Natural fibers faced compatibility challenges with hydrophobic polymers because of their hydrophilic nature. Surface modifications such as plasma treatment have been explored to improve adhesion and reduce water absorption. Plasma modification was favored for its efficiency, environmental benefits and ease of use. Non-thermal plasma proved especially effective enhanced sisal fiber adhesion while preserving mechanical properties.
This study examined the impact of non-thermal nitrogen plasma treatment (80 / 120 W for half an hour) on sisal fibers (SFs) focusing on mechanical and surface property modifications. Changes in diameter, tensile strength, breaking load and elongation were assessed via single fiber pull-out tests. Surface morphology is examined using Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy.
Non-thermal nitrogen plasma treatment at 120 W significantly enhanced SF mechanical properties, hydrophobicity, surface roughness and porosity improving adhesion. Treated fibers exhibited the highest total crystallinity index (1.16), lateral order index (0.96), % crystallinity (53.13%), crystallinity index (0.66) and amorphicity index AI (0.46). Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed reduced lignin and hemicellulose along with improved crystal size and morphology.
Chemical and physical treatments enhanced fiber surfaces but were limited by high chemical use and energy costs. Plasma treatments provide a consistent, cost-effective and eco-friendly alternative improving cohesion and biopolymer texture without affecting bulk properties.
The authors are confident that this technology will be accepted by the polymer, automotive, aerospace and related industries promoting the use of eco-friendly resources.
