木橡复合层积材的工艺优化及性能研究

Process optimization and properties research on wood-rubber laminated lumber

为拓展木质复合材料的应用领域,解决铁路轨枕等工程领域对高性能新材料的需求,研制开发了木橡复合层积材(LLVR)。选取杨木单板(W)和氯丙橡胶、丁腈橡胶、天然橡胶3种橡胶片(R),采用W-R界面胶合工艺、偶联剂优化W-R胶合界面、W-R层间结构优化三步骤研究木橡复合层积材的最优制备工艺与结构。通过分层施胶工艺(异氰酸酯PAPI用于木材-橡胶间胶合;酚醛树脂PF用于杨木单板间胶合)获得了制造LLVR的较优工艺:橡胶优选氯丙橡胶、PAPI和PF施胶量分别为80和200 g/m2,偶联剂KH69添加量9%(基于PAPI树脂质量)。采用该工艺试制了5种结构的九层LLVR,并研究了横向压缩和耐老化性能。结果表明:在未采取任何耐久性处理条件下,LLVR具有优异的力学性能、尺寸稳定性和较好的耐老化性能,可考虑用于铁路轨枕等工程材料领域;推荐采用表层橡胶包覆的层积结构。

A newdamping laminated lumber of wood veneers and rubber sheets（ LLVR） was developed to functionally extend traditional wood composites to special engineering applications such as railway sleepers. Planted poplar（ Populus spp.） veneers（ marked as W）,chloroprene rubber,nitrile butadiene rubber,natural rubber sheets（ all marked as R） were chosen as rawmaterials. The optimum preparation process and structure of wood-rubber composite laminated wood were investigated by three steps,namely,W-R interface bonding process,coupling agent optimization W-R bonding interface and W-R interlayer structure optimization. The polyaryl polymethylene isocyanate（ PAPI） and phenol formaldehyde（ PF） resins were used as bonding agents for wood-rubber and wood-wood veneers adhesion,respectively. The KH69 silane was chosen to strengthen wood-rubber adhesion. The hot-pressing temperature and pressure were pre-set as 160℃ and 1. 5 MPa,and pressing time was adjusted according to LLVR nominal thickness. Through preliminary experiments of three-layer hybrid plywood（ rubber sheet as the core）,an optimized process of manufacturing LLVR was obtained as follows： chloroprene rubber was demonstrated better to manufacture LLVR; proper spread contents of PAPI and PF resins were 80 g/m2 and 200 g/m2,respectively,and KH69 silane content was 9% based on the mass of PAPI resin. Then,nine-ply LLVR of five balanced laminated constructions with two or three chloroprene rubber sheets were fabricated. Sequentially,the physical and mechanical properties of the nine-ply LLVR were evaluated. Considering the potential utilization of LLVR in outdoor environment such as railway sleepers,the behaviors of LLVR under cyclic lateral compression loading and combined aging treatments（ i.e.,water showering,high-temperature conditioning and xenon lamp exposure） were specifically investigated. The results showed that LLVR have excellent bonding strength and dimensional stability,as well as good aging resistance performances,which could be chosen to manufacture engineering materials for the application such as railway sleepers,and the surface rubber laminated structure was recommended.