Polymer, Vol.126, 248-258, 2017
Graphene oxide reduces the hydrolytic degradation in polyamide-11
Graphene oxide (GO) was incorporated into polyamide-11 (PA11) via in-situ polymerization. The GO-PA11 nano-composite had elevated resistance to hydrolytic degradation. At a loading of 1 mg/g, GO to PA11, the accelerated aging equilibrium molecular weight of GO-PAll was higher (33 and 34 kg/mol at 100 and 120 degrees C, respectively) compared to neat PAll (23 and 24 kg/mol at 100 and 120 degrees C, respectively). Neat PAll had hydrolysis rate constants (k(H)) of 2.8 and 12 (x 10(-2) day(-1)) when aged at 100 and 120 degrees C, respectively, and re-polymerization rate constants (4) of 5.0 and 23 (x 10(-5) day-1), respectively. The higher equilibrium molecular weight for GO-PAll loaded at 1 mg/g was the result of a decreased k(H), 1.8 and 4.5 (x 10-2 day-1), and an increased k(p), 10 and 17 (x 10-5 day-1) compared with neat PAll at 100 and 120 degrees C, respectively. The decreased rate of degradation and resulting 40% increased equilibrium molecular weight of GO-PAll was attributed to the highly asymmetric planar GO nano-sheets that inhibited the molecular mobility of water and the polymer chain. The crystallinity of the polymer matrix was similarly affected by a reduction in chain mobility during annealing due to the GO nanoparticles' chemistry and highly asymmetric nano-planar sheet structure. (C) 2017 Published by Elsevier Ltd.