The influence of graphite on conductivity, crystallinity and tensile properties of hydroxyethyl cellulose (hec) / graphite composite films

Abstract

Abstract Conductive films based on natural polymers may find potential in food packaging and biomedical applications owing to their advantages of biodegradability and biocompatibility. This work demonstrated conductive composite films from hydroxyethyl cellulose (HEC) incorporated with graphite prepared by solution casting. Fourier Transform Infrared (FTIR) spectra confirmed the absence of covalent bond between the HEC matrix and graphite. The electrical conductivity of the composite films with various concentrations of graphite was investigated by a four-point probe. We observed that the conductivity of the HEC film increased remarkably from 10−8 S/cm to 10−5 S/cm upon addition of graphite. The highest conductivity of 9.44 x 10−5 S/cm to 10−5 S/cm upon addition of graphite. The highest conductivity of 9.44 x 10−5 S/cm was obtained for the film with 30 wt% of filler and further addition of filler reduced the conductivity. The correlation between conductivity and crystallinity was elucidated by X-ray diffraction (XRD) patterns. The difference in d-spacing values between HEC and HEC/Graphite films and the decrement of crystallinity percentage suggest that the rearrangement of ordered HEC crystalline structure was perturbed by the filler resulting in reduction of crystallinity phase. The tensile properties results clearly show that the incorporation of graphite into HEC films has reduced the tensile strength which is in agreement with the obtained electrical conductivity and crystallinity percentage.