N-methylol acrylamide grafting bamboo fibers and their composites

The present study focuses on the modification of four commercial bamboo fibers (BFs), namely bamboo particles (PF), mechanical pulp fibers (MP), chemical pulp fibers (CP) and original bamboo fibers (OF), with a water-soluble monomer, N-methylol acrylamide (NMA), in the presence of sulfuric acid as a catalyst, surface chemistry of the grafted BFs with NMA, and their reinforcing effects on unsaturated polyester (UPE) in terms of the interface and bonding mechanisms, and hence mechanical properties of the resulting BF-UPE composites. Fourier transform infrared spectroscopy (FTIR) analysis showed that the reaction degree of BFs with NMA followed CP > MP > PF > OF due to their different fiber morphology and chemical compositions. This was further confirmed by X-ray photoelectron spectroscopy (XPS) with the increase in N content and the reduction in O/C ratio on the fiber surfaces. NMA treated BF gave rise to an improved interfacial adhesion between the treated fibers and UPE resins, and hence mechanical properties of BF-UPE composites, although the magnitudes are dependent on the combined effect of NMA grafting efficiency and fiber characteristics (i.e. types) of BFs. (C) 2015 Elsevier Ltd. All rights reserved.