Properties Of Polyester Films Research Articles

The Influence of Functional Composite Coatings on the Properties of Polyester Films before and after Accelerated UV Aging.

The aim of this study was to cover biopolymeric packaging films based on PLA/PHBV blend with a functional composite coating (to retain their ecological character) and to investigate their antimicrobial properties before and after UV irradiation. As an active coating, the carrier hydroxypropyl methyl cellulose (HPMC), as well as its modified form with Achillea millefolium L., Hippophae rhamnoides L., and Hypericum L. extract (E) and a combined system based on the extracts and nano-ZnO (EZ), was used to obtain active formulations. Additionally, film surface morphology (SEM, FTIR-ATR) and color (CIELab scale) analysis of the pre- and post-UV-treatment samples were performed. The results confirmed that the E and EZ-modified films exhibited antibacterial properties, but they were not effective against phage phi6. Q-SUN irradiation led to a decrease in the activity of E coating against Staphylococcus aureus, Pseudomonas syringae, and Candida albicans. In this case, the effectiveness of EZ against C. albicans at 24 h and 72 h UV irradiation decreased. However, the irradiation boosted the antiviral effectiveness of the EZ layer. SEM micrographs of the film surface showed that UV treatment did not significantly influence the native film morphology, but it had an impact on the coated film. FTIR analysis results showed that the coatings based on HPMC altered the IR absorption of the nonpolar groups of the biopolyester material. The applied coatings only marginally affected film color changes and increased their yellowness after UV irradiation, whereas a composite layer of nano-ZnO limited these changes.

Investigation on aging mechanism of polyester under combined stresses

The physical properties of polyester film, such as thermal stability, combined with its mechanical properties, such as tensile break strength, and its electrical strength make it the preferred material for a wide variety of electrical insulation applications. Therefore, polyesters are widely used as insulating material for electric power system equipment such as cables, motors, transformers, and capacitors, since its high dielectric constant and resistance to degradation in high voltage and thermal stresses makes it ideal for mechanical barriers in wire and cable applications. For instance, in transformers and other high-voltage distribution equipment, polyester film is used to wrap the conductors [1]-[3].