Isothermal Crystallization Behavior of Poly(L-lactic acid)/Organo-Montmorillonite Composites

Abstract

Montmorillonite (MMT), as a very important layer silicate, is widely used in all field such as materials 1-2 , geosorbents 3 , chemistry 4-5 , waster repositories 6 , etc. Especially, the most important application of montmorillonite is additive of polymer in recent years 7-8. Montmorillonite can improve the impact resistance, dimensional stability, crystallization properties of polymer, for example, Zhang et al. 9 reported the preparation and properties of polyester-organophilic montmorillonite intercalated hybrid. The result of this investigation showed that when the content of organophilic montmorillonite was between 2 and 5 %, the tensile strength, impact strength, heat resistance and swelling resistance of the hybrid were obviously enhanced.The nonisothermal crystallization kinetics of polyoxymethylene/organic-montmorillonite (POM/organ-MMT) composites was investigated 10. The difference in the values of the exponent 'n' between polyoxymethylene and POM/MMT composites suggested that nonisothermal crystallization of POM/organ-MMT nanocomposites corresponds to a tridimensional growth with heterogeneous nucleation. And the crystallization rate of POM/organ-MMT nanocomposite is faster than that of neat POM at a given cooling rate. These results further indicated that the addition of montmorillonite may accelerate the overall non-isothermal crystallization process of polyoxymethylene. However, the montmorillonite as an additive of polymer usually modified by chemical method and compatibility ability