吸水膨胀橡胶的研究进展

吸水膨胀橡胶是重要的工程防水材料,其既可以吸水止水,还能膨胀受压止水,而且施工便利,在地下施工、水利工程中起到关键作用。但是由于其内部橡胶基体与高吸水树脂相容性差,常会造成反复吸水后止水效果下降,需要频繁更换产品,甚至带来巨大损失。因此,吸水膨胀橡胶的制备及改性研究受到关注。文中综述了吸水膨胀橡胶的机理、制备方法及相关改性研究,对吸水膨胀橡胶研究中存在的问题进行了分析,提出了今后的研究方向。     

温敏可控型吸水树脂的合成及性能研究

以丙烯酸钠为单体,采用四烯丙基氯化铵(TAAC)和N,N-亚甲基双丙烯酰胺(NMBA)复合交联剂,通过水溶液聚合法制备了温敏可控型吸水树脂。考察了复合交联剂用量、交联剂摩尔配比和温度对吸水树脂吸水性能的影响,并对所制备的吸水树脂结构进行红外表征。结果表明,吸水树脂的吸水倍率在100℃以下很小,高于150℃明显增大,且通过改变复合交联剂总用量及交联剂物质的量之比可控制吸水树脂在低温和高温下的吸水倍率。另外,吸水树脂对温度敏感,改变温度可控制其吸水速率和吸水倍率。     

腐植酸/丙烯酸型吸水树脂的研究进展

介绍了腐植酸/丙烯酸型吸水树脂的合成与表征,综述了腐植酸/丙烯酸型吸水树脂的性能及应用,指出了目前腐植酸/丙烯酸型吸水树脂的优点与不足,展望了其未来的发展方向。     

高倍吸水树脂抑尘剂在公路施工中的应用

本文论述了高倍吸水树脂及其主要性能,并对其抑尘机理进行了分析,在此基础上探讨了高倍吸水树脂抑尘剂在公路施工中的应用。     

吸水树脂粒径对吸水膨胀丁腈橡胶性能的影响

以丁腈橡胶为基体材料,不同粒径的聚丙烯酸钠为吸水组分,通过物理共混法制备了吸水膨胀橡胶,并对其力学性能、吸水性能以及吸水组分在橡胶中的分散性做了表征。结果表明,吸水树脂的粒径对吸水膨胀橡胶的性能有显著影响,吸水树脂粒径越小,其在橡胶中的分散性越好,吸水膨胀橡胶的力学性能和吸水性能越好。当吸水树脂的粒径为200目时,吸水膨胀橡胶的拉伸强度达到13.48MPa,吸水膨胀率达到150%。     

泡沫夹层复合材料耐水性能研究进展

泡沫夹层复合材料作为一种新型轻质高强材料，目前越来越受到航天、航海及能源等领域的重视，但其应用大部分仍局限于次级结构，主要是由于其可靠性评价未得到广泛深入研究。概述了其吸水性能、吸水后静态和动态力学性能及断裂韧性变化规律，最后提出了防水措施。     

腐植酸／丙烯酸型吸水树脂的研究进展

介绍了腐植酸／丙烯酸型吸水树脂的合成与表征，综述了腐植酸／丙烯酸型吸水树脂的性能及应用，指出了目前腐植酸／丙烯酸型吸水树脂的优点与不足，展望了其未来的发展方向。     

聚丙烯酸钠用量对聚丙烯酸钠/丁腈橡胶硫化胶性能的影响

以丁腈橡胶为基体材料,粒径74μm的聚丙烯酸钠为吸水组分,通过物理共混法制备了聚丙烯酸钠/丁腈橡胶硫化胶,对其流变性能、吸水性能以及吸水膨胀过程进行了表征,利用拉曼光谱仪、傅里叶变换红外光谱仪分别对其吸水过程和吸水后析出物进行了研究。结果表明:吸水树脂聚丙烯酸钠用量超过40份时,其在橡胶基体中更容易团聚,难以分散,Payne效应增强,储能模量和损耗因子增加。随着聚丙烯酸钠用量的增加,聚丙烯酸钠/丁腈橡胶硫化胶的吸水速率增大,且最大吸水膨胀率明显增大;当聚丙烯酸钠用量为50份时,聚丙烯酸钠/丁腈橡胶硫化胶最终吸水膨胀率达到171.65%。但是拉曼光谱研究发现,试样表层的聚丙烯酸钠在20s左右完全析出,当聚丙烯酸钠用量为50份时,质量损失率达到21.25%。傅里叶变换红外光谱及热重分析表明,聚丙烯酸钠/丁腈橡胶硫化胶析出物大部分为聚丙烯酸钠,同时还含有少量的橡胶加工助剂。     

共混型吸水膨胀橡胶的制备与表征

以丁苯橡胶(SBR)/氯丁橡胶(CR)和吸水型高岭土为主要原料,采用物理共混法制备了吸水膨胀橡胶(WSR),讨论了补强剂(改性白炭黑)、吸水材料和硫磺用量等因素对WSR吸水及力学等各种性能的影响,采用zry-2p综合热分析仪对其热性能进行了分析。结果表明:当SBR/CR(质量比7∶3):高岭土:白炭黑:硫化剂质量比为1:0.4:0.3:0.01时,WSR的拉伸强度大于0.2 MPa、质量损失小于16%、吸水膨胀率大于1000%,具有良好的综合性能。     

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。     

Analysis and interpretation of a test for characterizing the response of sandwich panels to water blast

Metallic sandwich panels are more effective at resisting underwater blast than monolithic plates at equivalent mass/area. The present assessment of this benefit is based on a recent experimental study of the water blast loading of a sandwich panel with a multilayered core, using a Dyno-crusher test. The tests affirm that the transmitted pressure and impulse are significantly reduced when a solid cylinder is replaced by the sandwich panel. In order to fully understand the observations and measurements, a dynamic finite element analysis of the experiment has been conducted. The simulations reveal that the apparatus has strong influence on the measurements. Analytic representations of the test have been developed, based on a modified-Taylor fluid/structure interaction model. Good agreement with the finite element results and the measurements indicates that the analytic model has acceptable fidelity, enabling it to be used to understand trends in the response of multilayer cores to water blast.     

复合结构隔声理论分析与实验特性研究

基于无限大分层介质波传递理论,采用传递矩阵方法和声能量分布理论,开展了水下复合阻尼结构隔声特性的研究。仿真结果表明橡胶材料属性对结果隔声有很大的影响。软和小泊松比的橡胶可以明显提高结构的隔声特性。多层橡胶复合结构在隔声方面比单层复合结构具有更大的优势,在多层橡胶中打孔可有效提高结构的隔声性能。空腔越多,隔声特性越好。蜂窝三明治复合结构的隔声特性要好于含圆柱空腔复合结构的隔声性能和多层均匀复合结构。结合现有的试验条件,在消声水池开展了蜂窝三明治复合结构自由场大样测试,实验结果表明,测量值与理论预测有很好的一致性。     

Effect of nanomodified polyester resin on hybrid sandwich laminates

Effect of nanoclay modified polyester resin on flexural, impact, hardness and water absorption properties of untreated woven jute and glass fabric hybrid sandwich laminates have been investigated experimentally. The hybrid sandwich laminates are prepared by hand lay-up manufacturing technique (HL) for investigation. All hybrid sandwich laminates are fabricated with a total of 10 layers, by varying the extreme layers and wt% of nanoclay in polyester resin so as to obtain four different combinations of hybrid sandwich laminates. For comparison of the composite with hybrid composite, jute fiber reinforced composite laminate also fabricated. X-ray diffraction (XRD) results obtained from samples with nanoclay indicated that intergallery spacing of the layered clay increases with matrix. Scanning electron microscopy (SEM) gave a morphological picture of the cross-sections and energy dispersive X-ray spectroscopy (EDS) allowed investigating the elemental composition of matrix in composites. The testing results indicated that the flexural properties are greatly increased at 4% of nanoclay loading while impact, hardness and water absorption properties are increased at 6% of nanoclay loading. A plausible explanation for high increase of properties has also been discussed.     

Geometrically nonlinear forced vibrations of the symmetric honeycomb sandwich panels affected by the water

Geometrically nonlinear forced vibrations of the symmetric rectangular honeycomb sandwich panels with the four edges simply supported and one surface affected by the water are investigated in this paper using the homotopy analysis method (HAM). The honeycomb core of hexagonal cells is modeled as a thick layer of orthotropic material whose physical and mechanical properties are determined using the Gibson correlations. The effect of water acting on honeycomb panels can be described as added mass, additional damping and additional stiffness coefficients which are obtained by the semi-analytical fluid pressures. The basic formulation of nonlinear forced vibrations has been developed base on the third-order shear deformation plate theory and Green Lagrange nonlinear strain–displacement relation. The equilibrium equations have been obtained using the Hamilton’s principle. Effects of water velocity, height and height ratio on the nonlinear forced vibration response have been studied for the honeycomb sandwich panels.     

Structural Performance of Precast and Cast-in-situ Ultra High Strength Concrete Sandwich Panel

This paper investigates the flexural performance of a sandwich panel made up of ultra high strength concrete (UHSC) as top and bottom skin and cold formed steel as sandwich. A novel sandwich panel has been designed such a way that bottom skin of UHSC is of precast in nature and top skin of UHSC is cast-insitu and cold formed steel (profiled sheet) as sandwich. The connection between top skin of UHSC and cold formed steel is made with self tapping screws. Flexural performance of UHSC sandwich panel has been tested under flexural loading and it is found that the post peak response of the panel is significant in terms of more energy absorption. It is observed that the final failure of the specimen is occurred by forming a dominant crack on the bottom face of the skin apart formation of many multiple cracks with increase of load. Numerical investigations have been carried out by simulating the experimental conditions and found that the response obtained through simulation is in good agreement with the corresponding experimental values. From the studies, it can be concluded that UHSC steel sandwich panels can be employed for structural and non structural applications.     

碳纤维增强聚合物复合材料方形蜂窝夹层结构水下爆炸动态响应数值模拟

基于ABAQUS有限元仿真软件,建立了不同夹芯相对密度的碳纤维增强聚合物（Carbon Fiber Reinforced Polymer,CFRP）复合材料方形蜂窝夹层结构在水中爆炸冲击波载荷作用下的仿真模型,分析了结构的变形过程、夹芯的压缩特性及结构的失效及破坏情况。数值模拟结果表明,CFRP复合材料蜂窝夹芯压缩量在前面板速度降至与后面板相同时达到最大; CFRP复合材料蜂窝夹芯的最大压缩量随着初始压力的增大呈先缓慢增大后快速增大的趋势,其增大趋势在夹芯接近完全压缩时又趋于缓慢; CFRP复合材料夹层结构失效随夹芯相对密度和初始压力的变化呈现不同的模式,且其防护性能优于等重的层合结构。研究结果可以为复合材料夹层结构在水中冲击波载荷防护中的应用提供参考。      

湿热环境对PMI泡沫夹芯复合材料性能的影响

采用聚甲基丙烯酰亚胺（PMI）泡沫、碳纤维增强环氧树脂（EW220/5258）复合材料面板制备了PMI泡沫夹芯复合材料,研究了PMI泡沫夹芯复合材料、EW220/5258复合材料面板及PMI泡沫芯材的吸湿特性,并讨论了湿热对PMI泡沫夹芯复合材料的压缩性能及介电性能的影响。结果发现：PMI泡沫夹芯复合材料的饱和吸湿时间...     

Analytical determination of the ultimate strength of sandwich beams

An analytical determination of the ultimate strength of a typical GRP/PVC sandwich beam has been performed. These beams represent common building practise in marine applications. Equations describing the behaviour of a sandwich panel under beam loading and various failure modes have been developed. The method has been applied to predict the ultimate load for a simple supported sandwich beam. The critical loads have been compared with those from the experimental investigation of a typical bulkhead-to-hull GRP/PVC sandwich T-joint under pull out forces.     

一种用于阻尼夹层板传声损失（TL）计算的等效参数法

本文给出一种用于阻尼夹层板传声损失（ＴＬ）计算的简化方法──等效参数法，将该方法应用于对称及非对称阻尼夹层板的ＴＬ计算，并与按照复杂的Ｃｈｏｎａｎ＆Ｋｕｇｏ关于复合板的波传递理论经数值计算得出的ＴＬ值进行了比较．结果表明：对于在噪声控制工程中人们感兴趣的频率范围，这种简化方法能够给出较为满意的结果．     

城市排水系统的现代观

在当今水环境劣化趋势日益严峻,水资源日益短缺的势态下,在污水深度处理、超深度处理和回收利用已经实用化了的今日,排水系统不应仅仅是排除雨水、污水及保护城市环境和公共水域水质的基础设施,更应升华为维系城市健康水循环和良好水环境,实现水资源可持续利用的人类社会的生命线工程。城市污水作为可贵的淡水资源已为世人所瞩目。文章阐述了在排水系统功能、规划和设计方面的新构想和新观念。