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Polymer composites with low dielectric properties and excellent radio transparency are essential for high signal transmission rates and high device integration. However, creating dielectric polymer composites with high radio transparency is a challenging task. This work presents comparative results of studying the dielectric loss, permittivity and radio transparency of composite materials, such as aramid-epoxy composite (AEC), glass fiber (GF), carbon fiber reinforced plastic (CFRP), and ultra-high molecular weight high-density polyethylene (UHMWPE). Based on the experimental results, the following transmission percentages were established for various materials: CFRP – 2.45%, AEC – 79.43%, UHMWPE – 80.16%, and GF – 78.88%. The dielectric loss tangent angle of carbon fiber is significantly higher compared to other polymer composites, UHMWPE exhibits the lowest tangent angle values, and AEC and GF have stable and low dielectric loss. The obtained polymer composites demonstrated low dielectric permittivity values: AEС 2.9, UHMWPE 2.56, and GF 3.64. [ABSTRACT FROM AUTHOR]

The influence of carbon nano fiber (CNF) along with organically modified nanoclay (OMMT) on the final properties of high density polyethylene (HDPE) hybrid nanocomposites has been investigated. The hybridized nanocomposites were prepared in a twin screw extruder by melt mixing to achieve better dispersion. The effect of nano fillers on the mechanical, thermal, rheological, and morphological properties has been reported. The incorporation of OMMT along with CNF slightly improved the mechanical properties of the resultant hybrid nanocomposite due to the good adhesion between the filler and matrix. On the other hand, as shown in DSC results, increasing reinforcing filler quantity has no significant influence on the thermal properties such as melting and crystallization temperatures. Thermogravimetric analysis (TGA) results have shown that increasing filler content in the hybrid nanocomposite matrix has enhanced drastically the thermal stability of the neat HDPE. Similarly, the rheological behavior of the hybrid system showed significant increase in the viscosity due to the synergetic effect. A marginal increase in moduli and complex viscosity was observed in the hybrid system, while loss tangent was found to be decreased due to the increase in the stiffness. The morphological features of nanocomposites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanoscale images showed the well dispersion of filler nanoparticles without any prominent aggregation, which further indicates the compatibilizing ability of nanofillers within the HDPE matrix. [ABSTRACT FROM AUTHOR]

The effect of UVC (254 nm) treatment on the mould-free shelf-life of par-baked wholemeal, rye and six-grain bread was examined. Currently, these breads are par-baked, wrapped in high-density polyethylene (HDPE)-foil and transported or stored at room temperature for a couple of days before being full-baked and sold/consumed. Generally, after five days, these breads show signs of mould spoilage. A shelf-life increase in one or more days would already offer immense economical and logistic benefits for the baker or retailer. In this study, the parameters fluence rate (irradiation intensity), fluence (UV dose), distance to the UV-lamp (DTL) and number of layers of a common wrapping HDPE-foil (20 µm) were diversified. The breads were subjected to a UVC treatment (0–2502 mJ/cm²), packed and stored at room temperature for a period of 15 days (21.5 ± 0.8 °C). Similar as for the breads, agar plates with mould spores of Aspergillus niger, Aspergillus montevidensis and Penicillium roqueforti were UVC treated (0–1664 mJ/cm²) and checked daily for visible mould growth during 15 days (25 °C). Aspergillus niger showed the strongest resistance towards UVC, a fluence of 800 mJ/cm² was needed to inhibit growth during 15 days of storage, whereas for P. roqueforti and A. montevidensis, respectively, UV levels of 291 and 133 mJ/cm² were found sufficient. Furthermore, the shelf-life of wholemeal, rye and six-grain bread can be prolonged from 5 to 6, 8 and 9 days, respectively, using 2502 mJ/cm². The effect of higher UVC dosage on shelf-life reached a maximal level and was strongly impacted by the wide spread on data of mould-free shelf-life. The main factors influencing the potential of UV decontamination were the rough bread surface, differences in DTL, the possibility of post-contamination and UV permeability of packaging materials. [ABSTRACT FROM AUTHOR]

Microplastics (MPs), measuring less than 5 mm, have been causing environmental concerns in aquatic ecosystems, and less work has been done in indoor environments, where humans spend most of their lives. This finding revealed a diverse range of MPs within indoor house dust samples. These MPs encompassed fibres, fragments, foams, pellets and films. Due to the ubiquity of textile-based items, fibres are the most common indoor MP. The MPs have different colours like black, red, blue, yellow, white and brown. The study revealed there were substantial differences in MP sizes across different households. The average size range was 178.87–3713.99 µm. One hundred eighteen particles were identified as MPs. The study identified 22 types of MPs, shedding light on these materials' extensive sources and applications in everyday household items. MPs in indoor environments raise concerns about potential human exposure and underscore the need for further research into their health implications. The MPs found in most indoor house samples were low-density polyethylene, polyethylene, polypropylene, polyamide, polyvinyl chloride, high-density polyethylene and polystyrene. Carbon, nitrogen, fluorine, sodium, sulphur, potassium, calcium, zinc, oxygen and magnesium were the common elements in all indoor house dust samples. Compared with the active sampling, slightly more work has been done on the indoor house dust samples. [ABSTRACT FROM AUTHOR]

Okra hessian cloth and Sunn hemp hessian cloth were prepared and treated with 5, 10, and 15 wt% alkali solutions for 1 h. The optimized concentration of alkali is 10 wt%. The untreated and treated hessian cloths reinforced high-density polyethylene (HDPE) composites were then prepared using the compression molding method. Alkali-treated, and 55 wt% fiber contents reinforced composites showed improved mechanical properties among 40, 45, 50, 55, 60, and 65 wt% fiber contents composites. 55 wt% fiber contents reinforced composites were then irradiated under gamma-ray at doses 2.5–7.5 kGy at the rate of 6 kGy/h. According to the X-ray diffraction analysis results, only alkali-treated Okra reinforced, and Sunn hemp-reinforced HDPE composites had higher crystallinity values than untreated and irradiated composites. Surface micrographs showed that the Okra-HDPE and Sunn hemp-HDPE had better matrix and fiber attachment. Cross-linking between the two varieties of fibers and matrix was seen using Fourier-transform infrared (FTIR) spectroscopy. Both irradiated composites exhibited greater hydrophobicity in their water intake characteristics compared to untreated and alkali-treated composites. The tensile strength (TS) value of Sunn hemp composite for 5 kGy gamma-ray irradiation dose is 68 MPa, which is 14% and 42% higher than that of treated and untreated composites, respectively. For comparison, the TS value for 5 kGy dose irradiated Okra composite is 66 MPa, which is 17% and 44% higher than that of treated and untreated composites, respectively. Young's modulus (Y) values of irradiated Okra composite and irradiated Sunn hemp composite showed higher values than that of other composites. Both irradiated composites have better thermal and structural characteristics than untreated and alkali-treated composites. [ABSTRACT FROM AUTHOR]

Untreated and alkali-treated Sunn hemp hessian cloth-reinforced high-density polyethylene (HDPE) composites were prepared by the compression molding method. The fabricated composites contained 40, 45, 50, 55, 60, and 65wt% fiber contents and were optimized. 55wt% fiber contents reinforced composites showed better mechanical properties. This composite was alkali treated and irradiated under gamma-ray at doses 2.5‒7.5 kGy at the rate of 6 kGy/h. The X-ray diffraction (XRD) result indicates that the crystallinity of the alkali-treated Sunn hemp-reinforced HDPE composites shows a higher value than those of untreated and irradiated composites. Better adhesion between fiber and matrix was observed from surface micrographs. Fourier-transform infrared (FTIR) spectroscopy reveals cross-linking between fiber and matrix. The water intake properties of irradiated composite show more hydrophobic nature than that of untreated and alkali-treated composites. The tensile strength of the gamma-ray irradiated composites are 20% and 33% greater than that of untreated and alkali-treated composites. Similar results are found for Young's modulus. At a certain dose of 5 kGy, the irradiated composites show improved thermal, mechanical, and structural properties than untreated and alkali-treated composites. [ABSTRACT FROM AUTHOR]

Okra hessian cloth-reinforced high-density polyethylene (HDPE) thermoplastic composites were prepared and characterized with both raw and alkali-treated fibers. The fiber contents were optimized for both the raw Okra thermoplastic composites and the alkali-treated Okra thermoplastic composites, and the optimum value of fiber content was 55 wt%. Samples that were alkali-treated and had 55 wt% fibers were subsequently exposed to gamma radiation at doses of 2.5, 5, and 7.5 kGy. Only the sample subjected to 5 kGy showed improved performance. Treated composites exhibited higher crystallinities than the untreated samples as observed by X-Ray diffraction analysis. The rupture surface micrographs of the composites exposed to 5 kGy gamma radiation revealed more compact than others. By using Fourier transform infrared spectroscopy analysis of composites, it was found that 5 kGy dose sample showed enhanced cross-linking between Okra fibers and HDPE matrix. The irradiated composite showed less water intake than the alkali-treated samples. Composites subjected to 5 kGy gamma rays showed improved tensile strength and Young's modulus of values 66 MPa and 1925 MPa, respectively. Compared to raw and treated composites, the irradiated composites with a radiation dose of 5 kGy showed improved structural, mechanical, and thermal properties. [ABSTRACT FROM AUTHOR]

High Density Polyethylene (HDPE) is one attractive technical option for the transportation and distribution of natural gas and hydrocarbons given the advantages in long-term mechanical strength, lifespan, maintenance costs and resistance to chemical aging. This study investigates the compatibility of extruded pipe material from copolymerized HDPE-80 with DOT 3 brake fluid. Machined standard specimens from inner (IL) and outer (OL) pipe layers are aged in commercial synthetic polyglycol-based oil for 7 days at laboratory conditions. The percent mass changes are +2.2% and +1.9% respectively for IL and OL pipe surfaces. These results are in the same range of published sorption data for other oils and fuels. Stress-strain parameters (E, σ y , σ CD , σ f , ε y , Δ ε CD , ε f ) and fracture work are established and thoroughly discussed for both pipe sides. For IL, the reduction of E, σ y and ε f are respectively 28.0%, 13.9% and 22.7%, while for OL they are 22.6%, 7.7% and 25.1%. Globally, it is concluded that strength properties degradation in DOT 3 oil is more important for IL compared to OL. There is an important loss of ductility for both pipe sides. Ageing caused IL crystallinity (Xc) to increase while OL showed inverse results probably because of frozen anti-oxidants in the outer surface layers following water quenching during extrusion. Before and after ageing, the as-received OL is found to be more resilient to oxidation than corresponding IL, as higher OIT parameters are also shown in the case of crude oil compatibility investigations. DOT 3 brake oil seem to accelerate the degradation of HDPE-80 thermal stability with a higher intensity for IL. [ABSTRACT FROM AUTHOR]

In this study, fly ash (FA) which mainly consists of SiO2, Al2O3, Fe2O3, MgO, and CaO, was used as a synergistic additive (1–5 wt %) to improve the effectiveness of an intumescent flame retardant (IFR) system (25 wt %) in high density polyethylene (HDPE). IFR system composed of ammonium polyphosphate and pentaerythritol (3/1 ratio), and different amounts of FA were incorporated homogeneously into HDPE. Thermogravimetric analyses and thermal conductivity measurements were performed to determine the thermal properties. Meanwhile, limiting oxygen index, UL 94 vertical burning, and cone calorimetry tests were performed to investigate the fire resistance. Furthermore, the effects of IFR/FA additions on the mechanical properties were determined. The experimental results showed that IFR and IFR/FA additions resulted in early degradation with lower rates, and the residual mass values increased due to the char layers and the FA content. Also, IFR addition increased the thermal conductivity coefficient from 0.451 W/mK to 0.462 W/mK and IFR/FA additions further increased the coefficient up to 0.506 W/mK. Although the sample included only 25 wt % IFR could meet the requirements of UL 94 V-2 with a LOI value of 25.0%, 2, 3 and 4 wt % FA additions satisfied the criteria of UL 94 V-0 with a LOI value of 26.6%. In addition, the cone calorimeter results revealed that the peak heat release rates and total heat released values decreased with IFR (25 wt %) and FA (2, 3, and 4 wt %) additions. Furthermore, CO, CO2, and soot emissions of the composites significantly reduced with respect to HDPE. The NO increased with IFR additions due to the nitrogen content of APP. 25% IFR addition caused decreases in the tensile strength, tensile modulus, and Izod impact strength. However, FA additions slightly enhanced the mechanical properties of HDPE/IFR composite. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of including teak wood in recycled high-density polyethylene wood plastic composites (WPC) with pine wood on their resistance to degradation caused by termite attack and accelerated weathering. A 23 factorial experimental design was conducted with three repetitions in the center to analyze the weight loss and termite mortality during the experiments. The factors studied were the days of exposure to accelerated weathering, days of exposure to termite attack, and the concentration of teak wood in the composite. Surface characterizations (SEM and FTIR) were carried out to analyze the exposed surfaces and determine the chemical modification of the composite components. The results showed that the WPC manufacturing process promotes a heterogeneous distribution of the wood particles, being greater within the center of the samples than on the surface. Specimens exposed to both accelerated weathering and termite attack resulted in a certain weight loss and termite mortality, depending on the material, conditions of exposure, and the content of teak wood in the WPC. When those compounds were subjected to accelerated weathering followed by termite attack they exhibited a higher termite attack. The presence of teak wood in the WPC produced a reduction in the effects of termite attack and accelerated weathering on weight loss and an increase in termite mortality compared to the WPC with only pine wood, as teak wood contains extractables with termiticidal action. The lowest value of weight loss (0.06%) was observed for the WPC with the highest amount of teak wood with termite attack, resulting in a termite mortality rate of 100% after 17 days of exposure. [ABSTRACT FROM AUTHOR]

This article provides updates on global food contact regulations for the second quarter of 2024. It highlights developments in China, where a positive list of substances allowed for use in adhesives used in food-contact materials was published. In Japan, an amendment to the Plastics Positive List was announced, adding new substances and their loading limits. The United States introduced a new test method to measure PFAS contamination in plastic materials, and Minnesota became the fifth state to enact Packaging Extended Producer Responsibility (EPR) law. The European Commission published a draft amendment to the Plastics Regulation, and the Codex Alimentarius Commission requested information on recycling guidance for food packaging. [Extracted from the article]

In this article, the effect of irradiation dose and incorporated nanoparticles of kaolin (K) and graphite (G) on the lattice structure, thermal analysis, electrical conductivity, morphology, and mechanical properties of high-density polyethylene (HDPE) were studied. Infrared spectroscopy analysis (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize and prove the nanostructure of kaolin and graphite. Subsequently, HDPE was reinforced with a fixed percentage of nanokaolin at 3 phr and different contents of nanographite at 2 and 4 phr via melt-mixing and then molded by the hot press to sheets of suitable thickness. The fabricated sheets will be exposed to various gamma radiation doses at 50, 100, and 150kGy to investigate the impact of ionizing radiation on the prepared nanocomposites. It was found that the presence of a fixed percent of nanokaolin and graphite nanoparticles at 2 phr inside the HDPE matrix improved various properties of the prepared nanocomposites. Furthermore, the synergistic effect of nanokaolin with nanographite and irradiation doses led to the improved crystal structure, thermal analysis, mechanical properties, and electrical conductivity of HDPE nanocomposites. [ABSTRACT FROM AUTHOR]

Demand for natural fibers has increased in recent years due to the requirement for biodegradable materials. Owing to the increasing awareness on the overuse and over-dumping of plastics in the environment, the current work focused on a solution by using tree leaves as a particulate reinforcement which is one of the common waste products of trees. In this regard, Norfolk pine (NOP) tree leaf particulates filled High-Density Polyethylene (HDPE) composites were fabricated through injection moulding technique with different filler weight % of 0, 10, 20, 30, 40, and 50 wt. %. The study of the crystalline structure of the fillers and the detection of functional compounds in the materials were carried out through X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopic (EDX) analysis. Tensile strength, compressive strength, and flexural strength of the fabricated composite specimens were also assessed. Results revealed that the mechanical properties of the 30 wt. % pine tree leaf-filled HDPE composites were found to be superior when compared to pure HDPE composites. The failure surface morphology of the composite samples was examined using scanning electron microscopy (SEM). The melting point and decomposition of 30 wt. % NOP leaf particulate-filled HDPE composites specimen, whose mechanical properties were higher, were examined using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). From the results, it was found that NOP fillers can be used as an effective reinforcement in polymer composites. [ABSTRACT FROM AUTHOR]

Following the emergence of new morphology geogrids, tensile tests on some of the new morphology geogrids were conducted in this paper for practical engineering options. The study focuses on the tensile testing of 3D printed geogrids to analyze the effects of morphology differences (material, planar structure, filling rate, rib width and rib height) on the tensile properties of geogrids. The test results show that the tensile properties of high density polyethylene geogrids are stronger than those of polylactic acid geogrids. Increasing the filling rate of geogrid can increase the tensile performance while decreasing the rate of tensile performance improvement. In contrast to the elongation at the break of the geogrid, the maximum tensile strength and the maximum tensile modulus increase in the order of bidirectional, triaxial and quadaxial geogrids. When the rib width and the rib height increase by the same amount, the rib height increases the maximum tensile strength of the geogrid more than that of the rib width. [ABSTRACT FROM AUTHOR]

Antimicrobial hybrid polymer composites are developed for application in floating solar power plants. To avoid the degradation of the floater because of microbes living in the water as well as possible biofouling, zinc oxide (ZnO) is used as an antimicrobial agent, varying the weight percent (1, 2, and 3 wt%) within the high-density polyethylene (HDPE) matrix, along with carbon black (CB) as a reinforcing agent (1, 1.5, 2, and 2.5 wt%). Escherichia coli (facultative anaerobic) and Pseudomonas aeruginosa (aerobic-facultatively anaerobic) gram-negative bacteria formed a biofilm on HDPE in a 96-well plate for 5 days. In vitro, biofilm formation was determined by measuring absorbance (A420) in crystal violet dye, and the colony-forming unit (CFU) was determined by the spread plating technique. The biofilm formation and disruption are observed through a scanning electron microscope (SEM), where both the CFU and the SEM revealed uniform formation of biofilm onto neat HDPE. The best performance in terms of reduced biofilm formation and biofouling onto HDPE floaters was achieved for E. coli (ZnO: 2 wt% and CB: 2 wt%), whereas for Pseudomonas aeruginosa (ZnO: 3 wt% and CB: 2 wt%). Application of greener polymers and nanoparticles for future studies is highly recommended. [ABSTRACT FROM AUTHOR]

We are now well on the path of transitioning away from the fossil fuel resources on cutting down their consumption as much as possible. The fuels chosen for this study include ethanol-butanol (EB) -gasoline, acetone-butanol-ethanol (ABE) -gasoline and methanol-butanol (MB) -gasoline blends. High density polyethylene (HDPE) is a polymer that is extensively used in several auto parts and fuelling infrastructure materials. Incompatibility between these blends and fueling infrastructure system should be studied comprehensively for the adoption of these alternative fuels to be faster and hassle free. This study intends to gauge the changes in HDPE because of its immersion in the gasoline-alcohol blends mentioned for a period of 4, 30 & 90 days. The changes were ascertained by studying the mass, tensile strength, elongation, and hardness of the samples before and after immersion into blends. Sophisticated techniques were used to characterize the morphological and chemical changes of the polymer. The results showed that there was an increase in the mass of the HDPE samples as a result of the absorption of the blends by the polymeric samples. A decrease in tensile strength and hardness values were recorded for the samples whereas the elongation values were found to increase. Studies revealed that there was neither fuel degradation nor any oxidative degradation of the polymeric sample. The results indicated an increase in the mass and elongation of the HDPE as a result of the absorption of the fuel leads to lesser stable polymeric matrix and decrease in the percentage crystallinity. Hence this investigation led us to the conclusion that all the fuels blends studied are highly compatible with HDPE, even in instances where a change in the mechanical properties is seen, it is similar to that seen in gasoline. [ABSTRACT FROM AUTHOR]

In ultrasonic structural health monitoring (SHM) and nondestructive evaluation (NDE), the scattered waves caused by damage sites and defects are the key to damage diagnosis. However, structural components and boundaries also interact with traveling waves, creating events that can bury damage scattered waves. The baseline subtraction method, which directly subtracts the waveform of a damage signal from that of a pristine baseline signal, is a common processing technique to separate these damage scattered waves. However, baseline subtraction is less effective when a component is measured in different environmental/loading conditions from when its baseline was recorded. For instance, baseline subtraction can be ineffective in aerospace structural parts because such parts expect significant and routine changes in ambient temperature, pressure, and humidity. To overcome the limitations of baseline subtraction, this paper proposes to develop an spex-shifted Radon transform (ASRT)-based damage scattered event extraction technique without baseline subtraction. Our proposed ASRT method converts the original time-space (t − x) domain signals to a time delay–curvature–apex offset (τ − q − y) domain, which targets specific geometries of scattered/reflected waves in the t − x domain and compresses them into a single point-like region in the new domain. In this domain, identifying and isolating targeted events becomes significantly easier. To benchmark the performance of this baseline-subtraction-free (BSF) method, ASRT is applied for signals acquired from (1) spectral finite element-based simulations to scan a water-immersed steel specimen (2) 3-D wave simulations in a bent aluminum plate, and (3) a full matrix capture for experimentally scanning a high-density polyethylene (HDPE) with multiple holes. The goal in each case is to target and separate events of interest from the original signals using the proposed algorithm. The results suggest the ASRT method is effective as a damage scattered wave extraction tool for ultrasonic SHM and NDE. [ABSTRACT FROM AUTHOR]

The use of pine wood in wood-plastic composite WPC promotes sustainability by incorporating recycled or renewable materials, reducing the reliance on traditional wood sources, and minimizing environmental impact. This study focuses on treating pine wood flour (WF) with biological treatments (xylanase, pectinase, laccase, steam explosion) for use in WPC. The Scanning Electron Microscopy (SEM), Fourier Transform Infared spectroscopy (FTIR), biochemical analysis, and Thermo Gravimetric Analysis (TGA) were used to evaluate the effectiveness of the treatments in terms of the morphological, compositional, surface, and thermal stability of WF. The wear behavior of WPC was exanimate before and after hydrothermal aging. Morphological analysis of WF revealed that the enzymatic treatment produced a clean surface; it removed Xylan and led to a higher cellulose content (70%), and more porosity, and improved thermal stability and adhesion between WF and high density polyethylene (HDPE). Through analysis of wear and aging, we found the best wear resistance for laccase treatment among all WPC before and after aging, and it was lower than the HDPE. These findings highlight the positive impact of the enzymatic treatment on the adhesion between WF and HDPE, leading to reduced water absorption and increased wear resistance. [ABSTRACT FROM AUTHOR]

The study aimed at investigating the impact of Microwave Heat Treatment (MHT) on the physical and mechanical properties of wood flour (WF)/Nano-SiO2/High-Density polyethylene composites by varying Nano-SiO2 loading from 0, 1, 2, and 3% wt with a constant WF loading at 50% wt. By milling the materials in which were firstly mixed in a twin-screw extruder (Brabender® Plasti-Corder®), wood-plastic composites ASTM Standard samples were produced by an injection molding machine. Microwave irradiation with a power of 900 W and a temperature of 85°C for 7 min was applied for post-treatment of WPCs. After applying the microwave treatment, samples were subjected to physical and mechanical tests. The results indicated that increased Nano-SiO2 loading up to 3 wt% led to increasing the flexural strength and modulus while decreasing the impact resistance, water absorption, and thickness swelling of samples. As such, morphological analyses revealed that MHT increased the flexural modulus and strength, as well as, decreased the impact strength, water adsorption, and thickness swelling of the samples. [ABSTRACT FROM AUTHOR]

In friction stir spot welding applications, there are some factors that provide welding strength, welding performance and the formation of defects that may occur in welding. Among these factors, machine parameters and welding tool design should be compatible with each other. If these factors are not chosen appropriately, the welding will not be of the desired quality. In this study, high density polyethylene sheets were joined using friction stir spot welding technique. It has been determined that some of the joints made have low weld strength, defects on the weld surface and around the stir zone. By investigating the causes of these defects, suggestions were made to prevent these defecs It has been observed that these defects are not repeated in the welds made with the suggestions made and it has been determined that high weld strength can be obtained. The highest weld strength and performance were obtained by 0.2–0.4 mm plunge depth, 45–60 s stirring time, 700–900 tool rotation speed and 30 mm shoulder diameters. In order to obtain a perfect weld in friction stir spot welding, it was determined that a homogeneous mixture should be formed between the stirring zone and the thermo-mechanically affected zone. Low weld strength was obtained in all joints with defects detected in these regions. Low weld strengths and weld defects were detected at dwell times of less than 30 s, at all tool rotational speeds with a stirring time of less than 45 s, at a plunge depth greater than 0.4 mm, and at low tool rotation speeds. [ABSTRACT FROM AUTHOR]

This work investigates the properties of different types of regenerated recycled rubbers (RR1 and RR2) to produce thermoplastic elastomers (TPE) based on recycled high-density polyethylene (RHD) as the matrix. The higher regeneration degree of RR2 (24%) compared to RR1 (15%) was able to better restore the plasticity and processability of the ground tire rubber (GTR). So better entanglement between RR2 free chains and the thermoplastic macromolecules was obtained inducing stronger interfacial interaction leading to higher elongation at break (159%) and impact strength (342 J/m) of the blends filled with 80 wt.% RR2. To further improve the adhesion and achieve rubber-like properties, ethylene vinyl acetate (EVA) was used as a compatibilizer. The microstructure analysis showed that uniform dispersion of the particles and ground tire rubber encapsulation by EVA increased the resistance to crack propagation and failure of the compatibilized blends. The swelling, mechanical and physical properties of the ternary blends (RHD/GTR/EVA) showed that EVA improved the interfacial interactions between GTR and RHD which was confirmed by enhanced elongation at break (203%) and impact strength (379 J/m) by the addition of 10 wt.% EVA. [ABSTRACT FROM AUTHOR]

This study explored the effect of multiple recycling on the dimensional stability of wood–plastic composite. For this purpose, the injection moulding parameters effective on dimensional stability were first optimized based on the response surface method. Optical scanning, melt flow index (MFI), and differential scanning calorimetry (DSC) tests were used to analyse the shrinkage and deformation of recycled samples. The obtained results revealed that some recycled samples were subjected to thermal changes during the grinding and injection moulding process. The MFI and DSC results showed that the high-density polyethylene thermoplastic used in the wood–plastic composite was broken with long chains. Also, thermal changes occurred during the grinding and injection moulding process. The samples recycled three times had the highest dimensional instability (2.8% of shrinkage values). Finally, with the reduction of DSC, the semi-crystalline structure changed to amorphous, and the samples recycled four and five times had 2.7% and 2.5% shrinkage percentage, respectively. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of the effect of the content of styrene-butadiene elastomer on the change in ultimate tensile stress, tensile yield strength, elongation at break, flexural strength, enthalpy and melting temperature, Vicat softening temperature, and melt flow rate of polymer blends based on a wide range of thermoplastic polyolefins: high-density polyethylene, low-density polyethylene, polypropylene, ethylene-hexene-1 copolymer, polypropylene random copolymer, and block copolymer of ethylene with propylene. Nanoparticles of technical carbon (TC), aluminum, and calcium stearate were used as fillers. It has been shown that, depending on the type of polyolefin used and the specific concentration of elastomer, the polymer mixture can acquire the properties of a thermoplastic elastomer (TPE). In high-density polyethylene and an ethylene-hexene-1 copolymer, the properties of TPE appear at an elastomer concentration of 30 wt %; in low-density polyethylene, this effect occurs at its 20 wt % content. In polypropylene, polypropylene random copolymer, and ethylene-propylene block copolymer, TPE properties appear at 40 wt % concentration of the elastomeric component. This was confirmed by the results of scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, as well as the "stress–strain" dependence of polymer mixtures. To achieve technological compatibility and miscibility of non-polar polyolefins with polar elastomer, compatibilizers based on high-density polyethylene and polypropylene modified with maleic anhydride were used. It is shown that the equality of the values of the ultimate tensile stress and the tensile yield strength is a consequence of the occurrence of phase inversion in the polymer mixture, that is, change of the dispersed medium to the dispersed phase and vice versa. [ABSTRACT FROM AUTHOR]

This study mainly aims both to prepare well-shaped crosslinked 3,3,4,4,5,5,6,6,7,7,8,8,8 tridecafluorooctyl-4-(acrloyloxy) benzoate (ABCF13) polymer microspheres and to investigate the influences of the prepared microspheres addition on the crystallinity, thermal, mechanical and morphological features of high density polyethylene (HDPE). The suspension polymerization method was used for the production of well-defined microspheres and, the content of the microspheres varied from 1.0% to 10.0% in the composites. The characterization of crosslinked poly(ABCF13) microsphere-loaded HDPE composites were performed via powder X-ray diffraction, differential scanning calorimeter, universal mechanical (tensile and impact) testers and scanning electron microscope (SEM) techniques. According to the experimental findings, a and b unit cell parameters increased initially and reached maxima with the sample including 5.0% microsphere, which were followed by dramatic decreases, while c parameter remained relatively unchanged. Thermal analysis also showed that the melting temperature of HDPE reduced with the initial loading of the microspheres, then stayed at a plateau value of about 129°C due to the formation of lattice distortions, generation of microstructural disorders and the defects in the crystal structures. The mechanical test results revealed that there existed considerable improvements in tensile strength, modulus and impact strength. The maximum tensile strength 25.66 MPa, elastic modulus 499.30 MPa and maximum absorbed energy in the impact test 26.84 kJ/m2 (29%, 42% and 41% improvement, respectively) were achieved with the blend involving 5.0% microsphere. After the maxima, the mechanical characters depicted weakening trend as the microsphere content increased in the matrix. The SEM analyses revealed that although there existed fibrillar formations in all samples, the extensions decreased with the increase of the microsphere content. While ductile behavior was observed with the formation of long-bulky extensions at low contents, brittleness started to prevail at high contents with some short and thin fibrils. [ABSTRACT FROM AUTHOR]

The effect of styrene-ethylene/butylene-styrene block copolymer (SEBS) on the thermal degradation of polystyrene (PS)/high density polyethylene (HDPE) blends have been investigated. Polystyrene and (HDPE) are widely used thermoplastics, which have extensive application in everyday life. The main disadvantage of PS/PE systems is their poor miscibility which can be improved by adding compatibilizer. The blends were prepared by melt mixing in a twin screw extruder Haake Record 90. The behavior of the thermal degradation of PS/HDPE and PS/HDPE/SEBS blends has been investigated in inert nitrogen atmosphere by using thermogravimetric analysis (TGA) to obtain the degradation temperature and activation energy (E a ). The E a for the PS/HDPE blends as well as for the PS/HDPE/SEBS blends was determined by the isoconversional Kissinger–Akahira–Sunose (KAS) method. The results indicated that the HDPE enhance thermal properties of the blends. The addition of SEBS in PS/HDPE blends increased the E a in all blends. [ABSTRACT FROM AUTHOR]

In the present study, trimodal high-density polyethylene (tri-HDPE) slurry phase samples from the polymerization reactors were subjected to high temperature gel permeation chromatography/size exclusion chromatography (HT-GPC/SEC) analysis. The molecular weight (Mw) and its distributions were evaluated using commercially available HT-GPC instruments equipped with different detection modes (DRI, IR5 MCT, and light scattering). The SEC studies reveal the fact that there is a considerable challenge in generating a repeatable and reproducible data for the reactor grade HDPE samples which could be attributed to different detection modes employed and instability of HDPE reactor grades which are susceptible to undergo thermo-oxidative degradation during HT-GPC analysis. Among various instrumentation and detection modes investigated, the HT-GPC with IR5 MCT detection showed reliable results (%Error <15) when compared with absolute Mw data obtained from MALS detection. Based on the findings, proposed suitable SEC mode to characterize the HDPE reactor grade polymer samples. [ABSTRACT FROM AUTHOR]

High-density polyethylene (HDPE) content significantly influences the structure and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE)/HDPE blend fibers. The molecular chain disentanglement and crystallization characteristics of as-spun filaments and fibers and how the structure affects the final mechanical properties of the fibers were thoroughly studied by adding different contents of HDPE. Dynamic mechanical analysis (DMA) and rheological analysis indicated that the molecular entanglement decreased with increasing HDPE content, improving the UHMWPE melt processability. Sound velocity orientation (SVO) studies indicated that the UHMWPE/HDPE as-spun filaments and fibers with an HDPE content of 40 wt% (U6H4) had a higher molecular chain orientation level. Furthermore, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analyses indicated that U6H4 had the highest crystallinity and the thinnest grains in the axial direction, respectively. The compact crystal structure and fully stretched molecular chains of U6H4 yielded the best mechanical properties. The present work disclosed the effect mechanism of HDPE contents on the preparation and properties of UHMWPE/HDPE fibers, which provided an effective and universal strategy for manufacturing high-strength UHMWPE/HDPE fibers with the melt spinning method. [ABSTRACT FROM AUTHOR]

This paper focused on the establishment of performance level and cost of plantain fibers reinforced High Density Polyethylene (HDPE) matrixes as gas pipeline material using pressure containment of the new materials as performance criterion. The cost of modified plantain fibers, the cost of plantain fibers reinforced HDPE (PFRHDPE) and the cost of PFRHDPE master batch (HDPE resin + plantain fiber particles + stabilizer, plasticizer) for pipes extrusion production and pipelines fittings injection productions were established. The burst pressure evaluated for available standard outside diameter ratio (SDR) using the ultimate tensile strength of PFRHDE is very much greater than the standard SDR design pressures even when the temperature derating factors were applied. The Maximum Allowable Operating Pressure (MAOP) of PFRHDPE and induced stresses of pressurized pipes established indicated that the new material is suitable for pipeline design for natural gas and liquid petroleum (LPG) lines. The PFRHDPE developed has better specific properties than the conventional steel and HDPE pipe material in terms of yield strength, elastic modulus and density of the new material. But in terms of cost, steel and HDPE has approximate desirability for selection with PFRHDPE. The energy required to manufacture and process steel products is about 480 MJ/m2, while that of plastics is about 320 MJ/m2. The study further established that PFRHDPE can be applied in the design of oil and gas gathering, transportation and distribution lines. [ABSTRACT FROM AUTHOR]

For more information on Toppan's mono-material packaging solutions, visit https://www.toppan.co.jp/living-industry/packaging/english/products/mono-material flexible packaging/ Toppan plans to expand sales of this and other mono-material packaging products as it works to contribute to a sustainable global society. Toppan has taken advantage of its proprietary GL BARRIER technologies to overcome the difficulty of vapor deposition on PE and deliver barrier performance superior to that of existing PE mono-material packaging (Figure 2). Features of PE mono-material barrier packaging for liquids Recyclability provided by PE mono-material composition Superior recyclability has been achieved by employing a packaging material composition that consists only of PE. [Extracted from the article]

Multi-walled carbon nanotubes and high-density polyethylene (MWCNTs/HDPE) nanocomposite sheets with (1.0, 0.5, and 0.1) wt.% MWCNT were successfully prepared by coating the MWCNTs on the surface of the matrix particles (HDPE). The sample resistivities of the nanocomposites were investigated in relation to the temperature influence. Several findings could be drawn from these experiments: For instance, among all of the prepared MWCNT/HDPE nanocomposite sheets with (0.1, 0.5, and 1.0) wt. % MWCNT, the electrical resistivity of the 1.0 wt. % MWCNT/HDPE nanocomposite was 33.18 kΩ.m, demonstrating the best electrical conductivity. The resistivities of 0.1 wt. % and 0.5 wt. % samples were found to be 2594 and 372.23 kΩ.m respectively. Also, the measurements of temperature versus electrical conductivity revealed that the rise in temperature causes the electrical resistivity for the MWCNT/HDPE nanocomposites to increase due to the expansion of the distances between the conductive nanofillers (CNT), i.e., the sample resistivity increased under heating due to the thermal expansion of the polymer matrix. For example, the initial electrical resistivity for the 1.0 wt. % MWCNT/HDPE nanocomposite sheet decreased from 36.25 kΩ.m to 33.18 kΩ.m after the heat treatment. Besides, heat treatment could effectively improve the reproducibility of the MWCNT/HDPE nanocomposites. The reproducibility of the 1.0 wt. % MWCNT/HDPE nanocomposite was better than that of the 0.5 wt. % MWCNT/HDPE nanocomposite. [ABSTRACT FROM AUTHOR]

High-density polyethylene (HDPE) content significantly influences the structure and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE)/HDPE blend fibers. The molecular chain disentanglement and crystallization characteristics of asspun filaments and fibers and how the structure affects the final mechanical properties of the fibers were thoroughly studied by adding different contents of HDPE. Dynamic mechanical analysis (DMA) and rheological analysis indicated that the molecular entanglement decreased with increasing HDPE content, improving the UHMWPE melt processability. Sound velocity orientation (SVO) studies indicated that the UHMWPE/HDPE as-spun filaments and fibers with an HDPE content of 40 wt% (U6H4) had a higher molecular chain orientation level. Furthermore, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analyses indicated that U6H4 had the highest crystallinity and the thinnest grains in the axial direction, respectively. The compact crystal structure and fully stretched molecular chains of U6H4 yielded the best mechanical properties. The present work disclosed the effect mechanism of HDPE contents on the preparation and properties of UHMWPE/HDPE fibers, which provided an effective and universal strategy for manufacturing high-strength UHMWPE/HDPE fibers with the melt spinning method. [ABSTRACT FROM AUTHOR]

The water transport kinetics and moisture-induced thickness swelling behavior of wood-plastic composites (WPCs) in the presence of two imidazolium-based ionic liquids (ILs) were studied. The wood flour chemically treated with ILs were compounded through melt mixing of high-density polyethylene and coupling agent, and finally, the test specimens were produced by compression molding. Hygroscopic rates of the composites were evaluated by immersing them in the water at room temperature and monitoring moisture sorption and thickness changes for several weeks. Besides, the water diffusion coefficients and swelling rate parameters were measured for all composites. It was found that the water absorption and thickness swelling of the WPC specimens reduced as a result of ILs treatment. The SEM analysis revealed that the presence of ILs can improve the quality of adhesion between the polymer matrix and the cellulosic materials, to decrease the gaps in the interfacial region and block the hydrophilic groups. Studying the water sorption process in the specimens showed that the process follows kinetics and mechanisms described by Fick's law. The highest water diffusion coefficients and swelling rate parameters were found in composites with untreated wood. [ABSTRACT FROM AUTHOR]

Rice husk ash (RiHA) was employed as the bio - originated and inexpensive filler prepared from agricultural wastes for reinforcing high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE). X-ray fluorescence (XRF) spectroscopy showed ∼80.82% for the silica content of RiHA as well as the values of other components present in this bio-based filler. The composites were obtained via melt mixing followed by the compression molding by the hot press forming. Characterization of the composites by FT - IR spectroscopy revealed that the filler has the sheer effects on the vibrational bands of the polymers. The usage of X-ray diffraction (XRD) analysis to investigate the d - spacing values and the crystallinity of the samples, exhibited the increase of d - spacing upon reinforcing the polymers with RiHA. The scanning electron microscopy (SEM) images showed an average size of 32 µm for the irregular RiHA particles which uniformly dispersed in the polymeric matrices. The energy dispersive X-ray (EDX) analysis displayed C, O, and Si as the main constituting elements of the composites and alternatively confirmed the well dispersion of the filler particles into the polymer matrices. The mechanical measurements showed the significant improvements in Young's modulus, yield stress, and hardness results of the polymers after reinforcing with the rice husk ash. For example, Young's modulus of HDPE was increased ∼15% after incorporating 7 wt.% of RiHA into this polymer. These mechanical properties of the polymers were increased upon increasing the RiHA content, while the parameter of elongation at break was decreased. [ABSTRACT FROM AUTHOR]

The nanocomposites of high-density polyethylene, low-density polyethylene, polypropylene, and poly(vinyl chloride) reinforced with Azadirachta indica wood flour (WF) and different amounts of the organomodified nanoclay and titanium dioxide (TiO2) nanopowder were produced by melt-blending process followed by compression molding. Polyethylene- co -glycidyl methacrylate (PE- co -GMA) was used as a compatibilizer. TiO2 nanopowder was synthesized by sol–gel method and characterized using transmission electron microscopy (TEM). The average size of the synthesized nano-TiO2 was 17.5 nm, which was confirmed both by TEM and X-ray diffraction (XRD) study. The distribution of nanoparticles in the nanocomposites was also examined by the XRD study. The surface modification of the TiO2 nanoparticles by organic surfactant cetyl trimethyl ammonium bromide and their interaction with the wood and the polymer were studied by Fourier transform infrared spectroscopy. Incorporation of compatibilizer PE- co -GMA, nanoclay, and nano-TiO2 significantly influenced the mechanical and thermal properties of the WF-reinforced composites. Wood polymer composites (WPC) reinforced with nanoclay and nano-TiO2 showed improved tensile strength, tensile modulus, flexural strength, flexural modulus, and hardness. Maximum improvement in mechanical properties was shown by WPC loaded with 40 phr WF, 2 phr nanoclay, and 2 phr of nano-TiO2. On inclusion of organically modified nanoclay and nano-TiO2, the WPC samples showed lower water uptake and higher chemical resistance. The nanocomposites were further examined by TEM study and thermogravimetric analyzer. [ABSTRACT FROM AUTHOR]

Alcohols are increasingly being looked upon as the most viable alternative to the conventional sources of energy. Methanol is the first member of the alcohol family and can be easily synthesized from syngas. It is an attractive blend to gasoline due to its advantageous properties. There is a necessity to make sure that the infrastructure is ready to adapt these alternative fuels. Hence, the aim of this study is to assess the degradation of widely used thermoplastics in fuel tanks, pipes, and the fuel injection system, namely, polytetrafluoroethylene (PTFE), polyethyleneterephthalate (PET), and high density polyethylene (HDPE) post exposure to methanol–gasoline blends (P100, M15, and M30) for a period of 4, 10, and 30 days. The effects of the exposure were examined by comparing changes in gain/loss of mass, hardness, elongation, and tensile strength. The surface morphology changes of the polymeric coupons were characterized by scanning electron microscopy and their elemental analysis was done by energy dispersive X-ray spectroscopy. The studied materials were found to gain mass in the order HDPE > PTFE >PET. The decrease in hardness was found to be more in HDPE followed by PTFE and PET. PTFE and PET showed reduction in strength but an increase in tensile strength was observed for HDPE post exposure to fuel blend. Highest change in elongation was found in HDPE followed by PTFE and PET. The changes were found to be the least in P100 followed by M15 and maximum in M30 blends for all immersion periods. [ABSTRACT FROM AUTHOR]

With its market demand expansion and increased application areas, products of wood-plastic composite (WPC) have been developing and growing rapidly in many countries over the last decades. This paper attempts to investigate the effect of wood species that are waste from the furniture industries on the performance of wood-plastic composites (WPCs). The samples were prepared by varying the wood flour species at 30wt% mixed with 70wt% HDPE (High Density polyethylene). The wood species used for samples preparation are Cordia africana's /wanza/ wood flour, Austria pine's wood flour, and the mixture of both wood species flour in 15wt% of each wood species and the resulted composites tensile and impact properties determined. Morphological and water absorption characteristics of these composites were also determined. The composite from the mixture of wood species exhibited best interfacial bonding between matrix and reinforcement that resulted in providing the best water absorption property, and the maximum tensile strength of the composite which is, 15.465 MPa. Compared with the pure HDPE, the reduction of impact strength with the addition of wood was also observed. Wood species in wood-plastic composites are an essential factor for the performance of WPCs. [ABSTRACT FROM AUTHOR]

Modern thermoplastic materials are used in an expanding range of engineering applications, such as in the automotive industry, due to their enhanced stress-to-weight ratios, toughness, a very short time of solidification, and a low thermal conductivity. Recently, friction stir welding has started to be used in joining processes in these areas. There are many factors that affect weld performance and weld quality in friction stir welding (FSW). These factors must be compatible with each other. Due to the large number of welding variables in friction stir welding processes, it is very difficult to achieve high strength FSW joints, high welding performance, and control the welding process. Welding variables that form the basis of friction stir welding; machine parameters, tool variables, and material properties are divided into three main groups. Each welding variable has different effects on the weld joint. In this study, friction stir welds were made on high density polyethylene (HDPE) sheets with factors selected from machine parameters and welding tool variables. Although the welding performance, quality, and strength gave good results in some conditions, successful joints could not be realized in some conditions. In particular, welding defects occurring in the combination of HDPE material with FSW were investigated. Welding quality, defects, and performances were examined with macrostructure. In addition, the tensile strength values of some the joints were determined. The main purpose of this study is to determine the welding defects that occur at the joints. The causes of welding defects, prevention methods, and which weld variables caused were investigated. Welding parameters and welding defects caused by welding tools were examined in detail. In addition, the factors causing welding defects were changed in a wide range and the changes in the defects were observed. [ABSTRACT FROM AUTHOR]

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD k – ω turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design. [ABSTRACT FROM AUTHOR]

To investigate the effects of incorporating gas and the associated influencing factors on polymer melt, a method of evaluating the gas-laden ability using modified rheometric measurements was proposed. In this study, common and widely used thermoplastic materials—polypropylene (PP) and high-density polyethylene (HDPE), and their blends with different weight ratios—were selected, and the rheological properties of neat melt and gas-laden melts were tested using a modified torque rheometer. The foamed samples were also produced using a regular injection-molding machine, and the foamed morphology was examined by scanning electron microscope (SEM). The comparison of rheological curves of neat melt and gas-laden melt indicated that the incorporation of gas influenced the rheological properties of the gas-laden polymer melts as evidenced by a decrease of zero-rotational torque and an increase in the melt flow index. The results also suggested that the gas-laden ability of polymer melt could be evaluated quantitatively by the decay (due to desorption) of gas using the modified rheological measurement method. This study also demonstrated that the gas-laden ability can be used to predict the foaming behavior of polymer melts. [ABSTRACT FROM AUTHOR]

In this study, foamed recycled high density polyethylene (rHDPE) parts were produced by rotational molding using different concentration (0 to 1% wt.) of a chemical blowing agent (CBA) based on azodicarbonamide. From the samples produced, a complete morphological, thermal and mechanical characterization was performed. The morphological analysis showed a gradual increase in the average cell size, while the cell density firstly increased and then decreased with increasing CBA content. As expected, increasing the CBA content decreased the foam density as well as the thermal conductivity. Although increasing the CBA content decreased both tensile and flexural properties, the impact strength showed a similar trend as the cell density with an optimum CBA content around 0.1% wt. Finally, neat rHDPE samples were also produced by compression molding. The results showed negligible differences between the rotomolded and compression molded properties indicating that optimal rotomolding conditions were selected. These results confirm the possibility of using 100% recycled polymers to produce rotomolded foam parts. [ABSTRACT FROM AUTHOR]

In this work, the effect of the vermiculite (VMT) clay loading on the rheological properties and flammability of bio-based high-density polyethylene/organically modified VMT (BioHDPE/OVMT) clay biocomposites containing 0.5–10 phr of OVMT clay was investigated. X-ray diffraction patterns showed that the BioHDPE was intercalated between the OVMT clay galleries. BioHDPE/OVMT biocomposites containing 5 and 10 phr of OVMT clay exhibited a shear-thinning behavior and a better dispersion/distribution in the BioHDPE matrix. The biocomposite containing 10 phr of organoclay presented a percolated network structure. The elastic modulus increased with the increase in the OVMT loading whereas the tensile and impact strength remained almost unaffected. For the biocomposites containing the unmodified VMT clay, the burning rate decreased with the increase in the VMT loading. The opposite was observed for the biocomposites containing OVMT clay. [ABSTRACT FROM AUTHOR]

The effect of oil palm trunk (OPT) natural fibers used as reinforcement in High density polyethylene on the mechanical, biodegradation and water absorption properties of polyethylene films were investigated. The composites were formulated and prepared using twin-screw extruder while the hot compression molding machine was used to prepare the bio-films. The results showed that the incorporation of OPT fiber into the film enhanced the tensile modulus of the matrix while the tensile strength and elasticity reduced. The Young's modulus of the composites reached 4450 MPa at 20% OPT fiber load while tensile strength and elongation at break reached its lowest at 7.11 MPa and 2.13% respectively at the same fiber load. Water absorption and biodegradability of the composites improved when OPT fibers were added. The composite film with 20% fiber load showed the highest fungal growth. [ABSTRACT FROM AUTHOR]

One of the main purposes of this research is to control environmental pollution and mitigate the impact of ignorantly discarded waste plastics in the environment through recycling of such plastics and using them to develop innovative composite materials. The present work investigates the influence of stone-dust particles and bagasse fiber on the mechanical and physical properties of reinforced recycled high-density polyethylene bio-composites. The bagasse fiber was first treated with 0.5 M NaOH solution at a temperature of 50°C for 2 h in order to improve the surface morphology and also modified the mechanical properties of the fiber. Likewise, the stone-dust particles were analyzed by using a standard sieve shaker to obtain particle sizes of 75 μm. Both reinforcements were used for composite development through the compression molding technique and the samples were subjected to mechanical and physical properties tests in accordance with standards. Analysis of the results revealed that flexural, hardness, wear, and hydrophobicity of the developed bio-composites were improved by stone-dust particles. The flexural strength at peak and modulus were enhanced by 88% and 92%, respectively. Also, it was discovered that, tensile, impact and thermal conductivity properties of the bio-composites were improved by bagasse fiber. The ultimate tensile strength and Young’s modulus were enhanced by 43% and 34%, respectively. Hence, the blend of these by-products showed that they are potential bio-materials for the development of bio-composites [ABSTRACT FROM AUTHOR]

Enormous amounts of plastic wastes are generated worldwide and the approaches related to plastic recycling or reusing have become the research focus in the field of composite materials. In this study, green composites were prepared via melt-blending method using high-density polyethylene (HDPE) sourced from plastic bags as a matrix and sugarcane bagasse (SCB) fiber as reinforcing filler. The effects of fiber loading (5, 10 and 15 wt%) and fiber modification on the mechanical and dimensional stability (weight gain by water absorption) properties of the green composites were investigated. Results showed that the inclusion of SCB fiber into recycled HDPE matrix increased the composite stiffness but decreased the mechanical strength and resistance to water absorption. With the fiber modification through alkali treatment, the mechanical strength was remarkably improved, and the modulus and water absorption of the composites were found to be reduced. From the finding, it can be concluded that the prepared green composites free of coupling agent could add value to the plastic and agricultural wastes, and serve a potential candidate to replace some conventional petroleum-based composites. [ABSTRACT FROM AUTHOR]

The study of the behavior of polymeric material used for insulators in the electrical system is extremely important in order to evaluate their lifetime as well as their performance when exposed to different environmental conditions. In the present work, the behavior of high-density polyethylene (HDPE) pin type insulators (15 kV), under accelerated aging conditions, was studied. Samples were exposed to aging, for 200 h, 1000 h, and 2000 h, in accelerated weathering chambers, according to two different methods. In Method 1, the parameters were established based on natural aging in location conditions, and in Method 2, ASTM G155 standard parameters were used. All samples were characterized by rheometry, Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The accelerated aging conditions, used in Methods 1 and 2, affected the aging of HDPE pin type insulators samples differently, the changes being more intense in Method 1. [ABSTRACT FROM AUTHOR]

Polypropylene/epoxy/synthetic graphite (PP/EP/SG) and high-density polyethylene (HDPE/EP/SG) composites were prepared by melt mixing followed by compression molding. The immiscibility of the polyolefins with epoxy was confirmed by thermogravimetric analysis. Scanning electron microscopy (SEM) studies showed that HDPE/EP blend exhibits inferior interfacial adhesion between the component polymers compared to PP/EP blend. Also, the effect of SG content on flexural properties, density, moldability, water absorption, and porosity of the PP/EP/SG and HDPE/EP/SG composites was investigated. For both PP/EP/SG and HDPE/EP/SG composites, flexural modulus, density, and porosity increased with increase in SG content. For PP/EP/SG composites, the water absorption decreased from 0.154% at 30 wt% SG to 0.072% at 70 wt% SG. Further increase in SG content to 80 wt% caused an increase in water absorption. On the other hand, water absorption for HDPE/EP/SG increased with SG content all through. At the same filler loadings, PP/EP/SG composites showed lower density and porosity and performed better in terms of flexural modulus and water absorption compared to HDPE/EP/SG composites. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs)/high density polyethylene (HDPE) composites were prepared by a masterbatch method (mPEC) in which a commercial HDPE was blended with a MWCNTs/HDPE masterbatch obtained from in situ polymerization. Owing to the interfacial interaction, a 13 cm−1 up-shift of the G band for the MWCNTs was observed in the Raman spectrum of the MWCNTs/HDPE masterbatch and the homogeneous distribution of MWCNTs in the mPEC was realized. Compared to the pure HDPE and the MWCNTs/HDPE composites prepared by a direct melt-blending method (dPEC), the mPEC had better electrical, mechanical and rheological properties, suggesting that the in situ polymerized HDPE covering on the MWCNTs surfaces played an important role in the reinforcing effects as an interfacial modifier. The tensile yield strength and the Young's modulus of the mPEC containing 3 wt% MWCNTs (mPEC3), and the flexural strength and the flexural modulus of the mPEC containing 1 wt% MWCNTs were improved by 38.3%, 41.7%, 24.4%, and 42.9%, respectively, compared to those of the pure HDPE. For, the electrical resistivity of mPEC3 was decreased by about three orders of magnitude relative to that of the pure HDPE. The | η *|, G′, and G″ of the mPEC were obviously higher than those of pure HDPE. Moreover, the polyethylene-modified MWCNTs obtained from in situ polymerization could facilitate the crystallization of the HDPE macromolecular chains more effectively compared to the unmodified MWCNTs. [ABSTRACT FROM AUTHOR]

The present study explains the preparation of high-density polyethylene (HDPE)-based nanocomposites containing different amounts of montmorillonite (MMT) nanoclay (1–10 wt%). These nanocomposites were obtained by melt blending in a co-rotating twin screw extruder in absence and presence of a compatibiliser (HDPE-g-MA). The melt rheological behaviour of HDPE/MMT nanocomposites has been investigated by using capillary rheometer at 190°C, 200°C and 210°C over the shear rate range of 50–1000 s−1. The melt viscosity of HDPE increased marginally at 10 wt% filler loading while addition of compatibiliser to HDPE/MMT composites did not show any significant effect on viscosity. All nanocomposites showed shear thinning and non-Newtonian flow behaviour. The power law index reduced with increase in MMT concentration and increased with increase in temperature while opposite trend was observed for the consistency index. The activation energy was highest for the nanocomposites containing 10 wt% MMT and decreased upon addition of coupling agent. [ABSTRACT FROM AUTHOR]

Wood plastic composites (WPCs) consisting of high density polyethylene (HDPE) reinforced with high-loading (55 wt%) of wood flour (WF) were fabricated with melt-blending technique. In this compounding method, processing parameters such as different mixing temperatures (of 165, 180 and 195°C), mixing times (of 5, 10 and 15 minutes) and coupling agent contents (of 2 and 4 wt%) were evaluated. Prepared specimens were analyzed with tensile, Izod, shore D, DMTA, short-term creep, DSC, TGA, water absorption and water contact angle characterizations. Results revealed that mixing temperature of 180°C, mixing time of 10 minutes and coupling agent concentration of 4 wt% were found as the best processing conditions. The mentioned conditions provided enhanced dispersion of WF particles within the HDPE matrix, due to optimum viscosity of the polymer melt and effective residence time of compound in the mixer, and beside them efficient interfacial adhesion between WF and polymer matrix. [ABSTRACT FROM AUTHOR]

In this study, two different polymer materials were used. In the joints made with friction stir spot welding, firstly (PP/PP and HDPE/HDPE) and then different materials (PP/HDPE, HDPE/PP) joining processes were carried. The influence of the tool rotational speed and the stirring time on joint formation and weld strength were determined. The temperature of the liquid welding materials varies according to the materials to be combined. High weld strengths were obtained at the friction stir spot welding of similar plastic sheets. The highest weld strengths were obtained in PP-PP welds. Low weld strengths were obtained at the friction stir spot welding of dissimilar plastic sheets because of immiscible and incompatible blends formed during the welding operation. The lowest weld strengths were obtained in PP-HDPE welds. The chemical composition and the phase morphology of the blends, the mechanical scission occurrence and the welding residual stresses determine the strength of the welds. [ABSTRACT FROM AUTHOR]