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Development And Characterization Of Biocomposites From Polyhydroxybutyrate (PHB)/ Polylactic Acid (PLA) Filled With Agricultural Residue

Date

2022-09-21

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0000-0002-9544-7010

Type

Thesis

Degree Level

Masters

Abstract

Abundant agricultural residues such as corncob are promising for making polymeric composites. Due to its capacity to replicate complicated shapes and geometries while maintaining outstanding mechanical qualities, three-dimensional (3D) printing has become a popular method for quick prototype development and manufacture. In order to create low-cost bio-polymer composites from a largely underutilized corncob biomass, this study investigates the potentials of employing this agricultural residue as filler material and to ultimately promote environmental sustainability. This is in-line with the drive for improved biomaterials as Canada anticipates banning single use non-degradable plastics by 2030. A manufacturing procedure was developed for producing affordable polyhydroxybutyrate (PHB) / polylactic acid (PLA) - corncob (PHB/PLA-CC) composite filaments for 3D printers. Test samples were made by blending generic PHB and PLA pellets in the percentage ratio of 55%:45% (PHB:PLA) w/w and, subsequently, corncob powder with an average particle size of 25.48 µm and particle density of 2.91 g/cm3 was added as a filler at varying weight percentages (wt.%) of 0, 2, 4, 6 and 8. The composite mix was extruded using a Filabot single screw extruder to produce a fused filament for 3D-printing having a consistent diameter of 2.85 mm. These filaments were tested under tensile loading until fracture to establish the tensile properties. Subsequently, the filaments were made into mechanical tensile test samples (dog bones), flexural test samples as well as Charpy impact test samples and tested. Results showed that the tensile strength of both the filament and dog bone samples, flexural strength and Charpy impact toughness of the composites all reduced with increase in filler loading. However, the tensile and flexural modulus of all samples tested showed a significant improvement with increasing filler loading. SEM analysis revealed that the cellulose content and grinding of the filler particles gave rise to dense, slightly elongated sheet-like shapes for the filler particles. The fractured surfaces of the composite samples displayed flat and cleavage features for pure polymer blends but turned rougher and jagged as filler loading increased. The fractured surface of Charpy impact samples tested at cryogenic temperatures showed smoother morphology compared to those tested at room temperature. Modulus generally improved as filler loading is increased, with best results mostly at 6 wt.% filler loading. The results show this is a promising composite filament material for 3D printing applications.

Description

Keywords

bio-composite, sustainable materials, fused filament, PHB, PLA, 3D printing

Citation

Degree

Master of Science (M.Sc.)

Department

Mechanical Engineering

Program

Mechanical Engineering

Advisor

Part Of

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DOI

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