Biodegradable cellulose based nanocomposites

Biodegradable cellulose based nanocomposites has been prepared. Cellulose diacetate(CDA) films incorporated with small amount of Montmorillonite nanoclay (MMT) were prepared from methylene chloride/ethanol (9:1 wt./wt.) casting solutions. The various nanoclays were incorporated into the cellulose structure in order to enhance the mechanical properties as well as thermal stability of cellulose. In order to substantiate the melt processability of cellulose derivatives, various structures of plasticizers were also incorporated. The plasticizers used were: dibutyl phthalate (DBP), diethyl phthalate (DEP), poly (ethylene glycol), LG Flex BET(BET), and LG Flex EBN(EBN). Among these, EBN and BET were chosen as biocompatible plasticizers. The plasticizer concentration was varied from 10 to 30 wt.% and the nanoclay 25 A from 1 to 7 wt.%. The composite films were characterized by DSC, XRD and mechanical test. Figure 1 compares the representative wide-angle x-ray diffraction (WAXRD) patterns for nanoclay, and its nanocomposite sample. It can be seen that interlayer spacing (d ₀₀₁) of clay 25A is 4.160 and 19.720 nm there is no indication of basal spacing in the composite films. This identifies that the CDA film does not have any crystallinity. In addition, the characteristic peaks representing d spacing of clay 25 A disappear in the compsoite film. The absence of the gallery height at 4.16 nm in film indicates that the regular spacing in composite is collapsed or the clay 25A layers are totally exfoliated to produce homogeneous dispersion. The films were completely transparent in the composition range of 10 to 30 w/w plasticizers and 1 to 7 w/w MMT. DSC thermo grams of CDA films with varied composition of plasticizer were shown in figure 1. A single Tg of plastisized CDA film was detected for each film. All the films gave a single glass transition temperature, Tg, which decreased sharply from 180 °C of the original CDA to approximately. 95 °C according to the content and kind of plasticizer, LG Flex EBN. Figure 3 shows the variation of tensile strength of plasticized CDA films as a function of their compositions. As can be seen in the figure, the strength of films decreased with the increase in the plasticizer content.