Low-density Polyethylene Films Research Articles

Evaluation of Biodegradation Efficiency of Xylene Pretreated Polyethylene Wastes by Isolated Lysinibacillus fusiformis

The ability of the bacterial degradation of low-density polyethylene (LDPE) waste by Lysinibacillus fusiformis isolated from hydrocarbon-contaminated soil was investigated in the present study. The potential of the bacterial isolate to utilize LDPE waste bags of two different thicknesses in a month as a sole carbon source in mineral salt media was assessed. Further, the effect of pretreatment by xylene on the bacterial degradation of LDPE waste bags (0.5 percent w/v) in 30 days was investigated. The isolated Lysinibacillus fusiformis was able to degrade 9.51 percent of LDPE with 30 μm thickness but able to degrade only 1.45 percent of LDPE having 50 μm thickness. The bacterial biomass was 1.77 times higher on LDPE- 30 μm containing media in comparison to LDPE- 50 μm. The xylene pretreatment of LDPE wastes enhanced the biodegradation efficiency of isolated Lysinibacillus fusiformis to 12.09 and 1.97 percent respectively in 30 μm and 50 μm thick LDPE bags. The xylene pre-treatment improved the bacterial growth on media with LDPE of both thicknesses. The adherence of bacterium on the surface of LDPE was found more on 50 μm thick xylene treated LDPE compared to its untreated LDPE than 30 μm thick LDPE films. The xylene pre-treatment of polyethylene waste had an additive effect on the biodegradation of waste LDPE films with a significant effect on thickness.

Effect of Packaging Materials on Antifogging Film Properties and Quality of Oyster Mushrooms at Different Storage Temperatures

Mushroom is highly perishable and easily damaged within a day after harvesting due to their high respiration rate which leads to the release of water vapour. The most effective way to preserve fresh mushrooms is by packaging. However, excessive water vapour inside the packaging can cause condensation or fog and subsequently, lead to product damage. Hence, appropriate material for packaging mushrooms is important to maintain the quality and prolong the shelf-life. The main objective of this study is to compare the effect of different packaging material types on the fogging effect. The studied materials are low-density polyethylene (LDPE), polypropylene (PP), nylon, and gelatin-based film. Based on the market survey prior to the study, it showed that the most plastic material used in the market is polypropylene (PP) compared to other materials. The experimental study then proceeded by comparing the different types of materials used for the packaging of mushrooms. Samples of 20 g mushrooms were filled in a cup covered with four different types of films and stored at three different storage temperatures (5 °C, 10 °C, 30 °C) for 7 days. It was observed that the gelatin-based film showed good antifogging behaviour when compared to other films. Additionally, the mushrooms showed high weight loss and severe browning for all types of packaging materials after 7 days of storage at high temperatures (30 °C). In conclusion, the gelatin-based film has revealed excellent water-adsorbing with antifogging behaviour to maintain the quality and shelf life of mushrooms at low temperatures for storage and distribution.

Microbial degradation of low density polyethylene by Exiguobacterium sp. strain LM-IK2 isolated from plastic dumped soil.

Low-Density Polyethylene (LDPE) is one of the significant environmental pollutants as it is resistant to natural degradation. In this study, we reported the LDPE-degrading bacterial straini.e., Exiguobacterium sp. strain LM-IK2 isolated from plastic dumped soil which shows potential degradation capability. The percent weight loss of LDPE was calculated as -5.70 ± 0.7 after 90days of incubation in a carbon-free MSM medium. The Field Emission Scanning Electron Microscopy (FE-SEM) analysis shows that LDPE films show slight surface disruption after treatment with bacteria. The Fourier Transform Infrared Spectroscopy (FTIR) revealed the chemical changes in LDPE films e.g., formation and reduction of typical carbonyl peaks after incubation with bacteria. The X-Ray Diffraction (XRD) analysis displayed an increase in percent crystallinity, with a slight change in total carbon content. Genetic analysis showed the presence of Laccase (167bp) and Alkane Hydroxylase (330bp) genes that are responsible for LDPE degradation.Thus, Exiguobacterium sp. strain LM-IK2 has the potential to degrade LDPE and could be further explored to improve its efficiency in the bioremediation of LDPE.

Mono and multilayer active films containing green tea to extend food shelf life

An active packaging film made of one and two-layers structure based on low-density polyethylene (LDPE) was produced with the incorporation of green tea extract (GTE) at different amounts by blown film extrusion. Film structure, optical, mechanical, antioxidant and barrier properties were characterized. The films revealed homogeneous film surface, the presence of GTE increases the tensile properties, improves friction coefficient and reduces LDPE films transparency. Moreover, the antioxidant capacity and barrier properties (water and oxygen) were enhanced, even at low concentrations. This study demonstrates the benefits of GTE incorporation into LDPE matrix, mainly in coextruded films, and its potential to develop an active and sustainable food packaging film at industrial scale.

Development and characterization of nitrocellulose/acrylic-based coatings with precipitated silica and kaolin for packaging applications

PurposeThe purpose of this study is to develop a multifunctional coating layer based on nitrocellulose (NC)/acrylic resins containing precipitated silica and kaolin and investigate its suitability for use in packaging applications.Design/methodology/approachDifferent loading levels (1 and 5 Wt.%) of precipitated silica or kaolin particles were incorporated into NC/acrylic-based coating formulations and applied on low-density polyethylene (LDPE) films. The coatings and coated LDPE films were characterized in terms of structural, physical, mechanical, thermal, optical, surface, morphological and water vapor barrier properties.FindingsThe glossiness of the coating formulations decreased by increasing the precipitated silica and kaolin content. The incorporation of kaolin (1 and 5 Wt.%) and precipitated silica (1 Wt.%) had no significant effect on the melting temperature of LDPE film; however, with the addition of 5 Wt.% precipitated silica, the melting and crystallization temperatures were significantly changed. The incorporation of 5 Wt.% precipitated silica and kaolin also enhanced the water vapor barrier properties of LDPE films. The light transmittance declined with the precipitated silica and kaolin addition, especially in the ultraviolet (UV)-A/UV-B spectrum regions indicating an excellent UV light protection.Originality/valueIt was concluded that NC/acrylic resins coatings containing precipitated silica and kaolin exhibit improved thermal stability, UV and water vapor barrier properties and have the potential for use in packaging applications.

Influence of nitric acid on biodegradation of polystyrene and low-density polyethylene by Cephalosporium species.

Petroleum-based polymers are not susceptible to microorganisms because of its high molecular weight. Acid treatments convert the polymers into a more oxidized form having low molecular weight. The present in-vitro degradation study focuses on the potential of Cephalosporium species to degrade acid-treated polystyrene (PS) and low-density polyethylene (LDPE) films. A weight loss of around 12% and 13% was achieved for PS and LDPE films respectively in eight weeks of treatment with Cephalosporium species. Fourier transform infrared spectroscopy analysis showed the formation of hydroxyl and carbonyl groups in nitric acid treated PS and LDPE films, respectively. Scanning electron microscopy indicated modifications in the surface morphology of PS and LDPE films after chemical and microbial treatment. An increase in crystallinity of pre-treated polymer samples was observed after fungal treatment. The observations of present study confirmed the enzymatic deterioration and assimilation of pre-treated PS and LDPE samples by the microbial species.

Guided-mode resonance pressure sensor based on a stretchable low-density polyethylene film

In this study, we demonstrate a method to fabricate a guided-mode resonance (GMR) device on a flexible and transparent low-density polyethylene (LDPE) film and present the measurement results of this device as a pressure sensor. A simple thermal-nanoimprinting process was used to fabricate a grating structure on the LDPE film substrate. This very flexible film was attached to a glass plate using an adhesive and sacrificial layer for coating high-refractive-index titanic oxide on the grating surface to form the GMR device. The LDPE-GMR device was equipped with a gas chamber to act as a pressure sensor. When the pressure inside the chamber was increased, the grating period of the GMR sensor also increased, resulting in a shift in the resonance angle of the GMR device. Owing to the higher flexibility of the LDPE film, a better pressure detection sensitivity and resolution can be obtained. Using the transmitted-intensity detection approach, we show that the transmitted laser power changes proportionally with the pressure increase. The experimental results showed that the LDPE-GMR pressure sensor could achieve a sensitivity of 8.27 µW/mbar and a limit of detection of 0.012 mbar at a power meter noise of 0.1 µW.

A Comparative Study of Several Properties of Plywood Bonded with Virgin and Recycled LDPE Films

In this work, to better understand the bonding process of plastic plywood panels, the effects of recycled low-density polyethylene (rLDPE) film of three thicknesses (50, 100, and 150 µm) and veneers of four various wood species (beech, birch, hornbeam, and poplar) on the properties of panels were studied. The obtained properties were also compared with the properties of plywood panels bonded by virgin low-density polyethylene (LDPE) film. The results showed that properties of plywood samples bonded with rLDPE and virgin LDPE films differ insignificantly. Samples bonded with rLDPE film demonstrated satisfactory physical and mechanical properties. It was also established that the best mechanical properties of plywood are provided by beech veneer and the lowest by poplar veneer. However, poplar plywood had the best water absorption and swelling thickness, and the bonding strength at the level of birch and hornbeam plywood. The properties of rLDPE-bonded plywood improved with increasing the thickness of the film. The panels bonded with rLDPE film had a close-to-zero formaldehyde content (0.01–0.10 mg/m2·h) and reached the super E0 emission class that allows for defining the laboratory-manufactured plastic-bonded plywood as an eco-friendly composite.

Enhancing the durability and performance of radiation-induced grafted low-density polyethylene-based anion-exchange membranes by controlling irradiation conditions

This study presents a systematic analysis of the influence of irradiation conditions (absorbed dose, temperature, and atmosphere) on the physicochemical properties of radiation-induced grafted anion-exchange membranes (AEMs) based on low-density polyethylene (LDPE). Detailed characterization of the polymeric electrolytes shows striking effects of the irradiation conditions on the AEM properties. The LDPE films are irradiated both at room temperature (RT) and low temperature (LT, ∼ −10 °C). At each temperature, samples are irradiated in air as well as nitrogen. By lowering the sample temperature from RT to LT during irradiation in air it is possible to obtain a threefold increase in the degree of grafting (DoG). The higher DoG reflects in the OH− conductivity (σ) of the AEM irradiated at LT, which exhibits σ (T = 80 °C) = 215 mS cm−1, while the sample prepared at RT and air has σ (T = 80 °C) = 127 mS cm−1. Such high conductivity of the LT irradiated LDPE-AEM results in high-performance anion-exchange membrane fuel cell (AEMFC) with enhanced stability, as inferred from the time dependence of σ (T = 60 °C) measurements. The experimental results evidence that the control of both the irradiation temperature and the atmosphere diminishes the degradation effects caused by the radiation. Therefore, the present study advances the understanding of the role played by the irradiation process on the final properties of radiation-induced grafted LDPE-based AEMs and offers new possibilities to guide future developments for anion-exchange membranes.

Biodegradable Films Prepared from Pulp Lignocellulose Adhesives of Urea Formaldehyde Resin Modified by Biosulfonate.

Traditional low-density polyethylene (LDPE) film causes environmental pollution; there is a pressing need to make new bio-based polymers for alternative products, to meet agricultural production needs and for sustainable ecological development. In this study, urea-formaldehyde resin (UF) was modified with polyvinyl alcohol (PVA) and 1–2.5% bio-based sulfonate (BBS). The influence of BBS inducing on the functional groups, microstructure, and thermal behavior was evaluated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). A biodegradable film was prepared with modified UF resin as adhesive and pulp lignocellulose as raw material. The biodegradable mulch film samples were tested for biodegradability, water retention, and cooling soil temperature characters using LDPE and no mulching (NM) as a control. The results showed that with the increase of BBS content, the viscosity and reactivity of modified PUF resin increased, and the free formaldehyde content decreased. A 2%BBS modified PUF resin (2.0BBS/PUF) accelerated the curing process of the PUF resin, formed a flexible macromolecular network structure, and enhanced the toughness of the resin. The biodegradable mulch prepared with PUF, BBS, and 2.0BBS/PUF as adhesives had good water retention. BBS modification increased the degradation rate of mulch by 17.53% compared to the PUF. Three biodegradable films compared with LDPE and NM significantly reduced the soil temperature under summer cucumber cultivation, and the 2.0BBS/PUF coating had the lowest diurnal temperature difference, which provided a suitable soil environment for crop growth.

Bactericidal Properties of Low-Density Polyethylene (LDPE) Modified with Commercial Additives Used for Food Protection in the Food Industry

This study investigated the influence of commercially available food preservatives: Natamax® (containing natamycin) and Nisaplin® (containing nisin) on the antimicrobial properties of LDPE film, commonly used for food packaging. Studies have shown that the addition of 3% Natamax® or, alternatively, the addition of 5% Nisaplin® provides an LDPE film with effective antimicrobial protection. The applied biocides did not significantly affect the strength and rheological properties of LDPE. However, differences in optical properties were observed. The transparency of the samples decreased slightly with the addition of 3% or 5% Natamax® (by approx. 1% and 3%, respectively). A significant change was observed in the film haze, the addition of 5% Natamax® increased this parameter by approx. 80%, while 5% Nisaplin® increased it by approx. 19%. Both Natamax® and Nisaplin® agents can be successfully used to manufacture food packaging materials with antimicrobial protection. Natamax® showed a stronger bactericidal effect, while Nisaplin® changed other properties less significantly.

A waterproof cellulose nanofibril sheet prepared by the deposition of an alkyl ketene dimer on a controlled porous structure.

This study prepared a waterproof cellulose nanofibril (CNF) sheet via the deposition of an alkyl ketene dimer (AKD) on the sheet’s controlled porous structure. The porosity of the CNF sheet was controlled by drying under different conditions, which included hot-press drying (HD) and solvent-exchange drying (SD), and the effect on the hydrophobization and water-related barrier performance of the sheet were investigated. When the SD sheet was immersed in an AKD wax solution, the sheet exhibited super-hydrophobicity and a lower water vapor transmission rate, compared with the HD sheet. This indicated that the porous structure of the SD sheet enabled AKD to be adsorbed on both the surface and the inner surface and it filled in the pores of the sheet, thereby giving rise to excellent waterproofing properties. The performance of a hydrophobized SD sheet as a water barrier material was comparable to a linear low-density polyethylene film. This study confirms the possibility for AKD wax to be immersed in a porous CNF sheet and used as a potential barrier material in hydrogel packaging.Graphical abstract

UV-assisted TiO2 photocatalytic degradation of virgin LDPE films: Effect of UV-A, UV-C, and TiO2

The effects of phases of TiO2, and UV-A and UV-C light on photodegradation of low-density polyethylene films (LDPE films) were investigated. TiO2 photocatalyst was synthesized via sol-gel method and followed by firing at two different temperatures (450 and 900 °C). Various reaction times used for studying the degradation of LDPE films were 0, 3, 5, 7 and 9 days. X-ray Diffraction (XRD), Tauc plot, Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS), Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR), and weight loss (WL) and Carbonyl Index (CI) were used to analyze crystal structure of catalyst, band gap energy of catalyst, catalyst morphology, elemental composition of catalyst, change in chemical structure of LDPE film, and LDPE degradation performance, respectively. The results showed that degradation of LDPE films with the use of TiO2-900 °C along with UV-C light demonstrated the highest degradation efficiency (WL = 17.30% and CI = 4.0754). The results of crystal structure of TiO2-450 °C and TiO2-900 °C, the occurrence of intermediates, and degradation mechanism of LDPE film were used together to contemplate and explain degradation process of LDPE film.

Biodegradation of polyethylene based films used in water packaging by dumpsite bacteria

Water sachet bags are Low-density polyethylene (LDPE) based polymers that are of widespread use in Nigeria. The accumulation of these sachet bags has resulted to severe environmental pollution. Microorganisms have been found to provide an eco-friendly and practical alternative to conventional methods in the clean-up of LDPE wastes in the environment. This study investigated the potentials of six bacteria strains Lysinibacillus xylanilyticus PE4, Pseudomonas aeruginosa PE2, Pseudomonas aeruginosa S1, Stenotrophomonas maltophilia S6, Pseudomonas aeruginosa W5 and Achromobacter xylosoxidans strain to degrade water sachet films. The degradation was monitored for a period of 56 days in vitro and the extent of degradation was measured using Fourier transform infrared spectroscopy and scanning electron microscopy coupled with EDX. FTIR spectroscopy analysis of the bacteria treated LDPE samples revealed changes in functional groups of LDPE samples as a result of hydrolysis and oxidation of bonds in the LDPE polymer. Also, the EDX elemental analysis of the treated LDPE and the untreated control showed a reduction in percentage elemental carbon and increase in the elemental oxygen of the treated LDPE films which is evident of degradation. The findings indicate strongly the degradation potentials of these bacteria strains on LDPE polymer, they therefore show significant promise for bioremediation of plastic wastes.

TiO2 nanorods doped with g-C3N4 – Polyethylene composite coating for self-cleaning applications

Visible-light-absorbing graphitic carbon nitride–TiO2 nanorod nanomaterials (g-C3N4@TiO2NR) were successfully immobilized using a one-step UVA-induced photocatalytic procedure on commercially obtained flexible low-density polyethylene (LDPE) films. Self-cleaning properties were evaluated in solid–liquid and solid–gas phases using malachite green as a model molecule under UV-A and visible light irradiation. For comparison purpose, LDPE films containing P25 TiO2 nanoparticles was prepared using the same synthetic strategy (P25/LDPE). Among the fabricated films, the g-C3N4@TiO2NR/LDPE films exhibited the highest photocatalytic activity both in solid–liquid and solid–gas phases after 120 min of visible light irradiation (λ > 455 nm) removing efficiently malachite green stains probably due to the attack of photoinduced reactive oxygen species (ROS) such as singlet oxygen (1O2), hydroxyl radical (•OH) and superoxide anion radical (O2−•). Furthermore, the g-C3N4@TiO2NR/LDPE films retained their visible-light-photoinduced photocatalytic properties after four reuse cycles. The g-C3N4@TiO2NR/LDPE films also exhibited significant visible-light-photoinduced hydrophilicity. The high visible-light-photoinduced photocatalytic capacity of g-C3N4@TiO2NR/LDPE films was found to be related to the textural and electronic properties, superior visible-light absorption, and surface roughness of the films.

A mechanistic understanding of polyethylene biodegradation by the marine bacterium Alcanivorax

Polyethylene (PE) is one of the most recalcitrant carbon-based synthetic materials produced and, currently, the most ubiquitous plastic pollutant found in nature. Over time, combined abiotic and biotic processes are thought to eventually breakdown PE. Despite limited evidence of biological PE degradation and speculation that hydrocarbon-degrading bacteria found within the plastisphere is an indication of biodegradation, there is no clear mechanistic understanding of the process. Here, using high-throughput proteomics, we investigated the molecular processes that take place in the hydrocarbon-degrading marine bacterium Alcanivorax sp. 24 when grown in the presence of low density PE (LDPE). As well as efficiently utilising and assimilating the leachate of weathered LDPE, the bacterium was able to reduce the molecular weight distribution (Mw from 122 to 83 kg/mol) and overall mass of pristine LDPE films (0.9 % after 34 days of incubation). Most interestingly, Alcanivorax acquired the isotopic signature of the pristine plastic and induced an extensive array of metabolic pathways for aliphatic compound degradation. Presumably, the primary biodegradation of LDPE by Alcanivorax sp. 24 is possible via the production of extracellular reactive oxygen species as observed both by the material’s surface oxidation and the measurement of superoxide in the culture with LDPE. Our findings confirm that hydrocarbon-biodegrading bacteria within the plastisphere may in fact have a role in degrading PE.

Effect of Used Engine Oil and UV-Thermal Pretreatments on Biodegradation of Low-Density Polyethylene by <em>Lysinibacillus fusiformis

The present study focused on the impact of Used Engine Oil (UEO) and abiotic pretreatments by ultraviolet (UV) radiation and thermal treatment at 70°C for 144 h on the potential of Lysinibacillus fusiformis TPB isolated from hydrocarbon contaminated soil for the biodegradation of low-density polyethylene (LDPE) in mineral salt medium at 30°C and 150 rpm for 30 days. The isolated L. fusiformis TPB degraded 9.51% of LPDE films without any treatment and used as the sole carbon source for biomass production. The supplementation of used engine oil (0.5% v/v) enhanced biodegradation of untreated LDPE films to 11.96% comparable to a non-ionic surfactant Tween 80. The abiotic pretreatments had also facilitated metabolism of LDPE by L. fusiformis TPB. The biodegradation of UV treated LDPE by L. fusiformis TPB was 13.78% and was significantly higher than thermally treated LDPE with 12.89% biodegradation. The Fourier Transform Infrared spectrum revealed structural and morphological changes in the LDPE films by abiotic pretreatments and were associated with addition of carbonyl groups and change in double bond index. The Scanning Electron Microscopy analysis of LDPE films from UEO and UV-thermal pretreated LDPE supplemented mineral salt media confirmed the improved bacterial colonization and biofilm formation. The isolated L. fusiformis TPB had LDPE degradation potential and biodegradation had improved by UEO supplementation and UV-thermal pretreatments.

Simulation of Space Charge Dynamics in Low-Density Polyethylene Using the Gaussian Disorder Model

Space charge dynamics in a low-density polyethylene (LDPE) film is calculated using mobility based on the Gaussian disorder model (GDM), which is commonly used to describe hopping conduction in disordered materials. The GDM exhibits a negative differential mobility under a strong positional disorder. In simulations, injected charges do not form packet-like space charges when using a constant mobility model, whereas packet-like space charges appear when using the mobility based on the GDM. The simulation using the GDM mobility can reproduce the time and voltage dependences of space charge behavior in LDPE. The calculated space charge, electric field, and current density profiles show good agreement with experimental results.

Biodegradation of cassava starch modified low density polyethylene by Bacillus cereus and Pseudomonas aeruginosa isolated from waste dumpsite

Low density polyethylene (LDPE) is used for packaging and other industrial application is a significant source of environmental pollution. The present study was aimed at testing the ability of bacterial strains identified as Bacillus cereus and Pseudomonas aeruginosa to degrade LDPE. These strains were isolated from soil samples collected from dump site. All bacterial isolates were screened for their ability to degrade synthetic LDPE. Bacillus cereus and Pseudomonas aeruginosa produced weight loss percentages of 0.18% and 0.17% respectively and were used for further studies. The biodegradation was further enhanced by blending pellets of the LDPE (90, 80 and 70 %) with cassava starch (10, 20 and 30%). The screened bacteria isolates were incubated along with the cassava starch modified LDPE for a period of 60 days. Degradation was observed in terms of weight loss and tensile strength of the modified LDPE. Bacillus cereus and Pseudomonas aeruginosa achieved a maximum weight loss reduction of 42.01 % and 51.03 % respectively in LDPE modified with 30 % cassava starch. However, the highest weight loss reduction of 54.03 % in 30 % Cassava starch modified LDPE by the bacterial consortium. Tensile strength of 42.01% was achieved in LDPE containing 30% starch. Therefore these results show that the bacteria used in this study can colonize, utilize and modify LDPE as a sole carbon source, signifying the potential of Bacillus and Pseudomonas spp. to degrade LDPE film. This work would also pave way for future studies on biodegradation to resolve the universal pollution issues.

Study of physical and mechanical properties of partially biodegradable LDPE polymeric films and their application for printing and packaging

Potato starch, glycerine, itaconic acid and molasses of different physical state (dry and liquid) were used for manufacturing partially biodegradable low density polyethylene (LDPE) films. The mechanical, physical properties of new polymeric films with different physical state were investigated using these test methods: scanning electron microscopy, FTIR spectroscopy, thermogravimetric analysis, tensile testing, heat seal testing and printability testing. Investigated film properties were determined and compared with the properties of the pure LDPE film. It was determined that thermal stability did not changed significantly with the addition of biodegradable additives. The tensile strength and elongation of LDPE films containing potato starch, glycerine and itaconic acid were about 50% lower than pure LDPE film but of the film containing dry molasses and glycerine - was only 25% lower. The heat seal strength of film containing dry molasses was the closest to pure LDPE film at 115 °C. The other tested films required a higher temperature range to form a seal of sufficient strength. The SEM microphotographs have shown the particles of biodegradable additives randomly oriented on the surfaces of some LDPE films, thus, the values of optical density of only one LDPE film containing potato starch and glycerine were the closest to pure LDPE film. LDPE with molasses has been found to be the most suitable film for printing and packaging processes.