PHA/Clay Nano-Biocomposites

Abstract

Polyhydroxyalkanoates or PHAs were first observed in a laboratory in France in the 1920s and, since then, their creation as a form of energy storage in bacteria as well as their practical uses have been much studied. There has been increased interest in commercial production of PHAs in recent times and, over the past 10 years in particular, there have been various reports on solution-cast or melt-processed PHA/clay nano-biocomposites and their properties. In most studies, these nano-biocomposites exhibit intercalated or mixed exfoliated/intercalated morphologies. The use of plate-like clays as additives can lead to some enhancement in the mechanical and gas barrier properties of PHAs as well as increased thermal stability, although the effects depend significantly on clay type, clay organomodifer and process conditions. The influence of clay addition on PHA biodegradability has been either positive or negative according to the particular study. There has been very little research to date on the migration properties of PHA in the context of use in packaging and none yet in which PHA/clay nano-biocomposites have been the focus. If economic and technical challenges can be solved, PHAs should have a promising future in various uses ranging from packaging through to medicine and PHA/clay nano-biocomposites may also play a role in the future by providing a way for PHA material properties to be tuned according to the particular need.