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.

Part B: Improvement of the Optical Properties of Cellulose Nanocrystals Reinforced Thermoplastic Starch Bio-Composite Films by Ex Situ Incorporation of Green Silver Nanoparticles from Chaetomorpha linum

“…Green algae were collected on the southwest coast of the Red Sea in Jeddah KSA (coordinates 21 • 37 41 N and 39 • 6 11 E). A CS:CL-CNC7:3-50% bio-composite (Table 1) was developed by reinforcing the thermoplastic starch matrix with cellulose nanocrystals (CL-CNCs) derived from C. linum algae biomass, according to the treatment detailed in our previous studies [6]. Silver nitrate-AgNO 3 (99.8%) was purchased from VWR, PROLABO.…”

“…AgNPs (5, 10, 20, 40 and, 50%) were ex situ incorporated in (CS:CL-CNC7:3-50%) biofilm employing the matrix containing CL-CNC from C. linum (3 g), CS (7 g) and 50% glycerol as plasticizer agent to improve the optical properties of our previous biofilm [6]. The reduction of AgNPs was carried out by UV-Visible, SEM-EDX, TEM, and FTIR.…”

“…For example, natural polymers including by-products of cellulose, starch, natural rubber, and biopolymers such as polyhydroxyalkanoate (PHA), polylactic acid (PLA), polycaprolactone (PCL), etc., were widely used as biodegradable polymers to prepare bio-nanocomposites reinforced with cellulose nanocrystals [4,5]. Therefore, in our recent studies [6], we sought to reinforce the bio-composite film, with the introduction of a green C. linum silver nanoparticle in order to improve the optical properties of the biofilm. The study provided not only the optical property but also the characterization that led to the development of an optoelectronic bio-nanocomposite.…”

“…The objective of this study was to Integrate ex situ AgNPs as an electron donor reinforcement at the bandwidth of the bio-composite developed in our recent study [6] in order to develop new low-bandgap bio-nanocomposites for an optoelectronic application. The main requirement was to reduce the HOMO energy level as well as the bandgap of the polymers in order to increase the open circuit voltage of organic photovoltaic solar cells.…”

Investigating the lap shear adhesion of coir and glass-fibre reinforced epoxy bonding to mild steel with varying volume fractions

“…In the process, the cellulose fibers swell and alter shape because of being exposed to the alkali, which enhances strength, luster, and resin uptake. The NaOH specifically hydrolyzes the cellulose molecules in the fibers, releasing the hydroxyl groups by dissolving the hydrogen bonds that connect the glucose chains, (Alsufyani and M'sakni, 2023;. The sodium ions in the NaOH solution subsequently react with the exposed hydroxyl groups to generate sodium celluloseate.…”