Research on the Long Time Swelling Properties of Poly (vinyl alcohol)/Hydroxylapatite Composite Hydrogel

Poly(vinyl alcohol)/hydroxylapatite(PVA/HA)composite hydrogel was prepared by repeated freezing and thawing.The water loss properties of the resultant hydrogel were investigated by using optical microscope.Long time immersion tests of PVA/HA composite hydrogel were carried out in the diluted calf serum solution to study the change laws of swelling properties with the freezing-thawing cycles and HA content.The micro-morphologies of PVA/HA composite hydrogel after long time immersion were observed by means of the high-accuracy 3D profiler.The results show that the swelling process of PVA/HA composite hydrogel is the converse process of its water loss.Long time swelling ratio curves of PVA/HA composite hydrogel in the calf serum solution are manifested as four stages of quick increase,decrease,slow decrease and stable balance,and its equilibrium swelling ratio decreases with the increase of freezing-thawing cycles and HA content.It is revealed that the network structure of the composite hydrogel immersed for a long period is significantly improved with the increase of HA content. Perfect network structures of PVA/HA composite hydrogel as well as full and equilibrium tissues after swelling equilibrium are obtained when the HA content is 3% and the number of freezing-thawing cycles is 7.

Synthesis and Swelling Properties of Thermosensitive Hydrogels based on Terpolymerization

Novel thermosensitive hydrogels based on polymerization of N-isopropyl acrylamide, Sodium acrylate, and diacetone acrylamide were synthesized. The swelling ratio and dynamic swelling were investigated. The results indicated that the hydrogels exhibited high water uptake and themosensitivity. The swelling properties and volume phase transition temperature could be adjusted by contents of the comonomers in the gels.

Impact of Swelling Indices of Sokoto Clays on the Moulding Properties of the Clays in Sand Mixtures

The Impact of Swelling Indices of Sokoto Clays on the Moulding Properties of the Clays in Sand Mixtures was investi- gated. Four clays (labeled A, B, C, D) from different locations in Sokoto state of Nigeria were sampled. The sampling method was that for each deposit five samples were taken at different positions and then mixed together. At the labora- tory they were washed to remove organic matter and then dried at 110°C in the oven. A laboratory ball mill was used to grind the dried clays. Each of the clay was then sampled for the determination of its swelling index. The determination of the moulding properties of the clays then followed. Only green compression strength, dry compression strength and green permeability, moulding properties were determined. The analysis of the result revealed that clay B has the highest green and dry strength values it had the highest green compression strength of 71.7 KN/m2 and the highest dry com- pression strength of 3225.75 KN/m2. Clay B also has the highest swelling index of 60% and very high degree of expan- siveness when compared to the other three clays. Clay B was followed by clay A with swelling index of 25%;the clay has high green and dry compression strength and a moderate degree of expansiveness. The inability of clay D with swelling index of 40% to be the next clay to clay B which has the highest swelling index of 60% among the four clays in terms of good moulding properties is an indication that high swelling index does not always mean good moulding properties in clay binders.

Swelling and thermal properties of porous PNIPAM/PEG hydrogels prepared by radiation polymerization

In this study,a series of porous intelligent hydrogels were synthesized by radiation exhibiting the lower critical solution temperature（LCST） and fast response involving a combination of A’-isopropyl acrylamideas monomer, polyethylene glycol（PEG） as pore-forming agent and N,N-methylene-bis-acrylamide as crosslinking agent.The hydrogels were analyzed by Fourier transform infrared spectroscopy,and the influence of radiation doses on their swelling and thermal behaviors were studied.Their surface morphologies were examined by scanning electron microscopy.The results showed that PEG molecules only acted as pore-forming agent in the cross-linked polymerization.Their swelling ratios reduced with increasing radiation doses.The LCST was around 37℃,and varied little with the radiation doses.The frozen water content of PNIPAM/PEG6000 hydrogel reduced with increasing the radiation dose,and was greater than that of PN1PAM hydrogel at 15 kGy.Hydrogel macropores were prepared by PEG agent,and the hydrogels without PEG had a dense surface.The porous hydrogels are expected to be applied in the field of artificial intelligence material.

Cure Characteristics, Mechanical and Swelling Properties of Marble Sludge Filled EPDM Modified Chloroprene Rubber Blends

In the present study, attempts have been made to modify Marble Sludge (MS) filled Ethylene-propylene-diene monomer (EPDM) with Chloroprene rubber (CR). Compounding was carried out on a two-roll mill and vulcanized at 155℃. The modified blend of MS filed EPDM/CR was characterized on the basis of the effect of blend ratio on cure characteristics, mechanical and swelling properties of blends were investigated. The effect of thermal aging on mechanical and swelling behavior in aromatic, aliphatic and chlorinated solvents of cured MS filled EPDM/CR blend was also examined. The minimum torque and maximum torque of the blend first increased and then slightly decreased after the increasing of CR content in MS filled EPDM/CR blends. Scorch time, cure time, cure rate index, tensile strength, tear strength, hardness increased with increasing CR content in the MS filled EPDM compound, but elongation at break, resilience, abrasion loss, mole % uptake, swelling index and percentage of soluble fraction decreased, resilience, abrasion loss, mole % uptake, swelling index and percentage of soluble fraction decreases. Accelerated aging performance of cured composites also influenced by increasing CR content in MS filled EPDM compound.

Swelling properties and molecular simulation of PNIPA porous hydrogels

A series of porous intelligent hydrogels, which exhibited appropriate lower critical solution temperature (LCST) and fast response behavior, were synthesized by radiation method. The structure and surface morphology of hydrogels were examined by the infrared radiation and the scanning electron microscopy, respectively. The influences of the content of crosslinking agent and relative molecular mass of polyethylene glycol (PEG) on the swelling properties of hydrogels were discussed. The molecular mechanics simulations were performed to investigate the phase transformation mechanism of poly(N-isopropyl acrylamide) (PNIPA) hydrogel. The results show that macropores are observed in hydrogels, whereas hydrogels prepared without using PEG have a dense surface. LCST of hydrogels increases with the increase of relative molecular mass of PEG. The swelling mechanism of PNIPA porous hydrogels follows non-Fickian diffusion model. The theoretical maximum water absorption S∞ is approximately consistent with experimental value according to the second-order kinetics model established by Schott. The molecule chains of PNIPA hydrogel begin folding and curling, resulting in volume shrinkage at 305 K. There are much intramolecular nonbonding interactions in molecule chains of hydrogels. The porous hydrogels are expected to be applied in the field of artificial intelligence material.

Swelling and deswelling kinetics of polyvinyl alcohol and lactic acid hydrogel films

In this work, we studied the swelling and deswelling kinetics of polyvinyl alcohol (PVA) and lactic acid (LA) hydrogel films between distilled water and acetone phase. The hydrogel films were prepared by dissolve 5.0 g of PVA in hot water. Then, 7.5 g LA solution was slowly added into the clearly PVA solution at room temperature. After that, the mixture solution was subsequently cured in an oven for different curing times at 100°C.

Swelling and Deswelling Kinetics of AT-O3S Polymer

In the oil industry, techniques decreasing unwanted water production have drawn large amounts of interest from many companies. During water injection operations, water is injected into the oil reservoir to extract oil trapped in the formation. Due to the heterogeneity in the reservoir formation, oil production will decline and water production will increase as the injected water sweeps the high permeability zones. In order to flush out the oil remaining in the low permeability zones, many treatments have been used. One such treatment involves the injection of an SAP （superabsorbent polymer） into the high permeability zones. The swelled polymer will decrease the heterogeneity of reservoir permeability, thus forcing water injection into the oil rich, unswept zones/areas of the formation. Proper application of an SAP can have a dramatic impact on both the production and lifespan of mature oil wells. Successful treatment is reliant upon the reservoir salinity, temperature, and pH.

Synthesis and Properties of Rosin-Based Composite Acrylamide Hydrogels

Hydrogels have been widely applied in agricultural drought-resistance,pollution regulation,drug delivery and so on.Acrylamide(AM)is usually used as raw material to synthesize acrylamide hydrogels.However,inherently low mechanical strength greatly limits their applications in some special areas.Therefore,it is necessary to choose suitable functional monomers to optimize acrylamide hydrogels and improve their mechanical performances.In this paper,a novel acrylamide monomer modified by rosin was synthesized,and then polyacrylamide/rosinbased acrylamide(RAM)composite hydrogels were prepared via free radical polymerization using potassium persulfate as initiator,N,N′-methylene-bisacrylamide(MBA)as a crosslinker.The influence of RAM monomer was investigated in detail.The chemical structure,pore structure,swelling properties,thermal performances and mechanical properties of composite hydrogels were characterized by Fourier Transform Infrared spectrometer(FT-IR),thermogravimetric analysis(TG),scanning electron microscope(SEM),and universal testing,respectively.The results showed that the thermal stability and mechanical property of RAM hydrogels were improved significantly.The compressive strength of RAM hydrogels was increased to 3.5 times than that of AM hydrogels,and the tensile strength was 5.1 times compared with AM hydrogels as well.Moreover,RAM hydrogels exhibited a faster initial swelling rate due to the new pore structure formed after introducing the RAM monomer.

Nano-CaO_(2)Promotes the Release of Carbon Sources from Municipal Sludge and the Preparation of Double-Network Hydrogels with High Swelling Ratios

In this study,hydrogels were prepared from municipal sludge to recycle and realize the value-added utilization of the carbon components in this abundant waste material.The carbon sources were extracted from the municipal sludge using synthesised nano CaO_(2)as an oxidant,and the carbon sources were graft copolymerised with acrylic acid monomer using N,N′-methylenebisacrylamide as a crosslinking agent and ammonium persulfate as an initiator.The factors influencing the hydrogel preparation were investigated by single-factor experiments.Based on the results of the single-factor experiments,a hydrogel with a swelling ratio of up to 19768.4%at 12 h was prepared with an oxidant dosage of 0.20 g,a monomer dosage of 5.8 g,a neutralisation degree of the monomer of 70%,an initiator dosage of 0.15 g,and a crosslinking agent dosage of 0.15 g.The hydrogel preparation conditions were optimized using the response surface method,and the interactions between the different reaction conditions were analysed to obtain the best preparation conditions.X-ray diffraction results showed that hydrogels were amorphous in structure.Scanning electron microscopy images showed that the SiO_(2)particles from the sludge acted as crosslinking points between different layers of hydrogel chains.The crosslinking polymerisation and crosslinking agent worked together to form hydrogels with an inorganic-organic double network structure,and this structure was highly stretchable,resulting in hydrogels with good swelling properties.

Synthesis and properties of physically crosslinked poly (vinyl alcohol) hydrogels

The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent,DMSO,by the freezing-thawing method.The water content,visible light transmittance,mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles.The results show that the properties of PVA hydrogels depend on the polymer concentration,the number of freeze-thaw cycles and the addition of the organic solvent.

Synthesis and Optical Properties of ZnO Nanoparticles in Submicron PS Hollow Reactors

ZnO nanoparticles were first encapsulated in submicron PS hollow microspheres through two-step swelling process of core-shell structured PMMA/PS （PMMA： polymethyl methao- rylate） microspheres in acid-alkali solution, and the ZnO precursors, i.e. the ethanol solu- tions of （CHaCOO）2Zn and LiOH. The transmission electron microscope, X-ray diffraction, and thermogravimetric analysis results show that the feeding order of ethanol solutions of （CH3COO）2Zn and LiOH in the second swelling step has great influence on the loading efficiency and the size of ZnO nanoparticles, but little on their crystal form. The photolumi- nescence and UV-Vis absorption behavior of ZnO/PS microspheres show that the PS shell can effectively avoid the fluorescence quenching effect.

Physical Properties of Chitosan Films Obtained after Neutralization of Polycation by Slow Drip Method

The development of new materials from biodegradable constituents is enticing for applications in bioelectronics and biomedicine, due to their considerable durability, versatility and biodegrada-bility. The present work aims to determine the chemical and physical properties of chitosan membranes after neutralization of the polycation solution. This work was divided into two stages: solubilization and neutralization. In the first stage, the chitosan was solubilized with three different concentrations of acetic acid (1%, 0.8% and 0.5%) in order to evaluate whether the acid affected the physical-chemical properties of the films. In the second stage, the chitosan polycation was neutralized with two strong bases (NaOH and KOH) using three different molar concentrations, by the slow drip method for obtaining films with pH values close to neutrality. The characterization of the membranes obtained from casting method showed that the different concentrations of acetic acid did not affect the physical-chemical properties of the films. In contrast, the neutralization process did affect their properties, and in particular, different behaviors were observed depending on the type of base used for neutralization. More ductile and plasticity were obtained in the films when the polycation was neutralized with KOH, whereas the films neutralized with NaOH exhibited a more fragile behavior.

HBP-g-PEGDGE凝胶聚合物的制备及性能

以超支化大分子-扫帚形聚合物(HBP-NH2)和线型二环氧化物封端的聚乙二醇(PEGDGE,Mn=600,1000,2000)为原料,采用溶液法制备了一类HBP-g-PEGDGE(HPD)水凝胶。利用傅里叶变换红外光谱、核磁共振氢谱、紫外光谱和扫描电镜等方法对产物的结构进行了表征,并对其溶胀、热稳定、流变和堵水性能进行了评价。结果表明,HPD水凝胶具有三维空间立体网状结构,且孔径随着聚乙二醇相对分子质量的增大逐渐增大。对于长链PEGDGE,较低温度、酸性pH和在没有盐的情况下均可获得较高的平衡溶胀比,水凝胶在温度为10℃~60℃、pH值为2~12范围内,表现出良好的溶胀-收缩可逆性。凝胶的热稳定性较好,随着聚乙二醇相对分子质量的增大而增强;表现出典型的弹性行为,随着聚乙二醇相对分子质量的增加,储能模量和损耗模量降低;其封堵率达到99%,封堵效果良好。

城市污泥-餐厨垃圾联合制备水凝胶及其溶胀性分析

以城市污泥和餐厨垃圾作为原料,辅助以单体丙烯酸,交联剂N,N-亚甲基双丙烯酰胺和引发剂过硫酸钠,通过接枝聚合反应合成水凝胶。通过单因素实验考察了水凝胶制备的影响因素,并利用响应曲面法进行了优化实验,结果表明在污泥与餐厨垃圾干质量比为2:3,浆液含水率为96.1%,反应温度为70℃,投加2.25mL的单体,0.10g的交联剂,0.2g的激发剂时,制得水凝胶的最佳溶胀率能达到5400.93%。通过扫描电镜表征发现水凝胶具有众多网络褶皱和沟壑结构,从而使其具有良好的溶胀性能。

采油螺杆泵定子橡胶研究综述

采油螺杆泵在高黏度、高含砂量原油开采中具有突出优势,螺杆泵工作原理和工作环境决定了其核心部件橡胶定子的使役寿命,提升螺杆泵定子橡胶材料的耐磨、耐溶胀等性能具有重要意义。介绍了采油螺杆泵的核心部件组成和采油工作原理,面向螺杆泵定子橡胶的实际需求,梳理了国内外学者在定子橡胶材料老化、溶胀、摩擦等关键性能方面的主要研究成果,并针对近年来新兴的材料多尺度研究手段,从概念、原理、方法及其在定子橡胶力学与摩擦学性能等方面进行了综述,对未来持续提升采油螺杆泵定子橡胶耐磨、耐溶胀等性能的方法与研究手段进行了展望。

高温溶胀下二硫化钼/丁腈橡胶力学和摩擦性能分子动力学模拟

为研究高温环己烷(C_(6)H_(12))溶胀下,二硫化钼(MoS_(2))对丁腈橡胶(NBR)复合材料力学及摩擦学性能的影响,使用蒙特卡洛法和Forcite模块分别建立纯NBR、溶胀NBR、NBR/MoS_(2)和溶胀NBR/MoS_(2)复合材料模型,研究MoS_(2)对NBR高温溶胀、力学和摩擦学性能的影响,并探讨MoS_(2)改善高温溶胀NBR的机制。结果表明:C_(6)H_(12)溶胀使NBR的力学性能下降,但在添加MoS_(2)后,复合材料的力学性能得到提高;C_(6)H_(12)溶胀使NBR内部分子链迁移、运动速率加快,但在添加MoS_(2)后,有效地抑制了C_(6)H_(12)溶胀;C_(6)H_(12)溶胀会使NBR复合材料表面分子链增加,导致NBR摩擦学性能下降,但添加MoS_(2)后,复合材料的摩擦学性能也有所提升。由于MoS_(2)较大的比表面积以及较强的范德华力和静电力吸附作用,添加MoS_(2)能改善高温C_(6)H_(12)溶胀下NBR复合材料的力学与摩擦学性能。

海胆状纳米二氧化硅增强水凝胶的制备与性能研究

利用溶胶-凝胶法制备海胆状的二氧化硅纳米颗粒(USN),并将其作为共价交联中心增强聚丙烯酰胺(PAM)水凝胶。利用硅烷偶联剂(3-(异丁烯酰氯)丙基三甲氧基硅烷)对USN进行表面改性,通过原位引发自由基聚合得到USN增强的聚丙烯酰胺水凝胶。利用傅里叶变换红外光谱(FTIR)、动态光散射(DLS)和透射电子显微镜(TEM)对改性前后的USN进行表征,考察了USN加入量对水凝胶溶胀性能和压缩性能的影响。结果表明:与纯聚丙烯酰胺水凝胶相比,掺杂USN后,水凝胶溶胀率由约70%降低到约30%,显示出明显的抗溶胀性能;在应变为90%的条件下,水凝胶的最大压缩应力由298.8 kPa增大到566.4 kPa。

疏水改性微球的制备及其膨胀性能与应用研究

通过反相乳液聚合法制备了一种疏水改性P(AM-N)微球.采用傅里叶变换红外光谱(FTIR)、热重分析仪(TGA)、扫描电镜(SEM)、流变及岩心驱替实验对所合成微球的结构、形貌、性能以及封堵效果进行了表征与测试,并考察了溶胀时长、温度和不同盐溶液浓度对P(AM-N)微球性能的影响.测试结果表明,P(AM-N)微球的平均粒径为76.42 nm,溶胀5 d后P(AM-N)微球的膨胀率高达17.21倍;在70℃下,P(AM-N)微球老化2 d后溶胀率高达17.14倍,在20000 mg/L NaCl溶液和2000 mg/L CaCl_(2)溶液中分别溶胀3 d后膨胀率高达5.31倍和6.03倍,说明其具有较好的耐温性和抗盐性;在注入量为0.5%的条件下,P(AM-N)微球封堵率可达到97.98%,与P(AM)微球相比具有更好的封堵性且弹性增强.

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。