Biodegradable Poly Lactic Acid Research Articles

Expanding the shelf life of chicken fillets by the use of polylactic acid (PLA) active films: An investigation of orange oil antibacterial potential

AbstractIn this study, orange oil was incorporated into biodegradable polylactic acid (PLA) at various concentrations (1.25%, 1.875%, 2.5%, and 3.75% w/v) to develop potential antimicrobial food packages. Increasing orange oil concentration caused a gradual increase in the films' opacity values, making them more appropriate for packaging of foods having a potential to be affected from UV‐light. Independent of orange oil concentration, the water vapor permeability of the films decreased. While orange oil incorporation did not alter thermal stability of the active films, a slight reduction in glass transition and melting temperature values was observed. The antimicrobial activity of the films was examined on the most common food‐borne pathogens (E. coli, S. aureus), and it is only the film containing 3.75% w/v (PLA_3) that showed an inhibitory activity on both microorganisms. Finally, the shelf life of the chicken fillets packed with neat PLA (PLA_0) and PLA_3 films was compared, and PLA_3 increased the shelf life up to day‐9.Highlights Various concentrations of orange oil were used to develop active polylactic acid (PLA) films. Opacity of the films increased with increasing oil concentration. Incorporation of orange oil resulted in decreasing water vapor permeability. Orange oil worsened both tensile strength and elongation at break of films. PLA_3 inhibited the growth of microorganisms and extended the shelf life of chicken fillet.

In vitro cell-transforming potential of secondary polyethylene terephthalate and polylactic acid nanoplastics

Continuous exposure to plastic pollutants may have serious consequences on human health. However, most toxicity assessments focus on non-environmentally relevant particles and rarely investigate long-term effects such as cancer induction. The present study assessed the carcinogenic potential of two secondary nanoplastics: polyethylene terephthalate (PET) particles generated from plastic bottles, and a biodegradable polylactic acid material, as respective examples of environmentally existing particles and new bioplastics. Pristine polystyrene nanoplastics were also included for comparison. A broad concentration range (6.25–200 μg/mL) of each nanoplastic was tested in both the initiation and promotion conditions of the regulatory assessment-accepted in vitro Bhas 42 cell transformation assay. Parallel cultures allowed confirmation of the efficient cellular internalisation of the three nanoplastics. Cell growth was enhanced by polystyrene in the initiation assay, and by PET in both conditions. Moreover, the number of transformed foci was significantly increased only by the highest PET concentration in the promotion assay, which also showed dose-dependency, indicating that nano PET can act as a non-genotoxic tumour promotor. Together, these findings support the carcinogenic risk assessment of nanoplastics and raise concerns regarding whether real-life co-exposure of PET nanoplastics and other environmental pollutants may result in synergistic transformation capacities.

Development of toughened and heat-resistant biodegradable injection-molded polylactide acid-based blend foams via enhancing interfacial bonding and PLA phase crystallization

Polylactic acid (PLA) foam is gaining increased attention as a biodegradable alternative to traditional petroleum-based plastic foams, which pose significant environmental pollution issues post-use. However, its potential application is greatly limited by inherent shortcomings such as brittleness and diminished heat resistance post-melting. Herein, high-performance biodegradable PLA/poly(butylene succinate) (PBS) blend foams with well-defined cell structure, high ductility, and enhanced heat resistance were fabricated using a core-back foam injection molding (FIM) process coupled with a straightforward annealing procedure. To enhance compatibility and tailor the dispersed phase morphology into a more fibrillar structure, an epoxy-functional chain extender (ADR) was incorporated. This addition resulted in a substantial increase in the notched impact strength, elevating it to 7.0 kJ/m2, compared to the mere 1.5 kJ/m2 of unmodified PLA foam. Moreover, with the inclusion of 1.0 phr ADR, the notched impact strength of the foam post-annealing soared to 20.7 kJ/m2, a 13.8-fold enhancement compared to pure PLA foam. The formation of a uniformly distributed and interlocked “shish-kebab" crystal structure in the blend facilitated effective stress transfer and distribution, leading to shear yield in the PLA matrix. Additionally, the heat deflection temperature of the annealed blend foam showed a significant increase significantly to 94.7 °C, in contrast to the mere 55.6 °C of pure PLA foam. This study demonstrates a viable and feasible strategy for preparing fully biodegradable PLA foams with high-toughness and heat resistance.

Feasibility of biodegradable material polylactic acid as a substitute for polypropylene for disposable medical masks production verified by life cycle assessment

The Corona Virus disease 2019 (COVID-19) outbreak has changed the lifestyles of billions of people. Face masks, as a daily protective tool, have become a must-have item. The number of masks discarded has soared, making environmental and hygiene problems impossible to ignore. The rapid development of biodegradable materials may be one of the solutions to this issue. In this study, life cycle assessment (LCA) was used as a method to quantitatively analyze the environmental impacts of two disposable medical masks, biodegradable polylactic acid (PLA) and fossil-based polypropylene (PP). The results show that human toxicity (63.93%), acidification (39.93%), global warming potential (36.29%), and abiotic depletion (83.55%) of disposable medical masks mainly made of PLA were significantly lower than those of PP. The photochemical oxidation (4.89%) for PLA masks was slightly higher. The manufacturing cost per unit hour was 0.060 yuan (PP) and 0.0675 yuan (PLA). It was estimated that the replacement could reduce global carbon emissions by 321,392,700 tons and 466,400 tons for China. Furthermore, the process improvements in the raw material acquisition stage could maximize the benefits of carbon reduction.

Preparation of photoluminescent nano-biocomposite nacre from graphene oxide and polylactic acid.

Nano-biocomposites of inorganic and organic components wereprepared to produce long-persistent phosphorescent artificial nacre-like materials. Biodegradable polylactic acid (PLA), graphene oxide (GO), and nanoparticles (13-20 nm) of lanthanide-doped aluminate pigment (NLAP) were used in a simple production procedure of an organic/inorganic hybrid nano-biocomposite. Both polylactic acid and GO nanosheets were chemically modified to form covalent and hydrogen bonding. The high toughness, good tensile strength, and great endurance of those bonds were achieved by their interactions at the interfaces. Long-persistent and reversible photoluminescence was shown by the prepared nacre substrates. Upon excitation at 365 nm, the nacre substrates generated an emission peak at 517 nm. When ultraviolet light was shone on luminescent nacres, they displayed a bright green colour. The high superhydrophobicity of the generated nacres was obtained without altering their mechanical characteristics.

Four-Element Biodegradable Substrate-Integrated MIMO DRA with Radiation Diversity

This article presents a four-element directional multiple input multiple output (MIMO) rectangular dielectric resonator antenna (RDRA) equipped with strategically placed copper reflector plates to enhance port isolation. This design aims to achieve an extended coverage range without compromising the coverage area. The proposed MIMO antenna is 3D printed using biodegradable polylactic acid to ensure mechanical robustness and then integrated with the substrate to prevent mis-mounting issues. The proposed design exhibits good MIMO characteristics, registering a 3-GHz bandwidth (4–7 GHz) for |S11|≤-10 dB and a minimum radiation gain of 7 dBi for all four RDRAs. The antenna demonstrates a rotation of radiation patterns for different ports, thus enabling beam formation in specific directions. With a beam width of 71.2˚, the antenna covers all directions without any fade zones. The proposed 3D printed antenna offers simplicity, strong MIMO properties, and practicality for wireless communication systems, making it suitable for industrial, scientific, and medical band applications.

Preparation of Biodegradable Polylactic Acid Membranes via Phase Separation: A Review

Preparation of Biodegradable Polylactic Acid Membranes via Phase Separation: A Review

Effect of molecular weight on the properties and structure of biodegradable poly-lactic acid melt-blown nonwovens

Effect of molecular weight on the properties and structure of biodegradable poly-lactic acid melt-blown nonwovens

Fabrication and properties of PLA/β-TCP scaffolds using liquid crystal display (LCD) photocuring 3D printing for bone tissue engineering.

Introduction: Bone defects remain a thorny challenge that clinicians have to face. At present, scaffolds prepared by 3D printing are increasingly used in the field of bone tissue repair. Polylactic acid (PLA) has good thermoplasticity, processability, biocompatibility, and biodegradability, but the PLA is brittle and has poor osteogenic performance. Beta-tricalcium phosphate (β-TCP) has good mechanical properties and osteogenic induction properties, which can make up for the drawbacks of PLA. Methods: In this study, photocurable biodegradable polylactic acid (bio-PLA) was utilized as the raw material to prepare PLA/β-TCP slurries with varying β-TCP contents (β-TCP dosage at 0%, 10%, 20%, 30%, 35% of the PLA dosage, respectively). The PLA/β-TCP scaffolds were fabricated using liquid crystal display (LCD) light-curing 3D printing technology. The characterization of the scaffolds was assessed, and the biological activity of the scaffold with the optimal compressive strength was evaluated. The biocompatibility of the scaffold was assessed through CCK-8 assays, hemocompatibility assay and live-dead staining experiments. The osteogenic differentiation capacity of the scaffold on MC3T3-E1 cells was evaluated through alizarin red staining, alkaline phosphatase (ALP) detection, immunofluorescence experiments, and RT-qPCR assays. Results: The prepared scaffold possesses a three-dimensional network structure, and with an increase in the quantity of β-TCP, more β-TCP particles adhere to the scaffold surface. The compressive strength of PLA/β-TCP scaffolds exhibits a trend of initial increase followed by decrease with an increasing amount of β-TCP, reaching a maximum value of 52.1MPa at a 10% β-TCP content. Degradation rate curve results indicate that with the passage of time, the degradation rate of the scaffold gradually increases, and the pH of the scaffold during degradation shows an alkaline tendency. Additionally, Live/dead staining and blood compatibility experiments suggest that the prepared PLA/β-TCP scaffold demonstrates excellent biocompatibility. CCK-8 experiments indicate that the PLA/β-TCP group promotes cell proliferation, and the prepared PLA/β-TCP scaffold exhibits a significant ability to enhance the osteogenic differentiation of MC3T3-E1 cells in vitro. Discussion: 3D printed LCD photocuring PLA/β-TCP scaffolds could improve surface bioactivity and lead to better osteogenesis, which may provide a unique strategy for developing bioactive implants in orthopedic applications.

Polyvinyl alcohol/collagen composite scaffold reinforced with biodegradable polyesters/gelatin nanofibers for adipose tissue engineering

Breast cancer has become the most diagnosed cancer type, endangering the health of women. Patients with breast resection are likely to suffer serious physical and mental trauma. Therefore, breast reconstruction becomes an important means of postoperative patient rehabilitation. Polyvinyl alcohol hydrogel has great potential in adipose tissue engineering for breast reconstruction. However, its application is limited because of the lack of bioactive factors and poor structural stability. In this study, we prepared biodegradable polylactic acid-glycolic acid copolymer/polycaprolactone/gelatin (PPG) nanofibers. We then combined them with polyvinyl alcohol/collagen to create tissue engineering scaffolds to overcome limitations. We found that PPG fibers formed amide bonds with polyvinyl alcohol/collagen scaffolds. After chemical crosslinking, the number of amide bonds increased, leading to a significant improvement in their mechanical properties and thermal stability. The results showed that compared with pure PVA scaffolds, the maximum compressive stress of the scaffold doped with 0.9 g nanofibers increased by 500 %, and the stress loss rate decreased by 40.6 % after 10 cycles of compression. The presence of natural macromolecular gelatin and the changes in the pore structure caused by nanofibers provide cells with richer and more three-dimensional adsorption sites, allowing them to grow in three dimensions on the scaffold. So, the hydrogel scaffold by reinforcing polyvinyl alcohol hydrogel with PPG fibers is a promising breast reconstruction method.

3D/4D printed versatile fibre‐based wearables for embroidery, AIE‐chemosensing, and unidirectional draining

AbstractFibre‐based wearables for embroidery, chemosensing, and biofluid's unidirectional draining with good flexibility, tunability, and designability drive technological advance. However, synthetic polymer fibres are non‐degradable, threatening the environment and human health. Herein, we have developed versatile microfibre‐based wearables by combining many advantages in one platform of biodegradable polylactic acid (PLA) and melt electrowriting strategy. Diverse potential applications of PLA wearables are achieved by flexibly designing their printing files, components and structures. Three‐dimensional printing files are generated from two‐dimensional images to fabricate ‘embroidery‐like’ patterns. PLA/aggregation‐induced emission fluorogens (AIE) chemosensors exhibit colorimetric and fluorescent colour changes upon exposure to amine vapours. Janus PLA‐cotton textiles with a hydrophobic/hydrophilic structure could facilitate unidirectional draining of sweats which is favourable for the management of temperature and humidity on the surface of skin. The proposed platform can not only broaden the design possibilities in 3D/4D printing but also offer wide potential applications for functional wearables.

Long-term effect of microplastics on anammox systems: From macro efficiency to micro metabolic mechanisms and antibiotic resistance genes proliferation

Wastewater treatment plants (WWTPs) are sinks for various types of microplastics (MPs), which have an undeniable impact on anaerobic ammonia oxidation (anammox) systems, yet their differential effects remain elusive. In this study, the long-term effects of non-biodegradable polyvinyl chloride (PVC) MPs and biodegradable polylactic acid (PLA) MPs in anammox systems were investigated from macro efficiency, micro metabolic mechanism, and antibiotic resistance gene proliferation. Results showed that the introduced 0.5 mg L−1 PVC MPs caused a 20.64 % decrease in nitrogen removal efficiency (NRE) compared to the control one, while PLA MPs resulted in a 10.73 % increase in NRE. Accordingly, the relative abundance of Ca. Kuenenia with the introduced PLA MPs was 16.68 % higher than the control group, while it was 10.89 % lower with the introduced PVC MPs. Furthermore, MPs inhibit the reactor performance by inducing intracellular reactive oxygen species (ROS) production in anammox cells. However, PLA MPs, as a slow biodegradable organic, have a reversible negative effect on ROS induction, which further improves nitrogen removal performance and sludge proliferation through dissimilatory nitrate reduction to ammonium (DNRA) and microbial interactions. Nevertheless, this also poses an increased risk of antibiotic resistance genes (ARGs) spread and proliferation in anammox sludge. This study clarified the comprehensive effects of different MPs types in anammox processes, highlighting the feasibility and potential risks in the engineering applications of anammox processes for MPs-contained wastewater treatment.

Polylactic acid microplastics have stronger positive effects on the qualitative traits of rice (Oryza sativa L.) than polyethylene microplastics: Evidence from a simulated field experiment

Soil pollution by microplastics (MPs) from different types of agricultural films has received substantial attention due to its potential effects on crop quality. To date, the effects of different types of MPs on rice grain quality and their underlying molecular mechanisms have not been clarified. In this study, we examined the effects of polyethylene MPs (PE-MPs) and biodegradable polylactic acid MPs (PLA-MPs) on rice grain quality at the environmental level (0.5 %) and evaluated the molecular mechanism through transcriptome analysis. PE- and PLA-MPs increased the number of rice grains per plant by 19.83 % and 24.66 %, respectively, and decreased the rice empty-shell rate by 55.89 % and 26.53 %, respectively. However, PLA-MPs increased the 1000-seed weight by 11.37 %, whereas PE-MPs had no obvious impact in this respect. Furthermore, MP exposure, especially that of PE-MPs, affected the content of mineral elements, fatty acids, and amino acids of rice grains by disturbing the expression of genes related to these functions and metabolism. Our findings provide insights into the response of rice grains to the stress caused by different MPs.

Earthworm-inspired mechanical toughened biodegradable polylactic acid microfiber for sustainable air filtration

Fully renewable and biodegradable polylactic acid (PLA) microfiber filters are attractive candidates for traditional unsustainable filters due to their unique advantages of maintaining mechanical strength while in service and rapidly degrading after waste. However, the toughness of sustainable PLA melt-blown microfibers (PLAMFs) with high polymeric chain orientation is poor, which makes it difficult to meet the requirements of air filtration applications. Here, a facile but effective polymeric chain limited domain rearrangement (PLR) strategy inspired by earthworms is developed to toughen PLAMFs. In this process, the short-time and high-temperature heat treatment can quickly break the original hydrogen bonds between polymeric chains and form new ones, which stimulates the thermal movement of polymeric chains from the low entropy position to the high entropy position, resulting in the intrinsically toughening of PLAMFs while maintaining strength. The resulting PLR-PLAMFs and PLR PLA melt-blown nonwovens (PLR-PLAMNs) exhibit enhanced toughness of 146.32 MJ m−3 (an increase of 143.99 %) and 0.80 MJ m−3 (an increase of 66.67 %), respectively. Moreover, toughened PLA melt-blown nonwovens (PLAMNs) after corona electret (CE) treatment exhibit high filtration efficiency (>90.00 % PM0.3 removal) and extremely low pressure drop (<0.02 % atmospheric pressure), which is highly promising for application in sustainable air filtration.

A universal eco-friendly flame retardant strategy for polylactic acid fabrics and other polymer substrates

Various polymer substrates have their particular combustion features, therefore, developing an effective universal flame retardant strategy for various polymer substrates is of great practical importance. Meanwhile, as substitutes for petroleum-based products, bio-based flame retardants and biodegradable polylactic acid (PLA) meet the requirements of sustainable development. In this work, a fully bio-based flame retardant coating (PAGS) was prepared using phytic acid (PA) and guanosine (GS). PAGS was used as a universal flame retardant coatings for polylactic acid (PLA) fabrics and other substrates, including cotton fabrics, polyethylene terephthalate (PET) fabrics, polyamide (PA) fabrics, polyurethane (PU) foams, polyethylene terephthalate (PET) films, and woods. The PAGS-treated substrates were able to self-extinguish and eliminate molten droplets. Similarly, the PAGS coating significantly suppressed the heat release of each substrate. The P-containing free radicals in the gas phase were able to interact with highly reactive H, HO and alkyl radicals, blocking the chain reaction during combustion. The flammable gas density was also diluted by nonflammable gases. The formed continuous porous and dense intumescent char layer hindered heat and oxygen. It is suggested that this work provides a simple and efficient flame retardant strategy for improving the fire safety of various polymer substrates.

Atmospheric Pressure Plasma Jet Exposure of Polylactic Acid Surfaces for Better Adhesion: Plasma Parameters towards Polymer Properties.

Polymers play a crucial role in multiple industries; however, surface modification is necessary for certain applications. Exposure to non-thermal plasma provides a viable and environmentally beneficial option. Fused deposition molding utilizes biodegradable polylactic acid, although it encounters constraints in biomedical applications as a result of inadequate mechanical characteristics. This study investigates the effects of atmospheric pressure plasma generated by a dielectric barrier discharge system using helium and/or argon on the modification of polylactic acid surfaces, changes in their wettability properties, and alterations in their chemical composition. The plasma source was ignited in either He or Ar and was tailored to fit the best operational conditions for polymer exposure. The results demonstrated the enhanced wettability of the polymer surface following plasma treatment (up to 40% in He and 20% in Ar), with a marginal variation observed among treatments utilizing different gases. The plasma treatments also caused changes in the surface topography, morphology, roughness, and hydrophilicity. Plasma exposure also resulted in observable modifications in the dielectric characteristics, phase transition, and structure. The experimental findings endorse the utilization of plasma technologies at normal air pressure for environmentally friendly processing of polymer materials, specifically for applications that necessitate enhanced adhesion and have carefully selected prerequisites.

Effects of Microplastics on the Leaching of Nutrients and Cadmium from Soil

The environmental effects of microplastics, which are considered a type of emerging contaminants, have attracted increasing concern due to their small size, large specific surface area, strong adsorption capacity, and low degradability. Microplastics can change soil properties and affect the migration ability of nutrients and pollutants in soil, but their effects on the leaching of soil nutrients and heavy metals have not been sufficiently studied. A soil column leaching experiment was conducted to explore the effects of polystyrene (PS) and polylactic acid (PLA) microplastics at different mass fractions (0%, 0.2%, and 2%) on the leaching of nutrients and cadmium under simulated rainfall scenarios. The results showed that increasing rainfall intensity enhanced the leaching of nutrients and cadmium from soil. During downpour conditions, 2% PS significantly increased the leaching of total nitrogen and the content of available phosphorus in soil and reduced the leaching of inorganic phosphorus and the content of ammonium nitrogen in the soil, whereas it increased the content of available potassium during heavy rain. By comparison, 2% PLA reduced the leaching of nitrate nitrogen during heavy rain and intense rainfall and decreased the content of ammonium nitrogen in soil during intense rainfall and downpour conditions and the content of total nitrogen in soil during downpours. In addition, 0.2% PLA significantly increased cadmium leaching during downpours. To conclude, the effects of microplastics on the leaching of nutrients and cadmium were dependent on the type and concentration of microplastics, as well as the rainfall level. Our findings showed that the microplastics derived from both nondegradable PS and biodegradable PLA could affect the leaching of nutrients and heavy metals from soil.

Environmental and economic assessment of biodegradable and compostable alternatives for plastic materials in greenhouses

Plastics and other materials commonly used in horticulture for plant support (e.g. raffia) and soil protection (e.g. mulching film) pose a challenge to achieving a circular economy. These materials contaminate plant residues, hampering their direct reuse due to the need for separation and cleaning. As a result, contaminated plant residues is often landfilled or incinerated. This study investigates the replacement of conventional plastic raffia and mulching film with biodegradable and compostable alternatives. Polypropylene raffia is compared with a biodegradable viscose polymer and compostable jute fibre, while polyethylene mulching film is compared with a biodegradable polylactic acid film. Conventional and novel alternatives are compared economically using Life-Cycle Costing and environmentally using Life-Cycle Assessment. The economic assessment is based on case studies with two horticultural companies in Almeria (south-eastern Spain), while the environmental analysis uses data from the Ecoinvent database. The use of biodegradable and compostable alternatives for raffia and mulching film proved to be 49% more expensive than conventional options. However, when conventional plastic waste is incinerated rather than landfilled, biodegradable and compostable alternatives have a lower carbon footprint. Although biodegradable and compostable options can be more expensive and have higher impacts in certain situations, proper waste management can lead to environmental benefits. With optimisation and incentives, these alternative options support the transition of horticulture to a sustainable circular economy.

Maximizing performance and efficiency in 3D printing of polylactic acid biomaterials: Unveiling of microstructural morphology, and implications of process parameters and modeling of the mechanical strength, surface roughness, print time, and print energy for fused filament fabricated (FFF) bioparts

Medical stents, artificial teeth, and grafts are just some of the many applications for additive manufacturing techniques like bio-degradable polylactic acid 3D printing. However, there are drawbacks associated with fused filament fabrication-fabricated objects, including poor surface quality, insufficient mechanical strength, and a lengthy construction time for even a relatively small object. Thus, this study aims to identify the finest polylactic acid 3D printing parameters to maximize print quality while minimizing energy use, print time, flexural and tensile strengths, average surface roughness, and print time, respectively. Specifically, the infill density, printing speed, and layer thickness are all variables that were selected. A full-central-composite design generated 20 samples to test the prediction models' experimental procedures. Validation trial tests were used to show that the experimental findings agreed with the predictions, and analysis of variance was used to verify the importance of the performance characteristics (ANOVA). At layer thickness = 0.26 mm, infill density = 84 %, and print speed = 68.87 mm/s, the following optimized values were measured for PLA: flexural strength = 70.1 MPa, tensile strength = 39.2 MPa, minimum surface roughness = 7.8 μm, print time = 47 min, and print energy = 0.18 kwh. Firms and clinicians may benefit from utilizing the developed, model to better predict the required surface characteristic for various aspects afore trials.

PLA/PVP/bio-synthesized hydrozincite nanocomposite films – photocatalytic and antibacterial activity

Nanocomposite films based on biodegradable polylactic acid (PLA) and PLA/polyvinylpyrrolidone (PVP) with embedded stabilized Hydrozincite powder were synthesized by solution casting method. The Hydrozincite was prepared by plant extract-mediated hydrothermal synthesis. Powder X-ray diffraction analysis and Fourier-transform infrared spectroscopy were used to establish the phase composition and structure of the films. The photocatalytic activity of the obtained nanocomposite films was tested and compared in the reaction of degradation of Malachite Green dye under UV illumination. The photocatalytic results revealed that the PLA/PVP-containing Hydrozincite nanocomposite film leads to a higher degree of degradation of the Malachite Green dye (87 %) after 150 minutes in comparison to that of PLA/Hydrozincite (31%). The antibacterial activity of the prepared nanocomposite films against an Escherichia coli control strain was also discussed. The investigated biocomposite films demonstrated high antibacterial efficiency. It was found that the concentration of viable bacterial cells decreases by about 99% after 1 hour of contact time for both investigated composites.