分子筛改性羧甲基纤维素类高吸水性树脂研究

以羧甲基纤维素(CMC),丙烯酸(AA),2-丙烯酰胺2甲基丙磺酸(AMPS)为原料,过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,经接枝共聚制备高吸水性树脂;为提高高吸水性树脂的耐热性能,使用分子筛对高吸水性树脂进行改性,探讨了分子筛种类和用量对高吸水性树脂性能的影响,测定了改性后高吸水性树脂的吸水倍率、吸水速率、再生性能和耐热性能,通过对其性能进行比较得出:添加0.5g的13X分子筛改性高吸水性树脂效果最佳,所得产物吸水倍率为675g·g-1,吸水速率、再生性能和耐热性能也比改性前有显著提高.     

农用高吸水性树脂及其前景展望

详细介绍了农用高吸水性树脂的吸水、保水机理,分类,作用机制,性能及近年来国内外的研究进展;认为对农用高吸水性树脂吸水机理的深入研究、降低成本、改善耐盐性、改善降解性能、研制功能性高吸水性树脂等,将成为下一步农用高吸水性树脂的研究热点。     

高吸水性树脂粒径与性能的研究

研究了高吸水性脂粒径与性能的关系及影响高吸水性树脂粒径分布的诸因素。结果表明，粒径为８０－１２０目的高吸水性树脂吸水（液）率高，吸水（液）速度快，保水性好，与ＰＶＣ共混性优良。在搅拌速度为８０－１２０ｒ／ｍｉｎ，分散剂和助分散剂用量分别为水相重的０．４％－０．６％和８％－１２％，水／油为２．５－３．５的条件下制得的高吸水性树脂平均粒径小，粒径分布范围窄，树脂综合性能好。     

农用高吸水性树脂及其研究进展

农用高吸水性树脂的使用是解决农业缺水、传统化肥农药对环境污染等问题的有效途径。详细介绍了农用高吸水性树脂的吸水、保水机理、分类、作用机制、性能及近年来国内外在这些方面的研究进展;认为对农用高吸水性树脂吸水机理的深入研究和对降低成本、改善耐盐性、改善降解性能的研究,以及研制功能性高吸水性树脂等将成为今后农用高吸水性树脂的研究热点。     

高吸水性树脂的合成及其应用

对高吸水性树脂的合成方法、性能改进及应用的现状进行了综述，讨论了微波辐射用于高吸水性树脂合成的技术优势及应用现状，对高吸水性树脂的分子设计与颗粒形状设计，以及在吸水与保水性能方面的应用等进行了评述。     

耐盐性高吸水性树脂的制备及性能研究

采用水溶液聚合法合成了耐盐性丙烯酰胺型高吸水性树脂,在系统地考察单体配比、中和度、交联剂和引发剂用量对高吸水性树脂加压(约2kPa)吸液性能影响的基础上,运用正交实验对工艺条件进行优化,制备出加压下在去离子水和质量分数为0.9%的盐水中的吸水倍率分别为75和23.1的高吸水性树脂。     

内交联型高吸水性树脂的合成及性能研究

采用反相乳液聚合法合成内交联型高吸水性树脂。研究了交联剂用量、丙烯酸中和度和浓度、引发剂用量对树脂性能的影响。制得的树脂吸水速度快,吸水倍数高,在4min内可吸去离子水1800(g/g)左右,吸0.9％NaCl水溶液150(g/g)左右。     

高吸水性树脂的性能研究

高吸水性树脂作为一种功能高分子,其应用越来越广,是一种很有发展前途的新材料。本 文介绍了高吸水性树脂的特点、性能、结构、吸水机理及性能测试方法。     

多孔高吸水性树脂制备方法及应用研究进展

多孔高吸水性树脂是一种新型的高分子材料,性能优异,用途广泛。综述了多孔高吸水性树脂的的吸水机理及应用,介绍了多孔高吸水性树脂的形成方法,并对其发展前景进行了展望。     

秸秆纤维素系高吸水树脂的研究

以小麦秸秆、丙烯酸(AA)、改性高岭土为主要原料,过硫酸钾为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,采用水溶液聚合法制得秸秆纤维素系高吸水性树脂,并对秸秆纤维素系高吸水性树脂进行了测试。研究结果表明:当AA与小麦秸秆质量配合比为1∶8,改性高岭土用量、交联剂用量、引发剂用量分别为AA用量的8%、0.1%、0.1%,AA中和度为70%,反应温度为80℃条件下,制得的秸秆纤维素系高吸水性树脂的吸水倍率达到558.4g/g,重复吸水6次后,其吸水效果为初始吸水倍率的53%左右,具有较好的吸水性能。     

Role of surface treatment on water absorption of poly(vinyl chloride) composites reinforced by Phyllostachys pubescens particles

Water absorption is one of key parameters in quality assessment of wood-plastic composites. The influence of surface treatment of lignocellulosic particles on water absorption of composites made from poly(vinyl chloride) (PVC) and moso bamboo (Phyllostachys pubescens) particles was studied. The effect of modification with three kinds of chemical treatment agent (alkali, silica and oxidant) on particle surface was examined. The concentration and pH values of the agent aqueous solutions were analyzed and their relationships with water absorption, porosity ratio, thermal property, micro-structure and hemicelluloses content were evaluated. Results showed that pH values of aqueous solutions had little impact on water absorption of the composites while the types of treatment agents did. Alkali treatment lowered the content of hemicelluloses in moso bamboo particles and thus reduced corresponding water absorption. Water resistance improvements of silicate or oxidant treated particles reinforced composites were due to changes of porosity ratio. In general, surface treatment improved water resistance of moso bamboo particles reinforced PVC composites. Compared with the other two agents, sodium bisulfite enhanced the compatibility between cellulose particles and granulated PVC.     

Water absorption study on pultruded jute fibre reinforced unsaturated polyester composites

Water absorption of natural fibre plastic composites is a serious concern especially for their potential outdoor applications. In this research, jute fibre reinforced with unsaturated polyester composites are subjected to water immersion tests in order to study the effects of water absorption in its mechanical properties. Water absorption tests were conducted by immersing composite specimens into three different environmental conditions included distilled water, sea water and acidic solutions at room temperature for a period up to 3 weeks. Water absorption curves obtained and characteristic parameter D (diffusion coefficient) and M_m (maximum moisture content) were determined. The water absorption of jute fibre reinforced unsaturated polyester composites were found to follow a so-called pseudo-Fickian behaviour. The effects of the immersion treatment on the flexural and compression characteristics were investigated. The flexural and compression properties were found to decrease with the increase in percentage water uptake. These flexural and compression behaviours were explained by the plasticization of the matrix–fibre interface and swelling of the jute fibres.     

Accelerated testing for long-term fatigue strength of various FRP laminates for marine use

The prediction of long-term fatigue life of various FRP laminates combined with resins, fibers and fabrics for marine use under temperature and water environments were performed by our developed accelerated testing methodology based on the time–temperature superposition principle (TTSP). The five kinds of FRP laminates were prepared under three water absorption conditions of Dry, Wet and Wet + Dry after molding. The three-point bending constant strain rate (CSR) and fatigue tests for these FRP laminates at three conditions of water absorption were carried out at various temperatures and loading rates. As results, the mater curves of fatigue strength as well as CSR strength for these FRP laminates at three water absorption conditions are constructed by using the test data based on TTSP. It is possible to predict the long-term fatigue life for these FRP laminates under an arbitrary temperature and water absorption conditions by using the master curves. The characteristics of time, temperature and water absorption dependencies of flexural CSR and fatigue strengths of these FRP laminates are clarified.     

Damage evolution behavior of CFRP laminates under post-impact fatigue with water absorption environment

In this study, the damage evolution behavior was evaluated considering the effect of the textile structure and water absorption. Damage observation was conducted by the integration of non-destructive and direct observation methods. Candidate textile reinforcements were T300-3k plain woven fabric (PW) and T700S-12k multi-axial knitted fabric (MA). The effect of water absorption on the performances of compression after impact (CAI) and PIF were small in PW CFRP laminates. Conversely, PIF properties of water-absorbed MA CFRP laminates drastically decreased than that of dry ones. CAI strength was not affected by water absorption. PIF performance of dry MA CFRP was fairly higher than that of the others. From the precise observation, some evidences of interfacial deterioration caused by water absorption were confirmed in both PW and MA CFRP laminates.     

高吸水树脂吸液率及其测定方法的研究

综述了吸水树脂吸液率及其测定方法的现状，提出用100mesh筛子过滤法作为测定吸液率的通用方法。并以合成的超强吸水树脂为例，测出其吸纯水率为1000g／g-4000g／g，吸自来水率400g／g～1800g／g，吸0．9%NaCl溶液120g／g-198g／g，与文献相比显著超过文献值。对吸液率测定中浸泡用水量和浸泡时间的影响作了探索。     

不同发泡倍率聚乙烯醇基缓冲包装材料性能

目的 探究聚乙烯醇(PVA)基发泡材料的缓冲包装性能,为PVA基发泡材料应用于易渗出水溶性液体的产品包装提供一定的理论依据和实践经验。方法 采用化学发泡法制备不同发泡倍率的PVA基发泡材料,研究其微观结构、吸水性能和不同条件下的缓冲性能。结果 不同发泡倍率下,5种密度PVA基发泡材料均具有良好的吸水性和保水性,且吸水率越高,保水性越差。在干燥状态下,材料的质地较硬,且其缓冲性能随着发泡倍率的增大而减小,材料吸水后变得柔软且富有弹性,当吸水率达到58.0%后,材料的缓冲性能则急剧下降。结论 经综合比较,密度为0.146 g/cm³ 的PVA基发泡材料具有良好的吸水性能、保水性能和缓冲性能,在材料的吸水率低于58.0%时,可满足易渗液体容器的锁水和缓冲包装需求。     

Synthesis of pH-sensitive water and oil dual-absorption material using microemulsion polymerization process

pH-sensitive water and oil dual-absorption material (WODAM) has been successfully synthesized through microemulsion polymerization. Firstly, microemulsions prepared with monomers were analyzed by pseudo-ternary phase diagram. In addition, conductivities of microemulsions were tested to identify microemulsion types. Meanwhile, the factors that affected microemulsion types were analyzed. Then WODAMs were prepared, and the chemical structure was characterized using Fourier transform infrared (FTIR) spectroscopy. Liquid absorption tests indicated that both monomer ratio and microstructure of WODAMs had influences on their water absorption rate (WAR) and oil absorption rate (OAR). In addition, pH sensitivity tests showed that WODAM absorbed much water in neutral and weak alkaline solutions, but little water in strong alkaline solutions. What’s more, liquid absorption tests in cement slurry filtrate (CSF) showed that WODAM was applied to oil well cement. This paper prepared a new self-healing agent, and is of great significance to realize self-healing cement in complex downhole condition.     

高折光紫外光-热双重固化树脂的合成及其性能

合成了同时具有光固化基团(双键)和热固化基团(环氧)的高折光紫外光-热双重固化树脂,用红外光谱、核磁共振氢谱、质谱表征了树脂结构。配制了一系列紫外光-热双重固化体系,用红外光谱表征了固化过程特征吸收峰的变化;测试了紫外光-热双重固化膜的凝胶率、吸水率、体积收缩率、折光率和表面水接触角。结果表明,高折光紫外光-热双重固化树脂固化后凝胶率可以达到96.4%以上,吸水率在0.87%以下,体积收缩率在6.87%以下,水接触角在60°左右,为亲水性表面。在相同稀释剂条件下,与双酚A环氧丙烯酸单酯光-热固化膜相比,其折光率由1.3014提高到1.5723。     

Weight change mechanism of randomly oriented GFRP panel immersed in hot water

This study deals with the weight changes of the fiber/matrix interface and the weight change mechanisms of the randomly oriented E-glass fiber continuous strand mat reinforced unsaturated polyester panels. The weight changes were evaluated by introducing the weight gain due to water absorption (M_g) and the weight loss due to matrix dissolution (M_l). The weight changes of the fiber/matrix interface (M_gI and M_lI) were obtained from the difference of M_g and M_l between GFRP and neat resin. Water absorption of the interface occurred after water absorption of matrix resin reached saturation. Weight loss due to dissolution of binder on glass-fiber mat and matrix from the interface occurred after water penetration into the interface. The debondings at the fiber/matrix interface occurred due to water penetration, and as a result, the binder and matrix dissolved easily in the water through the interface. The weight changes of the GFRP panel were classified into three phases. In phase I, only the resin matrix absorbed water. In phase II, the fiber/matrix interface absorbed water. After that phase, water absorption into the fiber/matrix interface and matrix dissolution from the interface occurred simultaneously.     

Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400-750 nm spectral range

The temperature and salt dependencies of absorption by liquid water (H2O) and heavy water (D2O) were determined using a hyperspectral absorption and attenuation meter (WET Labs, AC-S). Sodium chloride (NaCl) was used as a proxy for seawater salts. There was no significant temperature (PsiT) or salt (PsiS) dependency of absorption at wavelengths <550 nm. At wavelengths >550 nm, PsiT exhibited peaks at approximately 604, 662, and 740 nm. A small negative trough in PsiS occurred at approximately 590 nm, followed by a small positive peak approximately 620 nm, a larger negative trough at approximately 720 nm, and a strong positive peak at approximately 755 nm. The salt dependency of absorption by heavy water, Psis(H), exhibited a negative power-law shape with very low Psis(H), at wavelengths >550 nm. Our experiments with NaCl, clean open ocean seawater, and artificial seawater support the hypothesis that salts modify the absorption spectra of seawater by modifying the molecular matrix and vibrations of pure water.