Powder X-ray diffraction and thermal decomposition correlation studies of nano-crystalline styrene-maleic anhydride graft copolymer-ZnO composites

Abstract

AbstractNano-crystalline (nc) polymer-ZnO composite material has been successfully synthesized by treating styrene-maleic anhydride (SMA) and its graft copolymers with acrylic acid, (AAc), and acrylamide, (AAm), synthesized by chemical method with different wt% ratios of nZnO (40 nm), prepared indigenously in our laboratory, to yield polymer-ZnO nano-composite material. Characterization of SMA, grafted SMA, nc-SMA-ZnO, nc-grafted SMA-ZnO composites was carried out by X-ray diffraction and thermo-gravimetric analysis. Both the studies show an interesting correlation between X-ray and thermal data. XRD pattern of SMA copolymer shows it to be amorphous, while SMA-g-poly(AAc) and SMA-gpoly( AAm) graft copolymers show crystalline orthorhombic structure having (102) orientation with particle size of nano dimensions (44 and 40 nm respectively). Addition of nZnO to nc-SMA-g-poly(AAc) and nc-SMA-g-poly(AAm) shows appreciation in the crystalline behavior with increased intensity of the peaks in the XRD patterns. Thermo-gravimetric analysis (TGA) of SMA shows single stage decomposition with regular loss of weight while nc-SMA-g-poly(AAc) and nc-SMAg- poly(AAm) graft copolymers respectively show an abrupt weight loss up to 25% and 45% at 121.370C and thereafter proceeds with regular decomposition. However, the corresponding composite of SMA with nZnO (10 wt%) shows an abrupt weight loss of 50% similar to grafted SMA while the ZnO embedded composites of AAc and AAm grafted SMA lose 95% of the weight abruptly at the same temperature i.e.121.37 °C. The increased abrupt loss in nZnO- SMA and nZnO-nc-SMA grafted composite is correlated to the increased crystallinity upon addition of nZnO particles to the polymer system. Because of the spontaneous thermal decomposition and release of large amount of heat energy, the newly synthesized nano-composite polymer material can find use as high energy material