Biodegradable poly(propylene carbonate)/layered double hydroxide composite films with enhanced gas barrier and mechanical properties

Abstract

Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides (LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH (OLDH) in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A series of poly(propylene carbonate) (PPC)/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient (OP) and water vapor permeability coefficient (WVP) is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.