【摘要】 为探究较优热压工艺参数组合从而拓宽国产速生杉木的应用领域，采用正交试验方法，在预热温度120℃、预热时间20 min、预热前含水率50%的前提下设计正交试验，探究热压温度、保压时间、压缩率对杉木压缩木回复率和力学性能的影响，通过极差分析和方差分析来表示不同工艺参数对杉木压缩木性能的影响情况，并利用剖面密度仪和扫描电镜(SEM)观察密度分布和细胞变形情况。试验结果表明：保压时间和压缩率对压缩木回复率有显著影响；压缩率对抗弯强度、抗弯弹性模量和顺纹抗压强度均有显著影响，一定程度地提升压缩率可以达到固定变形和改善力学性能的效果，但压缩率过大会使木材细胞壁产生裂隙，从而降低木材的力学性能，并且提升压缩率会导致更多的木材材积损失，带来成本提高的问题，因此压缩率也不宜过高。当压缩率从40%提高到60%时，吸湿和吸水回复率绝对值分别降低了42.9%和35.4%,抗弯强度、抗弯弹性模量、顺纹抗压强度分别提高了58.0%,68.8%和43.9%;保压时间由1 h延长到3 h,吸湿和吸水回复率绝对值分别降低了58.7%和44.6%。根据试验结果，选择热压温度140℃,保压时间2～3 h,压缩率50%～60%作为杉木压缩木的热压工艺较优参数，此条件下的压缩木材能在有效提高其力学性能的同时达到较好的尺寸稳定性。更多还原

【Abstract】 Chinese fir is a unique species of fast-growing plantation in China, which is widely distributed, accounting for 1/4 and 1/3 of the total area and total stock of China’s plantation, respectively. Due to the low density, low strength and poor processing performance of fast-growing Chinese fir, its utilization is mainly limited to low-value-added products currently. Densification of fast-growing Chinese fir can effectively improve its added value. In order to extend the application field of the fast-growing Chinese fir and simplify the compression process, this study investigated the effects of hot-pressing process parameters on recovery rate and mechanical properties and explored the optimal combination of hot-pressing process parameters to provide theoretical basis and reference for follow-up research and industrial production. By pre-setting the preheating temperature of 120 ℃, the preheating time of 20 min, and the wood moisture content before preheating of 50%, an orthogonal test scheme was designed to explore the effects of hot-pressing temperature(120, 140 or 160 ℃), holding time(1, 2 or 3 h) and compression ratio(40%, 50% or 60%) on the recovery rate and mechanical properties of the compressed wood. Through the range analysis and variance analysis, the influence of different process parameters on the performance of the Chinese fir compressed wood was explored and the test results in combination with the profile density distribution and cell deformation of compressed wood were analyzed. During the hot-pressing process, when the compression ratio increased from 40% to 60%, the recovery for moisture absorption and the recovery for water absorption decreased by 42.9% and 35.4%, respectively. The mo-dulus of rupture(MOR) and modulus of elasticity(MOE), and compressive strength parallel to grain increased by 58.0%, 68.8% and 43.9%, respectively. When the holding time was extended from 1 to 3 h, the recovery for moisture absorption and the recovery for water absorption decreased by 58.7% and 44.6%, respectively, and the MOR and compressive strength parallel to grain decreased slightly. When the hot-pressing temperature changed in the range of 120-160 ℃, the effect on the recovery rate and the compressive strength parallel to grain was not significant. The MOR and MOE test results showed a trend of increasing first and then decreasing. The holding time and compression ratio had significant effects on recovery rate. The compression ratio had a significant effect on MOR, MOE and compressive strength parallel to grain. According to the test results, it is suggested that the hot-pressing temperature of 140 ℃, the holding time of 2-3 h, and the compression rate of 50%-60% can be selected as the optimal hot-pressing process parameters for making the Chinese fir compressed wood. Under this parameter condition, the mechanical pro-perties and dimensional stability of compressed wood can be effectively improved, achieving the enhancement of added value for the fast-growing Chinese fir.更多还原