Effect of Cobalt Oxide Nanoparticles on the Nano-scale Free Volume and Optical Properties of Biodegradable CMC/PVA Films

• Published in: Journal of polymers and the environment 2018-06, Vol.26 (6), p.2536-2545
• Main Authors: El-Gamal, S., El Sayed, Adel M., Abdel-Hady, E. E.
• Format: Article
• Language: English
• Subjects: ABSORPTION SPECTROSCOPY; Biodegradability; Biodegradation; Carboxymethyl cellulose; Carboxymethylcellulose; CELLULOSE; Chemistry; Chemistry and Materials Science; Cobalt; COBALT OXIDES; Crystal structure; Crystallinity; Degree of crystallinity; DIFFERENTIAL THERMAL ANALYSIS; Environmental Chemistry; Environmental Engineering/Biotechnology; Fourier transforms; Industrial Chemistry/Chemical Engineering; Infrared analysis; INFRARED SPECTRA; Infrared spectroscopy; Materials Science; MELTING POINTS; NANOPARTICLES; NANOSCIENCE AND NANOTECHNOLOGY; Optical properties; Original Paper; Polymer Sciences; Polyvinyl alcohol; Positron annihilation; Positronium; PVA; Refractivity; Scale (corrosion); Spectrum analysis; Swelling ratio; Thermal analysis; X-RAY DIFFRACTION
• ISSN: 1566-2543; 1572-8919
• DOI: 10.1007/s10924-017-1151-x

Chemically prepared cobalt oxide nanoparticles (NPs) were added to biodegradable carboxymethyl cellulose (CMC) (20%)/polyvinyl alcohol (PVA) (80%) blend films. The structural properties of these films were investigated by X-ray diffraction, Fourier transformation infrared spectroscopy (FTIR) and differential thermal analysis (DTA). Co 3 O 4 /(CMC + PVA) films show a semi-crystalline structure and the degree of crystallinity decreases with adding Co 3 O 4 NPs. FTIR confirms the good interaction between the blend chains and Co 3 O 4 NPs. The melting temperature T m for CMC/PVA is about 212 °C then decreased with increasing Co 3 O 4 content, due to some decrease in the ordered association of the blend which results in a decrease in the blend crystallinity. Positron annihilation lifetime spectroscopy (PALS) measurements were carried out with a conventional fast–fast coincidence spectrometer. It was found that ortho- positronium lifetime τ 3 and free volume V f increase while o-Ps intensity I 3 still constant as Co 3 O 4 concentration increases. This is because adding Co 3 O 4 NPs encourages the formation of o-Ps. The swelling ratio SR% as a function of Co 3 O 4 concentration was also studied and its value increases with Co 3 O 4 addition. The optical study illustrated the decrease of the transmittance T of the films from 87 to 35.5% with increasing Co 3 O 4 content from 0 to 0.9 wt%. Also, both the direct and indirect optical band gaps of the films red-shifted from 4.05 to 3.75 eV and 3.3 to 2.75 eV, respectively. The influence of Co 3 O 4 on the refractive index of the films is also reported.