Poly Lactic Acid Research Articles

A novel biobased prepreg from flax and thermosetting poly(lactic acid): Synthesis, curing and processing

Flax fiber-reinforced thermosetting poly (lactic acid) (PLA) composites, a fully degradable plant fiber-reinforced composites, were prepared by hot-melt pre-impregnation, which consists of two processes, the preparation and curing of the prepreg. Firstly, thermosetting PLA with intrinsic flame-retardancy was synthesized and its molecular structure was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. The non-isothermal viscosity of the thermosetting PLA resin system was investigated to determine the film-formation temperature (55°C) and the impregnation temperature (65°C) during the preparation of the prepreg. On this basis, novel flax fiber-reinforced thermosetting PLA prepreg was prepared and its curing kinetics was investigated using differential scanning calorimetry (DSC). A curing simulation model of the prepreg was developed using the finite difference method, which was used to design and optimize the curing cycle of the flax fiber-reinforced thermosetting PLA prepreg. Finally, the flax fiber-reinforced thermosetting PLA composites with different lay-ups were prepared using the optimal curing cycles and their mechanical and flame retardant properties were investigated, with tensile and flexural strengths up to 128 MPa and 98.8 MPa, and flame retardant ratings up to UL-94 V-1. Overall, the results of this study can provide an important basis for expanding the application of flax fiber reinforced thermosetting PLA composites.

Poly (lactic acid) electrospun nanofiber membranes: Advanced characterization for biomedical applications with drug loading performance studies

Traditional dressings have shortcomings such as poor moisture absorption and easy to adhere, making the development of new dressings crucial. In this work, a PLA/PVP crosslinked drug-loaded nanofiber membrane was prepared through electrospinning and ultraviolet crosslinking, with poly (lactic acid) (PLA), polyvinylpyrrolidone (PVP), and salicylic acid (SA) as starting materials. The results demonstrated that the inclusion of PVP notably boosted the viscosity and conductivity of the blend spinning solution. The roughness of the fabricated fiber was elevated, and the diameter of the fibers was more uniform. Additionally, the incorporation of PVP not only enhanced the porosity of the fiber membrane but also effectively decreased its contact angle. Notably, when the PVP content reached 40 %, the contact angle underwent a substantial reduction, decreasing significantly from 125.4° to 82.2°. The SA drug-loaded fiber membrane exhibited a notable bacteriostatic effect against Escherichia coli and Staphylococcus aureus, with its release behavior adhering to Fick's diffusion law. In the cell viability experiment, the cell proliferation rate increased from 94 % to 129 % after 3 days. This shows that the prepared membrane has good antibacterial effect and cell compatibility, which provides a theoretical basis for the construction of a new medical dressing.

Bactericidal and Antifouling Coatings with the "Killing-Repelling-Killing" Triple Function Based on Cationic Copolymers with Structure Conversion and Capsaicin Analogue Release.

The capsaicin analogue N-(4-hydroxy-3-methoxybenzyl) acrylamide (HMBA) was linked with polylauryl methacrylate-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PLMA-b-PDMAEMA) via a quaternization reaction with 4-(acrylamidomethyl)-2-methoxyphenyl 2-chloroacetate (AAMPCA). The amphiphilic copolymers were capable of transforming its structure in response to the solvent change from aprotic to protic, which was verified by the 1H NMR spectrum. The resulting cationic copolymers underwent a hydrolysis process in water, yielding zwitterionic groups on surfaces. Meanwhile, the bactericidal reagent HMBA was released. It was proved that the hydrolysis rate of the copolymers accelerated with higher temperature, higher pH value, and higher hydrophilic block units. And the controllable, sustainable release of HMBA was achieved with copolymer-mediated hydrolysis. Protein-repellent and bactericidal tests on the surface of the coating proved that antifouling and bactericidal performances of the coating correlated to the structure conversion abilities of the corresponding copolymer. The dynamic monitoring of Escherichia coli adhesion in 3 h evidenced the antifouling and bactericidal process of copolymers with different block ratios and concentrations. The coating incorporated with 3% PLMA120-b-(PDMAEMA-AAMPCA)120 in polylactic acid base materials showed an adhesion ratio of E. coli less than 1% within 1 h, and the survival ratio of the adhered bacteria is <1%, suggesting its rapid speed and high efficiency in "bacterial repelling and killing". Also, the PLMA120-b-(PDMAEMA-AAMPCA)120 copolymer demonstrated enhanced bactericidal ability compared with the mixture of cationic poly(laruyl methacrylate)120-b-poly(carboxybetaine methacrylate ester)120 (PLMA120-b-PCBMAE120) and free HMBA. The lowest minimal inhibitory concentration was 0.078 mg/mL against Staphylococcus aureus and 0.312 mg/mL against E. coli, respectively.

Electrosynthesis and characterization of poly(rhodamine B) coatings on 3d printed polylactic acid doped carbon black (PLA-CB) electrodes for promising sensor applications

Electrosynthesis and characterization of poly(rhodamine B) coatings on 3d printed polylactic acid doped carbon black (PLA-CB) electrodes for promising sensor applications

A bio-sorbent based on polylactic acid nanocomposites for thin-film microextraction

A bio-sorbent based on polylactic acid nanocomposites for thin-film microextraction

Aging of biodegradable microplastics and their effect on soil properties: Control from soil water

The ecological risks of biodegradable microplastics (BMPs) to soil ecosystems have received increasing attention. This study investigates the impacts of polylactic acid microplastics (PLA-MPs) and polybutylene adipate terephthalate microplastics (PBAT-MPs) on soil properties of black soil (BS) and fluvo-aquic soil (FS) under three water conditions including dry (Dry), flooded (FL), and alternate wetting and drying (AWD). The results show that BMPs exhibited more evident aging under Dry and AWD conditions compared to FL condition. However, BMPs aging under FL condition induced more substantial changes in soil properties, especially dissolved organic carbon (DOC) concentrations, than under Dry and AWD conditions. BMPs also increased the humification degree of soil dissolved organic matter (DOM), particularly in BS. Metagenomic analysis of PBAT-MPs treatments showed different changes in microbial community structure depending on soil moisture. Under Dry conditions, PBAT-MPs enhance the ammonium-producing process of soil microbial communities. Genes related to N nitrification and benzene degradation were enriched under AWD conditions. In contrast, PBAT-MPs do not change the abundance of genes related to the N cycle under FL conditions but significantly reduce genes related to benzene degradation. This reduction in benzene degradation genes under FL condition might potentially slow down the degradation of PBAT-MPs, and could lead to temporary accumulation of benzene-related intermediates. These findings highlight the complex interactions between BMPs, soil properties, and microbial communities, emphasizing the need for comprehensive evaluations of BMPs’ environmental impacts under varying soil water conditions.

A comprehensive study on the effects of printing parameters on the mechanical properties of PLA

Purpose This study aims to investigate the effects of five different printing parameters, namely, printing speed (PS), printing temperature/nozzle temperature/extrusion temperature, heated-bed temperature, raster angle (RA) and layer height (LT), on mechanical properties. Design/methodology/approach American Society for Testing and Materials (ASTM) standards were used for the specimen design. Then, the Taguchi method was used for the design of the experiment and an L16 orthogonal array was preferred. Tensile, Shore D and surface roughness tests were conducted on polylactic acid test specimens. The test results were analyzed using the signal-to-noise ratio and analysis of variance (ANOVA). Findings As a result of the study, it was seen that RA is the most important parameter for the tensile strength, PS is for the hardness and LT is for the surface roughness. According to the ANOVA results, the effects of the RA, PS and LT on the maximum tensile strength, hardness and surface roughness were 41.59%, 69.51% and 44.6%, respectively. Originality/value To the best of the authors’ knowledge, this study is one of the most comprehensive parameter optimization studies for additive manufacturing in the literature because it includes five different printing parameters and three mechanical test procedures.

Feasibility of polylactic acid and essential oil composite with insecticidal properties for prevention of Sitophilus oryzae and Oryzophilus surinamensis in Sorghum and Pearl millet

Current study provides insight on the feasibility of polylactic acid (PLA) integrated with (1:1 ratio) of essential oils belonging to Ocimum gratissimum (OG) and Mentha spicata (MS) for prevention of major stored insect pests (Sitophilus oryzae and Oryzophilus surinamensis) in Sorghum and Pearl millet. A combination of OG and MS essential oils (1:1) was incorporated into the PLA polymer matrix. Further, SPME analysis of synthesized PLA showed the presence of volatiles corresponding to carvone (6.44 %) and thymol (6.22 %). Synthesized PLA composites were tested against S. oryzae and O. surinamensis using Sorghum and Pearl millets, and insect mortality was equivalent to commercial super bags (CSB). The head space oxygen decreased significantly in CSB and slightly in PLA bags. Thickness of EO blended PLA composite was increased (99 μm), tensile strength (23.94 MPa), WVTR (1.42 g/m2.hr) analysis, significant folding ability, and swelling capacity (0.24 %) showed slight reduction in composite film. TGA showed good thermal stability (334˚C) and XRD displayed the increased crystallinity (38.35 %) in PLAOM films, SEM and FTIR analysis of the synthesized composite films revealed complete homogenization of EO and PLA matrix. In addition, SEM analysis of insects (control & treated) revealed less topology changes in the elytra. Biodegradability study confirmed the weight loss in PLA films. Hence, current approach of using composite EO's with PLA offers sustainable solution for prevention of infestation during storage of millets.

Antibacterial performance of biodegradable polymer and hazelnut husk flour antibacterial biofilm with silver nanoparticles

The antibacterial performance of biocomposite films prepared from lignocellulosic waste (hazelnut husk or hazelnut leafy green cover) modified with silver nanoparticles and polylactic acid (PLA) was determined. The amount of hazelnut husk in the PLA matrix ranged from 10 to 40% by weight in 10% increments. The composite pellets were produced using a twin-screw extruder. Biocomposite films of 0.6 mm x 40 mm x 200 mm were produced from the pellets in a laboratory hydraulic hot press. The surfaces of the modified hazelnut husk and biocomposite specimens were analyzed by scanning electron microscopy (SEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The antibacterial activity of the biocomposite films against Staphylococcus aureus bacteria was determined using the ASTM E 2149 (2020) method. The antibacterial activity of the biocomposite films increased noticeably with the addition of hazelnut husk modified with the silver nanoparticles. Compared to the pure PLA film, the biocomposite films with 10 wt% modified husk flour showed the lowest antibacterial activity (31.3%) against S. aureus over 24-h while the films with 40 wt% showed the highest antibacterial activity (99.9%). The biocomposite films made of hazelnut husk flour with silver nanoparticles and PLA matrix could be considered for food packaging applications.

Elasticity and plasticity of PLA, PETG, ABS polymers for printing automotive parts

The objective of this paper is to explore the elasticity and plasticity properties of PLA, PETG and ABS polymers in the context of 3D printing of automotive parts. The present research is qualitative, descriptive, focusing on the theoretical analysis of the mechanical properties of PLA, PETG and ABS polymers, which is based on the collection of information from different authors. An analysis of the properties of these polymers is very significant for their application in the automotive industry, allowing a correct selection of materials. The research found very important data, highlighting that PLA, with its high stiffness and low plasticity, is ideal for prototypes and low-stress parts, while PETG offers a balance between flexibility and strength, suitable for functional components that require durability. ABS, known for its high impact strength and ductility, is recommended for applications that demand shock absorption and durability under demanding conditions. Selecting the right material is crucial to optimize the performance and longevity of 3D printed automotive parts, contributing to the advancement of additive manufacturing technology in the industry.

Understanding the mechanism of microplastic-associated antibiotic resistance genes in aquatic ecosystems: Insights from metagenomic analyses and machine learning

The pervasive presence of microplastics (MPs) in aquatic systems facilitates the transmission of antibiotic resistance genes (ARGs), thereby posing risks to ecosystems and human well-being. However, owing to variations in environmental backgrounds and the limited scope of research subjects, studies on ARGs in MPs lack unified conclusions, particularly regarding whether different types of MPs selectively promote ARG enrichment. Analysing large-scale datasets can better encompass broad spatiotemporal scales and diverse samples, facilitating a more extensive exploration of the complex ecological relationships between MPs and ARGs. The present study integrated existing metagenomic datasets to conduct a comprehensive risk assessment and comparative analysis of resistance groups across various MPs. In addition, we endeavoured to elucidate potential associations between ARGs and bacterial taxa, as well as MP structural features, using machine learning (ML) methods. The findings of our research highlight the pivotal role of MP type in shaping plastispheres, accounting for 9.56 % of the biotic variation (Adonis index) and explaining 18.59 % of the ARG variance. Compared to conventional MPs, biodegradable MPs, such as polyhydroxyalkanoates (PHA) and polylactic acid (PLA), exhibit lower species uniformity and diversity but pose a higher risk of ARG occurrence. These ML approaches effectively forecasted ARG abundance by using the bacterial taxa and molecular structure descriptors (MDs) of MPs (average R2tra = 0.882, R2test = 0.759). Feature analysis showed that MDs associated with lipophilicity, solubility, toxicity, and surface potential significantly influenced the relative abundance of ARGs in the plastispheres. The interpretable multiple linear regression (MLR) model, particularly notable, elucidated a linear relationship between bacterial genera and ARGs, offering promise for identifying potential ARG hosts. This study offers novel insights into ARG dynamics and ecological risks within aquatic plastispheres, highlighting the importance of comprehensive MP monitoring initiatives.

Investigating the toxicity of polylactic acid microplastics on the health and physiology of freshwater fish, Cirrhinus mrigala.

The widespread presence of microplastics (MPs) in aquatic ecosystems has raised growing concerns among ecotoxicologists regarding their potential toxicity. This study explored the impacts of polylactic acid (PLA) MPs on the physiology and health of freshwater fish, Cirrhinus mrigala, by dietary exposure for 90 days. The experiment consisted of six groups: five treatment groups (0.5%, 1%, 1.5%, 2%, and 2.5% PLA-MP) and a control group (0% PLA-MP). Each group was comprised of fifteen fish, and the experiment was replicated three times. The exposure severity of PLA-MPs varied from low to high, with treatment levels ranging from 0.5% to 2.5% PLA-MPs, relative to the control group. This exposure significantly affected their growth performance. Additionally, the apparent digestibility of the SFM-based diet decreased with increasing PLA-MPs concentration. Exposure to PLA-MPs induced considerable changes in body composition, characterized by increased moisture and crude fat content and decreased ash content and crude protein. The blood profile, including MCHC, RBCs, Hb, PLT and PCV exhibited significant declines in the high treatment group (2.5% PLA-MPs), while MCH, WBCs and MCV showed notable increases. Furthermore, histopathological examination of the intestine revealed an increase in abnormalities in the intestine at 2.5% PLA-MPs level. The high treatment group (2.5% PLA-MPs) showed the lowest mineral content in the fish muscles. In summary, dietary exposure to PLA-MPs led to alterations in overall body performance across the treatment groups, ranging from low to high severity levels.

Phosphorus-nitrogen-containing flame-retardant plasticizers derived from L-lactic acid for poly (lactic acid) improved toughness, flame retardancy and crystallization

Designing highly-effective and environmentally friendly biobased flame-retardant plasticizers for polylactic acid (PLA) remains a formidable challenge. In this study, we synthesized four novel phosphorus-nitrogen-containing L-lactic acid-based flame-retardant plasticizers with adjustable chemical structures and phosphorus content, designated as NPDL-Cn, where ’n’ corresponds to the alkyl groups numbers in the alkylamine chain (with n = 4, 6, 8, and 10). Incorporating NPDL-Cn into the PLA matrix offered a twofold benefit, significantly enhancing both the flame retardancy and toughness of PLA. Remarkably, as incorporating 20 phr NPDL-Cn, the resulting blends all achieved UL-94 V-0 grade, and their limiting oxygen index reached about 30.8 %, 29.5 %, 28.3 % and 27.2 %, respectively. A comprehensive analysis of the volatile gases and char layer generated during combustion showed that the flame-retardant mechanism of NPDL-Cn in PLA significantly influenced both the condensed-phase and gas-phase behavior. Meanwhile, NPDL-Cn effectively overcame the brittleness and rigidity of PLA, thus realizing the enhancement of its toughness. In particular, as compared to a mere 3.7 % and 1.7 MJ/m3 for neat PLA, when the methylene numbers of NPDL-Cn were 4, the elongation at break and tensile toughness of the PLA/NPDL-C4 exhibited a substantial increase to 180.1 % and 43.4 MJ/m3, respectively, due to the best interfacial tension of NPDL-C4 with PLA matrix. Additionally, while the tensile strength of neat PLA is notably high at 50.7 MPa, the introduction of PLA/NPDL-C4 results in a significant decrease to 26.3 MPa. Interestingly, biodegradation experiments showed that NPDL-C4 was decomposed into non-toxic and harmless small molecules. This study presents a method for constructing toughened and flame-retardant PLA blends by modulating the alkyl chain length of flame-retardant plasticizers and elucidating their structure–property relationships.

Inclusion of modified nano-magnesium hydroxide as an adjuvant flame retardant in the development of PLA/hydroxyapatite nanocomposites

For the preparation of thermal stable and flame-retardant polylactic acid (PLA) nanocomposites two new modified nano-structures including imide-carboxylated chitosan modified Mg(OH)2 (ICMH) and imide-silane functionalized hydroxyapatite nanoparticles (ISHA) were prepared. The structure, morphology, and properties of ICMH and ISHA were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). The PLA nanocomposites were prepared via solution casting method. The results of Transmission electron microscopy (TEM) and SEM indicated a homogeneous structure for the PLA nanocomposites. The TGA results revealed that the presence of hydroxyapatite nanoparticles (HA) led to increase the thermal resistance of the PLA nanocomposites containing Mg(OH)2 (MDH). Compared to pure PLA, the Tmax value of the PLA sample containing 3 wt% of each filler (the PMH6 sample) enhanced from 364°C to 372°C. The results from the microscale combustion calorimeter (MCC) test illustrated that the key parameter values of the PLA nanocomposites were reduced, as compared to the pure PLA. The peak heat release rate (pHRR) and heat release capacity (HRC) values of PMH6 decreased 27% and 35%, respectively, as compared to the pure PLA. Also, flammability of PMH6 was reduced, as compared to the pure PLA, with UL-94 V-1 rating and LOI value 26.8%. Furthermore, the tensile strength of the mentioned sample increased from 36.04 MPa to 38.58 MPa.

Lipase etching effects-induced interaction between betanin nanocomplexes and polylactic acid and its 3D printing for food packaging

Etching effects by lipase on polylactic acid (PLA) could induce the exposure of active sites and promote the attachment of betanin nanocomplexes (BR-Ch) to obtain red color. 3D printing, regarded as emerging, innovative packaging fabrication technique, was applied to potentially develop creative, red PLA products for food application. BR-Ch was prepared based on betanin and nano chitin (around 195 nm) via electrostatic interaction and hydrogen bonding, obtaining nanocomplexes (around 24 nm) with excellent thermal stability. Pre-treatments mattered greatly in PLA functionalization, and especially, lipase pre-treatment 30 min promoted BR-Ch modification on PLA. Final PLA exhibited excellent red color characteristics (CIElab, Hue-Saturation-Brightness, K/S and CMYK), elongation at break and stable thermal resistance, ultimately achieving outstanding dyeing effect. This work indicates that BR-Ch can potentially replace synthetic pigments to functionalize lipase-pretreated PLA, and the dyed PLA demonstrate the excellent packaging application prospects in food field by 3D-printed products.

Evaluation of the layering adhesion between PLA and TPE materials

Abstract The additive manufacturing industry has witnessed rapid growth and has applications across various sectors such as aerospace, automotive, healthcare, and consumer goods. Both Thermoplastic Elastomer (TPE) and Polylactic Acid (PLA) hold significant relevance in these industries because of their unique properties and environmental sustainability, thus driving the demand for research aimed at improving their compatibility and performance in multi-material printing processes. This study delves into the interlayer adhesion aspects of multi-material filament fabrication, particularly focusing on the incorporation of TPE and PLA. TPEs offer elasticity and flexibility, while PLA provides rigidity and biodegradability, making them an intriguing combination for a wide range of applications. Experimental investigations of mechanical properties, specifically tensile, compression, and Charpy impact tests, are conducted to evaluate the interlayer adhesion between TPE and PLA. This study aims to contribute to the understanding of interlayer adhesion in multi-material filament fabrication, focusing on the integration of TPE and PLA. Through experimental analysis and exploration of industrial applications, we seek to shed light on the potential of these materials in additive manufacturing and outline future directions for research and development in this field.

Epoxidized cardanol oleate (ECD-OA) as an effective biobased chain extender of polylactic acid (PLA)

Moisture exposure during polyester processing can lead to degradation, resulting in the formation of carboxyl and hydroxyl end-groups. To preserve mechanical properties, thorough drying and the use of chain extenders like epoxy acrylates and isocyanates during extrusion are crucial for maintaining or enhancing molecular weight through in-situ reactions. Our study introduced epoxidized cardanol oleate (ECD-OA), containing epoxy and long-chain alkyl groups, as a potential chain extender, and compared its effectiveness with commercially available epoxidized cardanol glycidyl ether (cardolite NC514). Compared to neat PLA without chain extension, the addition of 1 phr ECD-OA resulted in an increase in the molecular weight (Mw) of PLA from 15.3 × 104 g/mol to 17.1 × 104 g/mol, demonstrating a chain extension efficiency of 11.8 %. The melt flow rate of PLA decreased from 9.9 g/10 min to 5.0 g/10 min, and the initial thermal degradation temperature of PLA increased by 5.7 °C. Upon chain extension, there was a substantial increase in both the elongation at break and tear resistance of the PLA film. The results demonstrate that ECD-OA can extend PLA molecular chains through chemical reactions and promote entanglement with the long alkane chain, consequently enhancing the mechanical and thermal properties of PLA. Due to the enzyme's preference for biobased small molecules, the PLA film with the addition of a biobased chain extender is more prone to enzymatic degradation compared to neat PLA. To conclude, ECD-OA acts as a bio-based chain extender that improves the performance of PLA while also enhancing its biodegradability.

Functional Silsesquioxanes-Tailoring Hydrophobicity and Anti-Ice Properties of Polylactide in 3D Printing Applications.

To explore the tailoring of hydrophobicity in 3D-printed polylactide (PLA) composites for advanced applications using additive manufacturing (AM), this study focuses on the use of Fused Deposition Modeling (FDM) 3D printing. PLA, a material derived from renewable sources, is favored for its eco-friendliness and user accessibility. Nonetheless, PLA's inherent hydrophilic properties result in moisture absorption, negatively affecting its performance. This research aims to modify PLA with organosilicon compounds to enhance its hydrophobic and anti-icing properties. Incorporating fluorinated siloxane derivatives led to significant increases in water contact angles by up to 39%, signifying successful hydrophobic modification. Mechanical testing demonstrated that the addition of organosilicon additives did not compromise the tensile strength of PLA and, in some instances, improved impact resistance, especially with the use of OSS-4OFP:2HEX:2TMOS, which resulted in an increase in the tensile strength value of 25% and increased impact strength by 20% compared to neat PLA. Differential scanning calorimetry (DSC) analysis indicated that the modified PLA exhibited reduced cold crystallization temperatures without altering the glass transition or melting temperatures. These results suggest that organosilicon-modified PLA has the potential to expand the material's application in producing moisture and ice-resistant 3D-printed prototypes for various industrial uses, thereby facilitating the creation of more durable and versatile 3D-printed components.

Tensile properties and deformation by different compatibilizers in bio-based polylactide/poly(4-hydroxybutyrate) blends

Blending chemically synthesized poly(4-hydroxybutyrate) (P4HB) with polylactide (PLLA) can overcome PLLA's brittleness, offering fully biobased blends. However, due to low compatibility between PLLA and P4HB, the influence of compatibilizers on the morphology, structure and tensile deformation of PLLA/P4HB blends remains to be unresolved. This article introduces reactive poly(methyl methacrylate-co-styrene-glycidyl methacrylate) (MSG) and non-reactive polyformaldehyde (POM) compatibilizers to improve the compatibility between P4HB and PLLA, achieving the maximal elongation at break exceeding 300 % at 2 wt% MSG or 3 wt% POM. MSG inhibits PLLA crystallization, extending stress stability in the silver streak stage, while POM enhances crystallization, prolonging the strain-hardening stage. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) analysis show that pristine PLLA forms voids before fracture, and PLLA/P4HB blends cavitate at the yield point and develop crazes in the silver streak stage. MSG effectively transmits stress and delays cavitation, extending the silver streak stage, whereas POM forms a microcrystalline network, lowering the energy barrier for stretching-induced recrystallization. These findings could provide theoretical guidelines on selecting compatibilizers for different PLLA based blends.

Preparation and characterization of Ag@MOF-eugenol/ poly (lactic acid) composite films for zucchini preservation

The rising demand for premium quality fruits and vegetables has resulted in an increased necessity for the advancement in active food packaging. This study aimed to develop eugenol-loaded Ag@MOF/poly(lactic acid) (Ag@MOF-EU/PLA) composite films to assess their efficacy in preserving zucchini. The results revealed that Ag@MOF-EU can be uniformly distributed within the PLA matrix, which significantly enhanced the tensile strength, hydrophobicity, and UV-blocking capacity of PLA films, and at the same time had no significant effect on the thermal properties and WVP of the PLA films. Moreover, the resulting Ag@MOF-EU/PLA films exhibited no cytotoxicity. In a food simulant (50 % ethanol), the release behavior of the EU demonstrated a sustained release over 20 days. Furthermore, Ag@MOF-EU/PLA had an enhanced antimicrobial activity and DPPH scavenging activity, compared to PLA films. The preservation experiment involving zucchini elucidated that the Ag@MOF-EU/PLA composite film could extend the shelf life of zucchini by maintaining color, reducing weight loss, delaying the decline in firmness, and inhibiting the growth of total viable colonies. These findings indicated that the Ag@MOF-EU/PLA films developed within the scope of this research possess the potential to serve as effective food-active packaging materials.