Poly (ethylene terephthalate) (PET) is widely used in packaging plastics and accounts for up to 26% of all plastics used in packaging in the U.S. The challenges with PET recycling that must be addressed to promote the PET circular economy incorporate the existence of thermoformed PET (PET-T) in PET bottle (PET-B) recycled bales and the purification of PET to remove contaminants for food contact applications, among others. The aim of this research was to develop potential value-added composites for non-food applications made of PET-B and PET-T. As reported in this thesis, carbon fiber-reinforced composites prepared from postconsumer PET T and PET-B blends were assessed. In total, three different carbon fiber lengths of 0.5, 1, and 2 inches and two different carbon fiber loadings of 1 and 3 wt.% were used in PET-T and PET-B blends, where PET-T was 20 wt.% and PET-B was 80 wt.%. These composites were prepared in the presence and absence of epoxy chain extenders. The mechanical properties of the obtained composites were evaluated with tests including measurements of their tensile strength, modulus of elasticity, impact strength, and percentage elongation at break. In addition, heat deflection temperature, glass transition temperature, melting temperatures, degree of crystallinity, and thermal degradation were also tested. Furthermore, SEM analyses were performed to assess fiber distribution and adhesion between polymer and fiber. Our results showed that recycled PET-B/PET-T carbon fiber-reinforced composites at 3 wt.% fiber loading had up to a 20% increase in tensile strength, up to a 50% increase in modulus of elasticity, and up to an 18% increase in impact strength compared to recycled PET-B/PET-T without carbon fiber. In addition, recycled PET-B/PET-T carbon fiber-reinforced composites had significantly better mechanical properties than virgin polypropylene (PP) carbon fiber-reinforced composites at 3 wt.% carbon fiber loading, albeit with lower elongation at break than PP composites. Furthermore, carbon fiber-reinforced recycled PET-B/PET-T had similar properties to those of virgin PET carbon fiber-reinforced blends. Moreover, the heat deflection temperatures significantly increased in the recycled PET-B/PET-T carbon fiber-reinforced blends, making them suitable for automotive and other value-added composite applications. While further studies are needed to gain insights into the effects of higher loads of carbon fiber and the use of treated carbon fiber, the current findings suggest that recycled PET-B/PET-T carbon fiber-reinforced blends can be of potential value in composites. Implementing these findings in real-world applications can promote the plastic circular economy and mitigate carbon emissions by reducing reliance on virgin PET.
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