Polyethylene Films Research Articles

FEATURES OF MANIFESTATION OF ANTIOXIDANT PROPERTIES OF HYDROLYSIS LIGNIN IN POLYETHYLENE FILMS, ANTAGONISM OF LIGNIN AND LICHEN EXTRACTS

The work experimentally studied the antioxidant properties of hydrolyzed lignin powder in the composition of polyethylene films, showing the possibility of increasing the antioxidant capacity of lignin powder in the polymer matrix due to the adsorption of compounds with antioxidant properties on its surface. 
 Samples of polyethylene films with a lignin content of 1–7% wt. obtained by thermal pressing. Thermal-oxidative testing of polymer films was carried out at a temperature of 150 °C. Monitoring of the oxidation process was carried out by IR spectroscopy, using the absorption band at 1720 cm-1, which corresponds to carbonyl groups.
 Experiments on adsorption of ascorbic acid and resorcinol (weak antioxidants) on the surface of lignin particles were carried out. An increase in the antioxidant properties of modified lignin in the composition of polyethylene films was noted. 
 Lignin modification with Evernia prunastri lichen extracts; Parmelia sulcata; Hypogymnia physodes led to antagonism (negative synergism) of antioxidant properties in the polymer composition: the thermal-oxidative stability of the experimental polymer films turned out to be extremely low. At the same time, the extracts of the lichens Evernia prunastri, Parmelia sulcata, Hypogymnia physodes themselves exhibit high antioxidant activity in the composition of polyethylene films. The ATR spectra of lignin powders and UV/VIS spectra of lichen extracts were studied before and after mutual contacting. Analysis of the spectra indicates a decrease in the number of oxygen-containing groups of lignin, which determine its antioxidant capacity.

In-situ straw return, combined with plastic film use, influences soil properties and tomato quality and yield in greenhouse conditions

To address the challenge of disposing vegetable waste in greenhouses while mitigating white pollution associated with the use of conventional polyethylene film, we compared polyethylene (PE) film with two types of fully biodegradable film in both straw-return and no-straw-return treatments. We systematically investigated the effects of mulching on soil properties, film degradation, and tomato quality and yield. The results showed that the humic acid biodegradable film with straw-return (FZS-SR) increased the contents of lycopene, vitamin C (Vc), and soluble sugars in tomato fruit by 20.77%, 16.68%, and 25.89%, respectively, and decreased the total acid content by 8.46% compared to polyethylene film with no-straw-return (PE-NR). Additionally, FZS-SR enhanced the relative abundance of soil bacteria and fungi in Chloroflexi and Basidiomycota, while reducing the relative abundance of pathogenic fungal groups. Moreover, the biodegradable film degraded 15 days earlier in the straw-return treatment, with significantly higher characteristic peaks in Fourier transform infrared spectral analysis compared to no straw-return treatment. In a greenhouse, the straw-return model accelerated the degradation rate of biodegradable film. In summary, our results indicate that using humic acid biodegradable film with straw-return is an effective and sustainable cultivation method, improving tomato quality and yield. This approach offers insights for addressing residual plant and film pollution in vegetable production.

Mechanical, Rheological, and Heat Seal Properties of 1‐Octene Grafted Low Density Polyethylene Films

AbstractHeat seal and mechanical properties of 1‐octene grafted low density polyethylene films containing various concentrations of Dicumyl peroxide as the initiator and 1‐octene grafting agent is investigated through using experimental measurements. The results of differential scanning calorimeter (DSC) measurements revealed that the melting temperature shifts to higher values and the peak of the DSC curve becomes wider with the increase of 1‐octene concentrations. Thermogravimetric analysis (TGA) revealed a higher thermal stability up to 20 °C for 1‐octene grafted PE compared with neat LDPE alloy. The results of stress–strain measurements revealed that the 1‐octene grafted PE alloys has higher tensile strength in comparison with neat PE alloy and samples containing only DCP initiator. The results of heat seal analysis indicated that both DCP initiator and 1‐octene tended to offer a moderate increase peel strength of PE alloy. DMTA measurements for various grafted PE alloys show a higher damping factor in comparison with neat LDPE alloy. Rheological measurements indicated a higher storage modulus up to 25% and higher complex viscosity for grafted PE samples containing 1‐octene comonomer.

Active Low-Density Polyethylene-Based Films by Incorporating α-Tocopherol in the Free State and Loaded in PLA Nanoparticles: A Comparative Study

In this work, alpha-tocopherol (α-TOC) was encapsulated in poly(lactic acid) nanoparticles (PLA NPs) and added to low-density polyethylene (LDPE) films with the aim of producing an active film for food packaging applications. PLA NPs loaded with α-TOC were produced through nanoprecipitation and dried using two methods (freeze-dryer and oven). LDPE-based films with final polymeric matrix concentrations of 10 and 20 g/kg were then produced through blow extrusion. The results showed that LDPE-based films loaded with α-TOC can be produced using blow extrusion, and a good distribution of PLA NPs can be obtained within the LDPE matrix as observed using scanning electron microscopy (SEM). The mechanical properties were affected by the incorporation of α-TOC and PLA NPs loaded with α-TOC, with the observation of a decrease in tensile strength and Young’s Modulus values and an increase in elongation at break. Regarding water vapor permeability, the films showed a reduction in the values with the addition of α-TOC and PLA NPs loaded with α-TOC compared to the LDPE film (control). Films with α-TOC in the free state and loaded in PLA NPs showed antioxidant activity, but their behavior was affected by the encapsulation process.

Distinctive Aspects of Early Open-Field Watermelon Production

This study emphasizes the economic significance of watermelon cultivation in the Republic of Serbia, introducing innovative techniques such as seedling production, grafting, mulching with black polyethylene film and low tunnels. Collectively, these methods contribute to earlier planting, improved crop development, and enhanced fruit quality. Grafting, particularly using Lagenaria siceraria and Cucurbita species, positively impacts yields and flowering. The incorporation of black polyethylene film aids in weed control, reduces herbicide usage, and minimizes labor inputs. Low tunnels, with transparent film covers, modify microclimates, allowing for earlier harvests. These integrated practices offer a sustainable approach to advancing watermelon cultivation techniques, potentially influencing agricultural practices on a global scale by promoting efficiency, yield optimization, and resource conservation.

Influence of a Constant Electric Field on the Structure and Properties of Chlorosulfonated Polyethylene Films during Formation from Solution

Influence of a Constant Electric Field on the Structure and Properties of Chlorosulfonated Polyethylene Films during Formation from Solution

LLDPE film development surface with nucleating agents to reduce fat stains from food adherence on the film surface for easy rinsing before recycling

The purpose of this research was to enhance the surface of linear low-density polyethylene (LLDPE) film by using single and hybrid nucleating agents to reduce fat stains from food adherence on the film surface for easy rinsing before recycling, consequently reducing energy consumption before recycling. The process begins with the preparation of a high-concentration masterbatch of LLDPE with nucleating agents and polyethylene glycol (PEG), followed by blown film and test analysis. The results showed that both single and hybrid nucleating agents resulted in substantial modifications in the surface characteristics of the film. The altered surface texture of the film makes fat stains easy to remove. In addition, the use of hybrid nucleating agents resulted in considerable roughness on the film's surface. It can calculate the average roughness (Ra) from atomic force microscopy (AFM) images, which is very low at 4.7 nm, and the roughness is consistent. The contact angle was 99.17 degrees, and the percentage of crystallinity was clearly higher than that of a single nucleating agent. As a result, the fat stains on the film surface are easier to remove. The visual appearance, morphology, functional group, and mechanical properties of the films, on the other hand, were not significantly different. In summary, using a nucleating agent helped to rinse fat stains from the film easily.

Self-sustained and Insulated Radiative/Evaporative Cooler for Daytime Subambient Passive Cooling.

Passive cooling technologies are one of the promising solutions to the global energy crisis due to no consumption of fossil fuels during operation. However, the existing radiative and evaporative coolers still have problems achieving daytime subambient cooling while maintaining evaporation over the long term. Here, we propose a self-sustained and insulated radiative/evaporative cooler (SIREC), which consists of a porous polyethylene film (P-PE) at the top, an air layer in the middle, and poly(vinyl alcohol) hydrogel with lithium bromide (PLH) at the bottom. In particular, the P-PE shows high solar reflectance (R̅solar = 0.91) and long-wave infrared transmittance (τ̅LWIR = 0.92), which reflects sunlight while enhancing the direct radiative heat transfer between outer space and PLH (ε̅LWIR = 0.96) for sky radiative cooling. In addition, the desirable vapor permeability (579 s m-1) of the P-PE also results in good compatibility with PLH for evaporative cooling (EC). Moreover, the PLH's ability to harvest atmospheric water at night provides self-sustainment for daytime EC. The air layer between P-PE and PLH further enhances the subambient cooling performance of the SIREC. These findings indicate promising prospects for the integration of passive cooling technologies.

Environmental Impact of Various Rice Cultivation Methods in Northeast China through Life Cycle Assessment

Rice, a crucial staple in China, is cultivated through various techniques, including seedling transplanting, dry direct seeding, and film mulching. Despite its significance, rice production is a considerable environmental burden. Using a life cycle assessment (LCA) methodology, this study aimed to evaluate the environmental impacts of four rice cultivation methods (transplanting rice, dry direct-seeding rice, dry direct-seeding rice with polyethylene film (PE), and dry direct-seeding rice with biodegradable film) in Northeast China. The results indicate that the magnitude of environmental impacts among treatments was consistent across years. The potential values of all environmental impacts of the four different cultivation methods of rice in the 2021 field trial were smaller than the results of the same cultivation method of rice system in the 2022 field trial. Among the four rice cultivation methods, the consumption of energy showed inconsistency over the two years, with the highest energy consumption in the first year being for dry seeding with PE film and in the second year for dry seeding without film. Additionally, transplanting exhibited the highest impact on water resource consumption and climate change. Dry direct-seeding rice displayed the highest eutrophication and ecotoxicity. Dry direct-seeding rice with a biodegradable film had the least impact in terms of acidification. Moreover, dry direct-seeding rice with a biodegradable film minimized water consumption and greenhouse gas emissions without compromising yield.

Mulching to improve sweet potato production

Sweet potato ((Ipomoea batatas L.) is a high-yielding nutritious specialty crop. There is a growing need for proactive information on sustainable production of sweet potatoes under short growing seasons. The objective of our study was to evaluate the effects of crop residue and synthetic mulches on the growth, yield, and quality parameters of three varieties of sweet potatoes. Three types of mulch, wheat straw (straw), white polyethylene film (white mulch), and black plastic film (black mulch), and a control (no mulch) were evaluated during the 2021 and 2022 growing seasons in the south-eastern region of Kazakhstan. The vine length, meristem number, tuber per plant, and tuber weight were significantly higher under white mulch and black mulch than under straw, and the results were significantly different from the control. The total yields of sweet potato tubers under white mulch and black mulch also varied significantly among the varieties, ranging from 20.5 t/ha for Rizi 0603 to 54.5 t/ha for Xushu 25. The results of the present study will be used to develop other technological sequences for the cultivation of sweet potatoes in the south-eastern region of Kazakhstan. More research is needed to ascertain the stability of the effects of varieties, mulch treatment, and their interactions on yields and to determine other treatments and varieties with better potential to improve sweet potato yields for cultivation in Kazakhstan.

Dry Direct-Seeded Rice Yield and Water Use Efficiency as Affected by Biodegradable Film Mulching in the Northeastern Region of China

In the realm of agriculture, biodegradable films are emerging as a promising substitute for traditional polyethylene (PE) films. Despite their potential, there has been a notable lack of extensive research on their effectiveness in the context of dry direct-seeded rice cultivation. Addressing this gap, a comprehensive biennial study was conducted in the northeastern regions of China, focusing on the ‘Baonong 5’ rice variety. This study meticulously compared three distinct cultivation methods: (1) employing biodegradable film mulching, (2) using conventional plastic film mulching, and (3) cultivating without any mulch. The findings revealed that biodegradable film mulching significantly enhanced soil moisture control, increased leaf area, and improved rice yield and water utilization efficiency (p < 0.05) compared to the plots without mulch. Notably, there was no marked difference in outcomes between the plastic film mulching and the unmulched plots. This research underscores the profound benefits of biodegradable film in rice cultivation, particularly from an environmental sustainability perspective. This innovative method not only boosts agricultural productivity but also addresses critical environmental challenges like climate change and water conservation. The application of biodegradable mulch has proven to be remarkably effective in improving irrigation efficiency and crop water conservation, leading to enhanced rice development and higher yields. The study recorded a substantial increase in water productivity—30% in 2021 and between 52.85% and 60% in 2022—compared to traditional cultivation practices. Furthermore, the use of biodegradable mulch resulted in significantly higher rice yields than the non-mulched plots, thus contributing to increased profitability. Such methods not only yield higher crop outputs but also mitigate environmental issues like water pollution and help alleviate prevalent water shortages in rice farming.

Effect of citric acid pretreatment on drying kinetics of tamarillo in a greenhouse solar dryer

The production and consumption of tamarillo (Solanum betaceum) is gaining momentum due to its immense nutritional, health, and commercial potential. However, like many other horticultural products, high postharvest losses are incurred in tamarillo production. In particular, decay is a major problem. Drying is a viable option that can address this problem and significantly increase the shelf life of tamarillo. Consequently, the objective of this study was to evaluate the effect of citric acid pretreatment on the drying kinetics and quality of tamarillo slices. The tamarillos were dried in a passively operated even-span greenhouse solar dryer (8 m long, 4 m wide, and 3.6 m high to the ridge) covered with a 200 μm thick ultraviolet-stabilised polyethylene film. Solar radiation, temperature, relative humidity, moisture content, colour, firmness, and vitamin C content were periodically measured, and the data were analysed statistically. The citric acid-pretreated and control (untreated) tamarillo slices were dried from an initial moisture content of 655% (db) to a final moisture content of 16.25% and 22.50% (db), respectively, in 10 hours. In addition, the pretreated slices attained a higher average drying rate of 42.01±0.23 g/g/hr compared to 40.23±0.12 g/g/hr attained by the control slices. Further, the Page model best described the drying kinetics of both tamarillo samples with R², χ2, and RMSE values of 0.9975, 0.0004, and 0.0005, respectively. The pre-treated samples had better colour retention with a total colour change of 15.07±1.12 compared to 35.99±0.98 attained in the control samples. Moreover, the pretreated tamarillo slices attained a lower percentage firmness increment of 281.82±3.21% compared to 337.5%±1.54 attained in the untreated samples. Further, the pretreated tamarillo slices had 42.94±0.41% vitamin C retention compared to 40.17±0.67% retention in the control samples. Generally, pre-treating tamarillo slices with citric acid improves their drying kinetics and both physical and nutritional qualities.

A Facile and Effective Design for Dynamic Thermal Management Based on Synchronous Solar and Thermal Radiation Regulation.

Passive solar heating and radiative cooling have attracted great interest in global energy consumption reduction due to their unique electricity-free advantage. However, static single radiation cooling or solar heating would lead to overcooling or overheating in cold and hot weather, respectively. To achieve a facile, effective approach for dynamic thermal management, a novel structured polyethylene (PE) film was engineered with a switchable cooling and heating mode obtained through a moisture transfer technique. The 100 μm PE film showed excellent solar modulation from 0.92 (dried state) to 0.32 (wetted state) and thermal modulation from 0.86 (dried state) to 0.05 (wetted state). Outdoor experiments demonstrated effective thermal regulation during both daytime and nighttime. Furthermore, our designed PE film can save 1.3-41.0% of annual energy consumption across the whole country of China. This dual solar and thermal regulation mechanism is very promising for guiding scalable approaches to energy-saving temperature regulation.

Improving the Quality of Tantalum Cylindrical Deep-Drawn Part Formation Using Different Lubricating Media-Coated Dies

Lubrication is one of the key factors to improve metal-forming quality. In the process of deep drawing, seizing tumors easily occur on the contact surfaces between the tantalum metal and the mold, which greatly affects the forming quality of the deep-drawn parts. Quality-forming quality problems that occur during the deep drawing of tantalum metal are studied from the perspective of lubrication in this paper. Three lubrication media, caster oil, PE (polyethylene) film, and DLC (Diamond Like Carbon) film, were adopted in the deep drawing of tantalum cylindrical cups. A universal testing machine and microscope were used to investigate the effect of lubrication media on the limit-drawing ratio, maximum forming force, and surface topography quality during the deep drawing process of the tantalum sheet. The results reveal that the lubrication of the PE film and DLC film can greatly improve the forming quality of the tantalum metal sheet, in which the DLC film has higher wear resistance and lower friction coefficient and can be used as the lubricating medium in the industrial forming process of tantalum deep-drawn parts.

Preparation of fullerene-containing nanocomposite materials based on high-density polyethylene via environmental crazing and their performance

This work offers a new concept relying on the Rehbinder effect in polymers for the preparation of fullerene-containing nanocomposite materials with added functionality. Tensile drawing of high-density polyethylene (HDPE) films in the solutions of 1,2–dichlorobenzene containing С60-С70 fullerenes (FL) proceeds via the environmental crazing according in the presence of surface active liquids (the Rehbinder effect). Environmental crazing provides the development of a highly developed surface and a mesoporous structure with a uniform distribution of monomeric FL within the HDPE matrix. The content of FL in the FL/HDPE nanocomposite materials can be varied from 1 to 8 wt%. Performance of the FL/HDPE nanocomposite materials (optical properties, thermal stability, mechanical characteristics) was studied by different physicochemical methods (TGA, UV- spectroscopy, tensile tests, etc.). Introduction of FL to HDPE is shown to increase the temperature of thermal degradation onset of HDPE by 30 °C. Rolling as the additional stage off post-treatment allows preparation of the FL/HDPE nanocomposite materials with high mechanical properties. This process can be upscaled using the existing technological equipment for the orientational drawing of polymers. The FL/HDPE nanocomposites with improved thermal resistance and good mechanical properties can be used as innovative optoelectronic materials within a broad temperature interval.

Enhanced radiative cooling with Janus optical properties for low-temperature space cooling

Abstract Passive daytime radiative cooling that could provide sub-ambient cooling emerges as a promising technology to reduce household energy consumption. Nonetheless, prevailing studies are predominantly focused on surface cooling, often overlooking its adaptability to enclosed spaces with active cooling technologies. Here we present a multilayer radiative cooling film (J-MRC) with Janus optical properties in the mid-infrared region, consisting of the nanoporous polyethylene films, the polyethylene oxide film, and silver nanowires. The top side of the J-MRC functions as a conventional radiative cooling material to supply sub-ambient surface cooling, while the bottom side with low mid-infrared emissivity transfers limited heat via thermal radiation to the low-temperature enclosures. Our experiments validate that the J-MRC possesses an enhanced space cooling performance in comparison to the conventional radiative cooling film. This work provides a valuable design concept for radiative cooling materials, thereby expanding their practical scenarios and contributing to reduce the carbon emission.

Evaluation of the sorption/desorption processes of pesticides in biodegradable mulch films used in agriculture

Microplastics from mulch films can be a source of chemical contamination to agricultural soils. In this context, biodegradable films have been widely positioned as a greener choice. However, their sorption/desorption capabilities, in contrast to the conventional plastic types remain understudied. It is for this reason that objective evaluation of their interactions with residual agricultural contaminants becomes important. Our findings reveal that polyethylene (PE) mulch films retained lower amounts of pesticide residues and demonstrated a higher desorption/release [median desorption = 71.86 μg/L or about 50%], while polybutylene adipate terephthalate (PBAT) mulch films retained higher amounts of pesticide residues onto their surface and demonstrated a much lower desorption [median desorption = 24.27 μg/L or about 17%] after a spraying event. A higher ambient temperature had no significant effect on final desorption amounts in both PE [median = 65.27 μg/L at 20 °C and 74.23 μg/L at 40 °C] and PBAT [median = 24.26 μg/L at 20 °C and 24.78 μg/L at 40 °C] mulch films. However, it did favour a faster desorption pace in PE films. Desorption in PBAT and PE plastic types was correlated with the log Kow value [Spearman's correlation: 0.857 and 0.837 respectively, p < 0.05]. However, only a moderate correlation with pKa was observed in PBAT [Spearman's correlation: 0.478, p < 0.05], while none for PE plastic type. Sorption of pesticides onto biodegradable PBAT microplastics were best explained by Elovich [R2: 0.937–0.959] and pseudo-second order kinetics [R2: 0.942–0.987], suggesting the presence of chemisorption. Furthermore, Weber Morris plots suggested the presence of a multi-step process and Boyd plots indicated that film diffusion or chemical bond formation was the rate-limiting step governing this phenomenon.

Assessing the Conformity of Plasticizer-Free Polymers for Foodstuff Packaging Using Solid Phase Microextraction Coupled to Gas Chromatography/Mass Spectrometry

Phthalates are the synthetic chemical plasticizers with the most varied uses and are a source of concern due to their toxicity and ubiquity, so much so that even plasticizer-free polymers can contain them as non-intentionally added substances (NIAS). Food packaging is among the materials with the greatest impact. In this study, a simple protocol is proposed for the location and identification of dimethyl phthalate, diethyl phthalate, dipropyl phthalate, and dibutyl phthalate which is applicable to compliance studies of food packaging materials and for the associated risk assessment. Solid phase microextraction gas chromatography/mass spectrometry was used to evaluate the migration of four NIAS from food packaging to release media simulating food substrates. Three plasticizer-free polymers were used: two that were lab-made and based on sodium alginate and a commercial polyethylene film. Linearity ranged from the LOQ to 10 µg/mL; within-day and between-day precision values were between 12.3–25.7% and 21.9–35.8%, respectively; the LOD and LOQ were in the range 0.029–0.073 µg/mL and 0.122–0.970 µg/mL. Migration tests were conducted for different periods of time at room temperature and at 8 °C. Exposure to microwaves (MW) was also evaluated. All packaging materials tested had global migration limits lower than 10 mg/dm2 of material surface.

Enhancing polyethylene degradation: a novel bioprocess approach using Acinetobacter nosocomialis pseudo-resting cells.

Despite the discovery of several bacteria capable of interacting with polymers, the activity of the natural bacterial isolates is limited. Furthermore, there is a lack of knowledge regarding the development of bioprocesses for polyethylene (PE) degradation. Here, we report a bioprocess using pseudo-resting cells for efficient degradation of PE. The bacterial strain Acinetobacter nosocomialis was isolated from PE-containing landfills and characterized using low-density PE (LDPE) surface oxidation when incubated with LDPE. We optimized culture conditions to generate catalytic pseudo-resting cells of A. nosocomialis that are capable of degrading LDPE films in a bioreactor. After 28days of bioreactor operation using pseudo-resting cells of A. nosocomialis, we observed the formation of holes on the PE film (39 holes per 217 cm2, a maximum diameter of 1440μm). This study highlights the potential of bacteria as biocatalysts for the development of PE degradation processes. KEY POINTS: • New bioprocess has been proposed to degrade polyethylene (PE). • Process with pseudo-resting cells results in the formation of holes in PE film. • We demonstrated PE degradation using A. nosocomialis as a biocatalyst.

Modelling the piezoelectric effect in a composite polymer film filled with disperse piezoelectric

Mesoscopic modelling of a composite material constituted by an electroneutral polymer (matrix) film filled with micropowder of piezoelectric ceramics (filler) is presented. The calculation scheme resembles that of the RVE (Representative Volume Element) method. The representative element (cell) is a right-angle prism with square cross-section, the height of which is equal to the film thickness. Around the midsection of the prism, there are a few (from 2 to 4) spherical piezoelectric particles positioned close to one another. The length of the base side of the prism is determined from the assumed solid phase content of the composite. To simulate the film, the cells are arranged in a continuous flat layer, inside which they are coupled by means of periodic boundary conditions imposed on their lateral surfaces. To reduce the artifacts of the model, the position of the center of each particle is chosen randomly within the area of the prism cross-section. In the framework of this approach, a low-density polyethylene film with embedded barium titanate particles is considered as an example. One of the surfaces of the film is fixed (no displacements), and the other one is left free. For the characteristics of the particles close to those used in the experiment and the typical matrix material parameters (elasticity moduli, Poisson coefficients, dielectric permittivity), the voltage output (piezoeffect) induced in the film in response to the uniform pressure applied to its free surface is evaluated. It is shown that the electric potential along the thickness of the film is nonuniform: it grows inside the particles and falls down in the interparticle gap. In order to present the results in the form applicative for comparison with the experimental data, for each variant of the system (number of the particles, weight fraction of the solid phase), the calculated values are averaged over a few tens of realizations of the particle positions inside the element.