Polymers, Vol. 17, Pages 2727: 1H Time Domain Nuclear Magnetic Resonance and Oscillatory Rheology as a Tool for Uncovering the Impact of UV-C Radiation on Polypropylene

Polymers doi: 10.3390/polym17202727

Authors:
Jessica Caroline Ferreira Gimenez
Sophia Helena Felisbino Bonatti
Marcos Vinícius Basaglia
Rodrigo Henrique dos Santos Garcia
Alef dos Santos
Lucas Henrique Staffa
Mazen Samara
Silvia Helena Prado Bettini
Eduardo Ribeiro de Azevedo
Emna Helal
Nicole Raymonde Demarquette
Manoel Gustavo Petrucelli Homem
Sandra Andrea Cruz

UV-C radiation has emerged as a germicidal agent against pathogens, particularly following the COVID-19 pandemic. While UV-C effectively reduces cross-contamination in hospitals, it induces photodegradation in polymer devices, potentially damaging and posing risks to patient safety. Therefore, it is crucial to detect the effects of UV-C photodegradation on early stages, as well as the effects of prolonged UV-C exposure. In this study, we investigated the UV-C photodegradation (254 nm, 471 kJ/mol) of isotactic polypropylene homopolymer (PP), commonly used in medication packaging. The impact of UV-C on PP was evaluated through rheology and infrared spectroscopy. Surface energy was measured by the contact angles formed by drops of water and diiodomethane. The effects of photodegradation on the polymer’s morphology were examined using scanning electron microscopy, and the melting temperature and crystallinity by differential scanning calorimetry. Lastly, the effect of UV-C on molecular mobility was studied using 1H Time Domain Nuclear Magnetic Resonance (1H TD-NMR). These techniques proved to be valuable tools for identifying the early stages of UV-C photodegradation, and 1H TD-NMR was a sensitive method to identify the chain branching as a photodegradation product. This study highlights the impact of UV-C on PP photodegradation and hence the importance of understanding UV-C-induced degradation.

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Jessica Caroline Ferreira Gimenez www.mdpi.com