Chapter 3 - Micromechanical Characterization of Poly(Lactic Acid)/Halloysite Bionanocomposite Membrane

Abstract

Solution-casted poly(lactic acid) (PLA) membranes reinforced by halloysite nanotubes (HNTs) were uniaxially stretched to rupture using a novel micromechanical tester to evaluate their mechanical properties in dry and wet environments. X-ray photoelectron spectroscopy indicated that the PLA was not chemically modified when HNTs were blended into the matrix. In all cases, statistical analysis revealed that the yield strength, fracture strength, and fracture toughness differed significantly among the different treatments. In particular, the yield strength of dry PLA/HNT was significantly higher than dry PLA membranes; the yield strength of dry PLA/HNT membrane was higher than wet PLA membranes. The fracture strength of dry PLA/HNT was significantly higher than dry PLA membranes, wet PLA membranes, and wet PLA/HNT membranes. The fracture toughness of the membrane differed significantly among the different treatments. In particular, the fracture toughness of dry PLA/HNT was significantly higher than wet PLA membranes. On the other hand, these findings revealed that wet PLA/HNT and PLA exhibit similar yield strength, fracture strength, and fracture toughness. It was concluded that there would be no advantage (no enhancement in the yield strength, fracture strength, or fracture toughness) in reinforcing PLA with HNT if these PLA-based membranes were deployed in applications that subject the membrane to hydration, in a wet environment.