Development and Characterization of Recycled PET-Based Adhesive Films for Supporting Insulin Injection Site Rotation

Abstract

Insulin injections are vital for diabetes management, but repeated injections at the same site may cause lipohypertrophy (LH), leading to poor glycemic control and inconsistent insulin absorption. Since proper site rotation is often difficult for patients to maintain, this study proposes a recycled poly(ethylene terephthalate) (PET)-based adhesive film, fabricated from plastic bottles using the Thermal Induced Phase Separation (TIPS) method, to support injection site rotation. Poly(vinyl alcohol) (PVA) was incorporated to enhance the film's adhesive properties. The film's performance was evaluated through mechanical testing, thermogravimetric analysis (TGA), and pH measurement, showing favorable results. TIPS was employed for film fabrication. The film demonstrated appropriate pH (5.4 ± 0.1), tensile strength (3.78 MPa), and good thermal stability (220℃), retaining structural integrity after UV sterilization. TGA showed weight loss of 86% at 480°C, suggesting significant mass loss associated with plasticizer evaporation and polymer degradation. Adhesion testing showed sufficient tackiness, with balls stopping at 1.5–2.0 cm on the 4 cm film, showing good adhesion. The film also remained stable after UV sterilization, supporting its safety and durability. Characterization of pH, tensile strength, and tackiness was performed in triplicate (n = 3). Repurposing PET helps reduce plastic waste while offering a cost-effective material for healthcare use. The adhesive film may serve as a visual aid for insulin injection site rotation, with potential to reduce the risk of lipohypertrophy and improve insulin absorption. These findings are preliminary and provide a basis for more comprehensive future study.