FAN Guodong;LIU Rongli
The research and the development of poly(lactic acid)(PLA) inorganic particles nanocomposites in recent years are reviewed in this paper. The nanocomposites are classified into two different kinds, i.e., the PLA/layered silicate nanocomposites. Montmorllonite is among the most commonly used layered silicates for the preparation of nanocomposites, with high cation exchange capacities, surface area, and surface reactivity. It is hydrophilic in nature, and its property makes it very difficult to be dispersed into the PLA matrix. The most useful way to overcome the difficulty is to replace the interlayer cations with the quaternary ammonium or phosphonium cations, preferably with long alkyl chains. The other is the inorganic oxide nanoparticles including SiO2, TiO2, MgO and ZnO. They have surface defects and high reactivity because a layer of hydroxyl (-OH) groups from the water dissociation covers the surface of oxide nanopaticles. Moreover, they could be modified by the hydrophobicity organic agent to improve the dispersion. In general, the ways to prepare the two kinds of nanocompositions include the in situ polymerization, the blending method and the Sol-gel method. With only a little inorganic nanoparticles being dispersed into the PLA matrix, the nanocomposite will exhibit significantly improved properties compared with pure PLA, including the mechanical properties, the thermal stability, the crystallization, the biodegradability, the rheological properties and the gas barrier properties.The trend of the PLA inorganic particles nanocomposites is to add the nanoparticles to achieve certain functions.
