Polyvinyl alcohol-graphene oxide nanocomposites: evaluation of flame-retardancy, thermal and mechanical properties

Abstract

The graphene-based additives containing polyethyleneimine (PEI) or hydroxyapatite (HAP) were synthesized and their effects on the flame retardancy, thermal, mechanical properties of polyvinyl alcohol (PVA) matrix were evaluated. Thermogravimetric analysis studies (TGA) and Scanning electron microscope (SEM) images were indicated that PEI and HAP have a strong influence on the fire behavior of the composites which might be explained by the forming of a uniform and compact char during combustion. The presence of nitrogen in PEI and phosphorus in HAP which are generated nonflammable gases and phosphoric radicals, respectively at combustion conditions could represent a significant role in the catalytic char residue formation, heat transfer limitation and then diminish or even stop the combustion reactions. The char yields of the 5 wt% PVA/GO-PEI nanocomposites were increased up to 22 folds without any significant change in mechanical properties; Moreover, the char yield of PVA/GO-HAP nanocomposites was more than pure PVA (24 folds) because of its thermal stability at high temperature. All these data demonstrated that not only did PVA/GO-PEI keep the mechanical properties nearly the same as in pure PVA but also improved flame retardancy. But, the PVA/GO-HAP has great potential as flame retardants between all obtained composites.

Keywords:

• Polyvinyl alcohol
• graphene oxide
• polyethyleneimine
• hydroxyapatite
• thermal stability

Acknowledgments

This study was supported financially by Tehran University and Tehran University of Medical Sciences.