Impact of graphite particle surface modification on the strengthening of cross-linked polyvinyl alcohol composites: A comprehensive investigation

To reduce the hydrophilicity of polyvinyl alcohol (PVA), various methods are employed. Acid cross-linking is one technique, but it decreases the polymer's strength. To address this, different reinforcements are utilized to enhance the polymer's strength while mitigating the side effects of acid cross-linking. The present research intends to improve the physical, mechanical, and thermal properties of PVA by cross-linking it with fumaric acid and reinforcing it with modified graphite particles. The particles were prepared through oxidative acidic treatment and added in different weight proportions (0.5, 1, 1.5, and 2 wt.%) to the PVA matrix. Water absorption (WA) tests were conducted to affirm the formation of cross-linked bonds, and Fourier transform-infrared spectroscopy was employed to confirm the oxidation of the graphite particles with acid. The composites were examined using scanning electron microscopy, which revealed a robust interfacial adhesion between the modified graphite and cross-linked PVA, resulting in better mechanical characteristics. The highest ultimate tensile strength was observed when using 1.5 wt.% of modified graphite particle reinforcement, resulting in a 31% increase in comparison to pure cross-linked PVA. Moreover, the thermal stability increased from 358°C (PVA alone) to 375°C (composite with 2 wt.% treated graphite particles). Dynamic mechanical analysis revealed an increase in glass transition temperature from 68.2°C to 72.9°C, and activation energy from 604.84 to 1028.21 kJ mol −1 (neat PVA to composite with 1.5 wt.% modified particles). The damping coefficient of the cross-linked composite was 0.257, making it suitable for acoustic damping applications like speakers.