Impact of Eucalyptus nitens and Pinus radiata fiber properties on the production process of lignocellulose nanofibrils

The physical and chemical properties of the plant cells that make up the raw material are diverse and affect the properties of lignocellulose nanofibrils (LCNFs). Due to their chemical differences, understanding the effect that the physical properties of the raw material confer on LCNFs is complex. This study aims at comprehending the impact that the physical properties and the chemical composition of the raw materials from Pinus radiata D. Don and Eucalyptus nitens Maiden have on the mechanical processes of fibrillation and the final properties of LCNFs. The anatomical, physical, and component differences of the fibers in the different fractions and species showed a non-effect on the longitudinal disintegration during the mechanical processes of fibrillation. In addition, the LCNFs produced from smaller fibers showed a smaller average width, with Eucalyptus nitens being the species that had smaller and more homogeneous nanofibrils. Nevertheless, the organization of the components (hemicellulose) from Pinus radiata on the surface of the fibrils, generates very hydrated and large fibrils and flocs, increasing the viscosities of the LCNF suspensions. A model was established between the intrinsic viscosity ( [ eta]) and aspect ratio ( p) of LCNFs ( rho[ eta] = 0.15p(1.68)) and delignified CNFs ( rho[ eta] = 0.031p(1.94)) that are independent of the pretreatments and the flexibility of the fibrils. Finally, the glass transition temperatures of lignin were not affected by physical changes in the raw material.

Automated summary

This study aims to understand the impact of physical properties and chemical composition of Pinus radiata D. Don and Eucalyptus nitens Maiden raw materials on the fibrillation process and final properties of Lignocellulose nanofibrils (LCNFs). The anatomical, physical, and component differences of the fibers did not affect the longitudinal disintegration during the fibrillation process. Smaller fibers produced LCNFs with a smaller average width, particularly in Eucalyptus nitens. The arrangement of components (hemicellulose) from Pinus radiata on the fiber surface resulted in larger and more hydrated fibrils, increasing the viscosities of LCNF suspensions. The glass transition temperatures of lignin were not affected by physical changes in the raw material.