Effect of angle of exposure on degradation of radiata pine during weathering trials

IRG/WP 2301

P D Evans

The importance of angle of exposure on the degree of weathering of materials has not been adequately resolved. In conventional tests, specimens are exposed at an angle of 45° facing the equator, but more recently experiments on polymeric materials have suggested that an angle of 0° may be preferable since this angle maximises levels of received ultra-violet radiation. In this paper the degradation of Radiata pine (Pinus radiata D. Don) during weathering was assessed at 5 angles of exposure (0°, 45°, 60°, 70°, 90°) over 50 days by measuring changes in weight and chemical composition. In order to confirm previous observations measurements of received ultra-violet radiation (< 320 nm) at these angles of exposure were also made using polysulphone polymer film dosimeters. Roth weight loss and chemical data indicate that degradation of Radiata pine during weathering was negatively correlated (p < 0.001) with increasing angle of exposure. The implications of these findings for the conduct of weathering trials are discussed.


Keywords: FIELD TEST; UV RADIATION; WEATHERING; ANGLE OF EXPOSURE; LIGNIN; CELLULOSE; EXTRACTIVES; PINUS RADIATA

Conference: 88-04-24/29 Madrid, Spain


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