HDPE Films Research Articles

Charge stabilization in corona electrets made of HDPE film due to the formation of deep electron traps during its orientational stretching

Charge stabilization in corona electrets made of HDPE film due to the formation of deep electron traps during its orientational stretching

Enhancing mechanical and rheological properties of HDPE films through annealing for eco-friendly agricultural applications

Abstract A composite of high-density polyethylene/ultra-high molecular weight polyethylene (HDPE/UHMWPE) was synthesized via a high-temperature melting process. We specifically examined the effects of annealing on the morphological and rheological properties of the composite. Using scanning electron microscopy and advanced rotational rheometry, we determined that annealing notably alters the composite’s microstructure, with a reduction in pronounced features post-treatment. Rheologically, UHMWPE content significantly enhanced mechanical properties, particularly in storage modulus (G′), loss modulus (G″), and complex viscosity (|η*|), which aligned with scaling law principles. Our findings highlight a distinct improvement in mechanical properties post-annealing, underscoring the potential of UHMWPE in enhancing polymer composite performance. The scaling laws relating G′, G″, and |η*| with UHMWPE were identified as follows: (1) pre-c e: G′ ∼ c 0.2, g″ ∼ c 0.07, |η*| ～ c0.07 and (2) post-c e: G′ ∼ c 1.20, g″ ∼ c 0.6, |η*| ∼ c 0.64, with a forward shift in c e noted after annealing. The addition of UHMWPE significantly enhanced the system’s properties, particularly after annealing. This study offers crucial insights into optimizing HDPE plastic films for enhanced durability and sustainability, ideally suiting them for eco-friendly agricultural uses.

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.

Biodegradation Patterns of Composite Materials Based on High-Density Polyethylene and Starch

Abstract—The degradation properties of high-density polyethylene composites filled with amylose and amylopectin polysaccharides were studied. At low dosages of the polysaccharides (0.5% wt/wt), no change in viscosity, molecular weight and physical and mechanical characteristics of HDPE samples were observed, while an increase in the proportion of the natural filler (starch) to 1 and 5% resulted in a decrease in mechanical properties, although the values of deformation and strength parameters satisfied the minimum necessary requirements for film packaging. After incubation in soil for one year, the sample of HDPE film with a corn starch content of 5% (wt/wt) was found to undergo the greatest changes in its properties. The study of ability of aerobic microorganisms to carry out the surface transformation of the studied film composites revealed that bacteria of the genus Bacillus efficiently colonized the polyethylene-starch composites. Among the identified microorganisms, micromycetes of the genus Penicillium and Trichoderma caused the most pronounced changes in the structure of the studied polymer composites, and the greatest effect was achieved in the case of synergistic action of different micromycetes genera.

Microplastic formation and simultaneous release of phthalic acid esters from residual mulch film in soil through mechanical abrasion

The application of plastic mulch film could effectively enhance the productivity of facility agriculture. However, releasing microplastic and phthalate from mulch films in soil has attracted increasing concerns, and releasing characters of microplastic and phthalate from mulch films during their mechanical abrasion remains unclear. This study elucidated the dynamics and impact factors of microplastic generation, including the thickness, polymer types and ageing of mulch film during mechanical abrasion. Releasing characters of the di(2-Ethylhexyl) phthalate (DEHP), a common type of phthalate in soil, from mulch film during mechanical abrasion were also explored. Results showed that 2 pieces of mulch film debris increased to 1291 pieces of microplastic after five days of mechanical abrasion, with exponential growth in the microplastic generation. After mechanical abrasion, the thinnest (0.008 mm) mulch film completely transformed into microplastics. However, the thicker mulch (>0.01 mm) suffered slight disintegration, making it feasible to be recycled. The biodegradable mulch film discharged the most microplastics (906 pieces) compared with the HDPE (359 pieces) and LDPE (703 pieces) mulch film after three days of mechanical abrasion. In addition, the mild thermal and oxidative ageing could result in 3047 and 4532 pieces of microplastic emissions from mulch film after three days of mechanical abrasion, which were ten times more than the original mulch film (359 pieces). Furthermore, negligible DEHP was released from mulch film without mechanical abrasion, while the released DEHP significantly correlated with generated microplastics during mechanical abrasion. These results demonstrated the crucial role of mulch film disintegration in phthalate emissions.

Influence of ultraviolet and chemical treatment on the biodegradation of low-density polyethylene and high-density polyethylene by Cephalosporium strain.

In the present work, the potential of Cephalosporium strain in degrading the pre-treated (ultraviolet irradiation followed by nitric acid treatment) low-density polyethylene and high-density polyethylene films was investigated. Our observations revealed a significant weight reduction of 24.53 ± 0.73% and 18.22 ± 0.31% in pre-treated low-density polyethylene and high-density polyethylene films respectively, after 56days of incubation with the Cephalosporium strain. Changes in the physicochemical properties of the mineral salt medium (MSM) were studied to assess the extent of biodegradation. The pH of the MSM decreased gradually during the incubation period, whereas its total dissolved solids and conductivity values increased steadily. Fourier transform infrared spectroscopy (FTIR) indicated the formation of hydroxyl and C = C groups in biodegraded low-density polyethylene films, while in the case of biodegraded high-density polyethylene films it indicated the [Formula: see text]CH2 stretching. Furthermore, the thermogravimetric analysis (TGA) revealed an enhancement in the thermal stabilities of both the LDPE and HDPE films post the biodegradation. Modifications in the polymer surface morphologies after UV irradiation, chemical treatment, and biodegradation steps were visualized via scanning electron microscopy (SEM) analysis. All our observations confirm the ability of the Cephalosporium strain in biodegrading the pre-treated LDPE and HDPE films.

Theoretical Analysis of Tubular Film Extrusion and its Applications for HMW-HDPE

Abstract Theoretical analysis of the tubular film extrusion using computer simulation presented has been used to preduct bubble shapes, velocity profiles and stretching stresses. From the theoretical analysis, maximum stretching stresses, which are closely related to film physical properties, were predicted under various process conditions. This theoretical analysis was applied to high molecular weight HDPE tubular film process. It was found that high strength HDPE film can be produced by maintaining high stretching stress, which is obtained on the conditions of high out-put rate, high take-up speed and low temperature by reducing the heat generated by viscous dissipation. Further, the processability of HDPE film produced using bubble stabilizing equipment was discussed.

Potential of low‐dose aqueous ozone treatment and packaging to extend quality and shelf‐life of green pea pods under cold storage

Appropriate packaging, low temperature and sanitization have immense potential in maintaining postharvest quality of whole green pea pods throughout the supply chain. Untreated green pea pods packed in perforated 38 µm LDPE, 25 µm PP and 25 µm HDPE films were stored at 5, 10, 15°C with 80% ± 5% RH for 12 days. Regular assessment of respiration rates, weight loss, firmness, color change, and biochemical attributes indicated significantly better quality in LDPE bags at 5 ± 1°C with 80% ± 5% RH. The synergistic effect of sanitization using sodium hypochlorite solution (100 ppm/2 min) and aqueous ozone (2 mg L−1/2 min) modified atmosphere packaging (O2:3%–5%, CO2:5%–10%) and low temperature (5°C) on microbial load, weight loss, respiration rate, and total color change was significant at 5% level with a slight change in biochemical attributes along with extended shelf-life of 16 days as compared to 12 days for tap-water washed samples. Novelty impact statement Green pea pods are prone to substantial losses during postharvest handling operations. Sanitization treatments and packaging materials have potential to slow down metabolic activity, reduce rates of respiration and transpiration, prevent induction of spoilage causing bacteria/microorganisms, stimulate the Phenylalanine Ammonia Lyase (PAL) activity, and effectively delay the decay and senescence of vegetables. The present study suggests ozone sanitization, packaging in polymeric pouches and storage under recommended low temperature conditions as promising interventions for retention of the postharvest quality of green pea pods with extended shelf life.

Oxygen plasma irradiation-induced surface modifications on HDPE and PET polymeric films

Oxygen plasma irradiation-induced surface modifications on HDPE and PET polymeric films

Effect of Packaging Materials on the Colour, Foaming Properties and Shelf Life of Foam-Mat-Dried Starch–Albumen Powder

Starch–albumen powder (SAP) as a new food ingredient combines foaming properties of egg albumen and stabilisation properties of starch in food products. Although foam-mat drying has been reported to modify powdered foods properties, its effect on SAP storage stability is yet to be reported. This study determined the shelf life of SAP using high- and low-density polyethylene (HDPE and LDPE) bags. Stored SAP was analysed for moisture content (MC), colour, foam capacity and foam stability (FC and FS) and microbial load for 12 weeks at 28 ± 1 °C and 85% RH. The shelf life of SAP was predicted from the isotherm curve. Water vapour permeability coefficient of HDPE and LDPE films was 5.2835 × 10–14 and 1.335 × 10–14, respectively. The MC of SAP in HDPE and LDPE increased with storage period from 6.9 to 11.96% and 6.9–19.29%, respectively. Lightness (L*) and greenness (− a*) of SAP reduced for HDPE and LDPE while yellowness (b*) increased with storage period. Colour stability was higher in HDPE than LDPE and FC and FS was significantly affected by storage period (p < 0.05). Bacteria and fungi count ranged from 26 × 101 to 82 × 106 and 2 × 101 to 19 × 102 cfu/ml for HDPE and 26 × 101 to 63 × 108 and 22 × 102 to 87 × 102 for LDPE. The estimated shelf lives of SAP were 343 and 213 days for HDPE and LDPE, respectively. In conclusion, storage period affected the colour and microbial stability of SAP for both packaging materials. However, HDPE extended the shelf life and retained the foaming properties of SAP than LDPE.

Fabrication of anti-bacterial, hydrophobic and UV resistant galactomannan-zinc oxide nanocomposite films

The use of organic and inorganic materials to prepare membrane materials with functional performance has attracted much attention in recent years. In this paper, galactomannan (GM) is used as raw material and nano zinc oxide (nano-ZnO) is used as functional modifier to prepare GM based food packaging films. The properties influence for films of different nano-ZnO content were studied. The obtained nano-ZnO/GM composite films showed superior hydrophobicity and almost absorbing all UVA and UVB. The tensile strength of composite film was superior to plastic HDPE film, and the oxygen barrier properties of composite films were better than PVC plastic film. The composite films against E. coli and B. subtilis showed great antibacterial properties. The antibacterial effect was demonstrated by Shine-Muscat grapes after storage for 5 days. The final prepared GM based functional food packaging film provides a foundation for the potentials for futural plastic packaging alternatives.

Investigation and modeling of odors release from membrane holes on daily overlay in a landfill and its impact on landfill odor control

In the present work, we studied the NH3 and H2S odor fluxes between the exposed working area and the HDPE covering film holes of the daily overlay in an actual landfill site with a daily operating area of 1600 m2 in Hangzhou, China. We showed that the odors were released from the membrane pores and the average concentrations of NH3 and H2S release reached 109.6 ± 56.6 and 86.0 ± 31.1 mg/m2/s, respectively. These concentrations are 43.8 and 57.3 times the exposed working surface. Furthermore, mathematical modeling based on the total amount of odor release revealed that there was a linear positive correlation between the total odor amount and the landfill operation area. However, the maximum number of film holes allowed on the covering layer has nothing to do with the working area and exposed working time, which is mainly determined by the HDPE film width in terms of ensuring the deodorizing effect of the covering operation. If the HDPE film with a width of more than 4 m is used, the number of film holes allowed within 100 m is more than 8. Therefore, in order to reduce the odor, the appropriate film width should be selected according to the actual operating conditions such as the mechanical operation level at the time of welding, the design of the landfill site, and the operational norms. This study explores the effect of film hole quantity of the daily cover in the landfill on the odor release from the landfill, which can provide an important reference for the design, operation, and decision-making of the daily cover operation of the sanitary landfill.

Consumer preferences and physical evaluation of shortbread stored in different packaging

AbstractThe work aimed to assess the quality of crackers and sponge, vanilla and butter biscuits stored for 28 days in an original packaging, plastic box (Polypropylene 0.2 mm), food film (HDPE 10 mm) and paper bag. Sensory tests did not prove influence of packaging on the product quality. The authors observed: water desorption for sponge biscuits (ca. 5%), water absorption of 0.06%–1.84% for other biscuits, hardness increase of 20% ÷ 40% for sponge biscuits, hardness decrease by 10% ÷ 23% for vanilla biscuits, hardness increase for crackers in original packaging (+46%) and paper bag (+20%), hardness decrease for samples in food film (‐ 8%) and plastic box (−26%), hardness change for butter biscuits (from +9% to −15%). Complex assessment proved that HDPE film and PP box most effectively protected the product against the environmental influence. Lengthening the biscuit lifetime requires introduction of innovations regarding the manufacturing technology and packaging design/structure. Presented tests indicate both the advantages and disadvantages of typical packaging, seen from the consumer perspective. It must be remembered that “manufacturer”—“consumer requirements” relation is one of the most important stages of product assessment and development. The authors believe that the obtained results are useful for packaging producers that are new on the market, but also for those which are experienced.

Relationship between morphological changes and mechanical properties in HDPE films exposed to a chlorinated environment

The effect of an oxidative environment on HDPE morphology and mechanical performance were studied. Extruded HDPE film samples of thickness (~70 μm) (as-extruded and heat treated) were exposed to 5 ppm chlorinated water at 70 °C for up to 1250 h. As extruded samples had an initial crystallinity of 75% and heat treated samples an initial crystallinity of 83%. The initial molecular weight for all samples was approximately 200 kg-mol−1. Changes in morphology and mechanical properties as a function of exposure time were evaluated. The most significant changes occur after 500 h exposure. Fourier-Transform Infrared Spectroscopy (FTIR) spectrum data indicate an increase in the carbonyl functional groups with increased exposure time. As the exposure time increased, the molecular weight (Mw) of the samples decreased, with Mw of the as extruded samples being consistently less than that of the heat treated samples. Crystallinity increased nearly linearly with exposure time. XRD data reveal that the interlamellar spacing decreases significantly between 500 and 750 h exposure, from 102 to 85 Å. Mechanical test data show a similar trend with tensile strength and strain at break. After exposure time of 500 h the samples become increasingly brittle. The combined morphology and mechanical data demonstrate, independent of exposure time, that there is a critical combination of molecular weight (<85 kg-mol−1) and interlamellar spacing (<85 Å) corresponding to the transition from ductile to brittle behavior.

Glue wood veneer to wood-fiber–high-density-polyethylene composite

Wood-fiber-reinforced thermoplastic plastic composite is a type of environmentally friendly material. However, its application in furniture and interior decoration is limited due to its lack of wood texture. In this work, wood-veneer-facing decoration was explored to beautify the composite's appearance. Surface planning and slight sanding were applied to wood-fiber–high-density-polyethylene (WF-HDPE) composite. Polyvinyl acetate emulsion was used as adhesive, and the veneer-faced WF-HDPE composite floor was prepared by the hot-pressing method. The bonding line was analyzed with Fourier-transform infrared spectroscopy and scanning electron microscopy. Planning plus sanding treatment removed the HDPE film on the composite surface and exposed the wood fibers to react with the adhesive. The rough surface provided all decorative samples bonding strengths higher than 0.9 MPa. The bond line could stand 63 °C water soaking for 3 h without delamination. The hot-pressing temperature exhibited a significant effect on surface bonding strength. The optimized hot-pressing technique included a hot-pressing temperature of 80 °C, a hot-pressing time of 10–20 min, and a hot-pressing pressure of 0.2 MPa. With this combination, the surface-decorative veneer retained the beauty of its original color.

Environmental scenarii for the degradation of oxo-polymers

The fate of oxo-polymers in nature is strongly dependent on environmental conditions, mainly on the intensity and duration of sunshine, which vary with the season and the climate. In this work, we report the effect of different scenarii on the production and the molecular composition of oligomers released from oxo-biodegradable HDPE films. Under our experimental conditions, the duration of accelerated weathering corresponded to a period of 3 months to 3 years of exposure to outside conditions under temperate climate. In addition, the oligomers were extracted in three different solvents: i) water to mimics the natural environment; ii) acetone and chloroform to identify oligomers trapped in the polymer matrix. The combination of high-resolution mass spectrometry and 1H NMR spectroscopy gives an extensive picture of the relative concentrations and the structural compositions of the extracted oligomers in the different tested conditions. In particular, the masses, the number of oxygen and carbon atoms could be determined for up to 2283 molecules. Globally the concentration and the size of oligomers increased with the duration of extraction, the level of aging of the polymer and the use of non-polar solvents. Surprisingly, the presence of highly oxidized molecules in acetone and chloroform extract, suggested an important swelling of HPDE films in these solvents and a better diffusion of these oligomers in the matrix. In nature, the biodegradability of oligomers could result from processes occurring both at the molecular (oxidation) and the macromolecular (diffusion and release) levels.

Effects of Packaging on Shelf Life and Postharvest Qualities of Radish Roots during Storage at Low Temperature for an Extended Period

To investigate the effects of packaging on the quality aspects of radish, Korean radish roots (Raphanus sativusL. var. Kwandong) were stored at 0°C after different packaging treatments such as keeping in paper cartoon box (control), keeping in plastic crates (PC), packaging with micro perforated HDPE film in PC (HDPE + PC), curing followed by keeping in PC (Curing + PC), and curing followed by packaging with micro perforated HDPE film in PC (Curing + HDPE + PC). Weight losses of radish roots were remarkably lower (&lt;3%) in both HDPE film packaged samples compared to that of control (10%) or without film (≈18%).L⁎values, whiteness index, total soluble solids, and flesh and skin firmness were better maintained in Curing + HDPE + PC treatment compared to other treatments. Lower color difference values were also found in this treatment. Both film packaged samples had lower scores of black spot, surface shrinkage, and fungal infection incidence which revealed significantly longer marketable periods. HDPE film packaged samples exhibited longer shelf life more than one and two months compared to control and unpacked samples, respectively. Results suggest that HDPE film packaging can extend postharvest life of radish while curing might have little but beneficial effects in maintaining the quality characteristics. To our knowledge, this is the first report on quality evaluation of Korean radish during an extended storage period simulating the Korean industrial practices.

Micromechanics of the internal bond in wood plastic composites: integrating measurement and modeling

In this study, an integrated approach combining experimental measurements and numerical modeling was used for characterization of load transfer in the wood/matrix interface in wood plastic composites (WPCs). The experimental methodology was based on optical measurement of surface displacements and strains in model WPC specimens subjected to tensile loads. The model specimens consisted of thin HDPE films with single embedded wood particles. The optical measurement of surface strains was based on the digital image correlation principle. The material point method was used for morphology-based numerical modeling of the loaded specimens. The exact location and morphology of the embedded particle determined by X-ray computed tomography were used as input for the numerical model. Imperfect interface characteristics, reflecting the efficiency of the load transfer through the interface in the numerical model of the composite, were determined using inverse problem methods. Good agreement was obtained between the simulated and measured strain maps determined on a number of specimens including particles with various orientations to the loading direction using the same values of interface parameters.

Corrigendum to “Investigating the Degradability of HDPE, LDPE, PE-BIO, and PE-OXO Films under UV-B Radiation”

Corrigendum to “Investigating the Degradability of HDPE, LDPE, PE-BIO, and PE-OXO Films under UV-B Radiation”

Influence of precursor film microstructure on properties of HDPE microporous membranes prepared by stretching

ABSTRACTOriented HDPE films having a stacked lamellar morphology were prepared to develop microporous membranes through cast film extrusion followed by stretching. Applying higher draw ratios (DR) and annealing the cast films improved crystal alignments remarkably. It was shown the improvement in c‐axis orientation upon annealing was more significant for the films prepared with lower DR. Furthermore, applying Raman spectroscopy, the amorphous mass fraction of the films was obtained. Subsequently, considering a three‐phase structure (i.e., crystal, amorphous and interphase), the interphase content of the films was also determined. A distinct DR dependence of the interphase content was noticed. It was observed that in addition to crystal perfection upon annealing, the amorphous phase fraction was also decreased due to possibly increase in free volume, promoting lamellar separation and cavitation during the subsequent stretching step. SEM images of the membranes surfaces as well as their normalized water vapor transmission rate (WVTR) values indicated a more uniform pore formation and increased permeability with DR. Furthermore, it was found that lower interphase content in the films with higher DR favors lamellar separation. However, permeability in the stretched precursor films with DR higher than a certain level (DR = 93) was not improved significantly. Moreover, crystallinity and crystal orientation of produced membranes were investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44725.