Neat PLA Film Research Articles

Active packaging film of poly(lactic acid) incorporated with plant-based essential oils of Trachyspermum ammi as an antimicrobial agent and vanilla as an aroma corrector for waffles

This study developed active packaging films of Polylactic acid incorporated with the plant-based essential oils of Trachyspermum ammi, T. ammi and Vanilla to package waffles, where the antimicrobial property was provided by T. ammi and its odor was masked by vanilla essential oil. Compared to conventional solvent-cast films of smaller sizes requiring a huge amount of solvents, bigger-size PLA-oil films with lower solvent demand were prepared by tape casting technique with 10, 30, and 50 wt% essential oil blends. Films were studied for their morphological, chemical, mechanical, barrier, and antimicrobial properties. The presence and time-bound release of volatile oils from the films was confirmed by infrared spectroscopy, with a continuous decrease of oils from the films till day 30. The plasticizing effect of oils in films was evidenced by decreased tensile strength and crystallinity. In contrast, an increase in elongation at break and water vapor permeability of oil films were also measured. Finally, when packed in PLA films containing 50 wt% blend of both oils, waffles shelf-life extended up to 30 days compared to 2 days for the neat PLA film, where Vanilla was found effective in masking the unpleasant odor of T.ammi as confirmed by sensory analysis.

Development of poly(lactic acid)-based natural antimicrobial film incorporated with caprylic acid against Salmonella biofilm contamination in the meat industry

Using a solvent-casting method, a poly(lactic acid) (PLA) film incorporated with caprylic acid (CA) was developed as an active packaging against Salmonella enterica ser. Typhimurium and S. enteritidis to reduce the risk of microbial contamination during distribution and storage of meat. According to the minimum inhibitory concentration (MIC) test results of the natural antimicrobial, CA was introduced at 0.6, 1.2, 2.4, and 4.8 % (v/v) into neat PLA. The biofilm inhibitory effect and antimicrobial efficacy of CA-PLA film against both Salmonella strains, as well as the intermolecular interactions and barrier properties of CA-PLA film, were evaluated. Biofilm formation was reduced to below the detection limit (<1.0 log CFU/cm2) for both S. typhimurium and S. enteritidis when co-cultured overnight with 4.8 % CA-PLA film. The 4.8 % CA-PLA film achieved maximum log reductions of 2.58 and 1.65 CFU/g for S. typhimurium and 2.59 and 1.76 CFU/g for S. enteritidis on inoculated chicken breast and beef stored at 25 °C overnight, respectively, without any quality (color and texture) losses. CA maintained its typical chemical structure in the film, as confirmed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra. Furthermore, film surface morphology observations by field emission scanning electron microscopy (FESEM) showed that CA-PLA film was smoother than neat PLA film. No significant (P > 0.05) changes were observed for water vapor permeability and oxygen permeability by the addition of CA into PLA film, suggesting that CA-PLA film is a promising strategy for active packaging to control Salmonella contamination in the meat industry.

Use of Compression Molding for the Production of Ternary Films Based on Poly (Lactic Acid), Montmorillonite, and Oregano Essential Oil

Poly (Lactic Acid) (PLA) is considered one of the most promising polymers. However, neat PLA films have limitations. An effective strategy to overcome these problems is incorporating clay or essential oils. Cloisite 30B (C30B) is an organoclay widely used to improve the properties of polymers. Notably, the development of films incorporating Oregano Essential Oil (OEO) has attracted significant attention. Compression molding manufactured neat PLA, PLA/C30B, and PLA/C30B/OEO films in this manuscript. The visual evaluation indicated that the films had a good surface finish, and the films thickness varied between 0.15–0.19 mm. The moisture content increased with the incorporation of C30B and OEO. Optical microscopy showed a good distribution of clay particles. The transparency of the films increased with OEO, while with C30B, it presented greater opacity. Incorporating C30B/OEO in the PLA matrix is a promising film proposal that can be directed to the packaging sector. However, other analyses must be done better to understand the films performance for such an application.

Effects of ZnO nanoparticles, polyethylene glycol 400, and polyoxyethylene sorbitan ester Tween 80 on PLA films properties

Abstract Polylactic acid has the potential to be an alternative to petroleum-based materials in the food packaging industry. In this study, the effect of zinc oxide nanoparticles, polyethylene glycol 400, and Tween 80 as plasticizers on the properties of polylactic acid films was investigated. In order to study the mechanical properties more accurately, the tests were repeated for four months. An experimental design method was used to investigate the effects of additives on the measurement factors and finally to choose the optimal combination with the help of the TOPSIS technique. The results showed that the addition of different materials increased the opacity, most of which being related to P400/ZnO (6.82 ± 0.07 mm−1). The presence of plasticizers increases the hydrophilicity of the film and the water vapor permeability. The highest contact angle (85.33° ± 4.00) and the lowest water vapor permeability (0.074 ± 0.002 g mm/kPa h m2) were related to neat PLA film. The lowest modulus of elasticity, the highest tensile strength and elongation at break were related to P400/T80/ZnO (1.18 ± 0.17 GPa, first month), PLA/ZnO (96.28 ± 3.17 MPa, fourth month), and P400/ZnO (76.82 ± 27.22 %, first month), respectively. The effect of plasticizers was significant in most of the measurement factors, but the effect of nanoparticles was significant in some cases such as opacity and contact angle. The results of an ANOVA analysis showed that the effect of film type on the mechanical properties was significant, and the effect of storage time was only significant on the elongation at break. According to the results obtained from the TOPSIS technique, P400/ZnO was chosen as the combination with the best features among the produced films.

Enhancement of elongation at break and UV-protective properties of poly(lactic acid) film with cationic ring opening polymerized (CROP)-lignin

In this study, the intrinsic brittleness of poly(lactic acid) (PLA) was overcome by chemical modification using ethyl acetate-extracted lignin (EL) via cationic ring-opening polymerization (CROP). The CROP was conducted to promote homopolymerization under starvation of the initiator (oxyrane). This method resulted in the formation of lignin-based polyether (LPE). LPE exhibited enhanced interfacial compatibility with nonpolar and hydrophobic PLA owing to the fewer hydrophilic hydroxyl groups and a long polyether chain. In addition, because of the UV-protecting and radical-scavenging abilities of lignin, LPE/PLA exhibited multifunctional properties, resulting in improved chemical properties compared with the neat PLA film. Notably, one of the LPE/PLA films (EL_MCF) exhibited excellent elongation at break of 297.7% and toughness of 39.92MJ/m3. Furthermore, the EL_MCF film showed superior UV-protective properties of 99.52% in UVA and 88.95% in UVB ranges, both significantly higher than those of the PLA film, without sacrificing significant transparency in 515nm. In addition, the radical scavenging activity improved after adding LPE to the PLA film. These results suggest that LPEs can be used as plasticizing additives in LPE/PLA composite films, offering improved physicochemical properties.

Processing Compostable PLA/Organoclay Bionanocomposite Foams by Supercritical CO2 Foaming for Sustainable Food Packaging.

This article proposes a foaming method using supercritical carbon dioxide (scCO2) to obtain compostable bionanocomposite foams based on PLA and organoclay (C30B) where this bionanocomposite was fabricated by a previous hot melt extrusion step. Neat PLA films and PLA/C30B films (1, 2, and 3 wt.%) were obtained by using a melt extrusion process followed by a film forming process obtaining films with thicknesses between 500 and 600 μm. Films were further processed into foams in a high-pressure cell with scCO2 under constant conditions of pressure (25 MPa) and temperature (130 °C) for 30 min. Bionanocomposite PLA foams evidenced a closed cell and uniform cell structure; however, neat PLA presented a poor cell structure and thick cell walls. The thermal stability was significantly enhanced in the bionanocomposite foam samples by the good dispersion of nanoclays due to scCO2, as demonstrated by X-ray diffraction analysis. The bionanocomposite foams showed improved overall mechanical performance due to well-dispersed nanoclays promoting increased interfacial adhesion with the polymeric matrix. The water uptake behavior of bionanocomposite foams showed that they practically did not absorb water during the first week of immersion in water. Finally, PLA foams were disintegrated under standard composting conditions at higher rates than PLA films, showing their sustainable character. Thus, PLA bionanocomposite foams obtained by batch supercritical foaming seem to be a sustainable option to replace non-biodegradable expanded polystyrene, and they represent a promising alternative to be considered in applications such as food packaging and other products.

Crystallinity and Gas Permeability of Poly (Lactic Acid)/Starch Nanocrystal Nanocomposite.

The present work seeks to determine the impact of weight percentage (wt%) of grafted starch nanocrystals (g-SNCs) on the oxygen and water vapour permeability of poly (lactic acid), PLA. Changes in the oxygen and water vapour permeability of PLA due to changes in PLA’s crystalline structures and lamellar thickness were quantified. To this end, 3, 5, and 7 wt% of g-SNC nanoparticles were blended with PLA using the solvent casting method in order to study impact of g-SNC nanoparticles on crystallization behaviour, long spacing period, melting behavior, and oxygen and water barrier properties of PLA nanocomposites. This was achieved by wide-angle X-ray diffraction (WAXD), small-angle X-ray diffraction (SAXD), differential scanning calorimetry (DSC), and oxygen and water vapour permeability machine. The results of the WAXD and SAXD analysis show that the addition of 5 wt% g-SNC in PLA induces crystal structure at a lower crystallization time, while it significantly increases the crystal thickness of PLA, in comparison to neat PLA. However, when g-SNC concentrations were altered (i.e., 3 or 7 wt%), the crystallization time was found to increase due to the thermodynamic barrier of crystallization. Finally, the oxygen and water vapour permeability of PLA/SNC-g-LA (5 wt%) nanocomposite film were found to be reduced by ∼70% and 50%, respectively, when compared to the neat PLA film. This can lead to the development of PLA nanocomposites with high potential for applications in food packaging.

Characterization of active and pH-sensitive poly(lactic acid) (PLA)/nanofibrillated cellulose (NFC) films containing essential oils and anthocyanin for food packaging application

Active and pH-sensitive films of poly(lactic acid) (PLA)/nanofibrillated cellulose (NFC) have been fabricated and tested. The PLA and PLA/NFC films with 1.5% NFC were prepared via solvent casting method, with different loadings of essential oil (EO), including thymol and curry, being added at 5, 10, and 15%. The fixed content of anthocyanin powder (1%) was incorporated into the films as a pH indicator. The active PLA and PLA/NFC films were characterised on their physical, mechanical, thermal, and biodegradation properties. The addition of NFC reduced the tensile strength but increased the flexibility of films due to the plasticizing effect of EOs. The PLA/EO and PLA/NFC/EO films containing curry demonstrated a slightly higher strength than the films with thymol. The flexibility of films was increased at higher loading of EO regardless of the types of EO. The thermal profile demonstrated that the neat PLA film had a higher maximum degradation temperature than the active PLA/EO and PLA/NFC/EO films. The active PLA/EO and PLA/NFC/EO films containing anthocyanin successfully changed its colour in pH 2.0 and 14.0. The PLA/NFC films with thymol and anthocyanin formulation could inhibit fungus growth better in the cherry tomato sample than the PLA/NFC films with curry and anthocyanin.

Fabrication of Electrospun Juglans regia (Juglone) Loaded Poly(lactic acid) Scaffolds as a Potential Wound Dressing Material.

Juglone (5-hydroxy-1,4-naphthoquinone) (J) is a naphthoquinone structured allelochemical that is mostly found in the roots, leaves, nut-hulls, bark, and wood of walnut (Juglans regia). In this study, the biocompatibility, mechanical, thermal, chemical, morphological, and antimicrobial properties of the poly(lactic acid) (PLA) (w/v)/J (10, 20, 30 mg) electrospun scaffolds were investigated. Based on the results of the study, it was shown that juglone addition increased the antimicrobial properties of the scaffolds against the Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), compared to the neat PLA film after 24 h of contact time. According to the tensile test results, the addition of J made the scaffolds more flexible but decreased the mechanical strength. The cytotoxicity properties of the J-added scaffolds demonstrated a toxic behavior on the first day of incubation. However, with an increase in the J ratio, the fibroblast cell metabolic activity increased for all incubation periods.

Utilization of lignin extracted from Thai ago-waste as UV-blocking agent for BG-lignin/PLA composite films

The improving properties of poly(lactic acid), PLA, by utilizing natural resources attracted great intrigue to make such a green composite material that can be used as a commercial product in human life [1]. Lignin is one of biopolymer that can be used as bio-based filler and multifunctional bio-additive in a polymer composite. The most exciting properties of lignin that can be provided in a polymer composite is UV absorption and anti-oxidation [2]. In this current study, organosolv lignin extracted from sugarcane bagasse (BG-lignin) was utilized as multifunctional bio-additive in PLA for improving the UV absorption. The physicochemical and thermal properties of BG-lignin were determined using several techniques including SEM, GPC, quantitative 31P NMR, and DSC. BG-lignin at different loading contents (0.1, 0.2, 0.5, and 1 wt.%) was mixed with PLA via melt-extrusion. The attained compounds were converted to composite films via blown film extrusion. With the 0.5 wt.% loading content, the PLA composite films (0.5BG-lignin/PLA) absorbed almost all UV radiation which exhibits almost 70% blocking of UVB. The onset oxidation temperature of the PLA/0.5BG composite film increased by 34% as compared to that of the neat PLA film. Adding of BG-lignin enhanced tensile strength and Young’s modulus but did not favour to elongation at break.

Potential of extrusion-blown poly(lactic acid)/cellulose nanocrystals nanocomposite films for improving the shelf-life of a dry food product

The potential of neat poly(lactic acid) (PLA) and PLA/cellulose nanocrystal (CNC) blown films in extending the shelf-life of crackers, a moisture-sensitive food product, was assessed. Product’s shelf-life, i.e., the time required by the crackers to reach its critical moisture content (CMC) of 8%, was determined experimentally from moisture content versus storage time plots at a constant temperature (25 °C) and various conditions of relative humidity (RH). Neither crackers within PLA nor PLA/CNC packages reached the CMC when stored below 50% RH at 25 °C, indicating that crackers packaged in both films were shelf stable at these conditions. Above this RH, the crackers inside both packages reached the CMC at different times, however crackers in CNC-based packages had approximately 40% longer shelf-life than those in neat PLA package. The shelf-life of crackers packaged in films predicted from various simulation mathematical models supported the experimental data that the crackers packaged in the PLA/CNC films had higher shelf-life compared to those packaged in neat PLA films; clearly demonstrating the potential of CNC-based films to extend the shelf-life of dry-foods.

Preparation of PLA based biodegradable nanofibre films and their characterization

Nanofibres have been obtained from sugarcane bagasse through different chemical treatments and mechanical grinding process. These nanofibres are then used for the preparation of their PLA-based biodegradable films by the solvent casing method using various weight percentages (0, 1, 2, 3, 4 &amp; 5) of nanofibres. The morphological analysis, tensile properties, thermal property and optical properties of the films are characterized by field emission electron microscopy, tensile test, thermogravimetric analysis and UV-Vis spectrometers respectively. The film with 2 wt. % of nanofibre is found to offer the highest tensile strength (24.5 %) which is 57-55 % more than that of neat PLA film. The thermal and optical properties of PLA films are also significantly influenced by the incorporation of nanofibres. Based on the results obtained from the present study, the prepared biodegradable nanofibre films can be used in nanofabrics and for packaging applications.

Enhanced oxygen barrier properties of poly(lactic acid) via oxygen scavenging strategy combining with uniaxial stretching

Poly(lactic acid) (PLA) films with significantly enhanced mechanical and oxygen barrier properties were obtained via oxygen scavenging strategy combining with uniaxial stretching. In this study, PLA was melt blended with 3 phr of hydroxy-terminated polybutadiene (HTPB) and different contents of acetyl(tributyl citrate) (ATBC) and cobalt neodecanoate. It was then followed by compression molding and uniaxial stretching. After uniaxial stretching, the crystallinity of all films was significantly improved, which contributed to the enhancement in the oxygen barrier performance of composite materials. The morphological analysis carried out using scanning electron microscopy (SEM) revealed that ATBC could obviously promote the dispersion of HTPB in PLA. Overall, the blend films showed a decrease in the oxygen permeability coefficient as compared with the neat PLA film, which reached a similar level to oriented PET film. The optical and mechanical properties of the blend films with ATBC also improved considerably. This work provides a method to prepare high-crystalline polymers with superior gas-barrier properties having great potential for use in high-barrier applications, such as polymers for oxygen-sensitive food packaging.

Effect of bubble nucleating agents derived from biochar on the foaming mechanism of poly lactic acid foams

Improvement and new technologies for effective poly (lactic acid) (PLA) foaming are still in developing. This study examines the ability of biochar (BC) to assist in PLA foaming through a supercritical CO2 batch process. To determine suitable foaming parameters, process optimization was conducted on neat PLA films. BC particles derived from three different sources – sludge (SLG), pistachio shells (PST) and green waste (GW) were ground, and ball milled to a microscale and then blended with PLA. The PLA/BC blends were extruded into films and then batch foamed. The effect of BC was found to be concentration and source dependent. At 0.25 wt%, BC particles were found to be effective nucleating agents showing an increase up to four orders of magnitude in cell density and 10-fold reduction in the mean pore size compared to the neat PLA foams. An increase in BC content to 0.5 and 1 wt% induced particle aggregation, which resulted in non-homogenous foam densities. BC particles derived from SLG were the most effective nucleating agents due to their narrow size distribution, improved dispersibility and mesoporous surface. This work shows that BC can act as an effective bio-derived nucleating agent for PLA.

Effectiveness assessment of TiO2-Al2O3 nano-mixture as a filler material for improvement of packaging performance of PLA nanocomposite films

Abstract The main objective of this study was to assess the effectiveness of TiO2-Al2O3 nano-mixture used as filler in improving packaging films performance. Polylactic acid/titanium dioxide (PLA/TiO2), polylactic acid/alumina (PLA/Al2O3) and polylactic acid/TiO2-Al2O3 (PLA/TiO2-Al2O3) nanocomposite films were successfully prepared via melt mixing process and thoroughly characterized by FTIR spectroscopy, X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties such as heat resistant, barrier, mechanical and antimicrobial properties, required for food packaging have also been investigated. As compared to the neat PLA film, the developed PLA nanocomposites have displayed superior properties particularly the PLA/ TiO2-Al2O3 nanocomposite film. This resulted material has showed a 22 °C increase in its thermal stability versus 14 and 2 °C in the cases of PLA/TiO2 and PLA/Al2O3 respectively, and a 54% reduction of its water vapor permeability in comparison with 47% for PLA/TiO2 and 39% for PLA/Al2O3. In addition, the PLA/TiO2-Al2O3 had a significant enhancement of its mechanical properties. Its Young modulus increased by 102% unlike 23.60% for the PLA/TiO2 and 44.66% for the PLA/Al2O3. It was also noticed that this nanocomposite film demonstrated stronger antibacterial activity than the two others. The bacterial growth inhibition effect of TiO2-Al2O3 nano-mixture against Pseudomonas aeruginosa and Escherichia coli bacteria was more effective than that of its two constituents.

Improvement of the Gas Barrier Properties of PLA/OMMT Films by Regulating the Interlayer Spacing of OMMT and the Crystallinity of PLA.

A high gas barrier performance should be ensured in case of biodegradable packing applications. However, the gas barrier properties of the biodegradable poly(lactic acid) (PLA) are not much effective. Nanocomposites can provide innovative solutions to enhance the barrier performance. In this study, different weight percentages of organically modified montmorillonite (OMMT) (0, 2, 4, 6, 8, and 10 wt %)-incorporated PLA/OMMT nanocomposites were prepared by melt mixing. Ethylene glycol diglycidyl ether (EGDE) was used to regulate the interlayer spacing of OMMT and increase the PLA crystallinity to further improve the gas barrier performance of the PLA/OMMT films. The crystallinity of PLA was significantly improved because EGDE-modified OMMT served as an efficient nucleating agent. The PLA/EGDE/OMMT films demonstrated a unique structure such that the adjacent OMMT layers were linked through the PLA crystals that serve as a bridge with respect to the spaces between the OMMT layers. The O2 permeability of the PLA/EGDE4/OMMT-6 film decreased by approximately 79% when compared with that of the neat PLA film. X-ray diffraction and differential scanning calorimetry analyses denoted that the reduced oxygen permeability of the PLA/EGDE4/OMMT-6 film can be primarily attributed to the high crystallinity of the PLA matrix and the bridging effect of the PLA crystals between two adjacent layers. Based on the experimental results, the relation between the relative permeability and vol % OMMT is in good agreement with that of the predicted values obtained using the Bharadwaj model when S = 0. The added EGDE weakened the thermal stability and tensile strength, mainly because of degradation of the hydroxyl groups of EGDE formed by epoxy ring opening, and these hydroxyl groups can promote PLA matrix degradation. However, the practical application temperature of the packaging film is considerably lower than the thermal decomposition temperature; therefore, the reduction of the thermal decomposition temperature does not affect the use of the packaging film.

Poly(lactic acid)/poly(butylene-succinate-co-adipate) (PLA/PBSA) blend films containing thymol as alternative to synthetic preservatives for active packaging of bread

Abstract Antifungal films based on poly(lactic acid)/poly(butylene-succinate-co-adipate) (PLA/PBSA) blends containing 3 wt% (LT-PLA/PBSA) and 6 wt% (HT-PLA/PBSA) of thymol were prepared using blown film extrusion technique. In vitro antifungal activity of the films against Aspergillus spp. and Penicillium spp. was evaluated using a vapor contact assay. The antifungal films containing thymol were highly effective against fungal growth as compared to the neat PLA film and PLA/PBSA blend film. The addition of PBSA and thymol resulted in decreased glass transition temperature and melting temperature. All active films exhibited significantly lower tensile strength and Young’s modulus but higher elongation at break compared to the neat PLA. The permeability coefficients of water vapor, oxygen, and carbon dioxide (CO2) of the PLA/PBSA blend films containing thymol were lower than those of the neat PLA film. The antifungal films were tested for bread packaging, compared with biaxially oriented polypropylene (BOPP) and neat PLA. Mold growth was observed on the bread packaged in LT-PLA/PBSA and HT-PLA/PBSA after storage for 7 and 9 d, respectively. Whereas, the bread in BOPP and neat PLA packaging showed visible mold growth after storage for 3 and 6 d, respectively. Yeast and mold counts increased throughout the storage period, which were 7.13, 5.83, 5.38 and

Impacts of cellulose nanofibril and physical aging on the enthalpy relaxation behavior and dynamic mechanical thermal properties of Poly(lactic acid) composite films

We herein report the influences of cellulose nanofibril (CNF) and physical aging on the enthalpy relaxation behavior, thermal transition, and dynamic mechanical properties of eco-friendly poly(lactic acid) (PLA) composite films with 0.5–7.0 wt% CNF loadings, which were fabricated by using a facile masterbatch-based melt-compounding process. For the purpose, melt-quenched neat PLA and PLA/CNF composite films were aged physically at 45 °C for different times. The FT-IR spectra revealed that specific hydrogen-bonding interactions exist between the carboxyl groups of PLA matrix and the hydroxyl groups of CNF fillers, and that the interactions are strengthened by the physical aging. Accordingly, the increments of the peak temperature (Tp) and area (ΔHrelax) of the endothermic enthalpy relaxation at the glass transition temperature region with the aging time were suppressed significantly for the composite films with higher CNF contents, unlike the neat PLA film. In addition, the characteristic relaxation time of PLA/CNF composite films was highly enhanced, indicating the improved enthalpy relaxation and dimensional stability. This result is associated with the fact that the CNF fillers restrict the segmental mobility of PLA chains in the composite films during the physical aging at the glassy state, which was supported by the dynamic mechanical thermal data.

Hydrophilic and Antibacterial Modification of Poly(lactic acid) Films by γ-ray Irradiation.

To improve the hydrophilicity and imparting antibacterial properties to poly(lactic acid), poly(acrylic acid) (PAA) and silver particles (AgNPs) were simultaneously introduced onto the surface of poly(lactic acid) (PLA) films by γ-ray irradiation. The morphology and structure of the modified films were characterized by scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) spectrometry and Fourier transform infrared (FTIR) spectroscopy. The interaction between PAA and AgNPs was investigated by X-ray photoelectron spectroscopy (XPS), confirming the coordination between AgNPs and the oxygen atom on the carboxylic group of PAA. The contact-angle (CA) measurements and antibacterial tests showed that the modified PLA films with a low silver content (PLA-g-PAA-Ag) exhibited excellent hydrophilicity as well as antibacterial activity compared with the neat PLA film.

Hydrolytic degradation and lifetime prediction of poly(lactic acid) modified with a multifunctional epoxy-based chain extender

The effect of adding chain extender (Cex) during the production of poly (lactic acid) (PLA) films on the hydrolytic degradation of the films was evaluated at temperatures from 40 to 95 °C. The hydrolytic degradation of PLA–Cex film estimated using the Pan model was significantly lower than that of neat PLA film (PLA–Con) at all temperature conditions. The Vogel-Tammann-Fulcher and Williams-Landel-Ferry models were used to study the hydrolytic degradation of the PLA films over a broad range of temperature crossing Tg. A master curve technique was constructed using the time-temperature superposition principle to predict the lifetime of PLA films at any temperature in the tested range. Specifically, accelerated degradation testing at 85 °C was used to predict the degradation behavior at 40 °C. Findings indicate that PLA–Cex would take approximately 130% more time than PLA–Con to degrade to the critical molecular weight for chain entanglement of PLA.