Gunnar Almkvist

I am working in a research project funded by Swedish Maritime Museums where we study degradation mechanisms in conserved waterlogged wood and the effect on mechanical stability of the material. Of particular interest is the long-term stability of the Vasa since the beams carry high loadings from the ship. My research has shown that degradation processes catalyzed by iron compounds have had a detrimental effect on the wood polymers which may affect the future stability. The processes are studied by means of FT-IR, NMR and MS in combination with monitoring of the oxygen consumption of both Vasa wood and modelled wood. Modelled wood is achieved by impregnating recent oak with iron compounds and expose it to air under climate control. By time the wood develop degradation patterns that are similar to those of the Vasa, e.g. increased acidity, depolymerization of polysaccharides and polyethylene glycol (conservation agent) in conjunction with loss of mechanical strength. In cooperation with Department of Applied Mechanics at The Ångström Laboratory we study the long-term effect on creep behavior related to chemical degradation. The aim is optimize a new support structure for the Vasa.