CATALYTIC COPOLYMERIZATION OF STYRENE AND ETHYLENE BY NEUTRAL NICKEL(Ⅱ) COMPLEXES IN EMULSION

Emulsion copolymerization of styrene and ethylene catalyzed by a series of neutral nickel(Ⅱ) complexes was carried out in an aqueous system to give high-molecular-weight copolymers.The copolymers and emulsions were characterized by an array of techniques including NMR,GPC,TEM,WAXD and DSC.The results indicate that the copolymers obtained are mostly block copolymers of polyethylene with random insertion of styrene units,and their M_W is in the range of 10~5-10~6.By enhancing the electron withdrawing of the s...

Study on N-Phenylmaleimide/Styrene /Acrylonitrile Copolymer Prepared by Emulsion Polymerization

The emulsion polymerization of N-phenylmaleimide, Styrene and acrylonitrile was studied. The thermal property of this copolymer was measures by dynamic thermomechanical analysis(DMA). The mechanical properties, such as tensile strength, hardness and fie-cural Strength were StUdied experimentally. The results indicated that not only the monomer component but also the polymerization technologies have effect on the properties of the copolymer. The optimum monomer content and suitable polymerization method were obtained.

Preparation of sulphonate-containing core/shell latex particles via seeded emulsion copolymerization

In this study, P（St-MAA） seed latex particles were first prepared via soap-free emulsion polymerization of styrene （St） and methacrylic acid （MAA）, then the seed particles were allowed to swell with St at room temperature, and the P（St-MAA）/P（St- NaSS） core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate （NaSS） using AIBN as initiator in the presence of N,N^-methylenebisacrylamide （BAA, water-soluble crosslinker）. Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%, the narrow dispersed P（St-MAA） seed particles with the diameter of 150 nm and the P（St-MAA）/P（St-NaSS） core/shell latexes with the particle size of about 200 nm were synthesized. When the 25/75 mole ratio of NaSS/（St ＋ MAA） and 2 tool% of BAA were used in the seeded emulsion polymerization, the resulted P（St-MAA）/P（St-NaSS） latex product showed a low weight loss after water extraction, and the NaSS unit content in the whole particle and in the shell reached 11.7 mol% and 34.6 mol%, resoectivelv.

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.

Thermal Emulsion Polymerization without any Conventional Initiators and Emulsifiers

Stable poly（styrene-co-sodium styrene sulfonate） （P（St-NaSS） nanoparticles with broader size distribution were synthesized by thermal emulsion polymerization without any conventional initiators and emulsifiers. The obtained polymer nanoparticles have higher potential, and the particle sizes have broad distribution. The stability of polymer particles originated from the addition of small amounts of ionic comonomer, NaSS, which can act as an emulsifier in somewhat. The monomer conversion could reach up to about 28 wt% in 48 h, and did not increase by further polymerization when higher polymerization temperature （120℃） was employed. This polymerization system may be give some further understand for mechanism of emulsion polymerization.

BEHAVIOUR OF INHIBITORS IN EMULSION POLYMERIZATION(Ⅰ)CaseⅡKinetics

The behaviour of water soluble and monomer soluble inhibitors in emulsion polymerization of monomersfollowing Case Ⅱ kinetics(e.g.styrene)has been investigated.Experimental studies reveal that inhibitors canhave an appreciable effect on both polymer particle nucleation and growth.A mathematical model showingthese effects has been developed and simulation studies have been done.The simulation results imply that theconsequences of these effects of monomer soluble inhibitors for industrial emulsion polymerization may be quiteserious.

Synthesis and Characterization of Poly(styrene-co-acrylamide) Polymers Prior to Electrospinning

Electrospun nanofibers present a new and rapidly growing research area due to their pronounced micro and nano characteristics associated with high surface area to volume ratio. Poly(styrene-co-acrylamide) and polystyrene polymers were synthesized by boiling temperature soap free emulsion polymerization in aqueous medium with potassium peroxosulphate as the initiator. The resulting polymers were dissolved in dimethylformamide and teterahydrofuran (DMF: THF) (4:1) to form polymer solutions that were electrospun into fiber mats with diameters ranging from 1.84 - 2.53 μm and 5.01 μm, respectively. The fibers were characterized by Fourier transform infrared spectroscopy (FTIR) equipped with universal ATR sampling accessory (4000 - 400 cm-1). The morphology and size were examined by a scanning electron miscroscope (SEM) and the thermal properties by thermogravimetric analysis (TGA). The FTIR spectra of the poly(styrene-co-acrylamide) revealed the presence of acrylamide on the polystyrene chain. Thus, surface modification of polystyrene with acrylamide is possible in a single step polymerization reaction prior to electrospinning.

A Comparative Study on Emulsion Polymerization Processes of Styrene Initiated by Water-soluble and Oil-soluble Initiators

The solubility of initiator determines its distribution and the roles played in emulsion polymerization as well as the final products, but this is still lack of systematic investigation. The present work focuses on this issue by comparing the kinetic behaviors and product properties of styrene emulsion polymerization initiated by 2,2-azoisobutyronitrile(AIBN) and potassium persulphate(KPS).Compared to KPS-initiated emulsion polymerization, the AIBN-initiated polymerization was found to be insensitive to the type of emulsifier, and have high polymerization rate as well as narrow molecular weight distribution and particle size distribution. This result indicates the effective free radicals are generated in micelles or colloids, which could decrease the proportion of homogeneous nucleation and make the process and product more controllable. As a consequence, there is a linear relationship between molecular weight of product and AIBN concentration in lg-lg coordinate. It provided a reference for the preparation of latexes with specified molecular weight and supported the possibility of the coexistence of multiple free radicals in one micelle or colloid when using oil-soluble initiator.

PREPARATION OF SULPHONATE-CONTAINING POLYMER PARTICLES VIA SEMI-CONTINUOUS EMULSION COPOLYMERIZAION OF STYRENE AND SODIUM STYRENE SULPHONATE

Submicron-sized P（St-NaSS） latexes were prepared via a semi-continuous emulsion copolymerization of styrene （St） and sodium styrene sulphonate （NaSS） in the presence of anionic surfactant, in which NaSS aqueous solution and St were separately dropwise charged into the polymerization system at the same time. The hydrodynamic diameter of the latex particles was measured by dynamic light scattering （DSL） method, and the NaSS unit content of the purified copolymer by water extraction was calculated based on the elementary analysis. Results showed that the copolymerization could be performed smoothly with the monomer conversion more than 96% in the absence of crosslinker, and PNaSS homopolymer could be removed from the latex product by water extraction for 28 h. The weight loss in the water extraction tended to decrease and the NaSS unit content of the purified copolymer tended to increase with the increase of monomer feeding time, and both of them increased with the increase of NaSS/St mole ratio in the charge. The introduction of divinyl benzene （DVB） could decrease the weight loss in the water extraction and increase the NaSS unit content of the purified copolymer. When 25/75 mole ratio of NaSS/St and 11 mol% DVB of total NaSS and St were used in the recipe, and the monomer feeding time was 3 h in copolymerization, the NaSS unit content of the purified copolymer reached 7.31 mol%.

Reverse atom transfer radical polymerization of styrene in emulsion initiated by AIBN or V50

Reverse atom transfer radical polymerization of styrene was conducted in emulsion by using Cu(II)/2,2′- bipydine or Cu(II)/phen complexes, AIBN or V50 as the ini- tiator, Brij-98 or OP-10 as the surfactant. The results of GPC showed that both polymerization processes exhibit living characters when using AIBN as the initiator. However, when V50 was used, the monomer conversion was fairly low and the whole polymerization was not controlled well. The meas- urement of particle size and its distribution told us that the latex particles were mean and stable when using Brij-98 as the surfactant.

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。

水性饰面型防火涂料的制备及其耐火性能研究

[目的]配方对防火涂料的性能有很大影响。[方法]以苯丙乳液和硅溶胶作为基料,聚磷酸铵、季戊四醇和三聚氰胺作为阻燃体系,二氧化钛作为颜填料,六偏磷酸钠作为分散剂,磷酸三丁酯作为消泡剂,羧甲基纤维素作为增稠剂,研制了一种适用于钢结构的水性饰面型复合膨胀防火涂料。利用模拟大板燃烧试验考察了各组分的质量分数对涂料性能的影响,并采用扫描电镜(SEM)对防火涂层燃烧后的微观结构进行表征。[结果]最佳配方为:苯丙乳液20.0%,硅溶胶4.0%,聚磷酸铵27.0%,季戊四醇22.0%,三聚氰胺21.0%,颜填料4.0%,助剂2.0%。此时涂料的耐燃时间长达57 min,燃烧后形成的炭层致密。[结论]该涂料具有良好的防火阻燃效果。

我国丁苯橡胶的供需现状及发展分析

分析了我国丁苯橡胶(SBR)的供需现状及发展前景。2023年,我国SBR的生产能力为1887 kt/a,表观消费量为1554 kt,预计2028年的生产能力和表观消费量将分别达到2200 kt/a和1700 kt。未来我国SBR产能将过剩,市场竞争更加激烈,今后要慎重新建或者扩建新产能,建议在完善现有生产技术的基础上,加快新产品和新技术的研究与开发,不断提高产品质量,降低生产成本,满足国内需求的同时积极开拓国外市场。

长开放期EPI木材胶粘剂的制备与性能表征

通过特定的乳液聚合工艺,制备了一款苯丙乳液(SAEP2),并将其应用于木材胶粘剂。系统地考察了聚乙烯醇的聚合度和浓度、异氰酸酯固化剂用量以及钙粉用量对胶粘剂开放期及粘接强度的影响。研究结果表明:胶粘剂开放期会随着聚乙烯醇的聚合度和浓度、异氰酸酯固化剂用量、碳酸钙粉末用量的增大而缩短;当m(SAEP2)∶m(10%的BP17水溶液)∶m(钙粉)=1∶1∶1,且异氰酸酯固化剂用量为13%时,制备的SAEP2胶粘剂湿强度达标(可达5.4 MPa),而开放期长达150 min。

极端顶点法制备碳酸钙超疏水涂层

目前,超疏水涂层存在着制备成本高、工艺复杂和环境污染等问题,阻碍了其工程化应用进程。文章以CaCO_(3)晶须及其纳米粒子为填料,水性苯丙乳液为粘结剂,以及硬脂酸锌为疏水改性剂制备超疏水涂层。首先采用油酸对CaCO_(3)晶须及其纳米粒子进行表面改性,然后基于极端顶点设计将改性后的CaCO_(3)晶须、改性后的纳米CaCO_(3)、苯丙乳液和硬脂酸锌为混合分量进行混料实验,以涂层接触角为响应变量建立回归模型,分析混合分量对接触角的影响。结果表明:采用不同形貌的CaCO_(3)粉体复合苯丙乳液可制备出超疏水涂层,在纳米CaCO_(3)与硬脂酸锌混合分量较高,CaCO_(3)晶须混合分量较低以及苯丙乳液适中的区域,接触角可达153.5°。通过表面形貌分析,涂层的黏附性与其表面的孔洞有关,而较高的纳米CaCO_(3)混合分量可降低涂层表面粗糙度,促进其超疏水性能。

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。

水性苯丙吸波涂层的制备与性能研究

吸波涂料是一种能够吸收和衰减入射电磁波的功能涂料,而水性吸波涂料更具有环保健康的特点。选择炭黑和羰基铁粉作为复合吸波剂,加入水性苯丙乳液中制备成本较低的复合吸波涂层。首先测试了炭黑和羰基铁粉的电磁参数,并计算得出成分为12%炭黑和70%羰基铁粉,厚度为2mm时吸波性能最佳,反射损耗优于-5dB的有效吸收频宽达到9.9GHz,反射损耗峰值达到-28.6dB。然后制备了含12%炭黑和70%羰基铁粉,厚度为2mm的苯丙吸波涂层,测试分析了苯丙吸波涂层的吸波性能以及涂料相关性能。

兼具高湿强度及长开放期EPI木材胶粘剂的制备与性能表征

首先分别制备了湿强度优异(6.4 MPa)但开放期较短(40 min),以及开放期较长(145 min)但湿强度偏低(3.8 MPa)的EPI木材胶粘剂用两款乳液(SAEP3和SAEP4),然后探索了两种乳液的配比对复合乳液胶粘剂性能的影响。研究结果表明:当两款乳液用量一样时,产生了协同效应,制得的乳液(SAEP5)胶粘剂开放期为100~120 min,湿强度达6.4 MPa。与同样条件下测试的市售SL6517胶粘剂相比,其开放期相当,湿强度高出SL6517胶粘剂(均值5.1 MPa)约25%。由此,成功制备兼具高湿强度及长开放期的EPI木材胶粘剂。

湿摩擦牢度提升剂的复配与应用性能

使用自制的苯丙乳液与水性聚氨酯乳液作为织物的湿摩擦牢度提升剂,探究其在织物整理中的复配效果并优化整理工艺。结果表明:两种乳液以1∶2复配,总质量浓度为40 g/L,柔软剂的质量浓度为40 g/L,130℃焙烘3 min,黑色纯棉针织物的耐湿摩擦色牢度能提升2级。