Effects of different oxidation systems on the interfacial properties of bamboo fiber/epoxy resin composites

The objective of this study was to improve the interfacial properties of bamboo fabric (BF)/epoxy (EP) composites and thus enhance their mechanical properties. BF was treated with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation system and N-hydroxyphthalimide (NHPI) oxidation system, respectively, to obtain BFO- T and BFO- N oxidation products with different surface morphologies. The effects of different oxidation treatments on the tensile strength (σc) and elongation at break (εc) of the composites were evaluated. Compared with the untreated BF/EP samples, BFO- T/EP showed a 56.9% increase in σc with a non-significant change in the increase in εc. BFO- N/EP showed a 30.1% increase in σc, but the improvement of εc reached 473.7%. The results of single-yarn pull-out tests and atomic force microscopy indicated that the proper size of grooves may be the key to improve the strength of the two-phase interface. The larger size of the grooves, the easier it is for the resin to infiltrate and fill the voids, thus forming occlusal structures that strengthen the interfacial bonding. Small-sized grooves, on the other hand, are not conducive to resin impregnation and therefore voids at the two-phase interface, thus hindering load transfer.