Production of biodegradable plastic from starch/PVA/glycerol/cellulose blends
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Date
2022-06
Authors
Lipharama, Mashudu
Journal Title
Journal ISSN
Volume Title
Publisher
Vaal University of Technology
Abstract
Most municipal waste consists of packaging waste, mainly petroleum-based plastics that are not biodegradable. There is a need to develop biodegradable plastics that naturally degrade after use. This research aims to develop a biodegradable polymer blend of starch/PVA/glycerol/cellulose that exhibits thermal and mechanical properties suitable for packaging purposes. Starch is an abundant biopolymer used to make bioplastics because of its thermoplastic properties. It is of great interest due to its attractive properties such as uncomplicated chemical structure, cost efficiency; biodegradability; availability and renewability. Polyvinyl alcohol is a white crystalline powder biocompatible with starch and is said to improve the thermal and mechanical properties of starch-based materials. It is also known for its remarkable film-forming ability, chemical resistance, and mechanical properties.
Cellulose is the most plentiful, ubiquitous, and stable biopolymer. It is reported that plastics composed of cellulose nanocomposites have better physical and mechanical properties than traditional plastics due to the reinforcement provided by the nano-dimensional particles. Plasticizers are used as processing additives to aid in processing, and water and glycerin work best for starch-PVA blends. The samples were prepared using a solvent casting process. The samples were then stored at room temperature in a large airtight plastic container and conditioned to 75% relative humidity.
Characterization Thermogravimetric analysis (TGA), Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), tensile tests, water absorption and solubility, were performed. Incorporating Hydroxyethyl cellulose (HEC) into cast samples improved the thermal stability of corn starch by 28%. The ultimate tensile strength (UTS) and elongation at the break of the Hi-Maize sample increased by 150% (i.e. from 0.46-1.15 MPa) and by 7.7 % with the addition of PVA. The corn starch samples had better thermal and mechanical properties and also retrograded more slowly than the dextrin samples.
Description
M. Eng. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology.
Keywords
Biodegradable, Bioplastic, Cellulose, Hi-maize starch, Dextrin, Polyvinyl alcohol