†Functional Nanomaterials Laboratory, ‡Department of Mechanical Engineering, and §Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, Oklahoma 74078, United States.
ACS Appl Mater Interfaces. 2015 Apr 1;7(12):6596-604. doi: 10.1021/am508832d. Epub 2015 Mar 18.
The present work demonstrates a high biomass content (i.e., up to 90% by weight) and moldable material by controlled covalent cross-linking of lignocellulosic particles by a thermoset through epoxide-hydroxyl reactions. As an example for lignocellulosic biomass, Eastern redcedar was employed. Using scanning fluorescence microscopy and vibrational spectroscopy, macroscopic to molecular scale interactions of the thermoset with the lignocellulose have been revealed. Impregnation of the polymer resin into the biomass cellular network by capillary action as well as applied pressure results in a self-organizing structure in the form of thermoset microrods in a matrix of lignocellulose. We also infer permeation of the thermoset into the cell walls from the reaction of epoxides with the hydroxyls of the lignin. Compression tests reveal, at 30% thermoset content, thermoset-cross-linked lignocellulose has superior mechanical properties over a commercial wood plastic composite while comparable stiffness and strength to bulk epoxy and wood, respectively. The failure mechanism is understood to be crack propagation along the particle-thermoset interface and/or interparticle thermoset network.
本工作通过热固性树脂的环氧化物-羟基反应，对木质纤维素颗粒进行可控共价交联，展示了高生物质含量（即高达 90%的重量）和可模塑材料。以东部红雪松为例，利用扫描荧光显微镜和振动光谱，揭示了热固性树脂与木质纤维素之间的从宏观到分子尺度的相互作用。聚合物树脂通过毛细作用和施加的压力浸渍到生物质的细胞网络中，导致在木质纤维素基质中形成热固性微棒的自组织结构。我们还推断，热固性树脂从环氧化物与木质素的羟基反应中渗透到细胞壁中。压缩测试表明，在 30%的热固性树脂含量下，热固性交联木质纤维素的机械性能优于商业木塑复合材料，而其刚性和强度分别与块状环氧树脂和木材相当。失效机制被理解为裂纹沿着颗粒-热固性树脂界面和/或颗粒间热固性树脂网络的扩展。
