Conductivity, thermal behaviour and ftir studies on different modified natural rubbers / Nur Atiqah Hamidun

Epoxidized natural rubbers (ENR-25 and ENR-50), methylated grafted natural
rubbers (MG-30 and MG-49) and deproteinized natural rubber (DPNR) doped
with 0 - 30 wt % of LiClO4 were prepared by solution casting technique.
Thermal stability ( d T ) and glass transition temperature ( g T ) of all the rubber
samples were investigated by Thermogravimetric Analysis (TGA) and
Differential Scanning Calorimetry (DSC), respectively. Quantities d T show that
ENR-25 and ENR-50 are thermally more stable than that of DPNR, MG-30 and
MG-49. The Tg values of all the rubber samples show no significant variation
with ascending salt content after 5 wt % of LiClO4 added. Ionic conductivity (
studied by impedance spectroscopy show that MG-49 and ENR-25 exhibit
higher  values of 8.810-8 and 9.510-8 S cm-1 than MG-30 and ENR-50,
respectively. ATR-FTIR was applied to examine the ion-dipole interactions
between the LiClO4 salt and the rubber samples. It is observed that the Li+ ions
preferentially coordinated to the epoxy oxygen of the ENR. For MG-30 and
MG-49, the Li+ ions are mainly coordinated to the C-O and the C=O of the ester
groups.