Microwave Radiation as Alternative to Modify Natural Fibers: Recent Trends and Opportunities – A Review
G. Y. Romero‐Zúñiga, Pablo González‐Morones, S. Sánchez‐Valdés, Roberto Yáñez Macías, Israel Sifuentes‐Nieves, Zureima García Hernández, Ernesto Hernández‐Hernández
Abstract
The main difference between microwave (MW) and conventional heating is the way heat is transferred, since the MW energy interacts directly with the material and it can be absorbed, transmitted, or reflected by the surface, while conventional heating proceeds through a conduction transfer heat. Natural fibers (NF) have been modified by MW treatment, and they can be useful in the development of polymeric biocomposites, biofuels, activated carbon and carbon nanostructures. This review summarizes the advances of MW radiation treatments on NF. Additionally, the relationship among the MW reactor design, MW processing conditions (temperature, time treatment, and radiated power) to the dielectric (Tan δ) properties of each fiber component (cellulose, lignin, and hemicellulose) was assessed in this paper. Furthermore, an overview of the main morphological and structural changes of NF after MW treatment is presented with the objective of suggesting processing methodologies that will increase the reproducibility data, as well as the functionality, applications and industrial process scale-up of the NF.