Enhancing thermal stability, mechanical properties, and flammability of polyvinyl alcohol using amide‐functionalized hydrogel and zinc oxide nanoparticles

Abstract

New polyvinyl alcohol (PVA) nanocomposites containing zinc oxide (ZnO) nanoparticles and a hydrogel were prepared by the solution casting method. ZnO nanoparticles grafted co‐polymer (Zn‐g‐CP) was synthesized through the reaction of ZnO nanoparticles with vinyltriethoxysilane and then the radical co‐polymerization with 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS). The amide functionalized hydrogel was prepared via an in situ polymerization of acrylamide and N,N′‐methylene bisacrylamide (MBA) as a crosslinker in a solution of PVA. The corresponding results indicated that the simultaneous presence of both Zn‐g‐CP and hydrogel could significantly increase flammability, thermal stability, and the tensile strength of PVA. The results of the X‐ray diffraction (XRD) and field‐emission scanning electron microscopy (FE‐SEM) indicated a uniform dispersion of ZnO nanoparticles and an enhanced compatibility with the PVA matrix. Thermogravimetric analysis (TGA) in both N2 and air atmospheres, indicated that the temperature at 50% mass loss and the char residue values of PVA nanocomposite containing 6 wt% of Zn‐g‐CP in the presence of hydrogel (PZH12 sample) were enhanced, which was evident by the increased thermal decomposition temperature. The peak of heat release rate (pHRR) value of the PZH12 sample was obtained 56.9% lower than that of the neat PVA demonstrating a significant improvement in flammability behavior. Also, the flame‐retardant performance of PZH12 improved, as compared to the pure PVA, with UL‐94 V1 rating and LOI of 27.2%. The tensile strength (Ts) and elongation at break (EB) values for the mentioned sample enhanced by 62.5% and 7.2% compared to those of the neat PVA, respectively.Highlights Preparation of vinyl functionalized ZnO nanoparticles (VZnO). ZnO grafted co‐polymer (Zn‐g‐CP) from a radical polymerization on the VZnO surface. Preparation of an amide‐sulfonated hydrogel in the PVA solution. The effect investigation of hydrogel and Zn‐g‐CP on the PVA properties. The results exhibited the enhanced flame retardancy and mechanical properties of PVA.