The effect on some properties of oriented strand board (OSB) of ureaformaldehyde resin different melamine containing and density differences

In this study, Oriented Strand Board (OSB) at density of 550 - 570 - 590 in size of 2440 x 1220 x 11 mm were manufactured using %9,5 solid resin to dry wood chip with melamine urea formaldehyde (MUF) resins prepared as 65% solid content and %0 - 2,5 - 5 - 15 - 20 melamine content. Statistical analysis of the boards produced were performed by determining density, thickness swelling, moisture resistance, formaldehyde content and elasticity modulus from physical properties together with bending and internal bond strength from mechanic properties. As wood mixture; Black pine (Pinus nigra A.) by 80%, Scots pine (Pinus sylvestris L.) by 15% whit Fir wood (Abies nordmanniana L.) by 5% was used. Test samples were taken by five for each resin and density of board and after samples prepared according to relevant standards were stayed until it reaches the constant mass in condition of temperature 20°C ±2 and humidity 65% ±5, experiments were tested under proper standards. Analysis of variance was carried out to evaluate the test result and Duncan test was used for binary comparisons between groups According to test results; maximum transversal bending strength and elasticity modulus value was observed in density 590 kg/m³, in MUF resin 15% melamin content. While the maximum lengthwise bending strength value was observed in density 590 kg/m³ as statistical much difference in lengthwise bending strength value between resins was not observed. Maximum lengthwise bending elasticity value was observed in density 570 and 590 kg/m³ and MUF resins 5% and 20% melamine content. Maximum lengthwise internal bond strength value was obtained in density 570 and 590 kg/m³ and in MUF resin 20% melamine content. Minimum swelling of thickness value was observed in density 550 and 590 kg/m³ and in MUF resin 20% melamine content. As a result of determination of moisture content, the best results were seen in melamine ureaformaldehyde resin 15% and 20% melamine content, the worst results was seen in ureaformaldehit resin 0% melamine content were obtained. According to result, determination of formaldehyde content; formaldehyde amount has been decreasing with increasing melamine contribution in values of all density of board. Maximum formaldehyde amount was obtained in ureaformaldehyde resin 0% melamine contribution; minimum formaldehyde amount was obtained in ureaformaldehyde resin 20% melamine content. As a consequence, all values have been increasing with density increase, except thickness swelling. Participation rate of melamine content (15% and 20%) has increased with the internal bond strength value, also decreased thickness swelling value, whereas, low participation rates of melamine (2,5% and 5%) were not effective. Accordingly, while urea formaldehyde resin which does not contain melamine content resin can be used for indoor purposes, melamine ureaformaldehyde resin which contains over than 15% melamine can be preferred for humid outdoor conditions. Key Words: Oriented strand board (OSB), physical properties, mechanical properties, melamine rate, melamine urea formaldehyde resin