Service life assessment and moisture influence on composites from renewable feedstock
2012 (English)In: Proceedings of Mechanics of Composite Materials XVII International Conference, 2012Conference paper, Meeting abstract (Refereed)
Composite materials are an important and growing material group in a large number of industries such as aeronautics, marine, automotive, energy production and infrastructure. The most common composite materials is manufactured from fibres such as glass fibres and carbon fibres together with oil based resins i.e. polyester, vinyl ester and epoxy. An increasing use calls for alternative environmental friendly, biobased, constituents. The new biobased materials have not only to compete in mechanical properties but it also has to restrain environmental loads like moisture and temperature over time. In the present work are predictions of the long term properties of biobased resins made. The work also presents the influence of moisture, comparison with creep test data and comparison with oil based resin. The long term property prediction is made by using dynamic mechanical thermal analysis, DMTA, measurements and time temperature superposition, TTSP, [1,2]. The procedure is to make DMTA measurements in 3p-bening mode of the storage modulus at different frequencies at increasing temperature. The method used in this case was to measure the modulus at 0.1, 0.3, 1, 3 and 10 Hz at temperatures 25 – 175°C with 5°C intervals. The frequencies where then transformed to time by Eq. (1) below t=2/πω (1)where ω is the frequency. 25°C were chosen as reference temperature where as all other curves where shifted horizontally creating a continuous master curve. The modulus time master curve was then inverted creating creep compliance time master curve, this curve is compared to creep test. The moisture behaviour is characterised in form of water uptake, change in glass transition temperature, Tg, and change in dynamic response. The water uptake is determined by submersion into water and tracking the weight change over time. The glass transition temperature is determined in DMTA by conducting a temperature sweep at constant frequency. The change in Tg is used as a knock down factor and a vertical shift of the master curve. An attempt to determine the dynamic response of wet samples has also been made with the insight that higher temperatures will dry the sample during testing leading to a non homogenous moisture distribution within the sample. The results from the study show on differences between TTSP and creep data, it also shows the differences between different biobased resins and a comparison to oil based epoxy. REFERENCES1. Christensen R.M., “Theory of viscoelasticity, an introduction” 2nd edition, Academic Press, 1982.2. Ward I.M. and Hadley D.W., “An Introduction to the mechanical properties of solid polymers” 1st edition, John Wiley & Sons, 1993.
Place, publisher, year, edition, pages
Research subject Polymeric Composite Materials
IdentifiersURN: urn:nbn:se:ltu:diva-38280Local ID: ca023cbc-8b1d-4ad9-9da9-b616194b4f68OAI: oai:DiVA.org:ltu-38280DiVA: diva2:1011779
International Conference Mechanics of Composite Materials : 28/05/2012 - 01/06/2012
Godkänd; 2012; 20120918 (joffe)2016-10-032016-10-03Bibliographically approved