Strength improvement of poly(vinyl alcohol) (PVA) reinforced by Halloysite nanotube (HNT) treated with sulfuric acid

Halloysite nanotube (HNT) is a natural clay mineral with a hollow and tubular structure, which can be a potential reinforcement for biodegradable polymers such as poly(vinyl alcohol) (PVA). This study investigates the improvement of interfacial adhesion between HNT and PVA by means of controlled acid etching on HNT surfaces. Such an improvement is attributed to a porous structure with rough HNT surfaces in that acid favors the dissolution of AlO6. The strength of PVA/HNT nanocomposites increased up to 10% when HNT were subjected to 1 h acid treatment. However, the reinforcement effect could have been more pronounced if HNT aspect ratio were maintained during the composite fabrication process.