木橡复合层积材对横向周期性压载的响应特性

为拓展木质复合材料在铁路轨枕、机电产品包装等特殊工程领域的应用,研制了9层木橡复合层积材(LLVR)。设计了5种木/橡层积结构,单元为杨木单板和氯丁橡胶(CR)片。采用分层施胶的工艺,即异氰酸酯PAPI用于木橡间胶合,涂布量80 g·m~(-2),添加质量分数9%硅烷偶联剂KH69;酚醛树脂PF用于杨木单板间胶合,涂布量200 g·m-2。热压工艺为温度160℃、压力1.5 MPa、时间10 min。根据国家标准GB/T 17657测试了胶合强度、弯曲强度、弯曲模量及24 h吸水厚度膨胀率。模拟实际承载特征,设计了5周期"加载—卸载"加压试验,重点揭示LLVR对周期性横向压载的力变及吸能响应特性。结果表明:木材与橡胶层积复合开发铁路轨枕、机电产品包装等特殊工程材料是可行的;LLVR具有优异的力学强度、湿稳定性和残余弹性形变吸能缓冲性能;推荐采用表层橡胶包覆的层积结构。

Response Characteristics of Laminated Lumbers of Wood Veneers and Rubber sheets (LLVRs) to Periodic Transverse Compressing Loadings

We developed nine-layer laminated lumbers of wood veneers and rubber sheets (LLVRs) to functionally extend traditional wood composites to such special engineering applications as railway sleepers or heavy electromechanical packaging cases.Planted poplar (Populus deltoids Bartr.cv.Lux) veneers (Marked as W) and Chloroprene rubber (CR) sheets (Marked as R) were glued layer by layer into LLVRs of five balanced laminated constructions.Polyaryl polymethylene isocyanate (PAPI) and phenol formaldehyde (PF) resins were used as bonding agents for wood-rubber and inter-wood veneers adhesives,respectively.KH69 silane was chosen as coupling agent to reinforce wood-rubber adhesion with PAPI resin.PAPI and PF resins spread content were,respectively,80 and 200 g · m-2,and KH69 Silane content was 9％ based on PAPI resin.Hot-pressing temperature and pressure were set as 160 ℃ and 1.5 MPa,respectively,while pressing time was 10 min.The physic-mechanical properties of the above-fabricated LLVRs were evaluated.General physical and mechanical properties including boding strength (Shear strength),bending modulus (MOE) and strength (MOR),and 24-h thickness swelling (24 h-TS) were tested according to the Chinese national standard GB/T17657.To disclose the responding behaviors of LLVRs to frequent compressing loads perpendicular to surface in such applications as railway sleepers or heavyload packaging cases,LLVRs samples were subjected to a self-designed five-cyclic compression loading experiment.LLVRs combining wood veneers and rubber sheets are feasible for engineering applications such as railway sleepers and heavy-load electromechanical packaging cases with strong shear strength,sound dimensional stability,and favorable energy absorption performances.The construction with covering rubber sheets was recommended.