Investigation of the Protective Function of a Lignin Coating of Natural Fiber Geotextiles against Biodegradation

Abstract

Natural fibers do not have a long life in soil; therefore, they cannot replace synthetic textiles in many applications. However, in order to solve ever-increasing global environmental problems due to microplastics, more and more natural polymers must be used, creating a need for research into the sustainable life extension of natural fibers. Lignin is, along with cellulose, a main component of wood, and is produced in large quantities as waste during paper production. With appropriate processing, lignin can be exploited/used as a textile auxiliary to combine the strength-enhancing properties of textiles made from natural fibers with the protective properties of a lignin coating. However, there is not yet sufficient research on how to integrate lignin into textile applications. For this purpose, in this study, we have investigated whether thermoplastic lignin can be processed as a surface protective coating. We tested lignin as a yarn coating to extend the service life of cellulosic textiles. Cotton yarns have been coated with lignin in variations of coating mass, characterized and investigated by means of soil burial tests. As the soil burial tests conducted in climate chamber and outdoor field environments showed, the lifespan of textiles made from natural fibers can be significantly extended with a lignin coating. Long-term resilience has been demonstrated in standard burial tests. In the outdoor tests, the lignin coating was still fully intact, even after about 160 days of burial. The textile materials coated in this way enable sustainable applications, especially for geotextiles. They have an adjustable, sufficiently long service life; however, they are still biodegradable, and can therefore replace some applications, such as vegetating trench/brook slopes, with synthetic materials. Lignin-coated textiles have the potential to significantly reduce the carbon footprint, reduce not only the dependence on petroleum-based products but also the amount of microplastics entering the environment. Further research can be conducted to improve lignin compounding in terms of other interesting properties for specific textile applications. Process optimization could increase the protective effect and further extend the life of useful textiles in soil.

Spray Coating of Wood with Nanoparticles from Lignin and Polylactic Glycolic Acid Loaded with Thyme Essential Oils

“…Other options to make wood protection more environmentally friendly is to replace fossil-based ingredients in traditional wood protection formulations with bio-based additives like lignin or to use lignin nanoparticles (LNPs) as coatings or as carriers of bioactives [37,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. Lignin coatings were investigated in a wide range of applications [61][62][63], including as water vapor and oxygen barriers in fiber-based packaging solutions [64], as protective coatings for natural fibers for textile production [65], or for the surface modification of paper products [66,67]. Others prepared novel, bio-based anti-viral surface coatings via spin-coating of lignin where the anti-viral effect was obtained due to reactive oxygen species formation through lignin phenol oxidation and therefore, the lignin coating is not consumed [68].…”