胶液含量对单板条层积材柱构件性能的影响

Effects of resin content on properties of parallel strand lumber columns

为促进利用速生杨木单板生产单板条层积材(parallel strand lumber,PSL)以制备木结构建筑中的柱构件,将杨木单板条浸渍不同质量分数(10%,20%和30%)的酚醛树脂胶,采用热压工艺压制单板条层积材,并测定试件热压过程中的温度传递和轴心抗压力学性能。结果表明,PSL热压升温曲线可分为快速升温阶段和缓慢升温阶段,在快速升温阶段,随着单板条浸渍胶液质量分数的增加,板坯传热速度逐渐增加。PSL柱轴心抗压力学性能随着单板条浸渍胶液质量分数的增加而提高,浸胶胶液质量分数为10%的PSL试件轴心抗压性能最低,浸渍20%和30%质量分数胶黏剂的PSL柱试件的初始弹性模量比浸渍10%质量分数胶黏剂的PSL柱试件分别提高841%和1577%,临界应力也分别提高3103%和3698%。单板条浸渍不同胶液质量分数的PSL柱试件轴心抗压破坏形式不同,主要包括顺纹贯穿的开裂破坏和柱端部压溃破坏。综合考虑,采用20%质量分数胶液浸渍单板条压制的PSL物理力学性能最为合适。

Parallel strand lumbers （PSLs） were manufactured from fast-growing poplar （Populus spp. ） veneer strand impregnated in various mass ratio（ 10%, 20% and 30% ） of phenol-formaldehyde （PF） adhesive using hot-pressing. The heat transfer performances during hot-pressing and axial compressive properties of PSL specimens were examined. The results showed that the moisture content and resin impregnation amount of strand increased with the increasing mass ratio of PF adhesive. The hot-pressing heat transfer curve of PSLs included the initial temperature fast rising stage and temper- ature slow rising stage, and the heat transfer speed increased with the increasing resin impregnation amount of strand. The axial compressive properties of PSLs columns increased with the increase of resin impregnation amount of strand. Group A, which was impregnated with 10% PF, had the lowest mechanical properties. The initial modulus of elasticity of Groups B and C, which was impregnated with 20% and 30% PF, respectively, were 8.41% and 15.77% higher than that of Group A. The critical stress of Groups B and C were 31.03% and 36.98% higher than that of Group A. Different groups of PSL columns specimens had different failure modes under the axial compression. The dominant failure mode of Group A was separation due to the low adhesive coverage, while the dominant failure modes of Groups B and C were that minor crack（s） occurred in the end of PSL columns specimens. The PSL manufactured from poplar veneer strand impregnated with 20% PF adhesive had better physical and mechanical properties based on the comprehensive consideration.