纳米蒙脱土对遇水膨胀丁腈橡胶性能的影响

以纳米蒙脱土为增强剂与丁腈橡胶、吸水树脂(交联聚丙烯酸钠)等共混,制备了遇水膨胀橡胶。用扫描电镜观察了遇水膨胀橡胶的形貌,测试了力学和吸水膨胀性能。结果表明,添加纳米蒙脱土能显著提高遇水膨胀橡胶吸水前后的力学强度,改善橡胶中吸水树脂的分散性,降低其质量损失率。另外,研究了纳米蒙脱土含量对遇水膨胀橡胶吸水率的影响,对遇水膨胀橡胶在酸、碱、盐水和高温去离子水等不同介质溶液中的膨胀行为进行了探讨。     

遇水膨胀聚氨酯后浇止水带的研制与应用

采用聚醚多元醇、TDI、MOCA等制备了遇水膨胀聚氨酯后浇止水带,研究了聚醚配比、预聚体异氰酸根含量、填料加入量、以及止水带反复遇水膨胀等对止水带性能的影响;阐述了遇水膨胀聚氨酯后浇止水带的施工方法.实验结果表明实验最佳的配比为:聚醚TEP5:聚醚TED28=80:20;异氰酸根含量4.5％;轻质碳酸钙用量为15％;产品经地铁实际使用3年未出现漏水现象,效果良好.     

遇水膨胀聚氨酯液体橡胶的研制与应用

针对遇水膨胀橡胶吸水膨胀后,吸水树脂从橡胶网络通道中游离析出问题,采用聚醚多元醇、甲苯二异氰酸酯以及助剂等,制备双组份遇水膨胀聚氨酯液体橡胶,探索了聚醚配比、-NCO含量、填料以及催化剂对产品性能的影响,确定了实验配比:聚醚TEP-505S∶聚醚TED2817=90∶10(质量比),w(-NCO)=4.5%,w(填料)=8%,w(二月桂酸二丁基锡)=0.1%,实验结果表明,遇水膨胀聚氨酯液体橡胶体积膨胀率518%,拉伸强度2.0MPa,用于建筑物的防水施工效果良好。     

遇水膨胀丁腈橡胶力学性能与膨胀性能的研究

以丁腈橡胶为基体,白炭黑为增强材料,混入高吸水树脂和其他橡胶助剂制备出树脂型丁腈基遇水膨胀橡胶.研究了吸水树脂用量、白炭黑用量对吸水膨胀橡胶的力学性能和吸水膨胀性能的影响,并研究了硫化时间、介质温度对吸水膨胀行为的影响.结果表明:吸水树脂用量的增加有利于提高橡胶膨胀性能,但力学性能降低;白炭黑用量的增加有利于提高力学性...     

钙矾石的结构变异对膨胀水泥膨胀性的影响

通过DTA,X射线衍射分析和SEM观察及与膨胀率和强度的对比分析,给出了钙矾石稳定存在和结构变异的温度范围及其对砂浆膨胀和强度的影响.结果表明,(1)在干热条件下钙矾石在87-150℃之间发生快速脱水,结构极度扭曲失去晶体特征,但结构并不崩溃分解,遇水后即可恢复.100℃以下的湿热条件下,钙矾石可生成和稳定存在;(2)尽管100℃以下的干燥条件膨胀水泥混凝土的强度不降低,但膨胀会完全丧失,甚至产生负膨胀.故膨胀水泥和自应力水泥不宜在70℃以上的干燥环境和干-湿交替的环境中使用.     

考虑膨胀土地基膨胀率和刚度沿深度变化的桩-土共同作用解析解

膨胀土地基中,土的膨胀率和刚度沿深度变化明显:较深位置的膨胀土应力水平较高,一方面遇水的膨胀率较小,另一方面土的刚度较大。该文基于桩-土相互作用机理,利用荷载传递法推导了考虑膨胀土沿深度膨胀率减小、刚度增加的单桩理论求解方程,并得到了级数形式的解析解。理论解与现场和模型试验数据符合较好,尤其是轴力沿桩身发展的模式。之后该文在膨胀土层的平均膨胀率和平均模量不变的前提下,分析了不同膨胀位移分布模式和刚度分布模式对桩受力和变形的影响,发现若按传统的土沿深度膨胀率和刚度为常值计算,将过高地估计单桩的轴力和位移。利用此解析解还讨论了膨胀土中桩的临界压重。     

膨胀土地铁车站深基坑桩间土失稳特征研究

膨胀土具有超固结性、多裂隙性以及遇水膨胀失水收缩开裂等特性,导致地下空间工程建设中经常发生桩间土坍塌等基坑失稳现象,造成人员受伤或设备损坏等安全事故,严重制约着工程施工的安全和进度。该文以成都轨道交通17号线二期东延线车站深基坑开挖支护桩桩间土为研究对象,运用现场调查、实测分析、失稳特征分析、桩间土稳定性计算推导等方法,对成都地区膨胀土地铁车站深基坑支护桩桩间土失稳特征进行系统研究,提出膨胀土地铁车站深基坑支护桩桩间土失稳特征及原因。     

新型固化剂加固膨胀土研究现状及展望

膨胀土具有遇水膨胀软化、失水干缩硬裂的不良工程性质，物理化学加固是膨胀土地区基础处理研究领域的重要课题，膨胀土固化研究对解决膨胀土工程病害有重要理论价值和广阔应用前景。为了系统分析化学材料对膨胀土物理力学特性的影响，探讨其加固机理，本文总结了目前已被证明能有效改善膨胀土工程特性的多种固化剂，并按照化学组成将其分为无机类、有机类和生物类，分别对其物质组成、加固机理、固化效果和应用现状展开详细阐述。然后总结分析已有研究成果，提出今后膨胀土加固研究需侧重以下方面：（1）紧密结合工程实际，加强固化膨胀土物理力学特性和耐久性研究；（2）探索组合型固化剂，以降低成本，增强加固效果；（3）重视学科交叉，深化固化剂加固基础理论研究。     

粉煤灰中SO3对路面基层的危害分析

石灰粉煤灰稳定碎石基层松散从而导致沥青路面结构开裂，起拱，经分析是由于基层中粉煤灰原材料SO3含量偏高，遇水后产生化学反应造成结构体积膨胀，最终导致基层和面层整体破坏。本文针对石灰粉煤灰稳定碎石基层沥青路面起拱开裂的问题对其原因进行深度分析。     

麻袋墙的施工

1992年笔者在肯尼亚塔依塔舔盐湖希尔屯旅馆的扩建工程中所遇到的混泥土的一种新的施工方法,即为混泥土麻袋墙的施工.本文针对麻袋墙的施工方法进行探讨,首先介绍了麻袋墙施工前需要做好麻袋、工具和材料这三方面的准备;其次,分析了麻袋墙的施工过程及方法;最后阐明了施工时需要注意的事项.该方法施工简单、易操作且能有效的节约模板,因此,值得推广.     

淀粉/NaAA/CR吸水复合材料的性能在去离子水和盐溶液中的差异

采用机械共混法制备了淀粉/丙烯酸钠(NaAA)/氯丁橡胶(CR)吸水复合材料,考察了去离子水和3.5%(质量分数)NaCl溶液两种吸水介质对其力学性能和吸水性能的影响,并且观察了复合材料吸水前后的微观形貌。结果表明浸水后,随吸水量的增加,材料力学性能的降低;复合材料在盐溶液中的吸水率远小于在去离子水中的吸水率;在反复使用过程中,能够很好地保持其原有的吸水性能,具有优异的反复使用性能;通过扫描电子显微镜(SEM)观察了复合材料吸水前后的微观形态结构,吸水组分聚NaAA颗粒吸水干燥后表面发生褶皱。     

吸水膨胀材料的研究现状

吸水膨胀材料是一种新型高分子功能材料,具有吸水、膨胀变形特性,在建筑工程、油田开采、农林生产、医疗卫生等诸多领域已有广泛的应用。本文概述了吸水膨胀材料的发展历史、吸水膨胀机理,重点介绍了吸水膨胀材料的制备方法、改性方式,并就吸水膨胀材料的发展趋势进行了展望。     

AMPS/AAM凝胶响应性能的研究

利用自由基聚合法合成了AMPS/AAM共聚凝胶,研究了该凝胶的溶胀性能和电响应性能,实验结果表明:凝胶的溶胀性能和电响应性能受凝胶的单体配比、溶液的离子强度和所施加的电场强度等因素的影响。     

大孔径深孔含水爆破混装乳化炸药性能研究

大孔径深孔含水爆破中,混装乳化炸药受到来自炸药本身重压、回填渣的压力以及炮孔中水的侵蚀,炸药爆炸性能发生改变。为了分析压力及水对混装乳化炸药的影响规律,提出了一种新型乳化炸药抗压性试验方法,模拟了深孔爆破环境气泡敏化的混装乳化炸药的爆速随孔压变化规律:0.1、0.2 MPa下24 h内爆速较高,随着压力增加及加压时间的延长,爆速下降直至拒爆;同时,通过测试乳胶基质中硝酸铵的溶失值以及乳胶基质的溶胀厚度,分析了乳化剂、油相材料对其抗水稳定性的影响。结果表明:添加质量分数1%的基础油,Span80、高分子型乳化剂EPE-1添加质量比达到1:1后,溶失值及溶胀厚度较小;再增加EPE-1的含量,抗水性、稳定性基本不发生变化。提出了提高混装乳化炸药抗水稳定性的方法。     

Electrospun multi-scale hybrid nanofiber/net with enhanced water swelling ability in rubber composites

Water-swellable rubber (WSR) is a kind of elastomeric material that possesses properties of rubber together with water swelling ability. In WSR, however, super water-absorbent resin does not disperse well in hydrophobic rubber, with very poor interfaces between them, so the hydrophilic part can easily break off from rubber networks and the swelling ability is ultimately lost. This study reports the improved water absorption property and stability of WSR obtained by using electrospun multi-scaled hybrid fiber mats of crosslinked poly(acrylic acid) (PAA) nanocomposite as water channels. Electrospinning of various superabsorbent fibers with hyperbranched polymer (HB) and/or graphene oxide (GO) was performed. With hybrid fillers added into PAA, spun fiber mats showed the increased water swelling ability due to the presence of spiderweb-like multi-scale structures and enhanced specific surface areas. The mats were added into conventional WSR and the resultant composites showed enhanced water swelling ability. The electrospun fibers acted as internal multi-scale water channels to bridge isolated PAA particles wrapped in hydrophobic rubber together and link the internal PAAs with the composite surface to enhance the short- and long-term water swelling ability of WSR. The effects and mechanisms of those fibers on enhancing water swelling properties of WSR are discussed.     

安全柴油燃爆性能的静爆试验研究

为掌握安全柴油的燃爆性能,以便进一步完善制备工艺,提高其安全性能,开展了炸药起爆、引燃普通柴油(1＃柴油)以及不同含水量(质量分数)的安全柴油(2＃、3＃柴油)的静爆试验,并采用高速照相机、红外热成像仪分别记录了试验过程和火球的表面温度。试验结果表明：1＃、2＃、3＃柴油云雾被引燃形成火球所需的初始点火能量逐渐增大,而2＃、3＃柴油火球的尺寸和表面平均温度则小于1＃柴油;1＃柴油的池火持续时间达到125 s,而2＃、3＃的池液只是出现闪燃现象,未形成池火,表现出了较强的自熄灭能力。因此,安全柴油具有较好的阻燃抑爆能力,而将它的含水量控制在合适的水平是提高其安全性能的重要方法。     

Polyampholytes superabsorbent nanocomposites with excellent gel strength

A series of novel polyampholyte superabsorbent nanocomposites with excellent gel strength were synthesized by in situ solution polymerization in aqueous solution. Acrylic acid and acryloyloxyethyl trimethyl ammonium chloride (DAC) were employed as ionic monomers and montmorillonite (MMT) was used as inorganic component. The addition of cationic component could supply the positive charge in the network of nanocomposite and promote the formation of nanostructure of composites due to the interaction between DAC and clay platelets. The performance of polyampholyte nanocomposites were investigated and the result showed that the gel strength of nanocomposite hydrogel in distilled water and 0.9 wt% NaCl solution could reach 198.85 and 204.23 mJ/g, respectively, which were 13 times of the gel strength of matrix. The investigation of swelling behaviors showed that the nanocomposites had particular swelling behaviors of polyampholytes hydrogel in solution with different pH values and concentration of NaCl.     

External stimuli response on a novel chitosan hydrogel crosslinked with formaldehyde

Keeping in mind the significance of hydrogels as an external stimuli sensitive super absorbing material, some transparent covalent hydrogels of chitosan were prepared by crosslinking with varying amounts of formaldehyde solution used as crosslinking agent. The characteristics of hydrogels were investigated by Fourier transform infrared (FT-IR) spectroscopy and swelling experiments. The effect of crosslinking agent on water absorbency has been investigated. The hydrogels exhibited a relatively higher swelling ratio in the range of 2066–3306% and equilibrium water content (EWC) in the range of 95-38–97 06% at pH 7 and 35°C temperature. The influence of external stimuli such as pH, temperature, and ionic strength of the swelling media on equilibrium swelling properties has been observed. Hydrogels showed a typical pH and temperature responsive behaviour such as low pH and high temperature has maximum swelling while high pH and low temperature show minimum swelling. An increase in the ionic strength of swelling media caused a continuous decrease in the swelling of hydrogels at both acidic and basic pH.     

Water Absorption and Thickness Swelling Behavior of Polypropylene Reinforced with Hybrid Recycled Newspaper and Glass Fiber

This study aims to investigate the moisture absorption of recycled newspaper fiber and recycled newspaper-glass fiber hybrid reinforced polypropylene composites to study their suitability in outdoor applications. In this work composite materials were made from E-glass fiber (G), recycled newspaper (NP) and polypropylene (PP), by using internal mixing and hot-pressing molding. Long-term water absorption (WA) and thickness swelling (TS) kinetics of the composites was investigated with water immersion. It was found that the WA and TS increase with NP content in composite and water immersion time before an equilibrium condition was reached. Composites made from the NP show comparable results as those made of the hybrid fiber. The results suggest that the water absorption and thickness swelling composite decrease with increasing glass fiber contents in hybrid fiber composite. It is interesting to find that the WA and TS can be reduced significantly with incorporation of a coupling agent (maleated polypropylene) in the composite formulation. Further studies were conducted to model the water diffusion and thickness swelling of the composites. Diffusion coefficients and swelling rate parameters in the models were obtained by fitting the model predictions with the experimental data.     

Disintegrating Agents in Hard Gelatin Capsules. Part II: Swelling Efficiency

Abstract

The wicking and swelling properties of pure disintegrants were investigated from plugs prepared under conditions similar to those used in encapsulation of powder mixtures into hard gelatin capsules. Pure AcDiSol exhibited the greatest wicking and swelling action followed by Primojel, Polyplasdone-XL 10 and corn starch. The swelling properties of pure disintegrants correlated best with the swelling of formulation mixtures and the efficiency of these materials in enhancing the dissolution of hydrochlorothiazide. A change in the penetrating liquid from dilute acid to water altered the liquid uptake and swelling of AcDiSol and Primojel but not those of Polyplasdone-XL 10 and corn starch. The extent of swelling per unit volume of liquid absorbed, defined as the swelling efficiency, varied with time and type of disintegrant. The swelling efficiencies of pure AcDiSol and corn starch were unaffected by the nature of the penetrating liquid while Primojel and Polyplasdone-XL 10 exhibited greater efficiencies in water than in dilute acid. All disintegrants lost part of their efficiency when incorporated in capsule formulations, especially in very hydrophilic matrices. The rate of wicking action could be a limiting step in the rate and extent of swelling of a disintegrant and hence hinder its efficacy in hard gelatin capsules.