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The Effect of Water Activity on the Sorption and Diffusion of Water in Thermosets Based on Polyester, Vinyl Ester, and Novolac Resins
(Swerea KIMAB)
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
2012 (English)In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 52, no 4, 718-724 p.Article in journal (Refereed) Published
Abstract [en]

In this work, the transport properties of water in various thermoset resins typically used for fiber-reinforced plastic process equipment (vinyl ester, novolac, bisphenol-A-epoxy-based polyester, and urethane-modified vinyl ester) were systematically studied with a focus on the effects of water activity. Sorption and desorption studies were carried out in aqueous solutions (water activity = 0.78–1) with different salts (NaCl, MgCl2, Na2SO4, and KCl) and one nonionic substance (sucrose) within the temperature interval 65–95°C. It was found that the water concentration in thermoset resins with different chemical structures could be predicted from the water activity, regardless of the actual solute (salt or sucrose) in the aqueous solution. The water quasi-equilibrium concentration decreased with decreasing water activity, whereas the average diffusion coefficient was considered to be independent of water activity in the studied water activity range. A relationship, based on a power law fit, was established describing the water concentration as a function of the water activity and the concentration of pure water. The relationship was independent of resin chemistry and temperature.

Place, publisher, year, edition, pages
2012. Vol. 52, no 4, 718-724 p.
Keyword [en]
thermoset, sorption, diffusion, water activity, calculations
National Category
Polymer Chemistry
URN: urn:nbn:se:kth:diva-13808DOI: 10.1002/pen.22042ISI: 000301539300002ScopusID: 2-s2.0-84858447261OAI: diva2:327405
QC 20120327. Updated from submitted to published.Available from: 2010-06-29 Created: 2010-06-29 Last updated: 2012-05-07Bibliographically approved
In thesis
1. Transport Properties and Durability of LCP and FRP materials for process equipment
Open this publication in new window or tab >>Transport Properties and Durability of LCP and FRP materials for process equipment
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on transport properties and durability of liquid crystalline polymers (LCP)and fibre reinforced plastics (FRP) with regard to application in industrial process equipment.In the first part of the study the possibility of using a thermotropic LCP of type Vectra A950as lining material for FRP process equipment was investigated. Its performance wascompared to that of a fluorinated ethylene propylene copolymer (FEP) with respect tochemical and permeation resistance. Transport property and chemical resistance data wereestablished for different types of LCP film (compression molded, uniaxially and biaxiallyoriented film) exposed to selected chemicals chosen to represent typical industrial processenvironments. Annealing of the LCP, which may reduce the disclination density and henceimprove the barrier properties, induced a crystallinity increase, but did not significantlyimprove the barrier and chemical resistance properties. Different surface treatments toincrease the bonding between the LCP and FRP were explored. The conclusion was that LCPhas potential to serve as lining material for FRP in contact with water, organic solvents andnon-oxidizing acid environments, although certain issues, such as jointing techniques, stillhave to be evaluated. The second part of the study focused on transport and long-termproperties of commercial thermoset and FRP materials for industrial process equipment inaqueous environments (50 – 95 °C, water activity 0.78 – 1, exposure time ≤ 1000 days). Thewater transport properties in different thermosets were related to their chemical structureusing the solubility parameter concept. The transport of water in the thermosets with differentchemical structures could be predicted from the water activity, regardless of the actual type ofionic or non-ionic solute in the solution. An empirical relationship, independent of boththermoset chemistry and temperature, was established to describe the water concentration inthe thermoset as a function of water activity and the water concentration in pure water. Inlong-term, the water concentration in the thermosets increased with exposure time. Thisseemed to be primarily related to stress relaxation processes induced by water absorption andcertain leaching effects. The effects of hydrolysis seemed to be small. The glass fibrereinforcement may to various extents affect the water transport properties by capillarydiffusion and additional absorption around fibre bundles. The extent of such processesseemed to depend on temperature, water activity and the type of thermoset and reinforcement.The present work may be a useful contribution to an increased understanding of water effectsand durability of FRP process equipment. However, open questions still remain for a morecomprehensive durability analysis.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. iv, 52 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2010:16
Liquid crystalline polymer (LCP), Vectra A950, disclination, annealing, transport properties, diffusion, lining, bonding, glass fibre reinforced plastics (FRP), thermoset, vinyl ester, novolac, water, water activity, sorption isotherm, long-term properties, FEP
urn:nbn:se:kth:diva-13221 (URN)978-91-7415-584-6 (ISBN)
Public defence
2010-06-04, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
QC20100629Available from: 2010-06-04 Created: 2010-06-04 Last updated: 2011-01-20Bibliographically approved

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