Effect of nanofibres on the curing characteristics of an epoxy matrix

Recently it is shown that nanofibrous structures have the potential to enhance the mechanical properties of epoxy composites. Even though it is well know that the curing cycle affects the final properties of the composites, up till today the effect of these nanofibrous structures on the curing characteristics of epoxies is not studied in detail. Therefore the influence of nanofibres of different polyamide types (PA 6, PA 6.6, PA 6.9 and PA 4.6) and of polyvinyl alcohol (PVAL) on the curing reaction of a diglycidyl ether of bisphenol A (DGEBA)–methylenedianiline (MDA) system was investigated, using non-isothermal and quasi-isothermal (modulated temperature) differential scanning calorimetry ((MT)DSC) measurements. The effect of the nanofibre fraction and polyamide type is examined, and a comparison with conventional PA 6 fibres is made. For polyamide nanofibres, the accelerating effect seems to result mainly from water present in the nano- and microfibers. PVAL nanofibres accelerated the curing more strongly than the PA nanofibres, though their moisture content was lower, indicating a catalytic effect of the surface hydroxyls.