Silicates as alternative pretreatment for cellulose pulp to obtain nanofibrils for application in biodegradable packaging: a technical review

ABSTRACT

Background:

The production of cellulose microfibrils/nanofibrils (CMF/CNF) has attracted increasing attention in recent decades due to their excellent barrier, mechanical, and surface chemistry properties. However, large-scale industrial production of CMF/CNF has been a major challenge due to their high energy consumption, limiting their application. In this context, in recent years many studies have focused on developing pre-treatments designed to facilitate the fibrillation of CMF/CNF by reducing energy consumption during their production. This review highlights the latest advances in the use of silicates as chemical pre-treatments for CMF/CNF production, covering the main aspects related to the effects of chemical modification on the production and the properties of materials for application in biodegradable packaging.

Results:

Energy consumption reductions of up to 30% were achieved by pretreating cellulose pulps using silicates. In addition, the pre-treatments resulted in smaller CMF/CNF diameters and greater individualization of the nanofibrils. Studies evaluating the thermal stability, hydrophobicity, mechanical properties, and porosity of CMF/CNF pre-treated with silicates have reported promising results. The application of CMF/CNF pretreated with calcium and magnesium silicates in cardboard coating resulted in packaging with low water vapor permeability and high ductility.

Conclusion:

Silicates interact well with cellulose surfaces, making them a promising material for the chemical pre-treatment of CMF/CNF. Furthermore, the modification by silicates could be an interesting strategy for expanding the use of CMF/CNF in the development of new products.

Keywords:
barrier properties; energy consumption; fiber modification; paper coating.

HIGHLIGHTS

Energy consumption in the production of CNF can be minimized with the use of silicates. Na2SiO3 is a potential alkaline agent capable of facilitating mechanical fibrillation. Ca2O4Si and MgO3Si can functionalize CNF, expanding their use in new materials. Coating cardboard with silicate functionalized CNF can improve the water vapor barrier..