Polylactic Acid Composite Films Research Articles

Preparation and characterization of the Leonardite and Boric acid added Polylactic acid films for food packaging applications

Polylactic acid (PLA), a biodegradable plastic, has begun to replace petroleum-based plastics used in thin film. According to the literature, various clays are used to develop PLA matrix film. In this study, PLA composite films containing specific proportions of Leonardite (LEO) and Boric acid (BOR) were prepared by casting method, and the physical, mechanical, thermal, barrier, and microstructure properties of these films were studied. As the amount of LEO in LEO and BOR/LEO added films increased, correspondingly increased the TS and EM values, while TR and MF values decreased, and the EB values fluctuated. As the amount of BOR increases in BOR added films, the increases and decreases in TS and EM values are similar, while the TR, MF and EB values decrease. In added films, the additive effect is clearly seen in the XRD patterns. While the addition of LEO significantly changed the surface color and opacity, BOR added films showed fewer changes in these properties. The Contact angle measurements demonstrated that, while the addition of BOR reduced the CA value, the addition of LEO partially increased it. The addition of BOR/LEO resulted in an increase in CA value because of the effects of LEO.

Effects of chitin nano-flake fillers on the mechanical and barrier properties of polylactic acid biocomposite films

Polylactic acid (PLA) is a biodegradable polymer extensively used in packaging; however, its mechanical and barrier properties require enhancement for wider applications. Chitin-derived nanoflakes (CNFL), a two-dimensionally separated nanomaterial derived from α-chitin, possess high strength and toughness, making them ideal additives for improved PLA performance. This study investigated the effect of CNFL on the properties of PLA composite films. Incorporating CNFL significantly enhanced the mechanical properties of PLA, increasing its tensile strength and stiffness while preserving flexibility. This enhancement was attributed to the nucleating effect of CNFL, which increases crystallinity. Additionally, CNFL improved the thermal stability of the composite films by mitigating thermal deformation. Notably, the oxygen barrier properties of CNFL-filled PLA composites were also enhanced, demonstrating a significant reduction in oxygen permeability at optimal CNFL concentrations due to increased tortuosity of the oxygen diffusion path. Overall, CNFL-filled PLA composites exhibit great potential as renewable packaging materials, particularly for protecting sensitive products, such as food and pharmaceuticals, from oxidative degradation, thereby extending shelf life and maintaining quality. These findings suggest that CNFL-filled PLA composites are promising materials for advanced applications, offering a combination of enhanced mechanical performance, improved thermal stability, and superior oxygen barrier properties.

Chitin/calcium carbonate complex microparticles and their effects on polylactic acid composite films

Chitin/calcium carbonate complex microparticles and their effects on polylactic acid composite films

Structure, performance, and crystallization behavior of Turkey leonardite and raw kaolin added polylactic acid composite films

Polylactic acid (PLA) film composites filled with two clays, Raw Kaolin (KAO), an inorganic structure, and Leonardite (LEO), an organic structure, as well as KAO/LEO mixtures, were prepared via solvent casting method. The main aim of this research was to investigate both the individual and the synergetic effects of LEO and KAO; they are incorporated together into a PLA matrix. The influence of these fillers content on the morphological and structural characteristics of the composites was investigated by the DSC, TGA, FT-IR, SEM, XRD, color, haze, and opacity analysis. According to the TGA analysis, significant decreases in Tmax2 were observed with the addition of LEO in PLA. It is also seen in films with KAO/LEO that support this result. Utilizing the solvent casting method, two melting points were formed in PLA films. The P0 film has lower Tg, Tcc, and Tm1 values than other films. However, there were small changes in Tg and Tm2 values in all films. Up to 7.5% amount of LEO and KAO, the mechanical properties of the films improved. The 3L film exhibited the best mechanical properties. The filler materials used were mostly homogeneously distributed, according to the SEM analysis, and as the amount increased, agglomerations were observed in the fillings on the surface. The addition of LEO and KAO changed the surface color, visual appearance, and opacity significantly. The haze values of films are near 100. These film composites have been shown to improve many properties of the P0 film.

Effect of curcumin-modified nanodiamonds on properties of eco-friendly polylactic acid composite films

Polylactic acid (PLA) has attracted much attention as a biodegradable polymer material, but its inherent brittleness limits its application. In order to improve the overall performance of PLA, thermoplastic polyurethane (TPU) was first blended with PLA to improve the toughness, and then curcumin-functionalized nanodiamond (ND-Cur) was added to the polymer matrix to improve the strength and toughness of PLA. The effects of nanoparticles on the structure, thermal and mechanical properties of polymer matrix were investigated by scanning electron microscopy, thermogravimetric analysis and tensile testing. When the addition of ND-Cur is 1.5 wt%, the mechanical properties of the composite are the best, and the elongation at break is 124.8%, which is 119.9% higher than that of PLA. At this time, the improvement of thermal stability is also the most significant, and the T5% (temperature at 5% heat loss of sample) of the film is 47.9% higher than that of pure PLA. In addition, the modification also improved the hydrophobicity of the composite film.

Effects of Titanium-Silica Oxide on Degradation Behavior and Antimicrobial Activity of Poly (Lactic Acid) Composites.

A mixed oxide of titania–silica oxides (TixSiy oxides) was successfully prepared via the sol–gel technique from our previous work. The use of TixSiy oxides to improve the mechanical properties, photocatalytic efficiency, antibacterial property, permeability tests, and biodegradability of polylactic acid (PLA) was demonstrated in this study. The influence of different types and contents of TixSiy oxides on crystallization behavior, mechanical properties, thermal properties, and morphological properties was presented. In addition, the effect of using TixSiy oxides as a filler in PLA composites on these properties was compared with the use of titanium dioxide (TiO2), silicon dioxide (SiO2), and TiO2SiO2. Among the prepared biocomposite films, the PLA/TixSiy films showed an improvement in the tensile strength and Young’s modulus (up to 5% and 31%, respectively) in comparison to neat PLA films. Photocatalytic efficiency to degrade methylene blue (MB), hydrolytic degradation, and in vitro degradation of PLA are significantly improved with the addition of TixSiy oxides. Furthermore, PLA with the addition of TixSiy oxides exhibited an excellent antibacterial effect on Gram-negative bacteria (Escherichia coli or E. coli) and Gram-positive bacteria (Staphylococcus aureus or S. aureus), indicating the improved antimicrobial effectiveness of PLA composites. Importantly, up to 5% TixSiy loading could promote more PLA degradation via the water absorption ability of mixed oxides. According to the research results, the PLA composite films produced with TixSiy oxide were transparent, capable of screening UV radiation, and exhibited superior antibacterial efficacy, making them an excellent food packaging material.

Antibacterial and degradable properties of β-cyclodextrin-TiO2 cellulose acetate and polylactic acid bionanocomposites for food packaging

Polylactic acid (PLA) and cellulose acetate (CA) as biodegradable polymers are being highly exploited in the development of innovative materials across several industrial sectors. PLA and CA composite films with TiO2 nanoparticles (NPs) and β-cyclodextrin grafted TiO2 NPs were prepared. Thermo- and photo-degradation studies were performed on PLA and CA films and noticed that higher amount of TiO2 induce greater color variations, structure modifications and weight losses. It has been observed 9.3 % and 5.1 % maximum weight loss for 5 % TiO2 CA and PLA matrices, respectively. βCD-modified TiO2 NPs increased the photo-degradation of the plain polymers to a lesser extent than TiO2 NPs. Benzoic acid (BA) and sorbic acid (SA) were incorporated to βCD-TiO2 NPs and the antibacterial activity of PLA and CA composite films was studied by inactivation of Escherichia coli and Staphylococcus aureus. CA film filled with 5 % TiO2 NPs presented the highest antibacterial activity and achieved 71 % inhibition of E. coli and 88 % inhibition of S. aureus. CA composite films showed potential to be used as antimicrobial food packaging.

Development and characterization of biodegradable ultraviolet protective and antibacterial polylactic acid-cellulose acetate film modified by phenyl salicylate

The polylactic acid composite films were successfully fabricated via the technique of solvent casting using cellulose acetate (20%, wt) as the reinforcing material and phenyl salicylate as the ultraviolet (UV) absorbent and antibacterial agent. Polylactic acid-cellulose acetate-phenyl salicylate composite films displayed complete absorption effect at the region of UV-C (280–100 nm) and UV-B (315–280 nm), and more than 95% UV absorption effect at the region of UV-A (400–315 nm). These results indicate that the UV shielding performance of the composite films could be significantly improve by addition of phenyl salicylate. Moreover, the addition of 20% phenyl salicylate could improve the steam resistance, mechanical properties and thermal stability of the films, and the composite films had also better antibacterial activity against Escherichia coli. The composite films could reduce the decay rate of fresh lilies and extend their storage time. The degradation characteristics of the films were explored in the natural environment and the laboratory level, which provided application prospect for the development of degradable food packaging materials with anti-ultraviolet and anti-bacteria effect.

Cotton noil based cellulose microfibers reinforced polylactic acid composite films for improved water vapor and ultraviolet light barrier properties

AbstractThe cellulose reinforced polylactic acid (PLA) composites are one of the most widely explored biopolymer composites in packaging applications. In this study, the cellulose microfibers (CMF) isolated from cotton noil were reinforced with 1%, 3%, 5%, 10%, and 20% in PLA matrix by solvent casting method. The strong interfacial adhesion and enhanced dispersion of CMF in PLA polymer matrix increased the tensile, water vapor, ultraviolet (UV) light barrier properties of the composites. The ultimate tensile stress and Young's modulus of 1% CMF reinforced composites were increased by 46% and 30% respectively than that of control films. A further increase in percent CMF reinforcement of up to 20% slightly reduced the tensile strength of composites but was comparable to that of low‐density polyethylene polymer. The water vapor permeability was decreased while increasing the CMF reinforcement due to the increased diffusion path by the dispersed CMF. The UV light absorbance of the composite was improved by up to 90% with the increase in CMF reinforcement by up to 20% due to the increased chromophore groups of cellulose. Hence, the PLA‐CMF composites could be used for packaging and storing light and moisture‐sensitive products.

Release of clove essential oil loaded by mesoporous nano‐silica in polylactic acid‐based food packaging on postharvest preservation of white button mushroom

SummaryThis work prepared a controlled release food packaging film by solvent volatilization using polylactic acid (PLA) and mesoporous silica nanoparticles (MSNs) loaded with clove essential oil (CEO). White button mushrooms were packaged with PLA and CEO‐loaded MSN PLA composite films to investigate postharvest qualities. The result indicated that PMC‐3 film improves the postharvest qualities of Agaricus bisporus, as reflected by lower weight loss (7.03%), higher total phenolics (2.29 g/kg), and ascorbic acid (27.1 mg/kg) compared with A. bisporus packaged with PLA film. In addition, PMC‐1, PMC‐2, and PMC‐3 treatment significantly improved the antioxidant system of A. bisporus, which inhibited the activity of polyphenol oxidase and peroxidase, as well as control the release of clove essential oil during the storage period. These findings suggest that PMC film is a promising method in postharvest preservation of A. bisporus.

A short review on mechanical and barrier properties of polylactic acid-based films

Polylactic acid (PLA), is a biodegradable plastic derived from renewable resources, and therefore it is a substitute for many conventional petroleum-based polymers. PLA has very good properties like excellent mechanical strength, great modulus, biodegradability, biocompatibility, bio absorbability, energy savings, less harmfulness, and easily processable. Owing to these properties PLA based composite films have been huge attention in Food Packaging (FP) applications. This paper reviews the mechanical and Barrier Properties (BP) of PLA based composite films investigated by the different researchers, and some of them have been discussed here. The widespread adoption of PLA composite films is limited by high brittleness, BP, poor thermal stability and less elongation. To overcome this, an enormous amount of research has been done on PLA based composite films by adding various organic, inorganic, and essential oil fillers. According to this study, PLA has the potential to be used in the synthesis of composite films.

Plasma-Assisted Synthesis of Multicomponent Nanoparticles Containing Carbon, Tungsten Carbide and Silver as Multifunctional Filler for Polylactic Acid Composite Films.

Multicomponent nanoparticles containing carbon, tungsten carbide and silver (carbon-WC-Ag nanoparticles) were simply synthesized via in-liquid electrical discharge plasma, the so-called solution plasma process, by using tungsten electrodes immersed in palm oil containing droplets of AgNO3 solution as carbon and silver precursors, respectively. The atomic ratio of carbon:W:Ag in carbon-WC-Ag nanoparticles was 20:1:3. FE-SEM images revealed that the synthesized carbon-WC-Ag nanoparticles with particle sizes in the range of 20–400 nm had a spherical shape with a bumpy surface. TEM images of carbon-WC-Ag nanoparticles showed that tungsten carbide nanoparticles (WCNPs) and silver nanoparticles (AgNPs) with average particle sizes of 3.46 nm and 72.74 nm, respectively, were dispersed in amorphous carbon. The carbon-WC-Ag nanoparticles were used as multifunctional fillers for the preparation of polylactic acid (PLA) composite films, i.e., PLA/carbon-WC-Ag, by solution casting. Interestingly, the coexistence of WCNPs and AgNPs in carbon-WC-Ag nanoparticles provided a benefit for the co-nucleation ability of WCNPs and AgNPs, resulting in enhanced crystallization of PLA, as evidenced by the reduction in the cold crystallization temperature of PLA. At the low content of 1.23 wt% carbon-WC-Ag nanoparticles, the Young’s modulus and tensile strength of PLA/carbon-WC-Ag composite films were increased to 25.12% and 46.08%, respectively. Moreover, the PLA/carbon-WC-Ag composite films possessed antibacterial activities.

Deposition of carbon–tungsten carbide on coir pulp to improve its compatibility with polylactic acid

To increase hydrophobicity of surfaces of coir pulp, carbon–tungsten carbide (WC) was synthesized and simultaneously deposited on coir pulp by applying in-liquid electrical discharge plasma, so-called solution plasma process (SPP). As a result, water contact angle of carbon-WC deposited coir pulp was 123.4°, whereas that of coir pulp was 82.8°. The carbon-WC deposited coir pulp was then used as a filler in polylactic acid (PLA) to attain composite films of PLA/carbon-WC deposited coir pulp. The deposition of carbon-WC on coir pulp not only increased hydrophobicity of coir pulp but also improved compatibility between the filler and PLA. Even at the low filler content of 0.75 wt%, tensile strength and Young’s modulus of composite films of PLA/carbon-WC deposited coir pulp increased up to 45.73% and 22.79%, respectively compared with those of neat PLA film. Furthermore, the presence of carbon-WC deposited coir pulp in the PLA composite films could enhance the formation of crystalline structure of PLA. Accordingly, SPP is an interesting tool for surface modification of coir pulp in order to achieve surface-functionalized coir pulp for using as a filler in green composites.

Changes of thermal properties and microstructure of nano‐ZnO/polylactic acid composite films during Zn migration

In this study, polylactic acid (PLA) films with different nano‐ZnO concentration (0, 1, 3, 5, 7, 9, and 15%wt) were obtained by casting method. Overall migration values and specific migration values were studied in different food simulants (10% [v/v] ethanol and isooctane). The results demonstrated that overall migration of the composite films and specific migration of Zn2+ was higher in 10% (v/v) ethanol solution than in isooctane solution. The release of Zn2+ was affected by the percentage of nano‐ZnO in the composite films and food simulants. The migration of Zn in this study was mainly caused by polymer softening and degradation leading to the dissolution of Zn. Scanning electron microscope analysis indicated that with the migration of Zn2+, the structure of the composite films changed greatly. Differential scanning calorimeter analysis indicated that the thermal stability was decreased and the glass transition temperature and crystallization temperature were reduced.

Effects of microcrystalline cellulose surface modification on the mechanical and thermal properties of polylactic acid composite films

ABSTRACT Microcrystalline cellulose (MCC), extracted from distiller’s grains by nitric acid-ethanol hydrolysis, was prepared for PLA composite films by solution casting. MCC based on the optimum comparison was characterised by particle size analysis and scanning electron microscopy. The results show that the ultrasound combined sulphonation treatment was remarkable for the surface structure of MCC, compared with that modified by sulphonation and ultrasound methods. The MCC/PLA composite films were analysed using Fourier-transform infrared spectroscopy (FT-IR), mechanical properties and thermal resistance. The results show that the properties and performance of MCC/PLA composite film using ultrasound combined sulphonation treatment are obviously better than those of modified films by other methods. For the modified MCC/PLA composite film by sulphonation and ultrasound methods, the FT-IR analysis carried out a large number of hydroxyl groups that are hydrolysed, the tensile strength upped to 505.24 MPa and the thermal-decomposed temperature increased to 320°C from 260°C. The modified MCC would be a beneficial filling material for the properties of PLA composites.

UV-A activated TiO2 embedded biodegradable polymer film for antimicrobial food packaging application

TiO2 nanoparticles embedded polymer films were fabricated by solution casting method using three biodegradable polymers (cellulose acetate (CA), polycaprolactone (PCL) and polylactic acid (PLA)). Optical and physical properties of the films were assessed by measuring the thickness, color, UV–vis absorption spectra and UV-A transmission. Photodegradation of methylene blue was used to evaluate photocatalytic activity of different TiO2 embedded polymer films. Photocatalytic bactericidal property of the films was evaluated by inactivation of Escherichia. coli O157:H7 under UV-A light illumination at a light intensity of 1.30 ± 0.15 mW/cm2 for 2 h. CA film incorporated with 5 wt% TiO2 NPs had highest bactericidal activity and achieved 1.69 log CFU/ml reduction. Whereas, TiO2 embedded PCL and PLA composite films did not show significant bactericidal property. TiO2 embedded CA film has the potential to be used as antimicrobial food packaging.

Barrier functionality of SiO x layers and their effect on mechanical properties of SiO x /PLA composite films

Silicon oxide (SiO x ) films are widely used as barrier layers in different types of commodity packaging and have caught the interest of manufacturers and researchers alike owing to their high barrier functionality, good acid and alkali resistance, ability to withstand high-temperature and microwave treatments, and good transparency. In this study, we first synthesized polylactic acid (PLA) films by extrusion calendaring and then deposited a SiO x layer on the PLA films by plasma-enhanced chemical vapor deposition to prepare SiO x /PLA composite films. We then evaluated the barrier functionality of the SiO x layer and elucidated its underlying mechanism. We also analyzed its effect on the mechanical properties of the composite films by comparing the oxygen and water vapor transmission rates, soil degradation performances, and surface morphologies of the two types of synthesized films (uncoated and coated with SiO x ). The results showed that, because of the SiO x layer, the barrier properties and mechanical properties of the SiO x /PLA composite films were better than those of the uncoated films. In particular, the oxygen and water vapor transmission rates of the composite films were approximately 8–10 and 6–8 times lower, respectively, than those of the uncoated PLA films. In addition, the SiO x layer lowered the rate of soil degradation of the composite films, owing to which the weight-loss rates of the composite films were also lower than those of the uncoated films. Further, the tensile strengths and elongations at break of the composite films were higher because of the SiO x layer.

Influence of polymer swelling and dissolution into food simulants on the release of graphene nanoplates and carbon nanotubes from poly(lactic) acid and polypropylene composite films

ABSTRACTThe study compared the effects of swelling and dissolution of a matrix polymer by food simulants on the release of graphene nanoplates (GNPs) and multiwall carbon nanotubes (MWCNTs) from poly(lactic) acid (PLA) and polypropylene (PP) composite films. The total migration was determined gravimetrically in the ethanol and acetic acid food simulants at different time and temperature conditions, while migrants were detected by laser diffraction analysis and transmission electron microscopy. Swelling, thermal analysis, and scanning electron microscopy were applied to characterize the degradation of polymer films at the migration conditions. The release of nanoparticles was found in a high‐temperature migration test of 4 h at 90 °C. The hydrolytic dissolution of the PLA polymer in the food simulants caused a migration of GNPs (>100 nm) from the PLA/GNP/MWCNT films into the simulant solvents, while the entangled MWCNTs formed a network on the film surface, preventing their migration from the PLA composite films. In contrast, the PP polymer slightly swells in ethanol solvents, allowing some short carbon nanotubes to be released from the surface and cut edges of the PP/MWCNT film into food simulants. Mathematical modeling of diffusion was applied that accounts for type of polymer, time–temperature conditions, and solvent concentration; model parameters were validated with experimental results. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45469.

Effects of Triclosan Contents on Antimicrobial Efficacy of Environmentally-friendly Biodegradable Polylactic Acid Composite Films

In this study, polylactic acid (PLA) and Triclosan with blending ratios 99:1, 97:3, and 95:5 wt% are dissolved in Dichloromethane via the solution method. The mixtures are then made into PLA/Triclosan composite films by using a casting method. The tensile strength test and differential scanning calorimetry (DSC) are used in order to evaluate the mechanical properties and thermal behaviors of composite films. Finally, Escherichia coli (E. coli) and Staphylococcus auresus (S.aureus) are used to culture with the composite films in order to examine the optimal antimicrobial efficacy of different PLA/Triclosan composite films. The test results indicate that the composite films have a slightly lower tensile strength when the films are composed of 5wt% of Triclosan. Increasing Triclosan contents decreases the Tg of the composite films according to DSC results. Moreover, the antimicrobial efficacy of composite films increases with the increasing Triclosan content, and the antimicrobial efficacy against S.aureus is higher than E. coli.

Thermal and Mechanical Properties of PLA/BN/BR Ternary Composite Films

In this research, the effects of boron nitride (BN) and polybutadiene (BR) on thermal and mechanical properties of polylactic acid (PLA) composite films were studied. PLA thin film in the thickness of less than 0.2 mm was fabricated using the solvent casting method. The loadings of BN and BR of 0-7 wt% were applied to the PLA matrix. The morphologies of composite films were characterized by scanning electron microscopy (SEM). The thermal and mechanical properties were also investigated. It was found that the addition of BN and BR can improve the thermal properties of PLA composite films. PLA/BN3%/BR5% ternary composite films provided the higher thermal properties, tensile strength and Young’s modulus, compared to PLA/BN1%/BR5% ternary composite films.