Effect of functional monomer GMA on the physical–mechanical properties of coatings from poly(BA–MMA) latexes

Functional acrylic latexes based on the terpolymer of butyl acrylate (BA)–methyl methacrylate (MMA)–glycidyl methacrylate (GMA) were prepared with different amounts of GMA via semi-batch emulsion polymerization at 75 °C, using potassium persulfate as an initiator, sodium dodecylbenzene sulfonate as an emulsifier and sodium bicarbonate as a buffer. The latexes were characterized by laser light scattering, apparent viscosity, and proton magnetic resonance (¹H NMR) and Fourier transform infrared (FTIR) spectroscopies. Physical and mechanical properties of cured and uncured latex films were investigated. For uncured films, gel content, solvent resistance, flexibility, and adhesion of uncured films were improved using higher GMA in the feed, while the glass transition temperature (T _g), surface hydrophobicity, water resistance, tensile modulus and strength, and hardness were decreased. For cured films, higher T _g values, more gel content, improved water and solvent resistances, and enhanced hardness and adhesion, were obtained with increasing the GMA contents. Curing the latex films resulted in hydrophilic surfaces.     

细乳液法制备有机硅氧烷改性苯丙乳液

采用细乳液法制备γ-甲基丙烯酰氧基正丙基三甲氧基硅烷(MPS)改性苯丙乳液。研究了引发剂、pH值、MPS的用量等对乳胶膜凝胶含量、溶胀比及动态力学性能的影响。溶胀实验表明,乳胶粒子和乳胶膜凝胶含量及溶胀比主要受体系的pH值影响比较大。动态力学分析表明,在中性条件下使用过硫酸钾(KPS)引发剂得到的乳胶膜的储存模量要高于偶氮二异丁腈(AIBN)乳胶膜的储存模量;增加MPS的用量以及对乳胶膜进行酸化处理或热处理可以提高乳胶膜的储存模量。     

细乳液聚合法制备聚丙烯酸/聚硅氧烷复合乳液

以聚硅氧烷为助稳定剂，采用细孔液聚合法合成聚丙烯酸／聚硅氧烷复合乳液。研究了乳化剂类型、聚硅氧烷用量、孔液固含量和甲基丙烯酸用量对细乳液聚合动力学和所得乳液性能的影响。研究结果表明：以十二烷基硫酸钠为乳化剂，聚硅氧烷用量为丙烯酸酯单体质量的3．33％～10．0％时，可获得稳定的聚合过程，所得复合乳液的数均粒径在73nm～77nm之间，乳胶膜吸水率低至4．54％～6．75％。透射电镜照片表明，复合乳胶粒内部存在一定程度的微相分离。     

MMA-BA-GMA三元乳液共聚合

以（ＮＨ４）２Ｓ２Ｏ８－Ｎａ２ＳＯ３为发体系用滴加还原剂的半连续方法,进行甲基丙烯酸甲酯－丙烯酸丁酯－甲基丙烯酸缩水甘油酯三元乳液共聚合,系统研究了乳化剂,引发剂、聚合温度和官能团单体ＧＭＡ含量对聚合转化率、乳液粘度和乳液稳定性的影响。     

细乳液聚合法合成大粒径羧基丁苯胶乳

采用新型的细乳液聚合技术,制备大粒径羧基丁苯胶乳。考察了制备工艺参数对反应动力学及产物性能的影响。研究发现,乳化剂浓度对细乳液稳定性及聚合动力学有较大影响。以HS作为乳化剂,能得到稳定的细乳液体系。随HS浓度增大,聚合体系的反应速率增大,胶乳粒子粒径减小。助稳定剂十六烷(HD)的加入对细乳液体系影响较大。随着HD浓度增大,转化率先降低后升高,乳胶粒径先升高后降低;功能单体衣康酸(IA)的加入使细乳液体系更加稳定。     

细乳液聚合研究进展

在综合国内外文献的基础上，介绍了细乳液的制备方法、反应器类型、均化方式、聚合动力学等，论述了各种添加剂对聚合过程的影响，以及胶乳性能及参数的测定，并预测了其发展方向。     

Radiation-induced grafting of glycidyl methacrylate onto cotton fabric waste and its modification for anchoring hazardous wastes from their solutions

Ion exchange adsorbents based on cellulosic fabric wastes carrying sulfonic acid and amine functional groups were synthesized by radiation-induced graft polymerization of glycidyl methacrylate (GMA) with subsequent chemical modification of the epoxy groups of poly-GMA graft chains with sodium sulfite/H₂SO₄ and triethylamine, respectively. The conversion of epoxy groups into the functional groups was investigated. Factors affecting on grafting process such as radiation dose, monomer concentration and solvent were studied. The synthesized adsorbent and its applications in the removal of different types of hazardous pollutants e.g. acidic dye, cobalt, dichromate and phenols from aqueous solution were also studied.     

Damping properties of epoxy-based composite embedded with sol–gel-derived Pb(Zr<Subscript>0.53</Subscript>Ti<Subscript>0.47</Subscript>)O<Subscript>3</Subscript> thin film annealed at different temperatures

Pb(Zr_0.53Ti_0.47)O₃ (PZT) thin films were prepared on Pt/Ti/SiO₂/Si substrate by sol–gel method. The effect of annealing temperature on microstructure, ferroelectric and dielectric properties of PZT films was investigated. When the films were annealed at 550–850 °C, the single-phase PZT films were obtained. PZT films annealed at 650–750 °C had better dielectric and ferroelectric properties. The sandwich composites with epoxy resin/PZT film with substrate/epoxy resin were prepared. The annealing temperature of PZT films influenced their damping properties, and the epoxy-based composites embedded with PZT film annealed at 700 °C had the largest damping loss factor of 0.923.     

用液态含环氧基丙烯酸酯低聚物改性环氧树脂

采用溶液聚合法合成了以丙烯酸丁酯为主链的液态含环氧基丙烯酸酯低聚物,并用其对环氧树脂进行增韧改性.讨论甲基丙烯酸环氧丙酯以及低聚物用量对改性环氧树脂力学性能的影响,并研究了改性环氧树脂的微观形态和耐热性能.结果表明:当低聚物用量为10%(质量分数),丙烯酸丁酯和甲基丙烯酸环氧丙酯的质量比为80∶20时,改性环氧树脂的拉伸强度和冲击强度比纯环氧树脂提高6.7%和219.1%,同时体系的耐热性能基本不下降;改性环氧树脂呈两相结构,随低聚物用量增加橡胶粒子粒径尺寸增大;且Tg先升高后降低.     

Adhesion of PE modified by capacitively coupled radio frequency plasma-induced graft polymerization of glycidyl methacrylate

A graft polymerization of glycidyl methacrylate (GMA) on the pretreated polyethylene (PE) sheet samples by oxygen capacitively coupled radio frequency (RF) plasma was carried out to improve the adhesive properties of PE. The PE samples were treated with a RF power of 200 W for a treatment time of 40 s and then exposed to an oxygen atmosphere for a saturation time of 10 min. The grafting of the plasma pretreated PE performed in an aqueous GMA solution with the monomer concentration from 20 vol.% to 100 vol.% at a temperature from 20°C to 90°C for a reaction period up to 50 h. The optimum wettability of the graft polymerized PE surface with the concentration of 40 vol.% at the temperature of 70°C and for the time of 24 h was obtained as the static contact angle decreased from 104.2° for the original PE to 67.6° for the graft polymerized. After the graft polymerization, a strong absorption peak of C-O bonding was shown at 1050 cm⁻¹ in Fourier transform infrared spectrum, indicating an introduction of epoxy groups on the graft polymerized surface. Correspondingly, the surface roughness (Ra) increased from 0.137 μm for the original PE to 1.660 μm for the graft polymerized. The maximal lap adhesive strength of the graft polymerized PE samples lapped using a mixture of epoxy resin and curing agent was achieved to about 160 N·cm⁻². The fractured surfaces by tearing of the PE sheet matrix were observed on the tensioned PE samples due to the higher adhesive strength than that of the PE matrix.     

Adhesion of PE modified by capacitively coupled radio frequency plasma-induced graft polymerization of glycidyl methacrylate

A graft polymerization of glycidyl methacrylate (GMA) on the pretreated polyethylene (PE) sheet samples by oxygen capacitively coupled radio frequency (RF) plasma was carried out to improve the adhesive properties of PE. The PE samples were treated with a RF power of 200W for a treatment time of 40s and then exposed to an oxygen atmosphere for a saturation time of 10min. The grafting of the plasma pretreated PE performed in an aqueous GMA solution with the monomer concentration from 20vol.% to 100vol.% at a temperature from 20°C to 90°C for a reaction period up to 50h. The optimum wettability of the graft polymerized PE surface with the concentration of 40vol.% at the temperature of 70°C and for the time of 24h was obtained as the static contact angle decreased from 104.2° for the original PE to 67.6° for the graft polymerized. After the graft polymerization, a strong absorption peak of C―O bonding was shown at 1050cm⁻¹ in Fourier transform infrared spectrum, indicating an introduction of epoxy groups on the graft polymerized surface. Correspondingly, the surface roughness (Ra) increased from 0.137μm for the original PE to 1.660μm for the graft polymerized. The maximal lap adhesive strength of the graft polymerized PE samples lapped using a mixture of epoxy resin and curing agent was achieved to about 160N·cm⁻². The fractured surfaces by tearing of the PE sheet matrix were observed on the tensioned PE samples due to the higher adhesive strength than that of the PE matrix.     

缩聚物/加聚物复合胶乳的制备 Ⅰ.环氧树脂/丙烯酸树脂乳液接枝聚合反应

用乳液接枝聚合方法制备环氧树脂／丙烯酸树脂的复合胶乳水分散体系，考察了不同引发剂用量、乳化剂用量、单体浓度对复合胶乳粒径、接枝率、分子量的影响，并对这类复合胶乳体系的接枝机理进行了探讨。实验结果表明，引发剂浓度增大，粒径增大，分子量减小，接枝率增大；乳化剂浓度增大，分子量和接枝率变化不大，粒径则有下降趋势；环氧树脂浓度增大，粒径倾向于增大，分子量和接枝率则显著降低。说明缩聚物／加聚物接枝乳液聚合与一般乳液聚合规律有所不同。     

含氟丙烯酸酯核壳乳液的合成与性能

采用三阶段种子半连续乳液聚合,制得了以BA(丙烯酸丁酯)-MMA(甲基丙烯酸甲酯)共聚物为核,BA-MMA-TFEA(甲基丙烯酸三氟乙酯)共聚物为壳的核壳型含氟丙烯酸酯乳液.对乳液聚合过程中单体转化率的变化,特别是乳胶粒子的增长及分布的演变进行了测试和分析,证实了乳胶粒子核壳结构的形成.乳液聚合物膜的性能测试结果表明,与相同含氟单体用量的常规孔液相比,含氟聚合物富集于壳层的核壳形态有利于含氟结构单元在聚合物膜表面的分布,使用少量的含氟单体即可显著降低聚合物膜的表面能,提高其耐水性.     

微滴乳液聚合制备纳米SiO2/聚丙烯酸酯复合材料

在硅溶胶中加入八甲基环四硅氧烷(D4)和偶联剂γ-(2,3-环氧丙氧) 丙基三甲氧基硅烷(KH560),以十二烷基苯磺酸(DBSA)催化D4的开环聚合,借助超声强化聚二甲基硅氧烷(PDMS)和偶联剂对硅溶胶的表面改性。将改性硅溶胶及其混合物分散在甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)的混合单体中,实施微滴乳液聚合,制备SiO₂/聚丙烯酸酯纳米复合材料。硅溶胶改性阶段的催化剂中和后成为后续微滴乳液聚合的乳化剂,而伴生的PDMS成为有效抑制单体珠滴Ostwald 熟化的超疏水剂。采用FTIR、TGA、TEM、马尔文纳米粒度仪、水接触角等测试方法对改性纳米粒、复合胶乳和胶乳薄膜进行表征。结果表明,PDMS和偶联剂在SiO₂表面形成了共价键合和包覆,且伴生的PDMS改善了复合胶乳薄膜的表面疏水性,复合粒子是聚合物基体为壳、SiO₂纳米颗粒呈海岛分散的 (多)核-壳结构形态,SiO₂占单体质量分数为3%时,平均粒径约98 nm。     

不同偶联剂对介孔分子筛MCM-41的表面修饰及对MCM-41/环氧树脂性能的影响

使用2种硅烷偶联剂(KH550和KH792)对介孔分子筛MCM-41进行表面改性,采取氮气吸附-脱附、FTIR和TGA等进行表征,并采用原位聚合法制备了MCM-41/环氧树脂复合材料,研究了偶联剂种类和MCM-41用量等对复合材料固化过程及性能的影响。结果表明:硅烷偶联剂可与MCM-41表面的硅羟基反应,在分子筛内外表面接枝上功能化基团。经表面修饰的MCM-41比表面积下降为原来的1/5,KH550在MCM-41表面接枝率仅为KH792的一半。KH550与MCM-41外表面反应得更充分,KH792对MCM-41孔道内壁的修饰效果更强。固化动力学结果表明:KH792的功能化基团有伯胺和仲胺,与环氧树脂具有更高的反应活性,但不利于环氧大分子进入孔道,仅以球形粒子的形式添加在环氧树脂中;KH550表面修饰的MCM-41可使环氧大分子进入孔道内形成互穿结构。KH550表面修饰体系更多体现出MCM-41多孔的特征,形成了有机-无机互穿结构的复合体系,大幅度提高了储能模量和玻璃化转变温度。KH792表面修饰体系则呈常规球形纳米粒子的特征,其储能模量和玻璃化转变温度较纯环氧树脂有所提高但幅度不大。     

多臂碳纳米管/聚丙烯酸酯复合乳液的制备

采用化学氧化法处理的多臂碳纳米管,经红外光谱分析表明其表面带有羟基官能团.TEM照片则显示碳管在乳化剂SDS水溶液中分散性良好.采用直接共混和接枝聚合法分别制备了多臂碳纳米管/聚丙烯酸酯复合乳液,静置一月后的粒径分析结果表明接枝聚合制备的乳液贮存稳定性优于直接共混法.对其成膜性的研究表明最低成膜温度随碳管用量的增加变化不大.     

室温界面自交联对PS/PBA乳胶IPN力学和阻尼性能的影响

利用种子乳液聚合以及双丙酮丙烯酰胺(DAAM)与己二酰肼和甲基丙烯酸缩水甘油醚(GMA)与乙二胺的交联反应合成了系列聚苯乙烯/聚丙烯酸正丁酯(PS/PBA)室温界面自交联乳胶互穿聚合物网络(IPN)。拉伸实验结果表明,自交联可提高LIPN的拉伸强度,减少永久形变,并且拉伸强度随DAAM和GMA用量的增加而增加。动态力学谱结果表明,自交联使LIPN的玻璃化温度升高以及阻尼性能下降,并且随DAAM用量的增加,阻尼性能降低;随GMA用量的增加,阻尼性能先增后降。GMA为5%时,LIPN具有较高的拉伸强度和阻尼性能。     

Encapsulation of magnetic nanoparticles with polystyrene via emulsifier-free miniemulsion polymerization

Magnetite nanoparticles (Fe₃O₄), with an average size of about 10 nm, were encapsulated with polystyrene using a new method based on emulsifier-free miniemulsion polymerization in the presence of 2, 2′ azobis (2-amidinopropane) dihydrochloride (V-50) as a cationic ionizable water-soluble initiator and hexadecane as a hydrophobe. Transmission electron microscopy (TEM) proved the presence of magnetite in polymer particles which appeared to be monodisperse in size, approximately 100-300 nm in diameter, through TEM and scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) measurement was used to determine the percentage of magnetite in the products. The results of emulsifier-free miniemulsion polymerization were compared with those of conventional emulsifier-free emulsion polymerization using (V-50) as the initiator in both cases.     

Influence of addition of silica particles on reaction-induced phase separation and properties of epoxy/PEI blends

Polyether imides (PEI)/silica nanocomposites, prepared by sol–gel process, were used to modify the epoxy resin (ER), and the effect of silica particles on reaction-induced phase separation and mechanical properties of these systems were investigated. SEM images of the fracture surface of ER/PEI/silica composites showed an interesting morphology transformation with the increase of silica particle content. SEM–EDX results indicated that silica particles once formed in the PEI gradually migrated and concentrated in epoxy-rich region during the phase separation because of the better affinity between silica particles and epoxy resin. FTIR measurement and rheological test confirmed that the silica particles make the polymerization reaction of epoxy faster and the dynamic DSC results demonstrated that the activation energy of these systems decreased with the increase of the silica particles. Mechanical measurements approved that the introducing of PEI/silica nanocomposites into the epoxy could lead to great improvement of the impact strength and storage module.     

Functionalized polymer networks: synthesis of microporous polymers by frontal polymerization

A series of glycidyl methacrylate (GMA)-ethylene dimethacrylate (EGDM) copolymers of varying compositions were synthesized by free-radically triggered thermal frontal polymerization (FP) as well as by suspension polymerization (SP) using azobisisobutyronitrile [AIBN] as initiator. The two sets of copolymers were characterized by IR spectroscopy and mercury intrusion porosimetry, for determination of epoxy number and specific surface area. Frontal polymerization was more efficient, yielding greater conversions at much shorter reaction times. The self-propagating frontal polymerization also generates microporous material with narrow pore size distribution. It yields higher internal pore volume and surface area than suspension polymerization, surface morphologies are, however, inferior.