Reinforcement of layer-by-layer self-assembly coating modified cellulose nanofibers to reduce the flammability of polyvinyl alcohol

Abstract

Cellulose nanofibers (CNFs) were modified with 2 bilayers coating composed of polyethlenimine (PEI), melamine and phytic acid using a layer-by-layer self-assembly technique. The (PEI + melamine/phytic acid)2 based coating was successfully deposited on the surface of modified cellulose nanofibers (MCNFs). Herein, the CNF referred to the carbon source and the phytic acid was chosen as the acid source. Polyethylenimine and melamine served as the blowing agents. Then the CNF and MCNF were introduced to the polyvinyl alcohol (PVA) matrix to investigate the thermal decomposition, flammability, light transmittance and mechanical properties of the PVA/CNF and PVA/MCNF composites. The thermal decomposition of PVA-MCNF-6 (with 6 wt% MCNF) was retarded compared with that of pure PVA. Meanwhile, the addition of 6 wt% MCNF obviously reduced the peak heat release rate of PVA, as evidenced by the 37% reduction. The PVA/CNF and PVA/MCNF composites exhibited similar light transmittance compared with the pure PVA film. Moreover, the addition of CNFs in the PVA matrix resulted in higher tensile strength and elongation at break than those of the PVA matrix.