Modification of Natural Rubber Latex by Graft Copolymerization of 2-Ethylhexyl Acrylate and Methacrylic Acid

Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.

Synthesis and properties of acrylate latex modified by vinyl alkoxy siloxane

Acrylate latex modified by vinyl triisopropoxy silane (C-1706) was synthesized by seeded emulsion polymerization with anionic emulsifier sodium dodecyl sulphonate(SDS) and nonionic emulsifier OP-10 as the multiple emulsifiers at (78±2) ℃. The effects of different factors, such as the emulsifier, C-1706 monomer and its feeding manner on the properties of acrylate latex modified by C-1706 were investigated. The particle size distribution and the structure, the configuration, the weather durability and stain resistance of copolymer latex were characterized by particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope(TEM), scanning electron microscope(SEM) and ultraviolet aging instrument respectively. The results show that SDS to OP-10 as multiple emulsifiers can lead to coordinated efficiency, the optimal emulsifier dosage is 2.4%?3.2%(mass fraction), and the mass ratio of SDS to OP-10 is 1?1? 1?2. The seeded emulsion polymerization can effectively introduce a organic-siloxane bonding in a macromolecule inter polymer, and the obtained acrylate latex modified by organic-siloxane possesses narrow distribution of particle size with mean diameter of 51.8?76.6 nm and has the excellent properties in weather durability and stain-resistance especially.

Effects of plasma treatment time on modification of acrylic denture material

Objective：To study the relationship between plasma treatment time acrylic resin denture material in the size of 2 mm × 10 mm × 10 mm. and efficacy. Methods：Test specimens were prepared from an Plasma treatment was carried out on the surface of Polymethyl methacrylate（PMMA） at different time. XPS studies, IR spectra studies and measurement of wetting angle were performed. Results： XPS showed the peak corresponding to C-O getting higher as the treatment proceeded, however at 120 seconds, the peak did not increase any longer and partly crossed with the peak at the duration of 60 seconds. IR spectra showed the wave corresponding to C-H was reduced as O2-plasma treatment proceeded, and then changed little, Wetting angle initially decreased dramatically, however, as the reaction proceeded, wetting angle increased slightly. Conclusion：Equilibrium was reached for introducing oxygen-containing groups and changing of C-H. As the treatment proceeded, wetting angle increased slightly.

Preparation of Styrene-acrylate Latex Used in Ultralow VOC Building Internal Wall Coating

Styrene-acrylate latex with high glass transition temperature （T）, low minimum film forming temperature（MFT） and good stability was prepared via core-shell emulsion polymerization. With semicontinuous process, high conversion rate of monomer and low gel rate were achieved. The weight ratio of core monomer to shell monomer was approximately 1.35. It is found that many factors such as emulsifiers, initiators, reaction temperature, pH value and polymerization technology have influences on the permormance of styrene-acrylate latex. The prepared latex was characterized by TEM and FTIR. The obtained latex with T of 20.57 ℃, MFT or5.0 ℃, and good stability, had good stability of film forming.

PREPARATION AND PROPERTIES OF SILICONE-ACRYLATE COPOLYMER LATEX

Silicone-acrylate copolymer latex was prepared through three different polymerization processes, i.e., the batch process, preemulsified monomer addition and the monomer addition process. The results revealed that the monomer addition process is a desirable approach to produce narrow particle size distribution latex with higher polymerization conversion and less amount of coagulum. The effect of silicone content on the glossiness and water absorption of latex film was investigated and the results showed that the glossiness of latex film is improved up to a silicone content of 10% of total monomers, but becomes impaired thereafter, whereas water absorption is reduced accordingly.

Microstructure and Mechanical Properties of Poly (Vinyl Chloride) Modified by Silica Fume /Acrylic Core-Shell Impact Modifier Blends

This research explored replacing acrylic core-shell impact modifier （AIM） by silica fume to toughen PVC. 100%, 75%, 50% and 25% of AIM （8 phr） were substituted by silica fume in PVC respectively, and then processed by dry blending and twin-screw extrusion. Severe silica fume agglomeration was observed by scanning electron microscope （SEM） in the PVC matrix when 8 phr pure silica fume was used and processed by screw speed of 20 rpm. Its tensile strength was thereby reduced by 38% comparing to unmodified PVC. The silica fume was successfully dispersed while the screw speed was slowed down to 10 rpm to give a stronger screw torque and a longer melt residential time in the extruder. The tensile strength was ’recovered’ to a level comparable to unmodified PVC. Impact test were performed on all formulations extruded at 10 rpm screw speed and synergetic toughening effect was found with 50% substitution and it had the impact strength that was comparable to 8 phr pure AIM toughened PVC.

SEED SEMICONTINUOUS EMULSION MULTI-COPOLYMERIZATION OF (METH) ACRYLATES WITH HIGH-SOLID CONTENT: EFFECT OF THE OPERATION CONDITIONS

The seeded semicontinuous emulsion multi-copolymerization of butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), methyl methacrylate (MMA), 2-hydroxyl propyl acrylate (HOPA) and acrylic acid (AA) was used to prepare the acrylic latexes with high-solid content. The effects of monomer emulsion feed rates (R(a)) and (R/E)(E) values, the ratio of emulsifier amount between the initial charge (R) and the addition monomer emulsion (E), on the polymerization reaction features, the viscosities, surface tensions,particle sizes and particle sizes distributions of latexes, T-g and the insoluble fractions of films, the 180 degrees peel strength, tack and holding power of pressure-sensitive adhesive (PSA) tapes, prepared from the latexes, were studied. Experimental study shows that the grafting and crosslinking fraction in the PSA tapes must be controlled within a suitable range to keep the balance of the 180 degrees peel strength, tack and holding power.

STUDY ON THE FORMATION MECHANISM OF MONODISPERSE PARTICLES IN THE EMULSIFIER-FREE EMULSION POLYMEAIZATION OF METHYL METHACRYLATE AND BUTYL ACRYLATE

The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formationmechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be thecoagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with highsurface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formedby the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization systemand then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leadsto the aggregation of the growing particles and the formation of larger latex pedicles therefrom. Aner the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards auniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D_(43)/D_(10)) in the first Stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation ofthe monodisperse particles.

Determination of Some Physical and Mechanical Properties of the Wood-Based Panels Modified by Acrylic Textile Fiber

In this research, a series of wood-based panels were produced by using wood chips [beech (Fagus Sylvatica L.) and Scotch pine (Pinus sylvestris L.)] as wastes of wood-working workshops and acrylic fibers as wastes of textiles factory. Four kinds of different panels (Eltapan I, II, III and IV) were obtained by mixing these components in different composition (0%, 25% and 50%). Some physical and mechanical properties of the samples taken from these panels were determined in accordance with ASTM D1037-12 and ASTM-C 1113. The values were compared to properties of industrially produced chipboard. As a result, the textile fibers used as additive material reduced density, thermal conductivity and bending resistance of wood panel and increased dimensional stability of wood panel.

HIGH SOLIDS-CONTENT NANOSIZE POLYMER LATEXES MADE BY A MODIFIED EMULSION COPOLYMERIZATION

Polymer nanoparticles were prepared in the methyl methacrylate (MMA)/buty lmethacrylate (BA) emulsion copolymerization process by a modified microemulsion copolymerization method. 2-Hydroxyethyl methacrylate(HEMA), acrylate (AA) and methyl acrylate (MAA) were used as reactive cosurfactants. With this process high polymer: surfactant weight ratios (40:1 or greater),relatively concentrated (~30wt. %) latexes and small (~60nm) particle diameters were obtained.Properties of the latexes were characterized by TEM, DSC, dynamic light scattering, and IR spectroscopy.

极性分子的结构异同性对接枝改性交联聚乙烯材料直流电性能的影响

为改善高压直流电缆运行过程中绝缘层材料的电导率对温度与电场强度敏感性所导致的电场反转问题,以及直流高压长时间作用下的空间电荷积聚现象,该文采用极性基团接枝改性的方式提升交联聚乙烯(XLPE)材料的直流电性能。由于接枝单体一般为沸点较低的极性小分子化合物,为避免材料在接枝过程中单体的气化损失,首先通过平行双螺杆挤出机配合低温高压计量泵装置实现熔融接枝反应。将丙烯酸酯类小分子化合物(丙烯酸甲酯(MA)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA))分别预先接枝到低密度聚乙烯(LDPE)大分子链上制备接枝材料,通过红外光谱测试分析得出接枝单体皆成功接枝到LDPE大分子链上,熔融指数与凝胶含量测定表明材料的流变性能并未发生显著改变,X射线衍射测试与扫描电子显微镜观测发现接枝改性材料的结晶特性保持与基础树脂相似。进一步对三种接枝母料按一定比例稀释并完成交联过程,通过变温直流电导测试发现三种接枝改性材料的电导率-温度敏感性均出现不同程度的下降,综合高温空间电荷测试可以得出,接枝MA的XLPE材料电导率-温度敏感性下降幅度最大、空间电荷分布特性优异;结合第一性原理仿真计算可以进一步得到,三种接枝单体改性XLPE模型的陷阱能级较为一致,其直流电性能的改善效果与接枝单体的静电势分布存在显著关联。

水性环氧乳液/海泡石复合改性苯丙乳液涂层粘结性能研究

采用物理共混法制备水性环氧乳液/海泡石复合改性苯丙乳液涂层,探讨了苯丙-水性环氧乳液配比,三乙醇胺、填料及乳化沥青掺量对涂层粘结强度的影响,同时考察了复合涂层的抗渗性和耐高低温性。结果表明,当苯丙乳液与水性环氧乳液的有效质量比为1∶2,三乙醇胺、海泡石和乳化沥青掺量分别为2%、3%、5%时,复合涂层粘结强度为3.54MPa,与钢板间具有较好的相容性,且不透水性和耐高低温性优良。

氟硅树脂共混复配对透明疏水涂层性能的影响

[目的]采用低表面能且耐候性较好的氟硅树脂(FSi)作为基底材料,与光泽度较好的双酚A型环氧丙烯酸树脂(EPA)或者环氧树脂(E51)共混,制备出适用于玻璃基底的透过率高、力学性能好的疏水涂层,探讨不同树脂配比对涂层性能的影响。[方法]通过扫描电镜、接触角测量仪、紫外可见分光光度计、附着力拉拔测试仪和铅笔硬度计,对涂层进行性能测试及微观形貌表征。[结果]随着FSi含量的增大,涂层性能会受到一定影响。FSi与E51复配的效果优于FSi与EPA复配。当FSi与E51的质量比为1∶1时,涂层的附着力可达6.16 MPa,铅笔硬度3H,水接触角124.98°,透过率在可见光波长范围内可达70%以上,吸水率则只有3%~6%,磨损后的质量损失最小且水接触角仍维持在105°左右。[结论]以氟硅树脂为基底复配环氧树脂作为成膜物,可以提高透明疏水涂层的性能,具有较好的应用前景。

氯醚-丙烯酸酯树脂二级分散体的制备及性能研究

以氯醚树脂为改性树脂,通过溶液聚合方法合成了氯醚-丙烯酸酯树脂二级分散体。然后按照m(氯醚-丙烯酸酯树脂二级分散体)∶m(氨基树脂固化剂)=5∶1的比例制备了双组分水性涂料。探究了溶剂含量、反应温度、中和剂种类和中和度、羟基含量对二级分散体的影响,测试表征了改性树脂的分子结构和分散体的粒径,研究了氯醚-丙烯酸酯树脂水分散体及其双组分烘烤涂料的性能。研究结果表明:氯醚树脂改性丙烯酸树脂溶液的优化制备条件是,反应温度为90~100℃,反应时间为5 h,溶剂为丙二醇丁醚及乙二醇丁醚(含量为水分散体总质量的11%左右),引发剂为BPO,HPA作为交联功能单体;在最佳的合成条件下制备了氯醚树脂改性的丙烯酸酯水分散体,改性水分散体外观为乳白色泛蓝光,固含率约为48%,黏度为3 015 mPa·s,平均粒径为185 nm左右,(50±2)℃/7 d的条件下贮存性稳定;与市售的羟基丙烯酸水分散体相比,本文制备的氯醚-丙烯酸酯树脂分散体的漆膜性能更优异。

硅烷改性环氧苯丙乳液的合成及性能研究

利用硅烷偶联剂KH-560和环氧E-51,通过种子乳液聚合的方法,对传统苯丙乳液进行有机硅与环氧树脂改性,制备了新型的硅烷改性环氧苯丙乳液,并探索了工艺条件对乳液性能和涂膜性能的影响。结果表明:乳化剂用量为6.5%、软硬单体比例为1.6∶1、环氧树脂E-51用量为5%、硅烷偶联剂KH-560用量为10%时,合成出的新型硅烷改性环氧苯丙乳液具有较高的固含量与转化率,分别为43.75%、87.5%,具有较低的凝胶率和吸水率,分别为0.98%、71.43%,乳液外观呈乳白带明显蓝相,乳液稳定性良好。初步研究了硅烷偶联剂KH-560和环氧树脂E-51对苯丙乳液的改性机理。

接枝型天然橡胶基吸水膨胀橡胶的制备及吸水膨胀性能

以脱蛋白天然橡胶(DPNR)胶乳作为改性橡胶的基材,在氧化还原引发体系作用下,基于橡胶大分子链中烯丙基与乙烯基单体的自由基乳液接枝共聚反应实现丙烯酸(AA)在DPNR链上的接枝共聚,从而制备了一种亲水性AA接枝改性DPNR共聚物(DPNR-g-PAA),通过傅里叶变换红外光谱、核磁共振氢谱、扫描电子显微镜和称重法表征了DPNR-g-PAA的分子结构、断面形貌和吸水膨胀性能。结果表明,DPNR-g-PAA作为吸水膨胀橡胶,其薄膜吸水率可达85.06%,DPNR的表面透湿性显著提高;与传统物理共混或溶液接枝共聚反应制备吸水膨胀橡胶工艺相比,由自由基乳液接枝共聚制得的DPNR-g-PAA具有一定的优势。

低吸水率水性隔热保温涂料的制备及性能

[目的]随着水性隔热保温涂料在工业涂装领域的广泛应用,其吸水率较高引发的涂层隔热性能下降问题亟需解决。[方法]以苯丙乳液作为主要成膜物,以偶联剂表面改性的中空玻璃微珠作为隔热填料,以涂层的导热系数和吸水率作为主要性能指标,制备了一种低吸水率的水性隔热保温涂料。通过傅里叶变换红外光谱仪(FT-IR)对不同偶联剂处理的中空玻璃微珠进行了表征,通过扫描电子显微镜(SEM)考察了涂层的微观结构和形貌,测试了浸水前后涂层的导热系数、力学性能和粘结强度。[结果]铝酸酯偶联剂的改性效果比硅烷偶联剂好。当铝酸酯偶联剂改性中空玻璃微珠添加量为25%(质量分数)时,涂层的综合性能最优,24 h吸水率为9.32%,浸水168 h后的导热系数为0.1228 W/(m·K),拉伸强度为2.45 MPa,断裂伸长率为28.37%,拉拔法粘结强度为2.32 MPa。[结论]采用合适的偶联剂对中空玻璃微珠进行表面改性可有效改善隔热保温涂料体系中有机-无机界面的相容性,从而降低其吸水率,增强其力学性能。

没食子酸酯/改性苯丙防腐转锈乳胶的制备及性能研究

为提升乳胶的相容性及防腐性能,以没食子酸(GA)与乙二醇丁醚(BE)为原料合成没食子酸酯(GA-BE)作为转锈剂,采用预乳化-半连续种子乳液聚合法合成有机硅改性苯丙乳胶(SALSi)作为成膜物,制备没食子酸酯/改性苯丙防腐转锈乳胶(GA-BE/SAL-Si)。采用稳定性分析仪测试乳胶的稳定性,采用中性盐雾测试、盐水浸泡测试和电化学分析探究其防腐性,采用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)和能谱(EDS)分析探讨锈蚀转化前后基体表面形貌及转锈机理。结果表明:制备的GA-BE/SAL-Si具有较好的稳定性;在3.5%NaCl溶液浸泡下,覆涂GA-BE/SAL-Si试样的自腐蚀电流密度相较于锈蚀钢降低了2个数量级,相较于覆涂GA/SAL-Si试样降低了1个数量级,当GA-BE添加量为2.0%时,防腐效果最佳;经过168 h的中性盐雾测试及盐水测试后,对比GA/SAL-Si及GA-BE/SAL涂膜,GA-BE/SAL-Si涂膜表现出更佳的防腐性能;GA-BE结构中的酚羟基可与锈蚀产物发生螯合反应,生成新的Fe—O—C配位键,达到转锈的作用,配合SAL-Si,使涂膜具有良好的防腐和转锈性能。

无氟拒水剂成膜表面形貌及其拒水性能研究

为考察无氟拒水乳液的成膜形貌对拒水性能的影响,将细乳液聚合得到的聚丙烯酸十八酯-丙烯酸丁酯[P(SA-BA)]胶乳分别与四种粒径的聚丙烯酸十八酯/γ-甲基丙烯酰氧基丙基三甲氧基硅烷[P(SA-A174)]胶乳按比例共混后,采用涂覆和浸轧两种工艺整理玻璃片和面料,以SEM和AFM考察了整理得到的两种基材表面形貌,并考察了对拒水性的影响。结果表明:P(SA-BA)和P(SA-A174)分别具有成膜和保型能力,二者复合而成的胶乳可形成具有纳米“指突”形貌的拒水膜,使整理基材的拒水性能明显提升。随着P (SA-A174)粒径的增大和用量的提高,涂层整理膜的“指突”高度和面密度同时增加,而浸轧整理时,仅“指突”高度增加,面密度和拒水性能变化不大。之后,通过降低浸轧液pH值,胶乳对织物亲和力以及吸附效率增强,浸轧整理织物拒水性能明显提升。

非离子改性水性醇酸树脂-丙烯酸树脂杂化体的制备及性能

首先用新戊二醇、间苯二甲酸–5–磺酸钠合成磺酸盐聚酯中间体,然后将其和非离子亲水单体(N120)、季戊四醇、豆油酸、邻苯二甲酸酐进行聚酯化反应合成水性醇酸树脂。再将水性醇酸树脂用丙烯酸酯单体进行自由基接枝聚合得到非离子改性水性醇酸树脂–丙烯酸树脂杂化体。用傅里叶变换红外光谱(FT-IR)、热重分析(TGA)对其结构进行了表征;探究了非离子亲水单体的用量、醇酸树脂分子量、油度、酸值对杂化体成膜性能和贮存稳定性的影响。结果显示:非离子亲水单体占水性醇酸树脂4%~8%(质量分数)、醇酸树脂分子量为2 200~2 500,油度为50%、杂化体酸值为10 mg KOH/g时制得的杂化体涂膜耐水性、干性、光泽及贮存稳定性最好。