Influence of Tea Tree Essential Oil and Poly(ethylene glycol) on Antibacterial and Physicochemical Properties of Polylactide-Based Films

Abstract

The aim of the study was to establish the influence of poly(ethylene glycol) (PEG) on the properties of potential biodegradable packaging materials with antibacterial properties, based on polylactide (PLA) and tea tree essential oil (TTO). The obtained polymeric films consisted of PLA, a natural biocide, and tea tree essential oil (5–20 wt. %) was prepared with or without an addition of 5 wt. % PEG. The PLA-based materials have been tested, taking into account their morphology, and their thermal, mechanical and antibacterial properties against Staphylococcus aureus and Escherichia coli. It was established that the introduction of a plasticizer into the PLA–TTO systems leads to an increase in tensile strength, resistance to deformation, as well an increased thermal stability, in comparison to films modified using only TTO. The incorporation of 5 wt. % PEG in the PLA solution containing 5 wt. % TTO allowed us to obtain a material exhibiting a satisfactory antibacterial effect on both groups of representative bacteria. The presented results indicated a beneficial effect of PEG on the antibacterial and functional properties of materials with the addition of TTO.

Antibacterial Films Based on Polylactide with the Addition of Quercetin and Poly(Ethylene Glycol)

“…Based on the obtained results the roughness parameters such as R q (mean square deviation of surface roughness), R a values (mean arithmetic deviation of the profile from the mean line) and R max (maximum distance between the highest and lowest point of the recorded image) have been discussed ( Table 3 ) [ 16 ].…”

“…It was previously discussed that the plasticizer as well as the biocidal agent can significantly affect the thermal stability of the polylactide-based films [ 16 ]. In the prevailing number of publications the temperatures at 5% mass loss are analyzed.…”

“…In the work of Rhim et al [ 42 ] and Tarach at al. [ 16 ], however, it was indicated that in the case of these types of materials, the mass loss of about 5% of the initial mass is connected with the evaporation of the solvent residue. As a result, the values of temperatures at 10%, 30% and 50% mass loss of all studied materials (signified as T10%, T30% and T50%, respectively) were selected and presented in Table 4 .…”

“…It is a commonly recognized fact that mechanical properties of packaging materials are extremely important [ 16 ]. In order to establish the impact different amounts of plasticizer and biocidal agent in form of quercetin have on the mechanical properties, the Young’s modulus ( E ), tensile strength ( σ m ) and elongation at break ( ε ) were determined.…”

“…In order to obtain antibacterial packaging materials based on polylactide, different compounds such as nanosilver, nisin, polyhexamethylene guanidine derivatives, cinnamon or tea tree essential oil [ 11 , 12 , 13 , 14 , 15 , 16 ] have been used. Among different active substances, flavonoids constitute a group of very interesting compounds characterized by varied antibacterial properties.…”