ETFE膜材料在地铁出入口设计中的应用研究

ETFE膜材料凭借其本身的耐久性、环保性、透光性及自清洁性等优良特性,近年来在国内外的大型建筑中被广泛应用,具有很好的发展前景。首先介绍了ETFE膜材料及其结构类型,其次主要在应用性能、视觉形态及低碳节能上,分析了ETFE膜材应用于地铁出入口设计中所表现出的优势,然后结合郑州大学(南区)地铁站出入口设计,介绍了以ETFE膜材料为依托的地铁站出入口新形式、轻钢骨架结构以及模数化的主要做法。     

新广州火车站ETFE膜结构应用及安装关键技术

从新广州火车站的膜结构屋盖的应用,介绍ETFE膜结构的膜材、结构、荷载、特点,并介绍ETFE膜结构在大跨度预应力索壳及网壳屋盖上部安装的有关关键技术及注意问题。     

ETFE膜结构在建筑中的应用

乙烯-四氟乙烯ETFE膜材作为特殊建筑材料,基于其优越的采光性能、材料及结构轻盈等专有特点,逐渐被广泛用于商业中庭、植物温室、高速收费站等建筑结构中。通过ETFE材料膜结构工程实例,介绍单层ETFE构成应用,双层或多层ETFE气枕构成应用,及ETFE与PTFE或PVC交叉构成应用。     

ETFE薄膜材料

ETFE薄膜材料是一种新型的建筑膜材,具有透光率高、耐久性好、自洁性能优异等特点,在植物园、游泳馆、体育场等大跨度建筑中得到越来越多的应用。本文对ETFE薄膜材料性能作了简单的介绍,对材料特点作了描述,为ETFE薄膜建筑提供材料方面的基本信息。     

大连体育场膜结构屋面及其防排水设计

膜结构技术主要采用的膜材有ETFE和PTFE,大连体育场膜结构屋面同时采用了这两种膜材。文章介绍了ETFE充气膜系统和PTFE张拉膜系统,重点阐述了膜结构屋面的防排水原理和防排水构造的细节处理。     

ETFE膜高空竖向平面张拉技术在延庆海坨塔中的应用

延庆海坨塔采用高空竖向平面聚氟乙烯（Ethylene Tetra Fluoro Ethylene，以下简称ETFE）张拉膜施工技术，目前国内ETFE膜大范围应用于屋面结构，对于竖向结构，仅在高度较低的环境下采用ETFE膜片或采用充气膜形式进行装饰，不能完全发挥ETFE膜的各项优点。因此，此类安装方式可提高ETFE膜的适用范围，能得到推广性应用，带来显著的社会效益。通过介绍ETFE膜从深化设计、加工制作到膜材安装的施工工艺，旨在形成完善的施工工艺流程及施工保障措施，为类似工程提供借鉴经验。     

ETFE膜材在绿色建筑中的应用前景

随着ETFE膜材使用超过30年,其结构形式也逐渐发生变化,从最初的整体充气,到后来的张拉膜,再到现在流行的充气气枕。膜结构作为技术与艺术完美的结合体,近几十年来正受到越来越多建筑师的青睐,特别是以ETFE气枕式膜结构为代表的充气式膜结构体系,其轻盈、通透、具有可持续性等特点使其在众多建设项目中大放异彩。然而,由于膜材本身的局限性(徐变、本构关系不清楚等),限制了ETFE膜材的进一步利用。本文从轻型建筑最优化原则入手,总结了ETFE膜材的各项性能,分析认为ETFE膜材是建造绿色轻质建筑的良好选择。指出该材料在未来将进一步替代玻璃幕墙,成为围护结构的重要组成部分。     

ETFE薄膜的材料性能及其工程应用综述

就ETFE薄膜的材料性能、在膜结构工程中的应用形式、ETFE气垫的工作原理、膜材连接方法、典型工程等进行综述     

空间仿生ETFE薄壳结构位形控制关键技术

ETFE膜材设计收缩率小、强度低,对钢结构施工有更高的安装精度要求。以广州宏城广场天幕的建造过程为背景,提出了单层网壳分块安装方法,介绍了三维坐标预调整技术,卸载全过程变形监测和大面积ETFE膜安装等整套空间仿生ETFE薄壳结构的施工技术,解决了ETFE膜边界精度控制要求高的难题。     

国家游泳中心(水立方)ETFE膜结构技术在水立方中的应用

国家游泳中心(水立方)是2008年北京奥运会三大标志性建筑物之一,采用ETFE膜结构作为围护系统.本文简述了ETFE膜材的特性和优缺点,重点介绍了国家游泳中ETFE膜结构的工作原理、设计、加工制作和现场安装.     

当前我国防水材料行业发展中存在的几个问题

指出了我国建筑防水行业发展中存在的一些问题，如屋面防水材料与地下防水材料不加区分，改性沥青防水卷材质量呈现明显劣化的趋势．高分子防水卷材发展偏离方向等等，以期引起行业人士的重视。     

为提高我国改性沥青卷材的质量建言献策

分析了我国改性沥青防水卷材生产与应用中存在的问题以及与国外相比存在的差距；提出提高我国改性沥青卷材质量的几个建议，涉及胎体、改性材料、粘接方法、质量保证等诸多方面。     

堆石体灌水法密度试验薄膜探讨

目前,我国堆石坝技术已较为成熟,堆石体是筑坝和围堰结构的重要组成部分,而碾压方式下堆石体的干密度是影响坝体变形的主要因素,也是大坝填筑质量的主要控制指标之一。现场常采用挖坑灌水法来测定其填筑的密实度,挖坑灌水法原理简单,操作简便,但要测定准确却非常困难,且薄膜厚度对测定结果也存在一定影响,现介绍某工程采用挖坑灌水法测定堆石体填筑密度过程中,采用两种厚度薄膜进行试验比对的工程经验。     

防水材料耐根穿刺性能植物检测试验阶段性研究报告

国内种植屋面用防水材料耐根穿刺性能植物检测试验参试试样中已有24种合格。试验表明,化学试剂对防水材料的耐根穿刺性能和模式植物的生长影响较大,改性沥青类防水卷材必须添加适量化学阻根剂才能通过试验;PVC卷材含有的增塑剂对植物生长不利。防水材料的施工工艺对其耐根穿刺性能有影响,各类材料都要注意搭接缝的处理。针对试验过程中发现的问题,文中还提出了应适时修改JC/T 1075—2008等建议。     

A transport mechanism in hollow nylon fiber reverse osmosis membranes for the removal of ddt and aldrin from water

The DuPont hollow nylon fiber reverse osmosis membranes were investigated for use in the removal of DDT and Aldrin from aqueous solution. Because these membranes were developed for the demineralization of brackish waters the removal characteristics for the pesticides were compared with the removal characteristics for the ions commonly found in brackish and hard waters. These membranes rejected 85–95 per cent of the brackish-producing ions. Such inorganic ions with respect to the membrane were classified as membrane-non-interacting solutes. DDT and Aldrin were classified as membrane-interacting solutes, and thus the concept of solute rejection by the membrane was different from that which had been developed for the inorganic ions.     

High-performance thin-layer hydrogel composite membranes for ultrafiltration of natural organic matter

Thin-layer hydrogel composite (TLHC) ultrafiltration (UF) membranes were synthesized by photo-grafting of either poly(ethylene glycol) methacrylate (PEGMA) or N,N-dimethyl-N-(2-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (SPE) onto commercial polyethersulfone (PES) UF membranes. The performance of TLHC UF membranes was evaluated for natural organic matter (NOM) filtration and compared to commercial PES UF membranes. The fouling evaluation was done by investigation of membrane-solute interactions (adsorptive fouling) and membrane-solute-solute interactions (UF). The results suggest that the TLHC membranes convincingly displayed a higher adsorptive fouling resistance than unmodified PES UF membranes. In long-term stirred dead-end UF, a much lower fouling was observed for TLHC membranes than for commercial membranes with the same flux and rejection. Further, water flux recovery was also much higher. An analysis using an existing blocking model was performed in order to elucidate the effect of a polymer hydrogel layer on fouling mechanism as well as cake layer characteristics. The TLHC membranes synthesized by photo-grafting of PEGMA (40 g/L) and PEGMA with a low concentration of cross-linker monomer in the reaction mixture (ratio: 40/0.4 (g/L)/(g/L)) showed a much better performance than the other composite membranes. Those membranes could reduce the cake resistance on the membrane surface. This work has relevance for the design of high-performance UF membranes for applications in water treatment.     

Assessing the effects of sodium hypochlorite exposure on the characteristics of PVDF based membranes

Sodium hypochlorite is commonly used as a cleaning agent to remove adsorbed foulants from PVDF based micro/ultra filtration membranes in water and wastewater treatment applications. Although effective for fouling control, extended sodium hypochlorite exposure can affect the physical/chemical characteristics and hinder the treatment performance of these membranes. To assess these effects, PVDF based membranes were exposed to sodium hypochlorite at different concentrations for varying periods of time, and the physical/chemical characteristics of the virgin and sodium hypochlorite exposed membranes were compared. The membranes were characterized based on chemical composition (FTIR and NMR), mechanical strength (yield strength), surface hydrophilicity (contact angle), pore size and porosity (scanning electron microscopy and challenge test), and membrane resistance (clean water permeation test). The results indicated that exposure dose and concentration of the sodium hypochlorite used have significant influence on the membrane characteristics. The impact of sodium hypochlorite exposure on the parameters investigated could be most accurately and consistently correlated to an exposure dose relationship of the form Cⁿt (where, C = concentration and t = exposure time) rather than the Ct relationship commonly used to define the extent of exposure to cleaning agents. For all the parameters investigated, the power coefficient n was less than 1 indicating that time had a greater impact on the changes than did the concentration of the sodium hypochlorite. The results suggest that the use of sodium hypochlorite for chemical cleaning, at concentrations that are higher than those typically used for chemical cleaning would have less of an effect on the characteristics of the membrane materials. Changes in the characteristics were attributed to the oxidation of the hydrophilic additives (HA) present in blended PVDF membranes.     

Performance evaluation of different membrane types in the textile mercerization wastewater treatment

This study investigates the performance of three ultrafiltration membranes, i.e. a submerged polyethylene (PE) hollow fibre membrane, a multibore polyethersulfone (PES) membrane and a tubular multichannel ceramic membrane in the textile mercerization wastewater treatment. Experiments were carried out on two laboratory dead end membranes and on a cross flow membrane set‐up using wastewater with and without the addition of MgCl₂ as a coagulant. Investigation into energy consumption was also carried out. According to the obtained results, the submerged membrane could be used as the pretreatment of mercerization wastewater to significantly reduce the amount of suspended solids, to remove organic carbon and to decrease turbidity. The results showed that the tested membranes could be used for the treatment of wastewater from the textile mercerization process in terms of permeate quality. The cross‐flow ultrafiltration consumes far more energy than the dead‐end process.     

Distillery wastewater treatment by the membrane-based nanofiltration and reverse osmosis processes

A hybrid nanofiltration (NF) and reverse osmosis (RO) pilot plant was used to remove the color and contaminants of the distillery spent wash. The feasibility of the membranes for treating wastewater from the distillery industry by varying the feed pressure (0-70 bar) and feed concentration was tested on the separation performance of thin-film composite NF and RO membranes. Color removal by NF and a high rejection of 99.80% total dissolved solids (TDS), 99.90% of chemical oxygen demand (COD) and 99.99% of potassium was achieved from the RO runs, by retaining a significant flux as compared to pure water flux, which shows that membranes were not affected by fouling during wastewater run. The pollutant level in permeates were below the maximum contaminant level as per the guidelines of the World Health Organization and the Central Pollution Control Board specifications for effluent discharge (less than 1,000 ppm of TDS and 500 ppm of COD).     

Aging of membranes prepared from PVA and cellulose nanocrystals by use of thermal compression

Novel membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs), nanosilica (NS), glutaraldehyde (GLA) and glycerine (G) were prepared using a compression moulding process. Rice husk is selected to isolate pure cellulose nanocrystals via mechanical and chemical treatment. The biodegradability of the membranes has been evaluated using UV accelerated weathering as well as a soil burial test. The chemical structure of the membranes were characterised by Fourier-Transformation Infrared (FTIR) spectroscopy. The microstructure of the membranes was characterised by using Scanning Electron Microscope (SEM). The mechanical properties of the membranes were evaluated using standard techniques. The swelling and weight loss resulting from biodegradation were also evaluated. The results showed that the developed membranes can be used as food packaging bags owing to biodegradability (weight loss) under irradiation and during soil burial. The membranes are environmentally friendly.