Characterization of an antimicrobial poly(lactic acid) film prepared with poly(ε‐caprolactone) and thymol for active packaging

Abstract

Antimicrobial active films based on poly(lactic acid) (PLA) were prepared with poly(ε‐caprolactone) (PCL) and thymol (0, 3, 6, 9, and 12 wt%) by solvent casting methods. The films were characterized by thermal, structural, mechanical, gas barrier, and antimicrobial properties. Scanning electron microscopy analysis revealed that the surface of film became rougher with certain porosity when thymol was incorporated into the PLA/PCL blends. Thymol acted as plasticizers, which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the films. The addition of PCL into the pure PLA film decreased the glass transition temperature of the films. The presence of thymol decreased the crystallinity of PLA phase, but did not affect the thermal stability of films. Water vapor barrier properties of films slightly decreased with the increase of thymol loading. The antimicrobial properties of thymol containing films showed a significant activity against Escherichia coli and Listeria monocytogenes. The results indicated the potential of PLA/PCL/thymol composites for applications in antimicrobial packaging. Copyright © 2014 John Wiley & Sons, Ltd.

Antifungal Poly(lactic acid) Films Containing Thymol and Carvone

“…The incorporation of thymol especially at 15 and 20 wt.% significantly reduced crystallinity of the antifungal films. This was consistent with the study of Wu et al (2014) [6] who reported that as the amount of thymol increased, the T g value decreased from 46.7°C of PLA/PCL to 41.3°C of PLA/PCL/T12 composite film. A decrease in T g value was a good indication of the extent of the plasticizing effect provided by thymol.…”

“…This was due to high plasticization effect of 20% thymol and 15% R-(-)-carvone in decreased brittleness and increased flexibility of the antifungal films [17]. As reported by Wu et al (2014) [6], thymol acted as plasticizer, reducing the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the films. Moreover, the presence of thymol decreased the crystallinity of PLA phase.…”

“…As shown in Table 2, incorporation of thymol and R-(-)-carvone resulted in decreased T g and T m of the antifungal films developed. The results suggested that thymol and R-(-)-carvone acted as a plasticizer and rearranged the polymer chains layers [6]. PLA-thymol films had lower T m than PLA-carvone films.…”

“…Thymol, a principle component of thyme (Thymus vulgaris) and oregano (Origanum vulgare) essential oil, has received extensive interest as effective antimicrobial and antifungal agent [5,6]. Thyme oil was incorporated into several films including soy edible film [7] and chitosan film [8].…”

Antibacterial and antifungal LDPE films for active packaging

“…carvacrol and thymol. [15] Essential oils are natural substances categorized as GRAS (generally recognized as safe) by the Food and Drug Administration (FDA), and most of them are derived from plants. [16] They have shown substantial antibacterial and antifungal properties achieved both in direct contact and in vapor phase.…”