Characteristics of poly(vinyl alcohol) films crosslinked by cinnamaldehyde with improved transparency and water resistance

Abstract

Poly(vinyl alcohol) (PVA) films crosslinked by cinnamaldehyde (CIN) at various concentrations were prepared. Their physicochemical and antibacterial properties were compared with those of uncrosslinked films. The results suggest that the crosslinked films exhibited higher transparency, tensile strength, and elongation at break in a certain CIN concentration range. They also displayed decreased water vapor permeability and water solubility. Although the antibacterial activity of the crosslinked film-forming solution was less slightly than that of the uncrosslinked film-forming solution, the crosslinked film-forming solution still demonstrated strong antibacterial activity when the concentration of CIN was 2% v/v. The aldol condensation reaction between the aldehyde group of CIN and the alcoholic hydroxyl group of PVA was determined by Fourier transform infrared spectroscopy. By the crosslinking reaction, the heat stability of the crosslinked film was enhanced compared with that of the uncrosslinked film. Meanwhile, a compact, smooth, and continuous cross-sectional microstructure present in the crosslinked film was observed by scanning electron microscopy. The higher water resistance and transparency gave the crosslinked films priority for use in food packaging.

Evaluation of the physicochemical and antimicrobial properties of the polyvinyl alcohol-mulberry leaf extract blend film

“…[37] Next, the absorption band occurred at 1040 cm -1 is assigned to the C-O stretching of PVA/MN structure. [24,17,41] The most appreciable changes were observed in the FTIR spectrum of PVA/MN blend films where the formation of absorption peak between 1410 cm -1 and 1290 cm -1 is the primary or secondary -OH stretch, phenol and tertiary alcohol OH bend. Furthermore, the cross-linking function was also confirmed by the reduction of the relative intensity of hydroxyl bond in the cross-linked film.…”

“…Conversely, this PVA/MN blend films remained transparent at high MN concentration. [24] Meanwhile, the film forming solution produced a homogeneous solution with transparent, odorless and easy to handle after drying steps. The thickness of the films was not sensitive to the changes of MN concentration, as presented in Table I.…”

“…Improved thermal stability in the PVA/MN blend film was observed where the third stage mass loss occurred above the region of 400 °C. [24].…”

“…[17,13,16,14,15] Poly ethylene glycol diacrylchloride adapted the structure of PVA to offer tremendous biotechnology and biomedical potential, whereas butyl glycidyl ether (BGE) modified PVA for use as a surface sizing agent in paper manufacturing. [18,19] The microbial activity also can be inhibited through other natural plant and herbs extraction, as reported neem, guava, indian acalypha, green chiretta and Holy basil leaves extraction enhanced the inhibition of microbial growth [20][21][22]7,[23][24][25][26][27][28][29]. In addition, natural sources such as cinnamaldehyde and syzygium cumini leaves extract have been successfully applied to change the structure of PVA and at the same time minimize the inhibition of microbial growth of Escherichia coli species.…”

“…In addition, natural sources such as cinnamaldehyde and syzygium cumini leaves extract have been successfully applied to change the structure of PVA and at the same time minimize the inhibition of microbial growth of Escherichia coli species. [24,25] Moreover, turmeric and clove oil are widely known as effective antimicrobial agents against foodborne pathogen. [23,27] Mulberry, or known as Morus nigra sp.…”