scispace - formally typeset
Search or ask a question
Dissertation

The permeation and moisture transmission properties of a thermosensitive membrane barrier for chemical protective clothing

TL;DR: In this paper, both modified thermally induced method and modified plasma induced method are employed to oxidise PVDF polymer for its copolymerisation with NIPAAM monomers.
Abstract: The liquid chemical permeation properties and water vapour transmission properties of temperature sensitive poly(vinylidene fluoride) (PVDF) grafted N-isopropylacrylamide (NIPAAM) (NIPAAM-g-PVDF) copolymer membranes as a smart barrier layer in chemical protective clothing are studied in this research. Both modified thermally induced method and modified plasma induced method are employed to oxidise PVDF polymer for its copolymerisation with NIPAAM monomers. In the thermal induced method, NIPAAM-g-PVDF polymer materials are synthesised via the copolymerisation of ozone activated PVDF polymer with NIPAAM monomers below a lower critical solution temperature of NIPAAM (30°C). An effective supercritical carbon dioxide drying method is used as an alternative drying method to remove the solvent from the ozone activated PVDF polymer in conventionally copolymerisation is successfully applied and a new direct copolymerisation route by adding NIPAAM polymer into ozone activated PVDF in solutions without the drying process of the activated PVDF polymers. The NIPAAM-g-PVDF made by the new copolymerisation process is much simpler than the conventional method and the processing time needed is much shorter. In the oxygen plasma induced copolymerisation method, the porous PVDF membranes produced from the phase inversion method are treated oxygen plasma before they were copolymerised with NIPAAM monomer in N,N-dimethylformamide (DMF) solvent aqueous solution below the lower critical solution temperature of NIPAAM (30°C). The structural characteristics of heat-pressed NIPAAM-g-PVDF nanoporous membranes produced from the above two methods are investigated. The influence of the microstructure of the nanoporous copolymer membranes on both their water vapour transfer properties and dynamic permeation rate has been studied. The mechanisms of liquid/vapour permeation through the thermal sensitive copolymer nanoporous membranes are analysed and investigated. In this study, it is found that the breakthrough time and permeation rate of nanoporous NIPAAM-g-PVDF membranes are influenced by the proportion of NIPAAM components, the membrane thickness, the crystallinity and the porous structure of the NIPAAM-g-PVDF membranes. It is also found that the water vapour permeability of the heat-pressed NIPAAM-g-PVDF membranes at both 20°C and 40°C are influenced by the membrane thickness, the total pore volume and the porosity of the membranes. The water vapour permeability coefficient of the NIPAAM-g-PVDF nanoporous membranes is determined by both the proportion of thermal sensitive NIPAAM components and associated porous structure of the copolymer membranes.
Citations
More filters
01 Feb 1987
TL;DR: A variety of clothing items are available for emergency response and other applications where chemical hazards may be encountered Data and information for selecting chemical-protective clothing is either not available or is inconsistant from source to source as discussed by the authors.
Abstract: A variety of protective-clothing items are commerically available for emergency response and other applications where chemical hazards may be encountered Data and information for selecting chemical-protective clothing is either not available or is inconsistant from source to source In 1983, the US Environmental Protection Agency sponsored the development of chemical-protective clothing selection guidelines to assist their own Office of Health and Safety in providing guidance to personnel, primarily EPA employees and contractors, working on hazardous-waste sites These guidelines allowed a user to select an appropriate protective material for a specific chemical, select a clothing item (glove, suit, etc) and then determine which manufacturers offered the clothing item in the selected material The US Coast Guard Office of Research and Development and the EPA have supplemented these guidelines with additional data on material chemical resistance, material physical properties, clothing design features, and specific-vendor products A chapter has been added for selecting chemical protective suits These guidelines contain data for over 750 chemicals and 700 clothing products Volume I provides the performance information and recommendations for selecting different types of protective clothing

2 citations

01 Feb 1987
TL;DR: The U.S. Environmental Protection Agency developed a set of guidelines for selecting chemical-protective clothing for emergency response and other applications where chemical hazards may be encountered as discussed by the authors, which allowed a user to select an appropriate protective material for a specific chemical, select a clothing item (glove, suit, etc.), and then determine which manufacturers offered the clothing item in the recommended material.
Abstract: A variety of protective-clothing items are commercially available for emergency response and other applications where chemical hazards may be encountered. Data and information for selecting chemical-protective clothing is either not available or is inconsistant from source to source. In 1983, the U.S. Environmental Protection Agency sponsored the development of chemical-protective clothing selection guidelines to assist their own Office of Health and Safety in providing guidance to personnel, primarily EPA employees and contractors, working on hazardous-waste sites. These guidelines allowed a user to select an appropriate protective material for a specific chemical, select a clothing item (glove, suit, etc.), and then determine which manufacturers offered the clothing item in the recommended material. The U.S, Coast Guard Office of Research and Development and the EPA have supplemented these guidelines with additional data on material chemical resistance, material physical properties, clothing design features, and specific-vendor products. A chapter has been added for selecting chemical-protective suits. These guidelines contain data for over 750 chemicals and 700 clothing products. Volume I provides performance information and recommendations for selecting different types of protective clothing. Volume II contains a detailed technical discussion, and the data on which Volume I recommendations are based. The U.S. Coast Guard intendsmore » to use these guidelines for protective-clothing selection by its National Strike Force and Marine Safety Offices.« less
References
More filters
Journal ArticleDOI

11,534 citations


"The permeation and moisture transmi..." refers background in this paper

  • ...Additionally, the apparent contact angles for a heterogeneous porous surface are suggested by Cassie and Baxter’s equation [40] as equation (2-4) below...

    [...]

Journal ArticleDOI

11,004 citations


"The permeation and moisture transmi..." refers background in this paper

  • ...The roughness factor (rw) is proposed in Wenzel’s equation [39]....

    [...]

Journal ArticleDOI

4,701 citations


Additional excerpts

  • ...Since its LCST value falls between human body temperature and the environmental temperature, it can therefore exhibit reversible swelling and shrinkage when the temperature changes....

    [...]

  • ...A hydrodynamic factor due to the surface interaction between the pore wall and the fluid. λ ......... Ratio of the diameters of the fluid molecules to the diameter of the pores L ......... Thickness of membrane (mm) LCST ............

    [...]

  • ...195 7.2.2 WVTR of the copolymer membranes at the temperatures below and above LCSTs .............................................................. 196 7.2.3 Relationship between WVTR and the structure of NIPAAM- g-PVDF membranes ..................................................................... 199 7.3 Liquid chemical permeation properties of the NIPAAM-g-PVDF copolymer membranes .......................................................................... 210 7.3.1 Dynamic permeation rate and breakthrough time ........................ 211 7.3.2 Permeation coefficient at steady state .......................................... 213 ix 7.3.3 Relationship between breakthrough time and the structure of NIPAAM-g-PVDF copolymer membranes.................................. 214 7.3.4 Relationship between permeation rate and the structure of NIPAAM-g-PVDF copolymer membranes.................................. 220 7.4 Mechanisms of water vapour and liquid chemicals permeation through NIPAAM-g-PVDF copolymer membranes ............................. 225 7.5 Conclusions .............................................................................................. 234 Chapter 8 Conclusions and further work ........................................................... 235 8.1 Main findings ..............................................................................................

    [...]

  • ...In this study, NIPAAM is proposed as the molecular formation of macroscopic aggregates due to a hydrophobic interaction among the collapsed polymer chains at the temperature around 32°C, this temperature is known as the lower critical solution temperature (LCST) [5]....

    [...]

Book
01 Jan 1991
TL;DR: In this paper, the authors introduce the concept of Membrane Fouling and discuss the properties and properties of synthetic Membranes, including material properties, properties, and processes.
Abstract: I: Introduction. II: Materials and Material Properties. III. Preparation of Synthetic Membranes. IV: Characterisation of Membranes. V: Transport in Membranes. VI: Membrane Processes. VII: Polarisation Phenomena and Membrane Fouling. VIII: Module and Process Design. Appendix 1. Appendix 2. Answers to Exercises: Solved Problems. Answers to Exercises: Unsolved Problems. List of Symbols. Index.

4,338 citations

Book
01 Jan 1985
TL;DR: In this article, the physical concepts and methodologies of heat and mass transfer are explained for advanced undergraduate engineering majors, using a systematic method for problem solving and discusses the relationship of heat transfer to many important practical applications through examples and problems.
Abstract: This book, designed for advanced undergraduate engineering majors, explains the physical concepts and methodologies of heat and mass transfer. It uses a systematic method for problem solving and discusses the relationship of heat and mass transfer to many important practical applications through examples and problems. A and significant contribution is the extensive use of the First Law of thermodynamics.

4,113 citations

Related Papers (5)