Date of Award

January 2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

First Advisor

Suroji Gupta

Second Advisor

Yun Ji

Abstract

This study explores the synthesis and characterization of soybean-based composites with a focus on their potential for sustainable material applications. Soybean meal (SBM), known for its high protein content, is blended with the biopolymer polylactic acid (PLA) using eco-friendly manufacturing processes. The solvent casting and hot-pressing methods are employed to fabricate composites, and their mechanical and thermal properties are investigated. Tensile strength of the composites decreases with higher concentrations of soybean meal, while thermal properties remain comparable to PLA. The hot press method, optimized at 250°C and 235 MPa, shows promising results in enhancing compressive strength with increased SBM concentration at higher concentrations. Water absorption tests reveal the hydrophilic nature of the samples, prompting the development of a fiber coating technique, leading to improved mechanical properties and water resistivity. It was reported that the PLA-coated SBM composites exhibited superior mechanical properties and lower water absorption over a 24-hour period compared to the uncoated SBM composites. The average Ultimate Compressive strength (UCS) for the 75% SBM – 25% PLA increased from 60.57 ± 7.63 MPa to 79.98 ± 5.85 MPa when coated with 1.0 g of PLA. Similarly, the average UCS of 90% SBM – 10% PLA rose from 62.77 ± 7.61 MPa to 83.48 ± 4.98 MPa with the same coating. Additionally, water absorption capacity decreased from ~110% to ~19.93% in the 75% SBM – 25% PLA blend and from ~111% to ~24.25% in the 90% SBM – 10% PLA blend after coating with 5.0 g of PLA. Scanning electron microscopy (SEM) analysis displays the presence of cracks which suggests opportunities for further research on fiber modification techniques. The study contributes valuable insights into sustainable material development, offering potential applications in industries such as packaging, automotive, and construction.

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