自交联型苯丙共聚乳液的研究

本文介绍了丙烯酸丁酯(BA)、苯乙烯(St)、丙烯酸(AA)与自交联单体N—羟甲基丙烯酰胺(NMA)和N—丁氧基甲基丙烯酰胺(BOA)的乳液共聚合,研究了乳液共聚合时的稳定情况、乳胶的表观粘度、乳胶对离心和电解质的稳定牲、膜的溶胀性。发现NMA可以提高单体预乳化液的稳定性,增加乳胶的表观粘度,离心稳定性和电解质稳定性; BOA则降低单体预乳化液的稳定性、离心稳定性和电解质稳定性。聚合时易产生凝聚物,而对表观粘度影响不大。     

自交联含氟丙烯酸酯共聚物乳液的制备

以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)等为主要单体,甲基丙烯酸六氟丁酯(HFMA)为含氟单体,N-羟甲基丙烯酰胺(NMA)为交联单体,采用种子乳液聚合法制备了自交联含氟丙烯酸酯共聚物乳液。研究了HFMA、NMA、复合乳化剂(SDS OP-10)、引发剂(KPS)用量、聚合温度、聚合时间和搅拌速度等因素对聚合反应最终转化率和乳液稳定性的影响,结果表明在m(MMA)∶m(BA)=1∶1及搅拌速率210 r/min条件下,HFMA、NMA、SDS OP-10和KPS加入量分别为总单体量的7%、3%、3%和0.5%(均为质量分数),以及聚合温度75℃、反应时间4 h时,制备得到的乳液单体总转化率高,乳液凝聚率低,聚合反应稳定,涂膜的综合性能优良。此外,含氟乳胶膜的FT-IR及TG-DSC分析结果表明,HFMA有效地参与了共聚反应,提高了涂膜的耐热性。     

自交联含氟丙烯酸酯乳液的合成与性能研究

以甲基丙烯酸十二氟庚酯(DFHMA)为含氟丙烯酸酯单体,甲基丙烯酸酯衍生物(HA)为交联单体,烯丙氧基壬基酚聚氧乙烯(10),醚单磷酸(ANPEO10-P1)为乳化剂,采用预乳化、半连续法聚合方式,合成了自交联含氟丙烯酸酯乳液.研究了HA和DFHMA的用量对乳胶粒子粒径及其分布和乳胶膜硬度、吸水性、对水接触角等性能的影响.结果表明:当HA用量为4%(wt),DFHMA用量为8%(wt)时,得到的乳液粒径小,分布窄,稳定性好,乳胶膜表现出良好的疏水性能,对水的接触角达到了97.5°.     

乙酰乙酰基丙烯酸酯聚合物乳液的合成及室温交联改性

采用半连续种子乳液聚合法合成了核壳型乙酰乙酰基丙烯酸酯聚合物乳液,并采用1,6-己二胺对其进行了室温交联改性。探讨了乳液聚合反应条件和交联单体甲基丙烯酸乙酰乙酰氧基乙酯(AAEM)用量对乳液及乳胶膜性能的影响。结果表明:当乳化剂十二烷基联苯醚二磺酸钠(DSB)、引发剂过硫酸钾(KPS)用量分别为单体总量的1.5%(wt)和0.5%(wt)时,单体转化率高,凝胶率低。透射电镜(TEM)分析显示乳胶粒呈明显的核壳结构,粒径约为130 nm。DSC、TGA和力学性能测试表明交联提高了乳胶膜的玻璃化转变温度、热稳定性及力学性能。随着AAEM用量的增加,乳胶膜的性能逐渐得到提高。当AAEM用量为单体总量的7%(wt)时,加入己二胺的乳液仍贮存稳定,可以单组分包装,并且交联后的乳胶膜性能优异。     

可聚合阳离子含氟表面活性剂在含氟丙烯酸酯乳液聚合中的应用

以可聚合阳离子含氟表面活性剂N-(乙酸全氟辛基乙基酯)-N-(乙醇丙烯酸酯)二甲基溴化铵(PF8DM)为乳化剂,进行含氟丙烯酸酯的细乳液聚合研究,考察了PF8DM用量对单体转化率和凝胶率的影响,PF8DM用量对乳液的稳定性和表面性能的影响;分别采用PF8DM和十六烷基三甲基溴化铵作为乳化剂考察其对乳胶膜性能的影响。结果表明,当PF8DM含量为单体总质量的4%时,单体转化率达95%,凝胶率为0.6%;所得乳液具有优异的贮存、稀释、离心稳定性;当PF8DM用量为单体总质量的6%时得到的乳胶膜接触角达118.6°。在总含氟量相同的条件下,采用PF8DM为乳化剂制备的含氟丙烯酸酯乳液,其乳胶膜的吸水率大大降低,拒水性也明显增强。     

N-羟甲基丙烯酰胺对硅丙乳液及乳胶膜性能的影响

将N-羟甲基丙烯酰胺(NMA)、端乙烯基聚硅氧烷大单体与丙烯酸酯类单体进行乳液共聚合反应,制备了稳定的自交联型的硅丙乳液。通过聚合过程的动力学,聚合稳定性,乳胶粒的粒径大小和分布,以及乳胶膜的耐水性和力学性能测试,结合乳胶粒的微观形态和胶膜的红外光谱和DSC分析,讨论了NMA的引入及聚合方法对硅丙乳液和乳胶膜性能的影响。结果表明,在NMA适量加入的情况下,聚合反应速度加快,聚合稳定性提高,乳胶膜的耐水性增强,并使乳胶膜的力学性能也得到较大的提高。     

NMA自交联丙烯酸酯乳液的合成及性能研究

以甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)为主单体,N-羟甲基丙烯酰胺(NMA)为交联单体,甲基丙烯酸(MAA)为功能单体,考察链转移剂十二硫醇用量、热处理温度及时间对自交联丙烯酸酯乳液交联性能的影响,并考察了交联反应对乳胶膜热稳定性和吸水性能的影响。结果表明,十二硫醇用量为0.2%的条件下,能有效阻止NMA在室温下的交联反应;提高乳胶膜热处理温度与延长热处理时间都可以提高乳胶膜交联度;交联反应可以显著提高乳胶膜的热稳定性,降低乳胶膜的吸水增重;体系加入MAA可以进一步提高体系交联度,在120℃时最高可增加13%。     

自交联型可再分散苯丙乳胶粉的制备及水分散性与耐水性的协同优化研究

软核硬壳结构苯丙乳液壳层引入自交联单体N-羟甲基丙烯酰胺(NMA),经喷雾干燥获得水分散性和涂膜耐水性俱佳的自交联型可再分散乳胶粉。采用FT-IR光谱、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、马尔文激光粒度分析、原子力显微镜(AFM)等手段对原乳液、乳胶粉、再分散乳液进行表征,研究了乳液中和、干燥和再分散过程,分析了乳胶粉能兼顾再分散性和聚合物涂膜耐水性的机理。研究结果表明,自交联型苯丙乳液具有规整的软核硬壳结构,乳胶粉的粒径在2~20μm,遇水可迅速分散得到平均粒径182 nm的再分散乳液。乳液壳层添加NMA能削弱乳胶粒表面的疏水缔合作用,形成更厚的"绒毛结构"和水化层,因而抑制干燥时的乳胶粒凝聚融合,阻止乳胶粒之间的交联反应,优化了乳胶粉的亲水分散性。自交联作用使可再分散乳胶粉所成聚合物膜的吸水性降低40%以上,因此,采用NMA交联改性同时优化了苯丙乳胶粉的水分散性与耐水性。     

具有核壳结构有机硅改性醋丙乳液的制备及其性能

采用半连续种子乳液聚合法,以聚合性乳化剂SVS制备核壳结构有机硅改性醋丙乳液,通过红外光谱和DSC表征乳胶粒化学组成和玻璃化温度。考察聚合性乳化剂SVS与有机硅单体用量对乳液聚合稳定性和制备乳液耐水性能的影响。DSC测试结果表明乳胶粒具有核壳结构;在SVS用量为2.5%（wt）,有机硅单体用量为3.0%（wt）时,乳液稳定性和乳胶膜的耐水性能较好。     

弹性含氟树脂乳液的制备研究

以氟树脂乳液作为种子乳液,MMA、AA、BA作为改性单体制备了弹性含氟树脂乳液。研究了乳化剂用量、AA用量、改性单体用量对聚合反应及膜性能的影响。结果表明:随着乳化剂用量的增加,聚合稳定性、膜吸水率增加;随着AA用量的增加,乳液的冻融稳定性提高,膜吸水率增加,凝胶率降低;乳液的平均粒径、膜吸水率、膜弹性随着改性单体用量的增加而升高,膜的拉伸强度随着改性单体用量的增加而降低。当m(改性单体)∶m(固体氟树脂)=4∶6时,乳胶膜具有良好的低温柔韧性。     

Redispersible polymer powder functionalized with NMA and its adhesive properties in dry-mixed coatings

One type of redispersible polymer powder functionalized with N-hydroxymethyl acrylamide (NMA) was developed in this work. The addition of NMA proved to have great influence on the properties of the original emulsion as well as the corresponding powders. The particle size and viscosity of original emulsions both increased with the increasing of NMA amount while the colloidal stability decreased due to the generation of oligomers. However, the fluidity and adhesive performance of the resultant powders were improved obviously by adding more amounts of NMA in polymerization. Taking the above factors into consideration, we found that 3.0?wt.% of total monomers was an acceptable percentage for the NMA to be used. Poly (vinyl alcohol) (PVA) was used as protective colloids in spray drying to prevent the coalescence of emulsion particles so that the reversible dispersion of powders could be realized. The morphology of powder particles was proved to turn into ‘donut’ shape with the increasing of PVA amount, and their reconstitution ability became better. Compared with original emulsion, the reconstituted emulsion had poorer stability and dispersity due to the coalescence of polymer particles in spray drying.     

Synthesis of a vinyl monomer containing β‐cyclodextrin and grafting onto cotton fiber

To chemically bond β‐cyclodextrin (β‐CD), which can form inclusion complexes, acrylamidomethyl CD (CD–NMA) obtained from the acid‐catalyzed reaction of N‐methylolacrylamide (NMA) and β‐CD was grafted onto cellulose fibers using CeIV as the initiator. The double‐bond content of CD–NMA increased with increase in the NMA/CD mol ratio, and a CD–NMA containing a maximum of three molecules of NMA bonded to a CD molecule could be obtained. Since the grafting condition is acidic, the hydrolytic stability of CD–NMA in aqueous nitric acid was studied. The temperature of hydrolysis proved to have a greater effect on the depletion of double bonds from CD–NMA compared with the concentration of the acid. Thus, CD–NMA was grafted onto cellulose fibers at a low temperature, and FTIR analysis of the CD–NMA‐grafted cotton fibers confirmed the chemical bonding of CD–NMA molecules to cellulose. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 438–446, 2001     

Properties of PHMS‐g‐p [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsions

Emulsion graft copolymerization of poly(hydrogenmethylsiloxane) (PHMS) and butyl acrylate (BA) in the presence of functional comonomer N‐hydroxyl‐methyl acrylamide (NMA) was conducted by batch emulsion copolymerization to modify the properties of polysiloxane. Morphology of graft copolymer particles was characterized by transmission electron microscopy. The effect of polymerization method, PHMS content, initiator concentration, and NMA content on stability of emulsion, morphology, size of particle, and rheological properties were investigated. It has been found that stability of emulsion is better by semicontinuous emulsion polymerization than that of batch emulsion polymerization and it increased with increasing PHMS‐NMA concentration. Increasing PHMS concentration and NMA concentration, the particle size and the viscosities increase. The property of resistance to electrolytes of graft copolymer emulsions and swelling property of film were also discussed. Results showed PHMS‐g‐P [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsion has good resistance to electrolytes and the water absorption of its film increases with increasing BA‐NMA content grafted onto PHMS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2209–2217, 1999     

PHMS/BA/VAc共聚乳液的研究

采用乳液滴加法将含氢聚甲基硅氧烷(PHMS)、丙烯酸丁酯(BA)和醋酸乙烯酯(VAc)进行乳液共聚,制得了稳定的PHMS／BA,／VAc聚合物乳液。讨论了PHMS和N-羟甲基丙烯酰胺(NMA)的用量对聚合物乳液的表面张力、离心稳定性及粒径大小的影响。结果表明：随着PHMS用量的增加,乳液的表面张力减小,平均粒径增大,稳定性提高;随着NMA用量的增加,平均粒径增大,在一定用量范围内,聚合物乳液的离心稳定性提高。     

Preparation of thermally curable conductive films PEDOT:P(SS-NMA) and their performances on weather stability and water resistance

In this research, sodium 4-styrenesulfonate (SSNa) and N-(methylol acrylamide) (NMA) were copolymerized to form the thermally curable copolymer P(SS-NMA). Moisture absorptivity and swelling index were used to evaluate the weather stability of P(SS-NMA). The P(SS-NMA) copolymers with high molar content of NMA exhibited better weather stability. Then, P(SS-NMA) was used as the polymeric template to carry out the oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) and yielded the thermally curable conductive dispersion, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate-N-(methylol acrylamide)) (PEDOT:P(SS-NMA)). The optoelectronic property and surface morphology for the PEDOT:P(SS-NMA) conductive thin films were investigated. In addition, the performance of the PEDOT:P(SS-NMA) conductive film was characterized in the two parts: weather stability and water resistance. The introduction of crosslinking structures into the conductive film improved the mechanical property and weather stability so as to resolve the drawbacks of the commercial products PEDOT:PSS.     

Synthesis and characterization of copolymers of styrene andN-methylolacrylamide

Copolymers of styrene (ST) and N-methylolacrylamide (NMA) were synthesized by emulsion polymerization for different initial weight ratios of ST/NMA. Fast reaction rates and high conversions are achieved regardless of the ST/NMA ratio. NMA content in copolymers, as deduced by DSC, FTIR and Kjeldhal analysis, is higher as the initial ST/NMA ratio decreases. Glass transition temperature of copolymers increases as the ST/NMA ratio decreases and it decreases with reaction time for a fixed ST/NMA ratio. The latter results and FTIR spectra as well as Kjeldhal analysis as a function of reaction time indicate that NMA reacts initially in the aqueous phase, after which ST, because of its overall larger concentration, is incorporated preferentially in the polymer.     

铜基催化剂的制备及其催化苯胺N-甲基性能

N-甲基苯胺(NMA)广泛应用于化工生产中,以苯胺和甲醇为原料,采用气相法合成NMA,研究的重点在于提高CuO/ZnO/Al_2O_3催化剂的稳定性。通过分析CuO/ZnO/Al_2O_3催化剂的制备条件及助剂的作用,为合成优良催化性能的催化剂提供理论指导。     

NMA改性VAE乳液的研制

通过在通用型VAE CW40-707基础上再聚合N-羟甲基丙烯酰胺(NMA),研制出了具有自交联功能的VAE乳液。研究了不同VAE和引发剂对产品性能的影响,以及影响聚合过程及产品贮存稳定的因素,最终确定了适合的原料VAE牌号和再聚合改性方式。结果表明,使用有一定油溶性的引发剂TBHP可以将NMA聚合物分子链紧密的缠绕在改性乳液粒子表面,使改性乳液既保留了原VAE的性能优点又获得了良好的湿粘强度和耐蠕变性,拓宽了VAE的使用范围,达到了研制目的。     

Effect of different crosslinkers on properties of melamine formaldehyde‐furfuryl alcohol copolymer/montmorillonite impregnated softwood (Ficus hispida)

Melamine formaldehyde‐furfuryl alcohol (MFFA) copolymer was prepared and impregnated into softwood Ficus hispida in combination with crosslinking agent and montmorillonite (MMT) under vacuum condition. Different crosslinkers namely n‐methylol acrylamide, (NMA), 2‐hydroxyethyl methacrylate (HEMA) and 1,3‐dimethylol‐4,5‐dihydroxyethyleneurea (DMDHEU) were used for evaluation of properties of the prepared composites. Nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FTIR) studies confirmed the formation of MFFA copolymer, NMA, and DMDHEU crosslinkers. X‐ray diffractometry (XRD) and FTIR studies were used to characterize the nanocomposites. The incorporation of MMT decreased the crystallinity of wood composites as revealed by XRD study. Maximum interaction was found in wood samples treated with MFFA/(NMA+HEMA+DMDHEU)/MMT as shown by FTIR study. The incorporation of MMT into the wood polymer composite was revealed by transmission electron microscopy study. Thermal stability and flammability were checked by thermogravimetric analyzer and limiting oxygen index instrument. Wood treated with MFFA, blended crosslinker and MMT exhibited higher dimensional stability, lower water uptake (%), enhanced chemical resistance, and better mechanical properties (flexural, tensile, and hardness). SEM study indicated the presence of polymer and MMT in the void spaces of wood. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers