Prof. Jonghwan Suhr's (School of mechanical engineering) research team at Sungkyunkwan University has pioneered an innovative approach to overcoming the limitations of biodegradable plastic (PLA) by utilizing suberin derivatives extracted from cork and potato peels, paving the way for new advancements in sustainable material research.

PLA, a prominent eco-friendly polymer material, is derived from glucose extracted from crops like corn, sugarcane, and potatoes through a fermentation process. It is widely used in various forms, including films, fibers, packaging materials, and 3D printing. However, PLA's inherent brittleness makes it vulnerable to impact, and its high shear viscosity and low glass transition temperature (Tg) pose challenges in achieving uniform molding and producing high-quality products during processing.

In this study, depolymerized suberin derivatives (DSD) extracted from cork and potato peels were repolymerized into a plasticizer (pDSD) to alleviate the intermolecular interactions between PLA polymer chains. This modification significantly enhanced PLA’s flexibility and increased its tensile toughness by 1148%. PLA with pDSD additives exhibited reduced viscosity and over a threefold increase in melt flow index (MFI), dramatically improving efficiency and quality in various processing methods, including injection molding, film manufacturing, and additive manufacturing (3D printing). Furthermore, improved crystallization speed and uniformity expanded its potential applications to structural components. This research goes beyond merely enhancing PLA’s mechanical properties by developing an environmentally friendly material that retains over 90% biodegradability within 12 weeks.

This study is being further developed in collaboration with Chiang Mai University in Thailand, aiming for industrial commercialization of plastic alternatives. Notably, the material has demonstrated potential for diverse applications in 3D printing, eco-friendly disposable products, medical materials, and structural components in various fields of daily life and engineering.

Professor Seo remarked, "We are committed to developing innovative and practical solutions for a sustainable future. Through global research collaboration, we anticipate continuously achieving breakthroughs that transcend technological limitations."

Related Journal: Yoon, Hyejung, et al. "Plasticizing effect of depolymerized suberin derivatives from natural cork and potato periderm in poly (lactic acid)(PLA) for improved toughness and processability." Industrial Crops and Products 209 (2024): 117990.

Fig.1 (a) Suberin composition from exodermis of the cork tree, (b) suberin domain between primary cell wall and cell membrane, and (c) schematic illustrations of the DSDs polycondensation

Fig. 2 (a) stress-train curves determined from tensile tests for the neat PLA and pDSDs/PLA blends, (b) melt flow index for the neat PLA and pDSDs/PLA blends, and (c) degree of disintegration for the neat PLA and 5 wt% pDSDs/PLA blends determined from biodisintegration test over a span of 14 weeks inset photographs of the specimen taken at intervals of 0, 4, 8, and 12 weeks.