酚醛树脂面粉添加量对竹层积材剪切强度的影响

Effects of Flour Addition Amount in Phenol-Formaldehyde Resin on the Shear Strength of Bamboo Laminated Lumber

以漂白竹片为原料,将不同比例的面粉添加至常规酚醛树脂胶（PF）和落叶松树皮粉和尿素改性酚醛树脂胶（PTUF）中,采用青面对青面和黄面对黄面两种胶合组坯方式制备双层竹层积材,探讨不同面粉添加量对两种结构竹层积材剪切强度的影响。结果表明：使用PF胶合的竹层积材,干强度随面粉的增加呈现先上升后下降的趋势,当面粉添加量为10%时达到最大值,而湿强度随面粉的增加呈现降低趋势,降低幅度为17%-51.7%;而使用PTUF胶合的竹层积材,干强度随面粉的增加呈现先上升后下降的趋势,当面粉添加量为5%时达到最大值,而湿强度随面粉的增加呈现降低趋势,降低幅度为35%-56.4%。因此,相比于PF,使用PTUF胶合的竹层积材,胶黏剂中面粉添加量不宜超过5%。

Different mass proportions of flour were mixed with conventional phenol formaldehyde （PF）, and phenol formaldehyde modified with larch thanaka and urea （PTUF） to investigate the influence of flour addition amount on the shear strength of bamboo laminated lumber.Bleached bamboo strips were used to make two-ply bamboo laminated lumber and the assembly pattern was outer to outer and inner to inner, respectively.The results showed that the dry shear strength of the bamboo laminated lumber bonding with PF increased first and then decreased with increasing flour addition amount.The highest strength reached as the flour addition amount was 10%.The wet shear strength decreased with increasing flour addition amount at a rate of 17%-51.7%.The dry shear strength of the bamboo laminated lumber with PTUF increased and then decreased with increasing flour addition amount.The highest strength was found as the flour addition amount was 5%.The wet shear strength decreased with increasing flour addition amount at a rate of 35%-56.4%.Thus, less than 5% flour addition amount for the bamboo laminated lumber bonding with PTUF was suitable,in comparison with that bonding with PF.