Effect of Lignin Loading and Glycerol Plasticization on the Mechanical and Biodegradation Properties of Agar-Based Films
Jaehee Kim, Taewoo Park, Myeongjun Song, Minseung Kim4
North London Collegiate School Jeju, Jeju, South Korea
St. Johnsbury Academy Jeju, Jeju, South Korea
Daegu Science High School for the Gifted, Daegu, South Korea
Newton South High, Newton, United States
Publication date: November 20, 2025
North London Collegiate School Jeju, Jeju, South Korea
St. Johnsbury Academy Jeju, Jeju, South Korea
Daegu Science High School for the Gifted, Daegu, South Korea
Newton South High, Newton, United States
Publication date: November 20, 2025
DOI: http://doi.org/10.34614/JIYRC2025II54
ABSTRACT
This study investigates the combined effects of lignin loading and glycerol plasticization on the mechanical and biodegradation properties of agar-based composite films for sustainable packaging applications. Agar–lignin films were fabricated with lignin fractions of 0–40% and evaluated for tensile strength, elongation, and soil biodegradability. Tensile strength increased from 25.1 ± 1.2 MPa to a maximum of 35.2 ± 0.9 MPa at 30% lignin with glycerol, whereas elongation at break decreased from 50 ± 2% to 36 ± 2% (p < 0.01), indicating reinforcement-driven stiffening offset by controlled plasticization. Biodegradation after four weeks rose linearly with lignin content—from 30 ± 2% to 50 ± 3% with glycerol and from 35 ± 3% to 58 ± 4% without glycerol—showing that lignin enhances microbial decomposition while glycerol moderates it by maintaining film cohesion. Together, these results identify an optimal formulation of 20–30% lignin with glycerol, balancing strength, flexibility, and biodegradability, and positioning agar–lignin composites as a promising, tunable platform for biodegradable food packaging materials that combine mechanical integrity during use with environmentally compatible post-use degradation.
This study investigates the combined effects of lignin loading and glycerol plasticization on the mechanical and biodegradation properties of agar-based composite films for sustainable packaging applications. Agar–lignin films were fabricated with lignin fractions of 0–40% and evaluated for tensile strength, elongation, and soil biodegradability. Tensile strength increased from 25.1 ± 1.2 MPa to a maximum of 35.2 ± 0.9 MPa at 30% lignin with glycerol, whereas elongation at break decreased from 50 ± 2% to 36 ± 2% (p < 0.01), indicating reinforcement-driven stiffening offset by controlled plasticization. Biodegradation after four weeks rose linearly with lignin content—from 30 ± 2% to 50 ± 3% with glycerol and from 35 ± 3% to 58 ± 4% without glycerol—showing that lignin enhances microbial decomposition while glycerol moderates it by maintaining film cohesion. Together, these results identify an optimal formulation of 20–30% lignin with glycerol, balancing strength, flexibility, and biodegradability, and positioning agar–lignin composites as a promising, tunable platform for biodegradable food packaging materials that combine mechanical integrity during use with environmentally compatible post-use degradation.
