Preserving the Cellular Tissue Structure of Maize Pith Though Dry Fractionation Processes: A Key Point to Use as Insulating Agro-Materials

• Published in: Materials Vol. 14; no. 18; p. 5350
• Main Authors: Mayer-Laigle, Claire, Haurie Ibarra, Laia, Breysse, Amélie, Palumbo, Marina, Mabille, Frédéric, Lacasta Palacio, Ana Maria, Barron, Cécile
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2021; MDPI
• Subjects: Alternative energy sources; Biomass; Cellular structure; Chemical and Process Engineering; Composite materials; Corn; Crop residues; Dissection; electrostatic separation; Engineering Sciences; Food engineering; Fractionation; gravity sorting; Insulation; Life Sciences; Lignocellulose; milling; Organs; Particle size; plant tissues; Scanning electron microscopy; Separators; Shearing; thermal properties; France; electrostatic separation; gravity sorting; plant tissues; thermal properties; milling
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14185350

Plant biomass has various compositions and structures at different scales (from the component organs to their constitutive tissues) to support its functional properties. Recovering each part of the plant without damaging its structure poses a challenge to preserving its original properties for differential dedicated end uses, and considerably increases its added value. In this work, an original combination of grinding based on shearing stress and separation based on particle size and density was successfully used to sort rind (65% w/w) and pith (35% w/w) from maize stem internodes. More than 97% of the rind was isolated. The pith alveolar structure was well preserved in coarse particles, making them suitable for insulation bio-based composite materials, a promising alternative to conventional nonbiodegradable insulation panels. Boards produced from the dry fractionated pith exhibited thermal conductivities like those produced from hand dissected pith, with values equal to 0.037 W·mK−1 and 0.039 W·mK−1, respectively. In the finest fraction (particle size <1 mm), the pith vascular bundles (around 300–400 µm in diameter) were dissociated from parenchyma cells and successfully isolated using a cutting-edge electrostatic separator. Their structures, which provide the plant structural support, make them potentially valuable for reinforcement in composite materials.