The purpose of this study was to investigate antibacterial potential of low-density polyethylene (LDPE) packaging films incorporating silver (Ag), copper oxide (CuO) and zinc oxide (ZnO) ...nanoparticles in measuring of coliform amounts of ultra-filtrated (UF) cheese. The initial LDPE/nanoparticle composites were produced by melting extrusion followed by extruding the obtained composites through a die to achieve a film thickness of 45 ± 5 μm. The number of surviving coliform bacteria was decreased by 4.21 log cfu/g after 4 weeks of storage at 4 ± 0.5 °C, whilst pure LDPE films showed a reduction of only 1.04 log cfu/g. A composition of 0% Ag, 1% CuO, 0% ZnO gave an optimum point in combined design using Design Expert analysis. A suitable microbial model was suggested for retarding coliform bacteria growth in UF cheese. The difference between the optimum point of nanocomposite film and its repeat was not significant (p < 0.05) by one-way ANOVA analysis using SPSS software, while the difference was significant for pure film. Migration of metallic nanoparticles into a food stimulant was within the accepted safe level.
•A microbial model was suggested for antibactierial effect of active LDPE films in UF cheese.•All films had antibacterial effects on colimforms after 4 weeks.•LDPE film with Cu-Zno and with no Ag nanoparticles provided optimum antibacterial effect.•Suggested statistical model verified optimum points obtained in microbial tests.
Polyethylene has become an essential part of the day-to-day activities of human life. However, its excess use led to accumulation in the environment-causing marine pollution without having any safe ...and proper disposable methods. Biodegradation is the most efficient method to control synthetic plastic waste pollution sustainably. In the present study, we used three identified marine bacterial isolates (two Marinobacter sp. (H-244 and H-246) and one Bacillus subtilis (H-248)) to degrade unplasticized low-density polyethylene film after screening and showed maximum weight loss up to 1.68% by H-246 bacterial isolate within 90 days. The degradation of LDPE film by bacteria was characterized by field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) analysis for topographical changes such as crack, pits, cavity and roughness. The attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis of degraded film showed the addition of extra-functional group at the range of 1025–1275 cm−1 with an increase in C-O stretching that is due to the addition of alcohol (–OH) group, which was further confirmed by the gas chromatography-mass spectrometry (GC-MS) analysis of degraded by-products release of fatty acids due to esterase activity. A decrease in tensile strength (0.43 MPa) and thermal weight loss (99.63%) in LDPE degraded by bacterial isolate H-246. Carbon content was also reduced in the bacterial degraded LDPE film from 86.10% to 80.45% for bacterial isolate H-244. All these characteristic changes in polyethylene were occurred due to esterase enzyme production by the bacteria and confirmed by isolation and purification, which showed 32, 32 and 43 KD of molecular weight for bacterial isolate H-244, H-246 and H-248, respectively. The present study of LDPE biodegradation by three marine bacteria has acted as a suitable candidate and will help in decreasing plastic waste.
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•Biodegradation of unplasticized LDPE by marine bacteria.•Marinobacter sp. and Bacillus sp. were used for LDPE degradation.•Thermogravimetric weight loss recorded was 99.63% by isolate Marinobacter sp.•Released LDPE degraded by-products confirmed by GC-MS analysis.•Purification of esterase enzyme from LDPE degrading marine bacteria.
Thickness of low-density polyethylene (LDPE) film might determine its mechanical strength, clean production and soil health. Yet, this issue is little understood. In situ aging effects were evaluated ...in LDPE films with the thickness of 0.006 mm, 0.008 mm, 0.010 mm and 0.015 mm in maize field. The data showed that maximum tensile force (TFmax), maximum tensile strength (TSmax) and elongation at break (EAB) were massively lowered with increasing thickness after aging. The greatest and lowest reduction magnitude of EAB was 27.6 % and 11.2 % in 0.006 mm and 0.015 mm films respectively. Also, the melting point (Tm) and crystallinity (Xc) under Differential Scanning Calorimeter (DSC) tended to decline with the increasing thickness. Moreover, the peak intensity of crystalline regions tended to transfer and concentrate on the amorphous regions, and such tendency became more pronounced in the thin films. Interestingly, there existed a pronounced distinct thickness-dependent effects on soil bulk density (SBD) and soil water-stable aggregate proportion. Thick plastic film mulching increased SBD but reduced the proportion of macroaggregates (mainly referred to 0.015 mm and 0.010 mm). In addition, thick film mulching slightly reduced the levels of soil organic carbon (SOC) and total nitrogen (TN), but significantly promoted the contents of soil labile C and N. Particularly, it significantly promoted above- & under-ground biomass of maize across two growing seasons (p < 0.05). To sum up, thickening LDPE film may act as a promising solution to improve LDPE film residue recycling, while benefiting for higher productivity. However, thick film mulching may cause a certain adverse impact on soil structure, and further investigations would be needed in the future.
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•Mechanical strength lowered with time but increased with thickness in LDPE films.•Melting point was significantly positively correlated with crystallinity in aging.•Higher surface energy was negatively associated with lower melting point in field.•Thicker films led to higher SBD and lowered macroaggregate proportion in soils.•Thicker films significantly increased soil labile C & N content and maize biomass.
It is established that when physical modifications to the blown film of LDPE in extrusion installation for large values of the ratio of the longitudinal drawing of the melt, Km from 7.2 to 12.4, ...there is the technological anisotropy Kat in the range of 2.8 to 3.7. It is 1.8 times higher than the anisotropy of strength of Kaσ films. At uniaxial tension of such films in polarized light, the appearance of isochromes associated with the value of Kat is observed.
Physical thickness of low-density polyethylene (LDPE) films might determine the release rate of phthalic acid esters (PAEs) & structural integrity and affect production efficiency. However, this ...critical issue is still unclear and little reported. Aging effects were evaluated in LDPE films with the thickness of 0.006, 0.008, 0.010 and 0.015 mm in a maize field of irrigation region. The Scanning electron microscope (SEM) results showed that the proportion of damaged area (Dam) to total area of LDPE films was massively lowered with increasing thickness after aging. The highest and lowest Dam was 32.2% and 3.5% in 0.006 and 0.015 mm films respectively. Also, the variations in peak intensity of asymmetric & symmetrical stretching vibrations (ASVI & SSVI) were detected using Fourier transform infrared spectrum (FTIR), indicating that the declines in peak intensity tended to be slower with thickness. Interestingly, the declines in physical integrity were tightly associated with increasing exhalation rate of PAEs. Average releasing rate of PAEs was 38.2%, 31.4%, 31.5% and 19.7% in LDPE films from 0.006 to 0.015 mm respectively. Critically, thicker film mulching can lead to greater soil water storage at plough layer (SWS-PL) and better thermal status, accordingly harvesting higher economic benefit. Therefore, LDPE film thickening may be a solution to reduce environmental risk but improve production efficiency in arid region.
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•Structural damage of LDPE films increased with time but lowered with thickness.•The physical integrity was negatively associated with its releasing PAEs amount.•Aging characterization under SEM & FTIR showed the thickness-dependent degradation.•Thicker film mulching had better soil hydrothermal status for higher yield and WUE.•Film thickening was a critical solution to reduce pollution but improve productivity.
Microplastics are persistent anthropogenic pollutants which have become a global concern owing to their widespread existence and unfamiliar threats to the environment and living organisms. This study ...demonstrates the degradation of fragmented microplastics particularly low-density polyethylene (LDPE) film in water, through visible light-induced plasmonic photocatalysts comprising of platinum nanoparticles deposited on zinc oxide (ZnO) nanorods (ZnO-Pt). The ZnO-Pt nanocomposite photocatalysts were observed to have better degradation kinetics for a model organic dye (methylene blue) compared to bare ZnO nanorods, attributed to the plasmonic effects leading to better interfacial exciton separation and improved hydroxyl radical activity along with a 78% increase in visible light absorption. These demonstrations of the plasmonically enhanced photocatalyst enabled it to effectively degrade microplastic fragments as confirmed following the changes in carbonyl and vinyl indices in infrared absorption. In addition, visual proof of physical surface damage of the LDPE film establishes the efficacy of using plasmonically enhanced nanocomposite photocatalytic materials to tackle the microplastic menace using just sunlight for a clean and green approach towards mitigation of microplastics in the ecosystem.
In this research, we synthesized a novel nanocomposite using reduced porous graphene/silica aerogel-graft-polystyrene coated by Polyvinylidene difluoride (PVDF/rPG/Silica-g-PS). FT-IR, XRD, FE-SEM, ...and EDX analyzes were utilized to dissect the structure of PVDF/rPG/Silica-g-PS nanocomposite. Then, the low weight ratios including 0.5–2 (wt. %) incorporated into the LDPE by solvent/vaporization solvent method (SVS) to reinforce the LDPE films. Based on tensile and contact angle tests, a LDPE film containing 2 wt. % nanocomposite was selected as the most proper film. A series of characterizations, including FE-SEM, AFM, TG-DTA, and DSC Analyzes were applied to compare the different characteristics of pristine and reinforced LDPE films by 2 wt. % nanocomposite. The FE-SEM images exhibited changes in the structure of reinforced LDPE that synthesized nanocomposite is coated on the LDPE matrix. The AFM analysis of LDPE films revealed that adding nanocomposite to pristine LDPE increases the roughness, which affirmed that the reinforced LDPE was more hydrophobicity. The comparison of thermal properties of reinforced LDPE with pristine LDPE depicted a slightly increasing thermal resisting.
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•A novel PVDF/rPG/Silica-g-PS nanocomposite was synthesized and characterized.•Using the synthesized nanocomposite for reinforcement of LDPE films.•Using a simple system (solvent/vaporization solvent) for production of LDPE films.•High tensile properties obtained for reinforced LDPE film by 2 wt. % nanocomposite.•Increasing the hydrophobicity and thermal insulation of LDPE films.
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•Ethanol vapor addition to a medium pressure dielectric barrier discharge.•Investigation of the wettability and the chemical composition of LDPE surfaces.•Ethanol vapor in an air ...plasma results in better wettability and a rougher surface.•2% ethanol vapor in a nitrogen plasma results in a 92% WCA reduction.•Polymerized layers with O/C and N/C ratios of 32% and 53% can be obtained.
In this paper, ethanol vapor up to 50% is added to an argon, air or nitrogen dielectric barrier discharge at medium pressure to profoundly investigate the effect of ethanol addition on the surface modification of low density polyethylene (LDPE). Water contact angle (WCA) and X-ray photoelectron spectroscopy (XPS) measurements show that the ethanol vapor addition effect on the LDPE surface depends on the used carrier gas. Adding ethanol to an argon plasma has no significant effect on the wettability nor on the chemical composition of LDPE compared to a pure argon plasma treatment. Ethanol addition does however slightly increase the LDPE surface roughness. Addition of small amounts of ethanol vapor to an air plasma makes it possible to incorporate additional nitrogen and oxygen groups on the LDPE surface, resulting in an extra decrease of 11% in WCA value. Moreover, the LDPE surface roughness is slightly increased due to the ethanol vapor addition. The most significant effect of ethanol addition is however observed when nitrogen is used as carrier gas. After an N2/2% ethanol plasma treatment, an 85% reduction in WCA value to 8.5° is found compared to a pure N2 plasma treatment. This very hydrophilic LDPE surface is obtained due to a significantly high incorporation of oxygen and nitrogen groups on the surface with an O/C and N/C ratio reaching 32% and 53% respectively. FTIR measurements also reveal that the observed extremely high wettability of LDPE is not the result of plasma activation but is due to plasma polymerization effects occurring on the surface resulting into the deposition of a plasma polymer containing ketones, amides as well as CN groups. In addition, ageing studies have also been conducted and these studies reveal that for all carrier gases, ethanol addition to the discharge gas significantly suppresses the ageing effect. All the above mentioned conclusions therefore indicate that ethanol vapor based plasmas can be an excellent tool to increase the surface energy of polymers.
The plywood industry still most often uses phenol-formaldehyde (РF) and urea-formaldehyde (UF) resins. In Ukraine, 55–60 % of plywood products are made using thermosetting UF resins, and 40–45 % of ...plywood products are made using - PF resins. However, their main disadvantage is formaldehyde emission. In addition, formaldehyde is emitted during the operation of plywood and other wood-based composite materials. This study is focused on the use of thermoplastic films in plywood technology as an alternative to replacing liquid thermoreactive and toxic adhesives. In this paper, the use of thermoplastic films of primary low-density polyethylene (LDPE) for gluing veneer in the production of plywood is offered. The aim of the study was to determine the mechanical properties of plywood, such as shear strength, bending strength and modulus of elasticity, made of peeled veneer of different wood species bonded with primary LDPE film of different thicknesses. For a better understanding of the gluing process of veneer with a thermoplastic film, different wood species were proposed – poplar, birch, hornbeam and beech, as well as different thicknesses of the film - 50, 80, 100, and 150 µm. The obtained results were compared with the properties of plywood glued with UF adhesive. The quality of bonding was evaluated by the shear strength value, which was determined in accordance with the EN 314-1 standard. The results of this study showed that the plywood samples made from veneer of various wood species and glued with primary LDPE thermoplastic film have satisfactory mechanical properties. It was found that the shear strength of plywood made from poplar, birch, hornbeam and beech veneer and glued with a primary LDPE thermoplastic film of different thicknesses meets the EN 314-1 standard for bonding class 1: dry conditions. It was also found that the wood species and thickness of the film significantly (p ≤ 0.05) affects the mechanical properties of plywood. The plywood made from poplar veneer had the lowest values of bending strength and modulus of elasticity, in addition to the shear strength values, which were at the same level as for birch and hornbeam plywood. Beech plywood samples had the best mechanical properties. Increasing the thickness of the LDPE film improved the mechanical properties of the wood composite. The values of mechanical properties meet the requirements of appropriate standards and confirm the suitability of using the thermoplastic film as adhesive instead of conventional UF adhesive for manufacture of plywood and its application under dry conditions. The production of plywood using thermoplastic films as an adhesive in comparison with the production of plywood glued with UF adhesive has a number of advantages due to the absence of: operations for preparing liquid glue; equipment for applying liquid glue to the veneer surface; washing the technological line for preparation and supply of glue; the need to clean equipment for applying glue; the need for disposal of waste resins and adhesives; emission of harmful fumes of formaldehyde and ammonia. However, further study should be done to solve the problem of poor compatibility of wood and LDPE film, which will help to expand their scope of application.
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