等离子体改性对施胶效果及定向刨花板性能的影响

Effect of plasma modification on resin efficiency and properties of OSB

为了获取高性能的速生材定向刨花板,本研究利用介质阻挡等离子体(DBD)改性方法,对辐射松大片刨花进行表面改性处理,在等离子体产生的物理刻蚀和化学改性的协同作用下,提高了酚醛树脂胶黏剂在大片刨花表面的施胶效果,研究了DBD处理功率和处理速度对酚醛树脂胶黏剂在大片刨花表面润湿性、铺展效果、渗透性的影响,分析了等离子体改性前后施胶效果的变化情况;同时,将改性刨花制备成定向刨花板并进行了板材性能测试,研究了DBD处理功率和处理速度对改性大片刨花所制定向刨花板性能的影响,优化了大片刨花等离子体改性工艺,从而获得了力学性能和尺寸稳定性优异的定向刨花板;分析了DBD等离子体优化参数处理前后刨花表面微观形貌和化学元素组成的变化情况,并阐释改性机理。结果表明:经过DBD等离子体改性处理,施胶效果和板材性能均有不同程度提升,当处理功率从1.5 kW逐步提升至6.0 kW、处理速度从4 m/min逐步提升至16 m/min时,施胶效果及板材性能均呈现先增后降的趋势,且制备的定向刨花板性能均满足GB/T 41715—2022《定向刨花板》中OSB/4型板材的物理力学性能要求。在4.5 kW、8 m/min的优化工艺参数下,酚醛树脂胶黏剂在辐射松大片刨花表面的初始接触角和平衡接触角分别下降了28.06%和44.46%;表面自由能从41.4 mJ/m^(2)提升至47.5 mJ/m^(2);胶黏剂平均铺展粒径和覆盖率分别提升了187.32%和136.45%;在大片刨花内部的平均渗透深度和有效渗透深度分别提升了121.33%和97.01%;制备的定向刨花板主向静曲强度、主向弹性模量、内结合强度分别是OSB/4型板材性能要求的219%,123%,98%;AFM分析表明,刨花表面粗糙度R_(a)从5.300 nm提升至6.560 nm,R_(q)从6.697 nm提升至8.640 nm;XPS分析表明,刨花表面各含氧官能团的相对含量有不同程度增加。研究证明了等离子体改性处理能够有效提升刨花表面粗糙度、极性和反应活性,从而提升刨花与胶黏剂间的相互作用,显著改善刨花表面的施胶效果,最终获得性能优异的速生材定向刨花板。

To enhance the performance of oriented strand boards(OSBs) using fast-growing wood flakes as raw wooden materials,this study employed a dielectric barrier discharge(DBD) plasma modification method to alter the surface properties of P.radiata flakes.The combined effects of physical etching and chemical modification induced by plasma improved the wettability,distribution,and penetration of phenol-formaldehyde adhesive resin(collectively referred to as resin efficiency).This study also investigated the impact of DBD treatment power and speed on the resin efficiency on P.radiata flake surfaces.Furthermore,the modified flakes were fabricated into OSBs,and their mechanical and swelling properties were subsequently assessed.The modification parameters were optimized to produce OSBs with enhanced load-bearing capacity and dimensional stability,outperforming untreated panels and meeting or exceeding national standard benchmarks.The changes of micro monography and chemical components of the flake surfaces before and after plasma modification with optimized parameters were analyzed and the mechanism of plasma modification was explained.The results showed that,after the DBD plasma modification with different parameters,the resin efficiency,mechanical and swelling properties of OSBs were enhanced to varying degrees and exhibited a trend of increasing firstly then decreasing as the modification power increasing from 1.5 to 6.0 kW and the speed increasing from 4 to 16 m/min.The properties of all DBD plasma enhanced OSBs met the requirements of OSB/4 Type panel in Chinese national standard GB/T 41715-2022 “Oriented strand boards”.Under the optimized parameters of 4.5 kW and 8 m/min,and compared with untreated samples,the initial and equilibrium contact angles were decreased by 28.06% and 44.46%,respectively.The surface free energy was increased from 41.4 to 47.5 mJ/m~2,the average resin droplet size and coverage were increased by 187.32% and 136.45%,respectively.The average and effective penetration depths were increased by 121.33% and 97.01%,respectively.Compared to the untreated OSBs,the bending strength and modulus of elasticity along the major axis,and the internal bond surpassing the benchmark of OSB/4 Type panel benchmarks by 219%,123% and 98%,respectively.The surface roughness values of R_(a) and R_(q) were increased from 5.300 to 6.560 nm and from 6.697 to 8.640 nm,respectively.The XPS analysis revealed an increase in the content of various oxygen containing functional groups on flake surfaces to varying extent.This study demonstrated that plasma modification effectively enhances resin efficiency on flake surfaces,leading to the production of high-performance OSBs using fast-growing wood as raw materials.