How Plant Fiber and Seaweed Gel Composites Affect Strength and Flexibility

Jim Crocker
9th July, 2024

How Plant Fiber and Seaweed Gel Composites Affect Strength and Flexibility

Image Source: Natural Science News, 2024

Key Findings

  • The study by KTH Royal Institute of Technology explored how cellulose nanofibrils (CNFs) and alginates can create strong, sustainable composite films
  • CNFs with carboxylated surfaces bonded well with alginates using calcium ions, making the films stiffer and stronger
  • The composite films, especially those made with high mannuronic acid alginate, showed impressive mechanical properties and effective barrier properties for food preservation
The demand for sustainable and high-performance materials has led researchers to explore natural resources, such as cellulose nanofibrils (CNFs), for advanced material applications. A recent study conducted by the KTH Royal Institute of Technology investigates the impact of CNF surface characteristics and the properties of alginates on the structure, mechanical, and barrier properties of CNF/alginate composite films[1]. This study builds upon previous findings on nanocellulose and its promising applications in various fields[2][3][4][5]. Nanocellulose, derived from biomass, plants, or bacteria, is recognized for its renewability, abundance, and intrinsic properties such as excellent strength and high Young's modulus[2]. The ability to modify its surface and combine it with other materials makes it a versatile component in the fabrication of nanocomposites[2]. Previous research has shown that cellulose nanofibrils and nanocrystals, due to their nanoscale dimensions and crystalline assembly, can be functionalized with various substances to form advanced materials with specific properties[3]. In this study, three types of CNFs with varying surface charges and dimensions were prepared from wood pulp fibers. The researchers focused on understanding how the surface characteristics of CNFs, the guluronic acid/mannuronic acid ratio, and the molecular weight of alginates influence the performance of CNF/alginate composite films. Alginates, polysaccharides extracted from brown seaweeds, were chosen for their ability to form gels in the presence of calcium ions, thus facilitating interfacial bonding with CNFs. The study revealed that the interfacial bonding through calcium ion cross-linking between alginate and carboxylated CNFs (TCNFs) significantly enhanced the stiffness and strength of the composite films. This enhancement is attributed to the formation of an interpenetrating double network structure, which was more pronounced compared to composites made from alginates and CNFs with native negative or cationic surface charges. Various alginates extracted from Alaria esculenta (AE) and Laminaria hyperborea (LH) were examined to understand the influence of their molecular properties. The TCNF/AE composite, prepared from alginate with a high mannuronic acid proportion and high molecular weight, exhibited impressive mechanical properties. Under dry conditions, it achieved a Young's modulus of 20.3 GPa and a tensile strength of 331 MPa. Even in the wet state, the composite maintained a Young's modulus of 430 MPa and a tensile strength of 9.3 MPa. Additionally, the TCNF/AE composite demonstrated effective barrier properties as a coating for fruit. It significantly reduced browning of banana peels and weight loss of bananas stored under ambient conditions, showcasing its potential in food preservation applications. This study ties together previous findings by highlighting the importance of surface modifications and the use of natural polymers in enhancing the properties of nanocellulose-based composites. The results align with earlier research on the functionalization of cellulose nanofibrils and the formation of advanced materials[2][3][4][5]. For instance, the use of TEMPO-mediated oxidation to introduce carboxyl groups on CNFs has been shown to facilitate the formation of individualized nanofibers with high mechanical properties[4]. Similarly, the combination of carboxymethylated cellulose fibers with polyelectrolytes has demonstrated the potential for creating well-defined and functional layers[5]. In conclusion, the study by the KTH Royal Institute of Technology provides valuable insights into the design of high-performance, sustainable materials using CNFs and alginates. By understanding the role of surface characteristics and molecular properties, researchers can develop composites with enhanced mechanical and barrier properties, paving the way for innovative applications in various fields.

BiotechBiochemPlant Science


Main Study

1) Cellulose Nanofibrils/Alginates Double-Network Composites: Effects of Interfibrillar Interaction and G/M Ratio of Alginates on Mechanical Performance.

Published 8th July, 2024

Related Studies

2) Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their Applications.

3) Advanced Materials through Assembly of Nanocelluloses.

4) Cellulose nanofibers prepared by TEMPO-mediated oxidation of native cellulose.

Journal: Biomacromolecules, Issue: Vol 8, Issue 8, Aug 2007

5) The build-up of polyelectrolyte multilayers of microfibrillated cellulose and cationic polyelectrolytes.

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