Pure Low-density Polyethylene Research Articles

Novel Polymer Composites for Lead-Free Shielding Applications.

Polymer nanocomposites have recently been introduced as lead-free shielding materials for use in medical and industrial applications. In this work, novel shielding materials were developed using low-density polyethylene (LDPE) mixed with four different filler materials. These four materials are cement, cement with iron oxide, cement with aluminum oxide, and cement with bismuth oxide. Different weight percentages were used including 5%, 15%, and 50% of the cement filler with LDPE. Furthermore, different weight percentages of different combinations of the filler materials were used including 2.5%, 7.5%, and 25% (i.e., cement and iron oxide, cement and aluminum oxide, cement and bismuth oxide) with LDPE. Bismuth oxide was a nanocomposite, and the remaining oxides were micro-composites. Characterization included structural properties, physical features, mechanical and thermal properties, and radiation shielding efficiency for the prepared composites. The results show that a clear improvement in the shielding efficiency was observed when the filler materials were added to the LDPE. The best result out of all these composites was obtained for the composites of bismuth oxide (25 wt.%) cement (25 wt.%) and LDPE (50 wt.%) which have the lowest measured mean free path (MFP) compared with pure LDPE. The comparison shows that the average MFP obtained from the experiments for all the eight energies used in this work was six times lower than the one for pure LDPE, reaching up to twelve times lower for 60 keV energy. The best result among all developed composites was observed for the ones with bismuth oxide at the highest weight percent 25%, which can block up to 78% of an X-ray.

Low-Density Polyethylene-Based Novel Active Packaging Film for Food Shelf-Life Extension via Thyme-Oil Control Release from SBA-15 Nanocarrier.

The use of natural raw substances for food preservation could provide a great contribution to food waste reduction, circular economy enhancement, and green process application widening. Recent studies indicated that the use of porous materials as adsorbents for natural essential oils provided nanohybrids with excellent antioxidant and antimicrobial properties. Following this trend in this work, a thymol oil (TEO) rich SBA-15 nanohybrid was prepared and characterized physiochemically with various techniques. This TEO@SBA-15 nanohybrid, along with the pure SBA-15, was extruded with low-density polyethylene (LDPE) to develop novel active packaging films. Results indicated that TEO loading was higher than other porous materials reported recently, and the addition of both pure SBA-15 and TEO@SBA-15 to the LDPE increased the water/oxygen barrier. The film with the higher thyme-oil@SBA-15 nanohybrid content exhibited a slower release kinetic. The antioxidant activity of the final films ignited after 48 h, was in the range of 60-70%, and was almost constant for 7 days. Finally, all tests indicated a sufficient improvement by the addition of thyme-oil@SBA-15 nanohybrids in the pure LDPE matrix and the concentration of wt. 10% of such nanocarriers provided the optimum final LDPE/10TEO@SBE-15 active packaging film. This material could be a potential future product for active packaging applications.

Reactive extrusion of caffeic acid functionalized ε-polylysine with low-density polyethylene as an antimicrobial and antioxidant film

In this work, a novel grafted film with both antimicrobial and antioxidant properties was developed. ε-polylysine (EPL) and caffeic acid (CA) were used as raw materials, and EPL-CA was synthesized by grafting CA onto EPL by the carbodiimide coupling method. Using dicumyl peroxide (DCP) as a radical initiator, EPL-CA was crosslinked with low-density polyethylene (LDPE) by reactive co-extrusion to produce grafted films with both antimicrobial and antioxidant properties. Compared with pure LDPE film, all graft films show antimicrobial and antioxidant properties. Specifically, when the EPL-CA concentration is >3%, the inhibition rates against Escherichia coli (>91%) and Staphylococcus aureus (>97%) significantly increase, and the DPPH free radical scavenging rate (>60%) also significantly increases. Compared with the control film, the grafted film exhibits increased tensile strength and decreased elongation at break. In addition, the migration levels of all graft films in food simulants are below the migration standards set by the European Union. Overall, immobilizing EPL-CA on the LDPE matrix improves antimicrobial, antioxidant, and mechanical properties. Among them, the film exhibits the best comprehensive performance when the EPL-CA content is 3%. Therefore, the development of antimicrobial and antioxidant active LDPE film is proposed. These results indicate that active packaging films can be prepared through reactive extrusion, a promising and industrializable technology, and have broad prospects in improving food safety and other aspects.

Polymer Composites of Low-Density Polyethylene (LDPE) with Elongated Hematite (α-Fe2O3) Particles of Different Shapes

Due to the intensive search for new types of advanced polymer materials for targeted applications, this work offers insight into the properties of low-density polyethylene/hematite composites. The specific feature of this study lies in the use of elongated hematite particles of different shapes. Uniform ellipsoid-, peanut- and rod-shaped hematite particles were hydrothermally synthesized and incorporated into the polymer matrix of low-density polyethylene (LDPE). LDPE/hematite composites are prepared by melt mixing. Hematite particles are characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD). The pure LDPE polymer and LDPE/hematite composites were studied by FT-IR and UV-Vis-NIR spectroscopy and by thermogravimetric analysis (TGA). The determination of the mechanical and barrier properties was also carried out. The obtained results indicate the influence of the elongated particles on the improvement of LDPE properties. An increase in thermal stability and UV-absorption was observed as well as the improvement of mechanical and barrier properties. The improvement of the composites’ properties in comparison to the pure LDPE is especially visible in the composites prepared with low content of hematite (0.25%). LDPE/hematite composites have promising characteristics for application as packaging materials with enhanced mechanical, thermal and barrier properties as well as UV-protective materials.

The Influence of TiO2-Lignin Hybrid Fillers in Low-Density Polyethylene Composites on Photocatalytic Performance and UV-Barrier Properties.

The main objective of this study was to discover new packaging materials that could integrate one of the most expected properties, such as UV protection, with a self-cleaning ability defined as photocatalytic performance. Accordingly, new hybrid additives were used to transform LDPE films into materials with complex performance properties. In this study, titanium dioxide-lignin (TL) hybrid systems with a weight ratio of inorganic to organic precursors of 5-1, 1-1, and 1-5 were prepared using a mechanical method. The obtained materials and pristine components were characterized using measurement techniques and research methods, such as Fourier-transform infrared spectroscopy (FTIR), thermal stability analysis (TGA/DTG), measurement of the electrokinetic potential as a function of pH, scanning electron microscopy (SEM), and particle size distribution measurement. It was found that hydrogen bonds were formed between the organic and inorganic components, based on which the obtained systems were classified as class I hybrid materials. In the next step, inorganic-organic hybrid systems and pristine components were used as fillers for a low-density polyethylene (LDPE) composite, 5 and 10% by weight, in order to determine their impact on parameters such as tensile elongation at break. Polymer composites containing titanium dioxide in their matrix were then subjected to a test of photocatalytic properties, based on which it was found that all materials with TiO2 in their structure exhibit photocatalytic properties, whereby the best results were obtained for samples containing the TiO2-lignin hybrid system (1-1). The mechanical tests showed that the thin sheet films had a strong anisotropy due to chill-roll extrusion, ranging from 1.98 to 3.32. UV-Vis spectroscopy revealed four times higher light absorption for composites in which lignin was present than for pure LDPE, in the 250-450 nm range. On the other hand, the temperature at 5% and 30% weight loss revealed by TGA testing increased the highest performance for LDPE/TiO2 materials (by 20.4 °C and 8.7 °C, respectively).

Characterization of migration behavior of organic electric-field regulator in polyethylene composite based on the synchronous spectra of space charge and polarization current

Organic electric-field regulator has the ability to suppress the space charge accumulation in the composite due to its electric-field and filler-content enhanced conductivity. Moreover, it can also migrate towards the high electric field region under the electric field gradient force, which further homogenizes the non-uniform electric field distribution. To characterize the migration behavior of the organic electric-field regulator in the composite under electric field, a distributed equivalent circuit model is firstly introduced, and it is solved to obtain the space-time distribution of conductivity in composite based on the synchronous spectra of space charge and polarization current. Combining the mathematical relationship between the direct current (DC) conductivity and electric field as well as regulator content, the space-time distribution of organic electric-field regulator in the composite is then settled. The allyloxy polyethylene glycol (APEG) is used as an example organic electric-field regulator and is filled into low-density polyethylene (LDPE) matrix to prepare composites. The DC conductivity and the synchronous spectra of space charge and polarization current are measured, respectively. The composites show noticeable electric-field and regulator-content enhanced conductivities. The space charge distribution shows that the APEG is capable of suppressing the space charge and homogenizing the electric field distribution compared with pure LDPE. The space-time distribution of regulator content in the 0.5 wt% composite is determined by the proposed method, and the regulator content near the electrodes is much higher than in the bulk, which is consistent with the infrared microscope images. The higher filler content means a higher DC conductivity, which lowers the high electric field near the electrodes and contributes to more uniform electric field distribution in the composite. The proposed method experimentally characterizes the migration behavior of the organic electric-field regulator in the polymer composite for the first time, and provides an effective way to study the migration mechanism of organic molecules (e.g. organic electric-field regulator) in the polymer composite.

Investigation on the synergistic effect between different components in pyrolysis of paper-plastic composite material

Pyrolysis characteristics of Tetra Pak, a paperboard-polyethylene-aluminium foil, were investigated in this study with a focus on the synergistic effect between its individual components. Scanning electron microscopy analysis indicated that molten LDPE coating on cellulose surface led to suppression on mass and heat transfer and the increased activation energy of pyrolysis reaction. Samples of individual components and simulated Tetra Pak packaging were pyrolyzed in a thermogravimetric analyzer at various heating rates. Synergistic effect between cellulose and LDPE on Ea and the formation of characteristic products are investigated: Kinetic analysis showed that the cellulose decomposition peak in the simulated mixture exhibited a higher Ea than that of pure cellulose at each conversion rate. For LDPE, the free radicals formed from cellulose pyrolysis enhanced the degradation of plastic polymers, resulting that Ea of its decomposition peak in the mixture being lower in comparison to pure LDPE, with a discrepancy of around 16–27 kJ·mol−1. The formation of characteristic products including levoglucosan, furfural, 5-hydroxymethylfurfural, and alkanes from pyrolysis of cellulose and LDPE mixture with different mass ratios was further investigated in a micro-pyrolyzer. The results suggested that synergistic effects and physical barrier existed during fast pyrolysis between cellulose and LDPE. The extent of the synergy effect depended on the proportion of cellulose and LDPE in the mixture.

Ecofriendly Biochar as a Low-Cost Solid Lubricating Filler for LDPE Sustainable Biocomposites: Thermal, Mechanical, and Tribological Characterization

The potential of ecofriendly biochar, a carbon-rich byproduct of biomass pyrolysis, as a low-cost solid lubricating filler for low-density polyethylene (LDPE) sustainable biocomposites is investigated in this work. Tensile strength, hardness, thermogravimetric analysis (TGA), melting flow index (MFI), tensile test, flexural test, and frictional tests were used to characterize the biocomposites’ mechanical, thermal, and tribological properties. Energy-dispersive X-ray spectroscopy (EDS) was used to assess the chemical composition of the biochar, while field-emission scanning electron microscopy (FESEM) was used to capture the biochar morphology. The results showed that the incorporation of biochar in LDPE matrix increased the mechanical characteristics of the biocomposites and resulted in a significant increase in tensile strength, flexural strength, and hardness. More specifically, the LDPE+10 wt% composite outperformed the pure LDPE matrix by 1.9% in tensile strength and 47% in flexural strength. Furthermore, integrating biochar into LDPE composites enhances thermal stability, lowers the melt flow index (MFI), and boosts the hardness by 24.3% for the composite with 10% biochar content. Furthermore, biochar improves wear resistance and durability, with the LDPE10 composite exhibiting a friction coefficient that is 56.3% lower than pure LDPE. These findings indicate that biochar is a viable, cost-effective, and environmentally friendly filler for improving the performance of LDPE-based biocomposites for many varieties of applications.

Polymer Packaging through the Blending of Biowaste Oyster Shell and Low-Density Polyethylene: A Sustainable Approach for Enhanced Food Preservation.

This research delves into the impact of incorporating thermally treated oyster shell powder (TOS), a biowaste filler, into low-density polyethylene (LDPE) to develop a LDPE/TOS blend, aiming at enhancing food packaging materials. The LDPE/TOS blend portrays advantageous characteristics such as augmented mechanical strength, thermostability, crystallinity, water absorption, and improved hydrophobicity with TOS content up to 50%. Microstructure analysis reveals a transition from a sparse to a more interconnected structure, contributing to the amplified tensile strength. The blend demonstrates increased barrier properties against water vapor transmission, which is attributed to elongated diffusion paths induced by the TOS particles. Application of the blend material in vegetable preservation trials manifested a substantial reduction in water loss compared to pure LDPE or no packaging. This biowaste-based blend film extends the shelf-life of chicken significantly when compared to that of pure LDPE. Importantly, the LDPE/TOS blend exhibits excellent antibacterial properties against both Escherichia coli and Staphylococcus aureus.

Optimizing BiOCl concentration for enhanced LDPE performance: Investigation of structure, thermal stability, and optical characteristics

This research article presents a comprehensive study on enhancing the structural, thermal alongside optical properties of LDPE by incorporating BiOCl nanoparticles. LDPE nanocomposites were synthesized using the solvent casting technique, employing different concentrations of BiOCl (3, 5, and 7 wt.%) nanoparticles. BiOCl demonstrated crystalline anisotropic growth along the (110) plane under solvothermal treatment, enhancing the interfacial interaction with LDPE chains. This interaction reduces electrostatic inter-chain interactions, promoting alignment and crystallization of molecular chains and yielding a smooth morphology. The optimal BiOCl concentration is determined to be 5 wt.%, as higher concentrations lead to nanoparticle aggregations and weak interactions. Raman spectroscopy shows broadened intensity peaks in the nanocomposite with increasing BiOCl concentrations, indicating the presence of defects and oxygen vacancies. These findings offer promising prospects for photocatalytic applications. The thermal analysis reveals enhanced thermal stability, fire resistance, and insulation in the nanocomposites compared to pure LDPE. The incorporation of BiOCl increases activation energy, melting, and glass transition temperatures, highlighting their positive impact on enhancing the thermal properties of LDPE. The red shift in absorption peaks of LDPE nanocomposites indicates π-delocalization, suggesting small band gaps. Additionally, higher weight percentages of BiOCl nanoparticles in the LDPE matrix result in increased absorption intensities in the UV region, providing enhanced UV radiation protection, with a maximum absorption of 96% of UV light. The results include improved interaction, morphology, alignment, thermal stability, fire resistance, and UV protection of BiOCl: LDPE nanocomposite, with potential for diverse industries.

Investigating the thermal and mechanical properties of novel LDPE/TiO2 and LDPE/TiO2/CNT composites for 3D printing applications.

The development of new materials is essential for advancing technology and improving the quality of life. With new materials, we can create products that are stronger, more durable, and more efficient. The ongoing research and development of new materials for 3D printing applications continue to drive innovation in various fields, leading to improved products and processes with great benefits. The main goal of this work was to produce a functional filament with a 1.75-mm diameter that may be used for 3D printing. Composite materials were prepared using a low-density polyethylene (LDPE) resin as polymer matrix, and titanium dioxide (TiO2) and carbon nanotubes (CNT) as fillers in various ratios. Up to 15 wt% of TiO2 and 0.25 wt% of CNT were added. Some of the greatest difficulties with high filler content composites are achieving good homogeneity, and in the case of the 3D printing, greatest difficulties are producing the filament with a specific and stable filament diameter. During the 3D printing itself, the fillers can also often cause the nozzle clogging. This paper reports findings of thermal and mechanical properties of the LDPE/TiO2/CNT composites which are significant for the 3D printing process and the applicability of the composite materials. All of the planed composite materials are successfully prepared and 3D printed into the tensile test specimens. The melting point shift caused by the addition of fillers did not show consistent pattern at differential scanning calorimetry, as all of the samples had melting temperatures around 113.5 ± 1.4 °C. The addition of filler, according to the TGA, increased the threshold temperature for the material decomposition, in case of TiO2 5.4 °C increase, while TiO2 and CNT combination increased the threshold temperature for 6.8 °C. The results of the tensile test show a general increase trend with addition of TiO2 filler but do not show to a trend for the tensile strength as a result of the addition of CNT filler. The sample with highest TiO2 filler ratio of 15% (LDPE 15T0C) showed the greatest tensile strength of 14.5 MPa, compared to the 13.0 MPa of pure LDPE. The sample with 5% of TiO2 filler and 0.1% of CNT filler (LDPE 5T0.1C) showed the greatest elongation of 73.9%, compared to the 68.9% of pure LDPE.

Thymol@activated Carbon Nanohybrid for Low-Density Polyethylene-Based Active Packaging Films for Pork Fillets’ Shelf-Life Extension

Τhe replacement of food packaging additives and preservatives with bio-based antioxidant/antibacterial compounds has been a common practice in recent years following the trend of bioeconomy and nanotechnology. Such bio-additives are often enclosed in nanocarriers for a controlled release process. Following this trend in this work, a thymol (TO)-rich activated carbon (AC) nanohybrid was prepared and characterized physicochemically with various techniques. This TO@AC nanohybrid, along with the pure activated carbon, was extruded with low-density polyethylene (LDPE) to develop novel active packaging films. The codenames used in this paper were LDPE/xTO@AC and LDPE/xAC for the nanohybrid and the pure activated carbon, respectively. X-ray diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy measurements showed high dispersity of both the TO@AC nanohybrid and the pure AC in the LDPE matrix, resulting in enhanced mechanical properties. The active film with 15 wt.% of the TO@AC nanohybrid (LDPE/15TO@AC) exhibited a 230% higher water/vapor barrier and 1928% lower oxygen permeability than the pure LDPE film. For this active film, the highest antioxidant activity referred to the DPPH assay (44.4%), the lowest thymol release rate (k2 ≈ 1.5 s−1), and the highest antibacterial activity were recorded, resulting in a 2-day extension of fresh pork fillets’ shelf-life.

A pyrolysis model for the thermal decomposition of low-density polyethylene blended with ammonium polyphosphate and pentaerythritol

In this work, a semi-empirical pyrolysis model is developed to predict the thermal decomposition behavior of an intumescent fire retardant (IFR) system consisting of ammonium polyphosphate/pentaerythritol (APP/PER) with the ratio 3:1 (wt/wt) in a low-density polyethylene (LDPE) matrix. This work is based on a previously developed semi-global reaction mechanism for the degradation of LDPE and APP/PER, which consists of two consecutive first-order reactions for the LDPE and five first and second-order reactions for the APP/PER combination. The apparent properties that define heat transport inside the pyrolyzing solid are determined via inverse modeling of cone calorimeter experiments for the pure LDPE and then for the complete IFR system. This is achieved by using the Shuffled Complex Evolution optimization algorithm. The flame heat flux in the cone calorimeter experiments is also evaluated by targeting the heat release rate (HRR) data in the optimization process of one of the cone radiative heat setups. The optimized parameters and flame heat feedback are in line with the literature and the robustness of the model is assessed by a comparison with the experimental data for a wide range of cone heat fluxes. Ignition times and peaks of HRR and total HRs are within the engineering accuracy whatever the flux conditions for both pure LDPE and the IFR system.

Mechanical, thermal, and morphological properties of low-density polyethylene nanocomposites reinforced with montmorillonite: Fabrication and characterizations

Nanoparticle incorporation in polymeric matrices to generate polymer nanocomposite with the intention of maximizing the “nano-effect” derived from the nanoparticles and minimizing the drawbacks of the polymer is an emerging field of research. In this study, low-density polyethylene (LDPE) was mixed with varying concentrations of montmorillonite (MMT) nanoclays to create a polymer nanocomposite with desirable characteristics. Composite sheets with nanoclays contents of (0, 1, 2, 3, and 4 wt%) were prepared for hardness, tensile-fractography, thermal conductivity, and tensile testing (elongation and stress-at-break). The results showed that, according to scanning electron microscope (SEM) study, LDPE has a low flexibility temperature and is prone to corrosion. For larger MMT filler loadings (>3% wt), tensile-fractography showed nanoclays particle micro-aggregation. The pure LDPE sample fracture’s tensile-fractography showed plastic deformation. MMT/LDPE samples with 3% wt hard MMT filler have brittle fractures without appreciable plastic deformation. Thermal conductivity test results show that LDPE/MMT composite thermal conductivity decreased with increasing clay concentration. The thermal conductivity values were reduced from a value of 0.13 W/m.K to a value of 0.039 W/m.K when reinforced with 0% wt to 3% wt filler loading, respectively. With 4% wt filler loading, LDPE/MMT composites had the highest shore hardness at 47.4. Yet, tensile tests indicated that increasing clay content improved the composite’s characteristics. At modest loading percentages (1–2 wt%), tensile results were excellent. Furthermore, the elongation at break of the unadulterated LDPE was reduced by 20% and 30% after introducing 1% wt and 2% wt of MMT as reinforcement additives, respectively. Hence, MMT clay can improve the mechanical properties and thermal insulation of LDPE polymer matrix.

Photocrosslinking of ethylene‐vinyl acetate (EVA)–polyethylene‐octene (POE) copolymer containing halogen‐free flame retardants

AbstractPhotocrosslinking of polymers for industrial applications show undoubted advantages related to the mild conditions needed and the economical equipment. However, some issues include: the use of (i) mercury lamps as light sources, which poses concerns about safety and energy consumption, (ii) typical additives, such as halogen‐free flame‐retardant fillers (HFFR) are powdered materials, which can scatter UV photons and avoid a deep penetration of the light. In this study, we explore the UV‐curing of an innovative EVA‐POE blend containing hydrotalcite and aluminum hydroxide as HFFR in the presence of a 370‐nm UV LED, namely Ekopren® XI1321, a plastic used as coverage for electric cables. Two commercially available photoinitiators (benzophenone and ethyl Michler's ketone) were analyzed as well as two crosslinking coagents widely used in industry, that is, triallyl cyanurate and trimethylolpropane trimethacrylate. A comparison with pure EVA and LDPE was performed to show a higher cross‐linked content of the proposed blend, even in the presence of light scattering mineral fillers at high concentration.

A new bio‐based flame retardant simply synthesized: Improving the flame retardancy and thermal stability of low‐density polyethylene together with melamine cyanurate

AbstractA novel bio‐based flame retardant, MHPA, was synthesized with magnesium hydroxide (MH) and phytic acid (PA) and was added to low‐density polyethylene (LDPE) with melamine cyanurate (MCA) to investigate the flame retardant, mechanical property and thermal stability of the LDPE composites. The limit oxygen index (LOI) and cone calorimeter test (CCT) results showed that the combination of MHPA and MCA can increase the LOI of LDPE composite to 21.6%, and its peak of heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) values reduced by 46.8%, 20%, and 31.6% respectively compared with pure LDPE, while the residue after CCT was increased to 24.4%. Moreover, the addition of MCA can effectively improve the thermal stability of LDPE/MHPA composites and suppress their early decomposition.

Effectiveness of co-solvents in boosting LDPE depolymerization in diesel

Plastic pollution is increasing as the management of plastic waste has become a global challenge. The possibility of turning plastic waste into fuel at low temperatures has been successfully reported in our recent research. However, the low recycling ratio and higher fuel viscosity were the main limitations. The focus of this research was to improve the depolymerization process of low-density polyethylene (LDPE) in diesel by introducing various amounts of co-solvents. The resultant product can be directly used as transportation fuel without further refining. Several co-solvents were examined in the LDPE/diesel blend: di-butyl ether, a-pinene, toluene, and o-xylene under various pressures (1, 5, 10, and 20 bar). The quality of fuel products was evaluated using differential scanning calorimetry (DSC), an Anton Paar MCR302 rheometer, and a bomb calorimetric thermometer. The degradation behavior of LDPE in diesel is affected by the co-solvents, and the highest dissolution occurred with 10 wt% co-solvent in diesel. Among the tested reactor pressures, the most effective pressure was 10 bar resulting in 92.4% LDPE dissolution. The addition of co-solvents improved the quality of the fuel blend in terms of the kinematic and dynamic viscosities compared with the PD/LDPE blend. The higher heating value (HHV) of the resultant fuel blend was higher compared to non-solvent, pure diesel-derived LDPE fuel blends. The values of HHV for PD, PD/LDPE (10% a-pinene and 1 bar), PD/LDPE (10% xylene and 1 bar), and PD/LDPE (10% xylene and 10 bar) were 45.24 MJ/kg, 45.60 MJ/kg, 46.05 MJ/kg, and 46.14 MJ/kg, respectively.

Green synthesized Pd-Ni nanohybrids for controlled degradation of low-density polyethylene films

This study reports the potential application of Pd-Ni bimetallic nanoparticles as a photo-catalyst for the degradation of low-density polyethylene films. Ananas comosus extract was used in the biosynthesis of Pd-Ni bimetallic nanoparticles. The extract’s phytochemical compounds served as reducing and stabilizing agents, facilitating the bioreduction process. The as-synthesized Pd-Ni bimetallic nanoparticles were incorporated into LDPE films with or without solar radiation. The reaction kinetics was used to observe the polyethylene films’ pattern of degradation. Photo-induced weight loss, FTIR, SEM, and TGA analyses were used to characterize the pure LDPE and nanocomposite films. After 210 h of solar irradiation, the weight loss of solar-treated Pd-Ni nanocomposite films and pure LDPE lost 40.04 ± 2.3% and 8.60 ± 0.5%, respectively. While the untreated Pd-Ni nanocomposite (dark) showed a weight loss of 1.79 ± 0.39%. The FTIR and SEM analyses confirmed the new peaks, carbonyl group generation, and formation of cavities on the polymer matrix of solar-treated Pd-Ni nanocomposite. However, this study suggests the use of Pd-Ni bimetallic nanoparticles as a photo-catalyst to enhance the photocatalytic degradation of low-density polyethylene, which could be useful in the polymer industry to combat environmental pollution.

The Influence of Different Hematite (α-Fe2O3) Particles on the Thermal, Optical, Mechanical, and Barrier Properties of LDPE/Hematite Composites.

There is an increasing need to develop new polymer composites with improved properties compared to conventional pure polymer materials. This work aims to develop composites of low-density polyethylene (LDPE) and iron oxide hematite particles. For this purpose, different types of hematite particles with well-defined shapes and narrow size distributions were synthesized: HC2 sample with pseudocubic hematite particles of an average diameter of 1020 nm, HE1 sample with ellipsoidal hematite particles of an average diameter of 533 nm, and HS1 sample with spherical hematite particles of an average diameter of 168 nm. The mass fractions of hematite in the composites were 0.25%, 0.5%, and 1%. Prepared LDPE/hematite composites were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The mechanical and barrier properties were also studied. The obtained results showed that all prepared composites have improved properties compared to the pure LDPE, especially the composites with pseudocubic hematite particles of well-defined shapes. The results of this study indicate that LDPE/hematite composites can be promising materials for a wide range of applications, especially as packaging materials where improved thermal and mechanical properties as well as resistance to ultraviolet (UV) irradiation are required.

Ethylene scavenging film based on low-density polyethylene incorporating pumice and potassium permanganate and its application to preserve avocados

The ethylene scavenging film was prepared to extend the shelf life of fresh fruit and vegetables. This film consisted of low-density polyethylene (LDPE) as matrix, the mixture of pumice and potassium permanganate (KMnO4) (weight ratio: 10 to 1) (pumice acted as the support of KMnO4) as active agents, and maleic anhydride grafted polyethylene (PE-g-MA) as compatibilizer. The study revealed that low loadings of active agents (1 wt% and 3 wt%) were evenly distributed in the LDPE matrix and were beneficial to the improvement of the mechanical property, crystallinity, and gas barrier performance against oxygen and water vapor. In addition, the film (thickness: 60 μm) incorporating 3 wt% active agents had an ethylene scavenging capacity of 7.31 μmol/(25 in2) within 12 d at 25 °C. Further, the ethylene scavenging film with 3 wt% active agents preserved avocados well for 20 d at 25 °C, inhibited the ethylene and carbon dioxide (CO2) concentrations in the packaging headspace, and reduced the flesh firmness loss, while the shelf life of avocados packaged with pure LDPE film was only 10 d.