Polyethylene Films Research Articles

Municipal Solid Waste Composition and Generation with Emphasis on Plastics in Nablus City, Palestine

The aim of this study was to characterize the municipal solid waste (MSW) in Nablus city in Palestine, while focusing on the plastic waste fraction. The plastic fraction—an environmentally problematic waste stream—was further characterized into the different polymer types and formats with the aim of suggesting feasible recovery and recycling solutions. Locally generated studies lack data about the recyclable fractions in the MSW and a thorough characterization of the plastic waste stream, although there is global action to minimize and optimally treat this waste fraction. The composition analysis was conducted by collecting 60 samples from five districts with different characteristics (e.g., income, density, level of education, building formats). The fraction of bio- and organic waste is significant in the collected MSW in Nablus, representing about 68% of the total MSW. The recyclables (paper and cardboard, glass, metals and plastics) amount to 27.4% of the generated MSW in the city. The plastic fraction (10.1%) is mainly composed of low-density polyethylene (LDPE) films (39.8%), polyethylene terephthalate (PET) bottles (21.9%), high-density polyethylene (HDPE) rigids (19.0%), and polypropylene (PP) rigids (11.5%), all of which are technologically recyclable. The polymer types and container formats indicated that the collected plastics originate mostly from packaging. The outcomes of this research indicate the need to implement a separate collection system for the organic waste fraction, which could be used to produce compost for the agricultural activities in the region. By having such a system, the dry recyclables (including plastics) can be easily recovered with less degree of contamination for recycling, helping the local recyclers to access cleaner materials. Furthermore, the state of Palestine lacks strict regulations for the end-of-life treatment of the different waste fractions; therefore, having clear guidelines and incentive systems will result in the minimization of the generated waste as well as better achievement of recovery and recycling targets. In addition, expertise, funding, public awareness, facilities, equipment and other provisions are currently lacking or inappropriate. In future, these factors must be addressed to enhance sustainable solid waste management.

Extracting Venom from the Parasitoid Wasp Trichogramma dendrolimi using an Artificial Host.

Parasitoid wasps are a diverse group of hymenopteran insects that serve as invaluable resources for pest biocontrol. To ensure successful parasitism, parasitoid wasps inject venom into their hosts to suppress their hosts' immunity, modulate hosts' development, metabolism, and even behavior. With over 600,000 estimated species, the diversity of parasitoid wasps surpasses that of other venomous animals, such as snakes, cone snails, and spiders. Parasitoid wasp venom is an underexplored source of bioactive molecules with potential applications in pest control and medicine. However, collecting parasitoid venom is challenging due to the inability to use direct or electrical stimulation and the difficulty in dissection because of their small size. Trichogramma is a genus of tiny (~0.5 mm) egg parasitoid wasps that are widely used for the biological control of lepidopteran pests in both agriculture and forests. Here, we report a method for extracting venom from T. dendrolimi using artificial hosts. These artificial hosts are created with polyethylene film and amino acid solutions and then inoculated with Trichogramma wasps for parasitism. The venom was subsequently collected and concentrated. This method enables the extraction of large amounts of Trichogramma venom while avoiding contamination from other tissues caused by dissection, a common issue in venom reservoir dissection protocols. This innovative approach facilitates the study of Trichogramma venom, paving the way for new research and potential applications.

Super-resolution Fluorescence Imaging of Recycled Polymer Blends via Hydrogen Bond-Assisted Adsorption of a Nile Red Derivative.

A key challenge in the recycling of multilayer plastic films of polyethylene and polyamide, as typically used for food packaging, is to assess and control the phase separation of the two types of polymers in the recycled material, the specifics of which determine the mechanical strength of the recycled material. However, visualizing the polyamide-in-polyethylene domains with conventional fluorescence methods or electron microscopy is challenging. We present a new approach that combines the point accumulation in nanoscale topography (PAINT) super-resolution method with a newly synthesized Nile Red probe (diOHNR) as the fluorescent label. The molecule was modified to undergo a hydrogen bond-assisted interaction with the polyamide phase in the blend due to its two additional hydroxyl groups but preserves the spectral properties of Nile Red. As a result, the localization density of the probe in the PAINT image is 13 times larger at the polyamide phase than at the polyethylene phase, enabling quantitative evaluation of the spatial polyamide/polyethylene distribution down to the nanoscale. The method achieved a spatial resolution of 18.8 nm, and we found that over half of the polyamide particles in a recycled sample were smaller than the optical diffraction limit. Being able to image the blends with nanoscopic resolution can help to optimize the composition and mechanical properties of recycled materials and thus contribute to an increased reuse of plastics.

Nanoscale mechanical and thermal properties of a multilayer polyethylene film with varying densities

Various atomic force microscopy methods for the imaging and measurement of the modulus of polyethylene (PE) layers in a five-layer multilayer film are described. The film includes linear low-density polyethylene (LLDPE) products with densities ranging from 0.940 to 0.912 gm/cm3. Conventional TappingMode AFM phase imaging can reveal the layers but is sensitive to measurement conditions. PeakForce Tapping AFM using quantitative nanomechanics (QNM) mode can resolve all five layers based on at least three different signals – stiffness mapping, penetration, and energy dissipation. In particular, the difference is statistically significant for the modulus and penetration data. This is remarkable considering that the method is sensitive to density differences of only 0.004 density units. Quasistatic AFM indentation was also done using the same probe and peak load. Here we see the effect of time dependence on the mechanical properties, where the slower interaction times yield estimated moduli much closer to the long-time moduli measured in bulk tensile experiments, compared to the value obtained at much higher frequency using PeakForce Tapping AFM. Nano-thermal analysis of the same five-layer film using heated tip technology can also discriminate the layers statistically, based on softening temperature, which shows excellent correlation with bulk properties.

Infrared Laser Inactivation of Pathogenic Bacteria through a Polyethylene Film

Infrared Laser Inactivation of Pathogenic Bacteria through a Polyethylene Film

Effective Enhancement of Post-Harvest Tomato Storage through Wrapping Using Deacetylated Chitin Nanofibril-Plasticized Honey Films

As one of the most grown seasonal fruit, tomato is widely consumed for making food products, drugs and ornaments. However, poor post-harvest handling system, transport and storage facilities deteriorate the quality of tomato fruits resulting into post-harvest losses. These problems have been addressed by the use of nanotechnology in this study. The combination of a chitosan surface and the core shell chitin results into novel deacetylated chitin nanofibril (DeChNF) with good biological activity and mechanical strength. The effectiveness of the DeChNF films for food preservation as an alternative material to chitosan is investigated. The DeChNF with degree of acetylation (DA) = 60.2% and chitosan (DA = 7.1%) were obtained from crab shells. Two appraches were employed to store freshly matured tomatoes harvested at a breaker stage. The tomatoes were coated with the colloidal suspension and wrapped in the films. Flexible wrapping films were prepared from the colloidal suspension through solution casting using bees honey (35%) and compared to those with glycerol (25%) as plastisizers. The main output storage parameters analysed include colour development, surface spoilage, and weight loss over 20 days at a 73% relative humidity. Tomatoes covered with DeChNF-honey and chitosan-honey films remained in good condition after 20 days, while the coated samples lasted for up to 15 days, except those coated with DeChNF, and those covered with a polyethylene films or stored in a refrigerator at 9 °C. The samples covered with DeChNF films plasticized with honey showed the best resistance against weight loss. The tensile strength of the DeChNF-honey films (strength = 21.32 MPa) and the chitosan-honey films (strength = 21.86 MPa) were higher than the polyethylene films (10.9 MPa). The current work increases understanding on DeChNF as an alternative material, with additional of honey as a plasticizer, over the superior chitosan, or commercial films based on fossil resources.

Investigation of angle-insensitive grating color filters at periods much smaller than the wavelength of incidence.

We designed and simulated one-dimensional (1D) and two-dimensional (2D) reflective grating color filters inside the aluminized polyethylene (PE) film. The filters have several advantages: high angle insensitivity (up to 45° for the 1D filter, 40° for the 2D filter), high reflectance at non-resonant wavelengths, deep resonance dips, and a large color gamut. Both structures are characterized by with their grating periods being much smaller than the wavelength of incidence. A grating modal analysis was utilized to reveal the physical mechanism behind such structures that exhibit angle-insensitive spectral responses which are favored in the fields of color display and packaging.

New Approaches to Stretched Film Sample Alignment and Data Collection for Vibrational Linear Dichroism.

Rapid measurements of vibrational linear dichroism (VLD) infrared spectra are shown to be possible by using stretched polymer films and an extension of existing instrumentation designed for vibrational circular dichroism spectroscopy. Earlier techniques can be extended using additional inexpensive polymer substrates to record good-quality VLD spectra of a significantly wider range of compounds with comparatively short sample-preparation times. The polymer substrates used, polyethylene and polytetrafluoroethylene, are commonly available and inexpensive, and samples are more easily prepared than that for many earlier stretched-film and crystal studies. Data are presented for neutral hydrophobic organic molecules on hydrophobic films including acridine, anthracene, fluorene, and recently synthesized S-(4-((4-cyanophenyl)ethynyl)phenyl)ethanethioate. We extend the approach to polar or ionic species, including 2,2'-bipyridine, 1,10-phenanthroline, and sodium dodecyl sulfate, by oxidizing polyethylene films to change their wetting properties. The combination of new instrumentation and modified sample preparation methods is useful in basic spectroscopy for untangling and assigning complicated infrared spectra. Nevertheless, it is not a panacea as surface-adsorbed molecules are often not monodispersed, and higher analyte concentrations can lead to aggregation and resonance phenomena that have previously been observed for infrared spectra on surfaces. These effects can be assessed by varying the sample concentration. The focus of this paper is experimental, and detailed analysis of most of the spectra lies outside its scope, including some well-studied compounds such as acridine and anthracene that allow comparisons with earlier research.

Cryogenic mechanical and hydrogen-barrier properties of carbon fiber composites for type V cryo-compressed hydrogen storage vessels

Carbon fiber composites for type V cryo-compressed hydrogen (CcH2) storage vessels should have both pressure-bearing and hydrogen-barrier properties. However, hydrogen leakage and delamination defects are prone to occur under cryogenic temperatures (CT) and high pressures. In the current work, polyethylene (PE) films were added to the interlayers of carbon fibers for blocking hydrogen permeation. After hot-pressing treatment, the films melted and wrapped the fibers to form a cross-linked network structure. Then, the resin impregnation and curing were conducted to obtain integrated composites with significant cryogenic mechanical and hydrogen-barrier properties. The results demonstrated that the cross-linked network structure resulted in a 22.7% increase in the cryogenic adhesion force. Under the toughening effects of PE, the longitudinal and transverse tensile strength increased by 23.2% and 21.2%, respectively, while maintaining high cryo-toughness. When 3 layers of PE films were added, the hydrogen permeability coefficients at room and cryogenic temperature were 1.0 × 10−15 mol/(m·s·Pa) and 0.6 × 10−15 mol/(m·s·Pa), respectively, which are lower than the international standard values. Numerous dense PE spherulites with irregular distribution were formed under the action of hot-pressing treatment, which generated tortuous paths within the composites to inhibit hydrogen permeation. The prepared composites may be useful in the manufacture of linerless type V CcH2 storage vessels.

Direct observation of radiation-induced graft polymerization on a polyethylene film

Radiation-induced graft polymerization is widely used in the synthesis of polymeric materials with various functionalities; however, the details of the reaction mechanism are still unresolved. Herein, the initial stage of the graft polymerization reaction was investigated through atomic force microscopy (AFM). We used glycidyl methacrylate (GMA) in methanol (monomer solution) and a high-density polyethylene (HDPE) film with a well-ordered lamellar structure as the substrate. Using polymer film surfaces with a maximum grafting degree of 0.5%, AFM can distinguish between crystalline and amorphous polyethylene (PE) phases as well as a grafted polymer GMA (PGMA) phase. The graft polymerization reaction started from the interface between the crystalline and amorphous PE phases. As the reaction proceeded, the PGMA covered the crystalline PE phase: i.e., the entire surface of the PE film were covered by the PGMA. Further, the crystalline lamellae of the PE film eventually became a scaffold for the formation of aggregates comprising grafted polymer chains alone. The graft polymerization reaction mechanism was explained by comparing the solubility parameters of the monomer solution, substrate, and grafted polymer chains. Understanding the reaction mechanism at a low grafting degree obtained in this study may contribute to enhancing the efficiency of the graft polymerization reaction on any polymeric material.

Transcrystallization, enhanced interface strength and mechanical properties in PE/(PA6 nanofiber)/graphene oxide thermoplastic polymer-polymer nanocomposites via annealing and increased remolding temperature

The importance of polymer-polymer thermoplastic composites is increasing due to ease of recycling. This work investigates the effects of remolding temperature and thermal annealing on the properties of polyethylene (PE) composites containing PA6 and GO/PA6 electrospun nanofibers. Nanocomposite samples were prepared by sandwiching several layers of PA6 or GO/PA6 electrospun mats and PE films in a hot press and subsequently were remolded at varying higher temperatures in a range of 180 to 210°C. Furthermore the remolded samples at 200°C were then annealed at 100°C for 10 h. SEM and DMTA results of the developed samples showed that the application of higher remolding temperatures, close to the melting point of PA6, improves wettability and interfacial strength in the composites. The DSC results of the samples revealed a slight increase in PE crystallinity due to the induced crystallization on the surface of nanofiber mat. It was also observed that an increase in the remolding temperature increases the tensile properties of the composites with the best properties obtained at a remolding temperature of 200°C. Increasing the remolding temperature beyond 200°C decreases the tensile properties of the composites due to melting and geometry degradation of the nanofibers. The results revealed that the annealing of the samples at 100°C for 10 h increases the degree of crystallinity and tensile properties. The highest yield strength, 16.4 MPa, and modulus, 277 MPa, were obtained for the composite containing 10.5 wt% of pure PA6 nanofibers. The elongation and toughness of this composite compared to those of pure matrix were increased by 61% and 83%, respectively. In the remolded and annealed nanocomposites, a crystalline region, as thick as 20 microns, grown on the surface of the nanofiber mat or nanofiber rich region, so called transcrystalline region, was observed by polarized reflected light microscopy.

Synthesis and characterizations of a novel composite films composed of polyethylene/oxide minerals

In this study, a new composite film consisting of polyethylene (PE)/oxide minerals (bentonite, silica, and diatomite) was successfully synthesized. Polymer modification was carried out by melting method. Coating of oxide minerals with PE has shown important results for size control, stabilization and increasing strength. Benzoyl chloride was used as a modifying material in the mechanism. According to the mechanism, it increases the interactions between the mineral and polyethylene through adsorption of the polymer backbone by ion pairing. The resulting composite materials were characterized using advanced analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), Derivative thermogravimetry (DTG) and Thermogravimetric Analysis (TGA). The morphological structures of the composites were examined by scanning electron microscopy (SEM). SEM and FTIR analyses showed that bentonite, silica, and diatomite were modified with PE using an extruder device. At the same time, mechanical test results showed that the tensile strength of films containing 5% oxide mineral is higher than that of pure polyethylene film. In addition, the homogeneous appearance of the surfaces of the films has changed from porous to brittle appearance with the increase in the oxide mineral ratio in composite films. It was found that with the increase in the percentage of minerals in composite films using modified oxide minerals, porous and brittle structures do not form much on the film surfaces, and the interaction of the mineral with the polymer matrix increases. The study had important results in terms of emphasizing the cost-effectiveness of the modification of different minerals with PE, the suitability of production by smelting method and the improvement of mechanical properties. In addition, it is important to obtain different composite derivatives for use in the industrial field.

Contribution of free hydroxyl radical to the formation of micro(nano)plastics and release of additives during polyethylene degradation in water

The omnipresence of secondary microplastics (MPs) in aquatic ecosystems has become an increasingly alarming public health concern. Hydrogen peroxide (H2O2) is an important oxidant in nature and the most stable reactive oxygen species occurred in natural water. In order to explore the contribution of free ˙OH generated from H2O2-driven Fenton-like reactions on the degradation of polyethylene (PE) and generation of micro- and nano-scale plastics in water, a batch experiment was conducted over a period of 620 days in water treated with micromolar H2O2. The incorporation of H2O2 in water induced the formation of flake-like micro(nano)-sized particles due to intensified oxidative degradation of PE films. The presence of ˙OH significantly enhanced the generation of both micro- and nano-scale plastics exhibiting a higher proportion of particles in the range of 200–500 nm compared to the Control. Total organic carbon in the H2O2 treated solution was nearly 174-fold higher than that of the Control indicating a substantial liberation of organic compounds due to the oxidative degradation of native carbon chain of PE and subsequent decomposition of its additives. The highly toxic butylated hydroxytoluene detected from the gas chromatography-mass spectrometry (GC-MS) analysis implied the toxicological behavior of secondary micro(nano)plastics influenced by the oxidation and decomposition processes The findings from this study further expand our understanding of the role of ˙OH in degrading PE micro-scale plastics into nanoparticles as an implication of naturally occurring H2O2 in aquatic environments. In the future, further attention should be drawn to the underlying mechanisms of H2O2-driven in-situ Fenton reaction mediated by natural environmental conditions targeting the alternation of light and darkness on the oxidative degradation of plastics.

Effects of polyethylene and polyvinyl alcohol on growth and protease activity of Acanthopagrus schlegelii juveniles

Many plastic products are used in aquaculture. Studying the toxicological effects of plastics differing in water solubility on marine organisms can provide valuable information. In this study, different amounts of polyvinyl alcohol (PVA) and polyethylene (PE) films were embedded in the feed and fed to Acanthopagrus schlegelii. After 1, 2, 4, and 8 weeks, the changes in percentage weight gain (PWG), feed efficiency (FE), pepsin activity (PA), and trypsin activity (TA) were observed. Either fed to PE or PVA, PWG, and FE of the experimental group were lower than those of the control group after eight weeks. Plastics level recovered from digestive tracts, feces, and water were higher in the PE groups than in the PVA groups. PA rose with increased feeding of plastics, but TA showed the opposite trend. TA activity decreased with increased feeding of plastics. Further analysis showed that TA was positively correlated with PWG.

Measuring Photosynthesis of Entire Tree Crowns and Pulse Label Trees in Large Closed Chamber with 13CO2 in the Field: Design and Testing

Measuring the photosynthesis of entire tree crowns and pulse labelling trees with 13CO2 are valuable approaches to study carbon acquisition, transfer, and allocation; however, it is challenging for trees in the field. The objective was to develop and field test large chambers (35 - 45 m3) that enclosed the entire crown of a tree, provided a reliable estimate of tree crown photosynthesis, and ensured efficient 13CO2 labelling. The chambers, made of transparent polyethylene film pulled tightly over a frame, were equipped with an air conditioner, fans, and air blowers. Air temperature, relative humidity, and photosynthetic photon flux density were measured outside and inside each chamber. Six of 4-year-old rubber trees (Hevea brasiliensis) were pulsed-labelled with 18 L of 13CO2 in June and October 2016. The mean air temperature inside the chambers was 1.2 °C higher and the relative humidity 8 % lower than the outside air. The crown photosynthesis, calculated from the decrease in the CO2 concentration inside the chamber, was in the range 140 - 249 µmol s–1 and was significantly related to photosynthetic photon flux density, total leaf area of the tree, and average net CO2 assimilation at leaf level. The labelling efficiency, estimated as the ratio of the amount of 13C recovered in the foliage immediately after labelling divided by the amount of 13C delivered to the tree, was in the range 43 - 68 %. The designed chamber was suitable to estimate crown photosynthesis and perform 13CO2 pulse labelling of 5-m-tall trees in the field. HIGHLIGHTS Measuring carbon acquisition, transfer, and allocation of entire trees in the field is a challenge The paper describes in detail the system including a 45 m3 chamber that was developed and tested to measure crown photosynthesis and to label trees 5 - 6 m tall with 13CO2 The system and methodology proved efficient in controlling the chamber temperature and providing appropriate conditions for leaf gas exchanges The rates of crown photosynthesis were consistent with measurements at the leaf and ecosystem levels, providing a clear relationship with photosynthetic photon flux density More than 1-half the injected 13CO2 was recovered in the leaves after the end of labelling, showing that the design of the chamber and the labelling protocol were effective for studying C allocation within the tree GRAPHICAL ABSTRACT

Microplastics affect soil bacterial community assembly more by their shapes rather than the concentrations

Polyethylene film mulching is a key technology for soil water retention in dryland agriculture, but the aging of the films can generate a large number of microplastics with different shapes. There exists a widespread misunderstanding that the concentrations of microplastics might be the determinant affecting the diversity and assembly of soil bacterial communities, rather than their shapes. Here, we examined the variations of soil bacteria community composition and functioning under two-year field incubation by four shapes (ball, fiber, fragment and powder) of microplastics along the concentration gradients (0.01%, 0.1% and 1%). Data showed that specific surface area of microplastics was significantly positively correlated with the variations of bacterial community abundance and diversity (r=0.505, p<0.05). The fragment- and fiber-shape microplastics displayed more pronounced interfacial continuity with soil particles and induced greater soil bacterial α-diversity, relative to the powder- and ball-shape ones. Strikingly, microplastic concentrations were not significantly correlated with bacterial community indices (r=0.079, p>0.05). Based on the variations of the βNTI, bacterial community assembly actually followed both stochastic and deterministic processes, and microplastic shapes significantly modified soil biogeochemical cycle and ecological functions. Therefore, the shapes of microplastics, rather than the concentration, significantly affected soil bacterial community assembly, in association with microplastic-soil-water interfaces.

Behavior of coffee plants under different cropping systems with a focus on mitigating water scarcity

ABSTRACT Sustainable cropping systems can enhance the development of young coffee plants under drought conditions. The objective of this study was to evaluate the behavior of coffee plants grown under different cover crops, soil conditioners, and fertilizers to reduce the effects of water scarcity. The treatments were the association of soil cover management (Urochloa decumbens, polyethylene film, and bare soil), fertilizers (conventional and controlled release), and soil conditioners (coffee husk, agricultural gypsum, water-retaining polymer, organic compost, and control). The assessments carried out were the growth, physiology, and anatomy of coffee plants and soil moisture and resistance to penetration. A multivariate analysis of the results was performed. The coffee plants grown with soil cover (Urochloa decumbens) and organic conditioners (coffee husk and organic compost) had better agronomic performance and higher soil moisture.

Development of Microporous Breathable Polyethylene Film Using Different Types of Linear Low-Density Polyethylene with Calcium Carbonate as Filler

In order to improve the conformity of the glove wearers, the microporous breathable polyethylene gloves are developed using Low-Density Polyethylene (LDPE), Ziegler-Natta Linear-Low Density Polyethylene (ZNLLDPE), Metallocene Linear-Low Density Polyethylene (MLLDPE) and calcium carbonate filler (CC). In this study, LDPE/ZNLLDPE/CC and LDPE/MLLDPE/CC microporous films were prepared to investigate the influence of ZNLLDPE and MLLDPE on the film breathability and elongation. The microporous films were characterized by Scanning Electron Microscope (SEM) analysis, X-ray Diffraction (XRD) analysis and Particulate Filtration Efficiency (PFE) analysis, Water Vapor Transmission Rate (WVTR) testing and mechanical properties testing. Based on the result, LDPE-MLLDPE film yielded film breathability of 335.73 g/m2 ∙ day which is 95.3% higher than LDPE-ZNLLDPE film due to the higher LDPE-MLLDPE film crystallinity and prominent dewetting behaviour between CC and LDPE/MLLDPE matrix. Moreover, the high degree of tie molecules in MLLDPE enabled the film to stretch further upon film elongation. Therefore, LDPE-MLLDPE film showed up to 207.2% comparatively better film elongation than LDPE-ZNLLDPE film. The improved film breathability and film elongation render the mixture of LDPE/MLLDPE/CC as a better material for breathable polyethylene glove production.

Peculiarity of the Mechanism of Early Stages of Photo-Oxidative Degradation of Linear Low-Density Polyethylene Films in the Presence of Ferric Stearate.

Ferric stearate (FeSt3) is very efficient in accelerating polyethylene (PE) degradation, but there is a lack of exploration of its role in accelerating the early stages of polyethylene photo-oxidative degradation. This study aimed to investigate the effect of FeSt3 on the photo-oxidative degradation of PE films, especially in the early stages of photo-oxidative degradation. The results show that FeSt3 not only promotes the oxidative degradation of PE but also contributes significantly to the early behavior of photo-oxidative degradation. Moreover, the results of the density functional theory (DFT) calculations proved that the C-H in the FeSt3 ligand was more easily dissociated compared with the PE matrix. The generated H radicals participate in the coupling reaction of the primary alkyl macro radicals leading to the molecular weight reduction, thus significantly increasing the initial rate of molecular weight reduction of PE. Meanwhile, the transfer reaction of the dissociation-generated C-centered radicals induced the PE matrix to produce more secondary alkyl macroradicals, which shortened the time to enter the oxidative degradation stage. This finding reveals the mechanism by which FeSt3 promotes the degradation of PE at the early stage of photo-oxidative degradation. It provides guiding significance for the in-depth study of the early degradation behavior in photo-oxidative degradation on polyolefin/FeSt3 films.

Enhancing interfacial adhesion through coupling agent incorporation in plywood/ plastic waste composite materials

The objective this study was to fabricate 5-ply boards using virgin and recycled high-density polyethylene (vHDPE and rHDPE) films as formaldehyde-free adhesives, respectively. To enhance the interfacial adhesion between the wood veneer and HDPE film, various loadings (0, 3, 6, 8, and 11 wt%) of polyethylene grafted maleic anhydride (PE-g-MA) were applied as a coupling agent. The physical and mechanical performance of the resulting plywood boards was evaluated using standard test methods, with a UF resin-bonded plywood used as a control for comparison. All materials used were for commercial-scale plywood production. Fourier transform infrared spectroscopy (FT-IR) results provided valuable information about chemical interactions that occurred during the coupling of poplar fibers with HDPE using PE-g-MA. The experimental results showed that the mechanical and physical properties of the plywood boards improved as the amount of coupling agent increased from 0 to 11 wt%. PE-g-MA played a crucial role in the properties of plywood boards made with rHDPE and vHDPE by enhancing the interfacial bonding ability between the HDPE and adjacent veneers, leading to good stress propagation and improved mechanical properties. The properties of samples bonded with vHDPE were significantly more improved than those made with rHDPE, likely due to the presence of color pigments, additives, fillers, and impurities in the rHDPE, which made the coupling agent less effective. In addition, the results demonstrated that the samples made with rHDPE and vHDPE were superior to the plywood bonded with UF resin (control), and the optimal content of the coupling agent was found to be 8 and 11 wt%. These findings suggest that incorporating recycled HDPE films and using coupling agents, such as PE-g-MA, can produce high-quality plywood composite materials with improved mechanical and physical properties, providing an eco-friendly alternative to traditional UF resin-bonded plywood.