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Short-Term and Long-Term Performance of Thermosets Exposed to Water at Elevated Temperatures
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
2009 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 116, no 2, 1057- p.Article in journal (Refereed) Published
Abstract [en]

The water-transport, mechanical, and chemical-structure changes in various vinyl ester, novolac, and urethane-modified vinyl ester thermosets exposed to water at 50 to 95oC for times up to 1000 days have been studied within the framework of a larger study of osmotic blistering in fiber reinforced plastics (FRP) process components. The water sorption saturation concentration did not reach a steady-state value but gradually increased in many cases upon long-term exposure. The diffusion coefficient was not significantly affected. Infrared spectroscopy and gas chromatography-mass spectrometry indicated that the net mass loss from the thermosets on immersion in water was due to the leaching of non-reacted styrene, monomer, and additives. It is suggested that this, together with polymer relaxation processes (as measured on specimens under tension in water at 80oC), is the primary reason for the time-dependent increase in the water saturation concentration. Infrared spectroscopy indicated that, even at the highest temperatures, hydrolysis of the polymer ester groups was small. Correlations were found between the styrene content in the uncured thermosets, the estimated solubility parameters, and the sorption and diffusion coefficients.

Place, publisher, year, edition, pages
2009. Vol. 116, no 2, 1057- p.
Keyword [en]
thermoset, transport properties, water, long-term performance
National Category
Polymer Chemistry
URN: urn:nbn:se:kth:diva-13806DOI: 10.1002/app.31548ISI: 000274646300054ScopusID: 2-s2.0-75449114646OAI: diva2:327399
QC 20100629Available from: 2010-06-29 Created: 2010-06-29 Last updated: 2011-01-20Bibliographically 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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