalization following radical transfer to the unsaturated groups of the fatty acids in the alkyd. The conversion could be raised to nearly 100% by adjusting the reaction conditions. The application properties of hybrids prepared according to this method could be varied over a broad range by changing either the acrylic part, the alkyd part or their ratio. The homogeneity of the hybrids differed from blends of acrylic dispersions and alkyd emulsions, as was shown by the minimum film formation temperature (MFFT). A good film formation was found without the use of co-solvents. Mixing of alkyd and polyacrylate on microscale, however, could not be determined. In some cases a true synergistic behaviour was observed, where the hybrid had properties superior to those of the acrylic polymer and the alkyd.     

The water absorbency of hydrolyzed polyacrylonitrile-grafted cellulose fibers

The water absorbency of a bleached softwood kraft pulp, as measured by its water retention value (WRV), was increased up to 30 times by graft polymerizing polyacrylonitrile (PAN) and subsequently hydrolyzing it to sodium polyacrylate–polyacrylamide copolymer. WRV was found to be related to the initial PAN graft level rather than to the final sodium polyacrylate content, and was independent of the grafting process used. However, the ceric ion process was found superior to both the cellulose xanthate–H₂O₂ and ferrous ion–H₂O₂ redox systems in that it occasioned only a minor loss during the hydrolysis stage and the WRV was less affected by drying. The WRV remained constant as pH was lowered from 9 to 5 but dropped to the level of unmodified pulp at pH 3.5 where the sodium salt is fully converted to poly(acrylic acid). Retention of 1% aqueous NaCl was about 60% of the WRV. The swelling properties of the grafted fibers under various conditions appear to be explained by considering the grafting to act in two ways: (a) the introduction of a potentially hydrophilic component capable of generating swelling pressures and (b) the reduction in the cohesion of the fiber by the interposition of graft polymer chains in the fiber structure.     

Particle coagulation at semicontinuous emulstion polymerization. I. Some factors affecting the process

The factors affecting the amount of coagulum appearing during the semicontinuous emulsion polymerization of acrylic monomers were studied. Monomers were added into the polymerization reactor in the form of emulsion. The stability of the polymerization system was greatly affected by the distribution ratio of a constant amount of emulsifier between the initial charge in the polymerization reactor and the monomer emulsion. The amount of arising coagulum was dependent also on the alkyl length of the alkyl acrylate and increased from ethyl acrylate to 2-ethylhexyl acrylate. The amount of appearing coagulum was essentially decreased by copolymerization with acrylic acid and sulfoethyl methacrylate, respectively. In the case of insufficient covering of particle surface by emulsifier, the colloid stability of polymerizing system was greatly increased by the presence of strong as well as weak acid groups chemically bound on the particle surface.     

Particle coagulation at semicontinuous emulsion polymerization. II. Characterization of surface groups

Semicontinuous emulsion polymerization of acrylic monomers with a monomer emulsion feed has been investigated. The amount of coagulum appearing during the polymerization under conditions of insufficient covering of particle surface by emulsifier was studied from the point of view of particle surface charge. Increasing the surface group concentration via copolymerization of butyl acrylate with acrylic acid or sulfoethyl methacrylate caused increased colloid stability of the system and a rapid decrease in coagulum formation. It was established that during the polymerization acid hydrolysis of ester groups took place, which caused an increase in the carboxyl groups concentration at the particle surface. These carboxyl groups contribute to the colloid stability of the polymerizing system.     

The effects of MEHQ on the polymerization of acrylic acid in the preparation of superabsorbent gels

The effect of the monomethyl ether of hydroquinone (MEHQ) on the polymerization of acrylic acid was studied. The rate of polymerization was quantified at various levels of MEHQ by use of an in situ NMR technique. While oxygen functions as an inhibitor in acrylic acid polymerizations, MEHQ was shown to function as a retarder. The decrease in the rate of polymerization allowed the calculation of an inhibition constant for this system. MEHQ was found to remain in the polymerizing mixture throughout the course of the reaction, significantly reducing the rate of polymerization, but not reducing the molecular weight of the polymer. The data are consistent with direct reaction of MEHQ with initiator fragments, but not termination of growing chains. Superabsorbent polyacrylic acid gels were prepared and the properties measured. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 577–589, 1997     

PA乳液对VAE乳液的共混改性研究

用系列聚丙烯酸酯 (PA)乳液对VAE乳液进行共混改性 ,研究了共混乳液的稳定性、乳胶膜性能、相容性等。结果表明 ,获得稳定的共混乳液的最佳条件是将VAE乳液本身的PH值调至 7;共混乳液胶膜的性能依赖于共混乳液的组成和PA配方的玻璃化温度 (Tg)及其聚合工艺 ;共混体系具有部分相容性     

复合金属氧化物催化丙烷选择氧化制丙烯酸

采用溶液法制备Mo-V-Te-Nb-O催化剂,研究了焙烧次数对催化剂性能的影响,考察催化剂在普通密封条件下储存时间和连续反应过程中的稳定性。结果表明,二次焙烧制备的催化剂中M1和M2相增强,对丙烯酸生成有利,且晶相形态不随焙烧次数的增加而改变,而烧结现象逐渐增加。催化剂可在普通密封条件下储存24个月,性能不发生变化,催化剂活性和选择性随反应进行不断震荡升高,丙烯酸初期收率为24.7%,反应180 h左右达31.8%,随后催化剂迅速失活。XRD、BET表征及催化剂再生实验表明,其失活的主要原因是Te流失。     

Polyacrylate/(carboxymethylcellulose modified montmorillonite) superabsorbent nanocomposite: Preparation and water absorbency

Montmorillonite (MMT) was modified with carboxymethylcellulose (CMC). The X‐ray diffraction (XRD) and FTIR analyses showed that the CMC chains had intercalated into the MMT sheets, and the strong chemical interaction between the ether bonds from CMC and Si? O bonds from MMT was the driving force for intercalation. Polyacrylate (PAA)/modified MMT superabsorbent nanocomposites were fabricated by effectively dispersing the modified MMT in acrylic acid solution and polymerizing the acid. The superabsorbent composites were characterized by XRD, TEM, and FTIR. The influence of modified MMT, weight ratio of CMC to MMT, and modified MMT content in the nanocomposites on the water absorbency was investigated. Results showed that the introduction of pure MMT could decrease the water absorbency of the gel, but adding modified MMT could not only effectively increase the water absorbency of the gel, but also improve its water retention ability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

聚丙烯酸水凝胶的制备研究

以丙烯酸为单体,N,N＇-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,通过自由基聚合制备了聚丙烯酸水凝胶.考察了交联剂、引发剂、单体中和度、聚合温度以及盐溶液对水凝胶溶胀性能的影响.结果表明,引发剂为单体质量的0.6％,交联剂为0.8％,单体的中和度为70％时,凝胶的溶胀性能最佳,吸水率达到了3 000％以上,聚丙烯酸水凝胶的溶胀性能随着盐溶液浓度的增大而降低.