Study: Hemp Seed Hulls May Strengthen Bioplastics While Improving Biodegradability
- The study found that chemically modified hemp seed hulls can enhance the strength and biodegradability of cellulose acetate-based bioplastics.
- Researchers treated hemp seed hulls with 8% to 12% sodium hydroxide, which improved tensile strength by 21%-23%, tensile modulus by 17%-24%, and hardness by 11%-13% in biocomposites.
- Alkaline treatment removed hemicellulose, lignin, proteins, and fats from hemp seed hulls, increasing cellulose content and creating rougher surfaces that improved filler-matrix interaction.
- Biocomposites with alkali-treated hemp seed hulls biodegraded faster than those with untreated hulls, suggesting potential for more sustainable plastic materials and better use of hemp byproducts.
A study published recently in the peer-reviewed journal Molecules found that hemp seed hulls, an often-overlooked agricultural byproduct, may help improve the strength and biodegradability of cellulose acetate-based bioplastics.
Researchers from Kaunas University of Technology examined whether chemically modified hemp seed hulls could be used as biofillers in thermoplastic biocomposites. The study focused on cellulose acetate, a plant-derived polymer, combined with triacetin, an environmentally friendly plasticizer.
The researchers treated hemp seed hull particles with sodium hydroxide solutions at different concentrations, as well as acetylation in some samples, before incorporating them into bioplastic formulations. They found that moderate alkaline treatment produced the best results, particularly when using 8% to 12% sodium hydroxide.
According to the study, biocomposites containing hemp seed hulls treated with 8% and 12% sodium hydroxide saw tensile strength improve by 21% to 23%, while tensile modulus increased by 17% to 24%. Hardness also increased by roughly 11% to 13%.
The study found that alkaline treatment altered the hemp seed hulls by removing portions of hemicellulose, lignin, proteins and fats, while increasing the relative cellulose content. This helped create rougher particle surfaces, improving the interaction between the hemp-based filler and the cellulose acetate matrix.
The researchers also found that biocomposites made with alkali-treated hemp seed hulls biodegraded slightly faster under aerobic conditions than the base cellulose acetate material or composites made with untreated hulls.
The findings suggest hemp seed hulls could serve as a useful filler in more sustainable plastic materials, while giving value to a hemp byproduct that remains largely underused. The researchers said additional work is needed to further assess durability, processing and end-of-life impacts.