Improved mechanical and thermal properties of spent coffee bean particulate reinforced poly(propylene carbonate) composites

ABSTRACT

Using biodegradable polypropylene carbonate (PPC) as the polymer matrix and 5 to 25 wt% content of spent coffee bean powder (SCBP) as filler, completely biodegradable composite films of PPC/SCBP were prepared. These composite films were characterized by polarized optical microscopy (POM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The POM images indicated the uniform distribution of the SCBP in the composites. The FTIR spectra indicated that the PPC structure was retained by the composite films. The XRD analysis found that the composite films had lower crystallinity than the PPC due to the presence of amorphous hemicellulose containing SCBP. A significant enhancement in thermal stability of the filler reinforced composite was noticed which was more than 30% of the PPC matrix due to the presence of polyphenols in SCBP. A maximum increase of 35% of tensile strength was observed with the addition of 20 wt% SCBP filled composite films. These biodegradable composite films with higher thermal stability and tensile strength can be considered for packaging applications.

KEYWORDS:

• Polypropylene carbonate
• solid waste
• spent coffee bean powder
• tensile strength
• thermal stability

Acknowledgments

The corresponding author wish to thank the Department of Science and Technology, India for the funding through Young Scientist Start up Scheme YSS/2015/001353 project. The authors thankful to the Kalasalingam University, Tamil Nadu, India for supporting this research by providing fabrication facility to the authors.