Differential behaviour of nodes and internodes of wheat straw with various pre-treatments

This study is aimed at fully understanding wheat straw by investigating important properties for the processing of wheat straw (node and internode) for further production of bio-composites and bio-fuels as they server as great renewable resource. A combination of mild physical treatments and the synergetic effect of each physical treatment were investigated in terms of chemical, surface and mechanical properties. Functional groups changes were monitored in two anatomical sections of wheat straw stem inner and outer surface and the results showed a reduction in the intensities assigned to aliphatic fractions of waxes and silica after each stage of pre-treatments when compared to the untreated samples. The penetration rate (wettability) and hydrophobicity of wheat straw internode outer surface was analysed through contact angle measurements which indicated 35% decrease in hydrophobicity of straw surface therefore increasing the wettability of surface after the combinational pre-treatment. The relationship of surface characteristics to the mechanical properties of wheat straw was also investigated by testing the single strand tensile strength of nodes and internodes before and after pre-treatments. Mechanical test revealed 35% increase in tensile strength of wheat straw after the pre-treatment in comparison to untreated wheat straw. The thermogravimetric analysis clearly illustrate that the thermal stability of the wheat straw increased after the pre-treatment which is encouraging for the biocomposite application. (C) 2015 Elsevier Ltd. All rights reserved.