Surface Free Energy of Bast Fibers - A Review

Bast fibers, known to humanity for thousands of years, are currently gaining a new role in industry thanks to pro-ecological trends and innovative technologies. However, utilizing their potential in creating biodegradable products requires an in-depth analysis of surface properties, particularly the determination of surface free energy. Although the issue of surface free energy is complicated, the availability of various mathematical models and measurement techniques allows for an increasingly better understanding of the phenomena occurring on the surface of these natural raw materials. This article provides an overview of surface free energy in the context of phenomena occurring on the surface of bast fibers. It discusses the theoretical foundations and research methods, with particular emphasis on methods based on contact angle measurement. It also presents research challenges arising from the inherent heterogeneity of fibers and methods for their modification to optimize functional properties in various industrial sectors, which aligns with the growing demand for eco-friendly materials.