Mechanical, thermal and characterization of chitosan, nano precipitated calcium carbonate single and hybrid filler/ poly (vinyl chloride) composites

Abstract

The aim of this study is to investigate the mechanical, thermal and characterization of chitosan, nano precipitated calcium carbonate single and hybrid filler/ poly (vinyl chloride) (PVC) composites. Graft copolymerization of poly (methyl methacrylate) (PMMA) onto chitosan (CS) was carried out under nitrogen atmosphere by free radical initiation in aqueous medium. Hydrogen peroxide (H2O2) and ferrous ions were used as a redox initiator/co-catalyst system. The PMMA homopolymer formed during the reaction was removed from the graft copolymer by extraction using acetone. The presence of PMMA functional groups in Fourier transform infra red (FTIR) spectra of grafted CS at peak 1731 cm-1 proved that the grafting process was successfully done. The single fillers (grafted CS, CS and nano-precipitated calcium carbonate (NPCC)) and hybrid fillers ((CS (2 phr)/NPCC (4 phr) and CS (4 phr)/NPCC (2 phr)) were pre-mixed with PVC using a high speed mixer. The dried blend formulations were milled into sheets using a two roll mill at temperature of 170 oC and then hot pressed at temperature of 175 oC. The tensile, flexural, impact strength and elongation at break of hybrid composites were increased compared to single fillers. Differences in surface morphology between the single composites and hybrid composites were observed. The hybrid PVC composites had better thermal stability than single composites. The increased of water resistance of the hybrid composites proved good filler-matrix interaction. Overall, the study showed that the hybrid PVC composites had good mechanical and thermal properties compared to the single filler PVC composites. PVC/CS (4 phr)/NPCC (2 phr) had reached a balanced properties in mechanical as well as thermal properties.