Improvement of water vapor barrier and mechanical properties of sago starch-kaolinite nanocomposites

The composite films of sago starch were prepared by incorporation of various amount of kaolinite (K) and kaolinite intercalated by dimethyl sulfoxide (DMSO) (KD) via solution blending method in order to reduce the water vapor transmission and enhance mechanical properties of starch based films. The kaolinite intercalation by DMSO and the composite films were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscope techniques. The result showed that well-dispersed kaolinite layers were delaminated in the starch matrix attesting to intercalate and exfoliate composite films. The effect of kaolinite content on the water vapor transmission and tensile properties of the composite films was investigated. The water vapor transmission of the starch film (neat starch film ca. 0.132 g.cm(3)/h) decreased with the addition of K and KD to the starch. It was also observed that the maximum tensile strength (5.18 MPa) was attained for the composite film with 4% by weight of clay content. The improvement in the tensile strength and modulus of starch-based composites was due to the strong interfacial interaction between matrix and kaolinite clay, correlating to the change of morphology of the starch composite films as revealed by scanning electron microscopy.