反相悬浮聚合膨润土复合聚丙烯酸钠-丙烯酰胺高吸水性树脂的研究

以N，N-亚甲基双丙烯酰胺为交联剂，过硫酸铵／亚硫酸氢钠为乳化还原引发剂，Span 80／Tween 80为复合悬浮分散剂，采用反相悬浮聚合法合成出膨润土复合聚丙烯酸钠—丙烯酸胺高吸水性复合树脂。研究了膨润土的添加量对复合树脂的吸水性、吸水速度及保水性等的影响，并用TGA和DSC分析研究了膨润土复合高吸水树脂的保水性和脱水动力学。     

反相悬浮聚合技术的研究进展与应用

介绍了反相悬浮聚合技术合成球状亲水性高分子材料的优势及其在球状超强吸液树脂、酶固定化载体和高分子絮凝剂等领域的应用,着重讨论了反相悬浮聚合体系中成球聚合的影响因素,指出与单体相匹配的分散剂和分散介质的选择是影响聚合体系稳定性和产物性能及制备成本的关键,具有分散和隔离保护双重作用的高分子表面活性剂的开发应用是发展趋势和研究热点。     

Morphology and permeability in extruded polypropylene/ethylene vinyl-alcohol copolymer blends

Studies of the morphology of extruded polymer blend systems have shown that it is feasible to produce a laminar structure of an ethylene vinyl-alcohol copolymer (EVOH) dispersed phase in a polypropylene (PP) matrix phase. The laminar structure forms in the core of the extrudate when a slit die is incorporated into the extrusion process. Morphological studies, including a study of morphology development inside the die and studies of the effect of processing conditions on the morphology of the final product, revealed that the laminar structure is a result of die design. Processing conditions influence mainly the shape and dimensions of the laminar core region of the extrudate. Oxygen permeation tests have shown that the blend exhibits lower oxygen permeability than pure PP, when EVOH is incorporated as a dispersed phase into the system. Oxygen transmission rates obtained with a blend system approach those obtained with a multilayer coextrusion product, although only at high EVOH concentrations. Comparison of experimental data with theoretical permeation predictions shows that, up to 20 wt% EVOH, the reduction in oxygen transmission rate follows the prediction for a homogeneous system. At 25 wt%, a considerable decrease in oxygen transmission rate is noticeable, and the trend for higher EVOH contents is towards the behavior of a multilayer system.     

Morphology of polymer of ethylene sulfide and its block copolymer with styrene

It has been found that poly(ethylene sulfide) obtained by anionic polymerization in tetrahydrofuran assumes the shapes of platelets, microhedrites, microspherulites, or particles of irregular structure, depending upon the molecular weight of poly(ethylene sulfide). In the case of block copolymers of ethylene sulfide and styrene, the morphological form has been found to be dependent upon the composition of the copolymer.     

Morphology and rheology of HDPE/LCP blends compatibilized by a novel PE-g-LCP copolymer

A novel graft copolymer (PE-g-LCP) consisting of polyethylene (PE) backbones and liquid crystalline polymer (LCP) branches was synthesized via reactive blending of an acrylic acid-functionalized PE (Escor 5000 by Exxon) with a semiflexible LCP (SBH 1 : 1 : 2 by Eniricerche S.p.A.). The crude reactive blending product (COP) was shown by investigation of the fractions soluble in boiling toluene and xylene and of the residue to contain unreacted Escor and SBH, together with the graft copolymer forming the interphase. The compatibilizing activity of COP for PE/SBH blends, compared to that of pure Escor, was investigated using two PE grades. The COP addition into 80/20 PE/SBH blends caused a much stronger reduction of the SBH droplet dimensions and morphology stabilization than did that of pure Escor. The rheological behavior of the samples showed that COP leads to a slight increase of interfacial adhesion in the melt as well and that the effect is more pronounced when lower molar mass PE grade is used as the blend matrix. Melt-spinning tests demonstrated that deformation of the SBH droplets into highly oriented fibrils can be obtained for the blends of lower molar mass PE, compatibilized with small amounts of the novel PE-g-SBH copolymer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2069–2077, 1999     

反相悬浮法制备磁性高分子微球的研究

本文采用反相悬浮法,通过聚乙二醇的缩醛化反应,制备了具有灵敏磁响应性、表面富含羟基的微米级的磁性高分子微球。主要探讨了反应时间、聚乙烯醇浓度、搅拌速度、戊二醛(GA)用量及磁流体用量的变化对磁性高分子微球制备及性质的影响,用红外(FTIR)、激光粒径分析仪、扫描电子显微镜(SEM)、振动样品磁强计(VSM)进行表征。结果表明,所制备磁球表面羟基含量高,分散性好,磁含量高,具有超顺磁性。     

Nonlinear temperature control of a batch suspension polymerization reactor

This paper concerns nonlinear temperature control of a batch polymerization reactor where suspension polymerization of methyl methacrylate (MMA) takes place. For this purpose, four control algorithms, namely, a fix proportional‐integral (PI) controller, an adaptive proportional‐integral‐derivative (PID) controller and two globally linearizing control (GLC) schemes, one for known kinetic model (GLC‐I) and the other for unknown kinetic model (GLC‐II), are selected. The performances of these controllers are compared through simulation and real‐time studies in the presence of different levels of parameter uncertainty. The results indicate that GLCI and GLC‐II have better performances than fix PI and adaptive PID, especially in case of strong gel effect. The worst performance belongs to adaptive PID because of rapid model changes in gel effect region. GLC‐II has a simpler structure than GLC‐I and can be used without requiring the kinetic model. In implementation of GLC‐I the closed loop observer should be used because of model uncertainties.     

Fabrication of interconnected macroporosity in geopolymers via inverse suspension polymerization

A new approach to fabricate geopolymer monoliths with interconnected macroporosity and a permeable structure is presented. This was achieved using an unconventional route of inverse suspension polymerization in which the aqueous geopolymer slurry consisting of potassium hydroxide, fumed silica, and natural metakaolin was dispersed in a continuous phase of soybean oil. The geopolymer monolith was synthesized by taking advantage of the so-called “sticky period” that occurs during inverse suspension polymerization. During this period, individual droplets can coalesce but cannot re-divide because of the partially polymerized matrix. We deliberately brought the partially polymerized geopolymer particles in proximity during the sticky period to fuse the particles. Hence this method, termed as “sticky period particle fusion,” helped to form a monolithic structure with inter-particle spacing as macropores which resulted in high permeability. The sticky period was observed to depend on synthesis conditions such as stirring speed, temperature, and viscosity of continuous phase which in turn helped to tune the surface and pore properties of geopolymer monoliths. The BET surface area up to 67 m²/g and total pore volumes of 0.4 cm³/g from pycnometry were obtained.     

Morphology and blowing agent encapsulation efficiency of vinylidene chloride copolymer microspheres synthesized by suspension polymerization in the presence of a blowing agent

Polymer microspheres were synthesized by the suspension copolymerization of vinylidene chloride (VDC), acrylonitrile (AN), and/or methyl methacrylate (MMA) in the presence of a paraffin blowing agent. The effects of the monomer composition, crosslinking agent content, blowing agent type, and content on the morphology and blowing agent encapsulation efficiency of the microspheres were investigated. The porous and non‐core–shell structure microspheres with a low encapsulation efficiency of blowing agent were formed when VDC was copolymerized with individual AN or MMA, whereas microspheres with a good core–shell structure and a high encapsulation efficiency of blowing agent were formed when the feeding monomer mass ratios of VDC–AN–MMA were 50/20/30, 60/20/20, and 70/20/10. The addition of 0.2–0.4 wt % divinyl benzene crosslinking agent (on the basis of monomer mass) was favorable to the formation of core–shell structure microspheres with a high encapsulation efficiency of blowing agent. Microspheres with wrinkled surfaces and a pronounced internal topography were formed as the carbon atom number of paraffin increased from 5 to 7. The encapsulation efficiency of blowing agent increased as the carbon atom number and content of paraffin blowing agent increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44376.     

Synthesis of ethylene and butyl methacrylate-based copolymer by emulsion polymerization

The emulsion copolymerization of ethylene with butyl methacrylate (BMA) was carried out in an aqueous medium at 60 °C under moderate reaction conditions. The polymer system is well controlled with a linear increase in the molecular weight (M_n) versus ethylene feed pressure and narrow molecular weight distributions (>1.36) were observed throughout the copolymerization reaction. The spectroscopic analyses confirm the presence of acrylate functional as well as methylene group in the synthesized poly(ethylene-co-BMA) copolymer. Morphological behavior of poly(ethylene-co-BMA) has been studied using SEM and TEM analyses. Thermal stability of the copolymers was investigated by thermogravimetric analysis and it was observed that the copolymer is stable up to 380 °C. X-ray diffraction analysis confirmed the amorphous behavior of poly(ethylene-co-BMA). Dynamic light scattering measurement confirms the formation of poly(ethylene-co-BMA) nanoparticles. The particle size of copolymer nanoparticles were in the range of 85–108 nm with low polydispersity indexes (>0.2). The viscous and the elastic property of the copolymer were investigated and established that at high temperature elastic behavior predominant over viscous effect. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47994.     

Fabrication of a fast‐swelling superabsorbent resin by inverse suspension polymerization

A novel, fast‐swelling superabsorbent polymer (SAP2) was fabricated with an anionic–nonionic surfactant [poly(oxy‐1,2‐ethanediyl)–(3‐carboxy‐1‐oxo‐3‐sulfopropyl)–(nonylphenoxy) sodium salt] as the stabilizer by inverse suspension polymerization. The microstructure, chemical structure, and gel strength of the superabsorbent polymers (SAPs) were characterized by scanning electron microscopy, porosity, and specific surface area analysis, Fourier transform infrared spectroscopy, and rheometry. The results show that SAP2 had irregularly shaped particles with a large number of pores and presented a greater specific surface area, pore volume, and gel strength than the prepared SAP1 with a nonionic surfactant (Span 60) as the stabilizer. The amount of residual monomer and the gel fraction of SAP2 were 202 mg/kg and 80.6%, respectively. Meanwhile, SAP2 demonstrated a faster swelling and deswelling rate as well as greater water absorbency than SAP1. The fast swelling rate mainly resulted from the capillary effect of the pores in the irregularly shaped particles. Superfast swelling SAPs should possess outstanding potential for healthcare products, communication cables, and the biomedical field. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46142.     

Morphology of polyvinylidenefluoride and the copolymer of tetrafluoroethylene with ethylene using thermomechanical analysis

The morphology of polyvinylidenefluoride (PVDF) and the copolymer of tetrafluoroethylene with ethylene (CTE) were investigated by thermomechanical analysis. Both granules and highly dispersed powders of the polymers have similar morphology. Polymer granules contain amorphous and crystalline regions. The morphology of the polymer powders were determined under two analytical conditions: coaxial, when the vectors of polymer loading and vector of compression pressure are in the same plane, or when they are perpendicular to each other. One amorphous and two crystal blocks were found at coaxial orientations of the vectors. Thermomechanical analysis showed that the polymers had a completely amorphous diblock morphology at the perpendicular orientation of the vectors. Parameters that characterize a degree of interchain interaction, such as coefficients of thermal expansion, free volume, and temperatures of polymer transformation into the glassy, high‐elastic, or flow‐viscous state were determined. PVDF and CTE have similar topographic composition, but different molecular mass and temperatures of phase transitions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poisoning effect of CO on ethylene polymerization with Ni(II)-diimine/MAO

CO was not a comonomer but an inhibitor in ethylene polymerization catalyzed over [1,2-bis(2,6-diisopropylphenylimino)]acenaphthene nickel(II) dibromide (1)/MAO. The average number of active sites, , and the average rate constant for chain propagation, of the (1)/MAO system was determined using CO inhibition method based on the assumption that two molecules of CO coordinate to each active center. At 0 °C, the average number of active centers, , was increased with the Al/Ni ratio, and , was not influenced by the Al/Ni ratio. Up to Al/Ni ratio of 3000, the average number of active sites was saturated. Single active site was present at the high ratio of Al/Ni and its reactivity with CO is uniform at 0 °C. The maximum average activity was 5262.07 (kg-PE/mol-Ni/atm/hr) and 65.7% of (1) was converted to form active cation complexes at 0 °C and Al/Ni molar ratio of 5000, while 36.5% of (1) was activated at the Al/Ni molar ratio of 250. Above 30 °C, the complicated CO poisoning behavior was observed because the reactivity and stoichiometry of active centers with CO were not uniform and their thermal stability was very poor.     

甲基丙烯酸甲酯-苯乙烯悬浮聚合共聚物粒度的控制

以过氧化二苯甲酰为引发剂,以聚乙烯醇-羟基磷酸钙复合分散体系为分散剂,采用悬浮聚合法制备甲基丙烯酸甲酯-苯乙烯共聚物珠粒.研究了单体配比、引发剂用量、分散剂用量、反应温度、搅拌速度对聚合物珠粒的影响;并用红外光谱对产物结构进行了表征.     

D/3集散控制系统在悬浮聚合中的应用

1 概述 氯乙烯(VC)聚合反应是一个间歇化工生产过程,其控制对象呈现非线性和时变性,而且是一个大容量、纯滞后的难控对象,我公司应用美国GSE公司生产的D/3集散控制系统,成功地实现了悬浮聚合的温度控制。 氯乙烯在一定水比和助剂作用下,升温至树脂对应的标号温度,再用低温差大流量循环进行控制直至反应结束。带控制点工艺流程图见图1。     

Improvement of polyamide/thermoplastic polyurethane blends with polyamide 6-polyurethane copolymer prepared via suspension polymerization as compatibilizer

The polyamide 6-polyurethane copolymer (PA6-b-PU-b-PA6) was synthesized through anionic suspension polymerization and then mixed with polyamide 6/thermoplastic polyurethane (PA6/TPU) and polyamide 6, 6/thermoplastic polyurethane (PA66/TPU) blends using as the compatibilizer. The results show that the PA6-b-PU-b-PA6 copolymers powders several can be obtained through suspension polymerization using dimethicone as disperse medium. The average diameter of PA6-b-PU-b-PA6 copolymer powders decreased with the increasing of PU content. With the addition of PA6-b-PU-b-PA6, the TPU phase dispersed more uniformly in PA6 or PA66 matrix, and the size of TPU dispersed phase decreased obviously. The PA6-b-PU-b-PA6 copolymer with higher PU content shows better compatibilizing effect. Addition of PA6-b-PU-b-PA6 can improve both strength and toughness of the PA/TPU blends. When the amount of PA6-PU25% copolymer was 5 phr, the tensile strength and notched impact strength of PA6/TPU/PA6-PU25% blends increased 29 and 159.4%, respectively, compared to the PA6/TPU blend without compatibilizer.     

淀粉/AA/AM/MA反相悬浮法合成高吸水树脂

以含阻聚剂的工业级丙烯酸(AA)、丙烯酸甲酯(MA)及木薯淀粉、丙烯酰胺(AM)为原料,采用反相悬浮法,使用自配分散剂,环己烷为连续相,过硫酸钾和亚硫酸氢钠为引发剂,N,N-亚甲基双丙烯酰胺为交联剂合成了高吸水树脂。结果表明,最佳工艺条件为:m(淀粉)∶m(AA)∶m(AM)=1.0∶4.5∶0.9,MA、交联剂加入量分别为5.0%,0.3%(相对AM和AA总质量),引发剂(两次引发)浓度分别为2.0,13.5 mmol/L,油水比例为1.90∶1.00(体积比)。在上述条件下制得的树脂的吸水率≥600 g/g,吸盐率≥60 g/g,环己烷回收率为97.3%。由于引入适量的MA,产物吸水率和吸盐率提高了20%,产物形态由最初的粘接颗粒变成分散颗粒。     

反相悬浮聚合法制备水溶性固体聚丙烯酸

以环己烷为连续相,失水山梨醇单油酸酯(Span-80)为分散剂,K2S2O8为引发剂,采用反相悬浮聚合法合成了水溶性良好的固体聚丙烯酸(PAA),详细探讨了搅拌速度、分散剂用量、单体浓度、反应温度及反应时间等对聚合产物颗粒特性的影响。结果表明,较优的工艺条件是:搅拌速度500r/min、分散剂质量分数4%~8%(相对于单体质量)、单体质量分数50%、反应温度70℃、反应时间3.0h。     

Preparation of superabsorbent slow release nitrogen fertilizer by inverse suspension polymerization

A superabsorbent, slow release nitrogen fertilizer (SSRNF) was prepared by inverse suspension polymerization of partially neutralized acrylic acid using N,N′‐methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator in the presence of urea. The polymer was characterized using infrared spectral analysis, and network structural parameters such as molecular weight between crosslinks (M_c) and crosslink density (q) were calculated. The effects of reaction conditions, such as reaction time, reaction temperature, initiator, crosslinker and the degree of neutralization of acrylic acid, on water absorbency were investigated. The nitrogen content of SSRNF synthesized under optimal conditions was 22.7%, and the water absorbencies were about 965 g g^?1 in distilled water and 185 g g^?1 in tap water. The nitrogen slow release behaviors of the SSRNF in water and water retention capacity of soil with the SSRNF were also investigated. A possible slow release mechanism was proposed and the release rate constant K and the diffusion coefficient D of urea in the hydrogel was calculated. The results showed that the product not only had good slow release properties but also excellent soil moisture preservation capacity, which could effectively improve the utilization of fertilizer and water resources simultaneously. Therefore, the SSRNF is a multifunctional water managing material, which would find application in agriculture and horticulture, especially in drought‐prone areas where the availability of water is limited. Copyright © 2006 Society of Chemical Industry     

Crystallization of a miscible propylene/ethylene copolymer blend

The crystallization behavior and morphological patterns of a miscible blend of two propylene/ethylene (P/E) copolymers that differed in ethylene content were studied. Metallocene-catalyzed P/E copolymers containing 3.1 and 11.0 mol% ethylene were chosen for blending. The difference in ethylene content was small enough to ensure miscibility of the pair in the melt, and the ethylene content was low enough to ensure that both were crystallizable. The blends were characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), optical microscopy (OM) and atomic force microscopy (AFM). The complex melting endotherm of the blends consisted of a broad low temperature peak at T_m1, a high temperature peak at T_m2, and an intermediate peak at which was not characteristic of either constituent and depended on blend composition. The multiple melting peaks arose from distinct crystal populations. All the blends exhibited a mixed morphological texture of α-radial lamellae with short, densely packed γ-overgrowths, interspersed with areas of α-crosshatch. The high temperature peak at T_m2 was assigned to the melting of the α-radial lamellae which formed from chains of the lower comonomer constituent. The broad low temperature peak at T_m1 was attributed to the melting of γ-crystal overgrowths on the radial lamellae. The new peak at was thought to arise from the melting of the α-crosshatch lamellae. The lamellar thickness, and hence , correlated with the crystallization temperature, which decreased as the blend was made richer in the higher comonomer constituent.