Part A: Biodegradable Bio-Composite Film Reinforced with Cellulose Nanocrystals from Chaetomorpha linum into Thermoplastic Starch Matrices

Abstract

In recent years, macroalgae and microalgae have played a significant role in the production of organic matter, fiber, and minerals on Earth. They contribute to both technical and medicinal applications as well as being a healthy and nutritious food for humans and animals. The theme of this work concerns the development and exploitation of Chaetomorpha linum (C. linum) biomass, through the elaboration of a new starch-based composite film reinforced by cellulose nanocrystals (CL-CNC) derived from C. linum. The first step involves the chemical extraction of CL-CNC from dry C. linum algae biomass. To achieve this, three types of cyclic treatment were adopted: alkalinization (sodium hydroxide) followed by bleaching (sodium hypochlorite) and acid hydrolysis (hydrochloric acid). We then studied the optimization of the development of bio-composite films based on corn starch (CS) reinforced by CL-CNC. These polymeric films were produced using the solution-casting technique followed by the thermal evaporation process. Structure and interactions were modified by using different amounts of glycerol plasticizers (20% and 50%) and different CS:CNC ratios (7:3 and 8:2). These materials were characterized by UV visible (UV/Vis), Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM) spectroscopy to understand structure-property relationships. The result revealed that the best matrix composition is 7:3 (CS: CL-CNC) with 50% glycerol, which reflects that the reinforcing effect of CL-CNC was greater in bio-composites prepared with a 50% plasticizer, revealing the formation of hydrogen bonds between CL-CNC and CS.