Effect of water repellents on the surface characterisation of scots pine (pinus sylvestris) exposed to accelerated and outdoor weathering

Abstract

Numerous chemicals have been investigated to inhibit photodegradation of wood and to protect it long term against weathering in-service. However, most of these chemicals cannot provide a long-term protection on wooden surface. Therefore, water repellent materials are needed to stabilize the wood surfaces and make it permanent against photodegradation. In this study, the influence of Poly Ethylene Glycol (PEG 600), N,N-(1,8-Naphthalene) hydroxylamine (NHA-H) and Methyl Hydrogen Silicon (MHS) were investigated against UV light. For this purpose, wood samples were impregnated with these chemicals according to full cell process (pressure or vacuum). After impregnation, the samples were exposed to accelerated weathering (500 hours) and to outdoor weathering for 6 and 12 months respectively. Optical and chemical changes on the surface of treated and untreated wood samples were studied by colour changes, glossiness and Fourier Transform Infrared Spectroscopy (FTIR) analysis. When the results regarding total colour change were examined, the best results were obtained in the samples impregnated with MHS both in the accelerated and outdoor weathering test. In the control specimens, new peaks were formed at 2927 cm-1 and 1697 cm-1, while the chemical structure maintained its integrity in samples impregnated with MHS.