Highly transparent films of new copolyesters derived from terephthalic and 2,4-furandicarboxylic acids

In this study transparent films of poly(ethylene terephthalate)- co -(ethylene 2,4-furandicarboxylate) (PET- co -2,4-PEF) copolymers were developed for the first time, exploring the ability of 2,4-furandicarboxylic acid (2,4-FDCA) to impart excellent optical properties to the polymers thereof. The properties were fine-tuned by feeding this furan monomer content. For example, specifically up to 15 mol% the copolyesters were semi-crystalline in nature, and they were amorphous materials when exceeding the limits of 50 mol% and above. The amorphous polymers had excellent thermal stability over 400 °C, in combination with high transmittance at the wavelength of 555 nm. Transparent films of poly(ethylene terephthalate)- co -(ethylene 2,4-furandicarboxylate)s (PET- co -2,4-PEFs) were developed here for the first time, exploring the ability of 2,4-FDCA to impart excellent optical properties to the polymers thereof.