SYNTHESIS AND CHARACTERIZATION OF GRAFT COPOLYMERS OF WITH ACRYLONITRILE AS A GRAFTING AGENT

Graft copolymerization is a promising method for properties modification of natural polymers. Cassava starch, a natural polymer was extracted using wet extraction route. Part of the obtained starch was pre-gelatinized at above 70oC and esterified using phthalic anhydride. CaO (catalyst) was prepared by calcining snail shell powder in a muffle furnace at 800oC for 4 h. The native and pregelatinized/phthalated starch solutions were grafted with acrylonitrile at 120oC in the presence of CaO catalyst. The prepared CaO catalyst was characterized using SEM, EDS, TGA, XRD, and FTIR for surface assessment, elemental evaluation, thermal degradation, amorphosity/crystallinity determination, and functional group evaluation, respectively. The SEM-EDS of the prepared CaO catalyst revealed spherical shape and the elemental compositions. The FTIR spectra of the grafted native cassava starch copolymer and grafted phthalated cassava starch copolymer revealed the existence of C equivalent to N-peak at 2364 and 2262 cm-1, respectively which is an evidence of grafting. The surface of the native cassava starch grafted copolymer granules was eroded with cracks, while that of the phthalated cassava starch grafted copolymer showed coagulated and coerced morphology. The XRD result of the native cassava starch grafted copolymer revealed one major sharp peak at angle 2 theta=25o while that of the phthalated cassava starch grafted copolymer revealed numerous peaks. The TGA analysis revealed that the phthalated cassava grafted copolymer framework was completely broken at 500oC unlike the native cassava starch grafted copolymer whose complete decomposition was about 420oC. It was observed that the modified samples had improved features over the native sample.