This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Korean researchers have developed a method to strengthen biodegradable plastics using hemp hurd, an agricultural byproduct. The approach is expected to be applicable to other large-volume agricultural residues, including soybean stalks and rice straw.
A research team led by Dr. Hoyong Kim of the Korea Research Institute of Chemical Technology (KRICT) extracted cellulose from discarded stalks of industrial hemp, which is used to produce traditional hemp textiles. The team then applied a drying process that preserves the microfibrillar structure of the cellulose, enabling it to serve as a reinforcing biofiller for biodegradable plastics.
The research was published in the Chemical Engineering Journal. Biodegradable films made from thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT) have attracted attention for use in eco-friendly packaging and agricultural mulch films because they can biodegrade in soil. However, these films tend to tear easily and have limited resistance to moisture.
Cellulose obtained from cotton or wood pulp can be processed into microfibrils and used as a reinforcing material, but the additional microfibrillation and processing steps can make such materials costly. Industrial hemp is currently cultivated in designated Regulation-Free Special Zones, including Andong, Gyeongsangbuk-do. While the outer part of the stalk is used to obtain fibers, the remaining woody core, known as hemp hurd, accounts for roughly 70% of the stalk by weight and has had relatively limited applications.
Using discarded hemp hurd as a feedstock for microfibrillated cellulose instead of commercial pulp could reduce both agricultural waste and raw material costs. A major challenge, however, is that cellulose microfibrils tend to aggregate tightly when dried using conventional methods. This phenomenon, known as hornification, causes the fine fibrillar structure to collapse as the fibers form strong hydrogen bonds with one another.
For a biodegradable film to become stronger, the reinforcing fibers must be uniformly dispersed throughout the polymer matrix so that mechanical stress can be distributed effectively. When the fibers form large aggregates, however, they cannot effectively bear or transfer stress, making the film prone to tearing. Freeze-drying and spray-drying can help suppress such aggregation, but their high energy consumption and equipment costs make them less suitable for large-scale production.
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