Masters Theses

Date of Award

8-2025

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Uday Vaidya

Committee Members

Uday Vaidya, Chad Duty, Jeff Reinbolt

Abstract

Thermosets comprise 80% of the market for reinforced composites with epoxy-based systems representing a substantial portion of wind turbine blade (WTB) manufacturing due to their superior mechanical strength, fatigue resistance, and chemical stability. As a result, WTB comprising of glass fiber reinforced polymers (GFRP) using epoxy resin systems are costly and difficult to manage at end-of-life. By modifying the composite with high-performance anime-based epoxy curing agents, Recyclamines, wind blade waste can be reclaimed and reused to reduce the impact on landfills. In this study, an epoxy-based resin with Recyclamine, Epotec (EP), was used to produce nonwoven carbon fiber reinforced polymers (CFRP) using low-cost carbon fiber (LCCF), GFRPs, and hybrid composites through a traditional vacuum-assisted resin transfer molding (VARTM) process and compared to an epoxy resin and infusible methacrylate-based thermoplastic resin with thermoset-like processability, ELIUM (EL). Rheological and thermal analysis showed EP’s suitability for WTB manufacturing, with low viscosity (~10 Pa.s), extended gel time (>200 min), and enhanced thermal stability, further improved by LCCF reinforcement. Mechanical testing showed that EP and nonwoven discontinuous LCCF significantly improved tensile and flexural strength and stiffness compared to EL with flexural strengths up to 858 MPa and tensile modulus reaching 48.2 GPa. Microscopy showed nonwoven composite failure was attributed to fiber pullout and debonding indicating enhanced stiffness compared to interlaminate shearing between hybrid and knitted fiber structures. Solvolysis demonstrated near 100% fiber recovery as 70.72% of the total mass was recovered as reusable fiber using low energy input conditions. The findings presented in this study displayed composite properties offered by LCCF, EP, and nonwoven fabrics for WTB manufacturing and recycling.

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