Density Polyethylene Composites Research Articles

Relationship between surfactant content and the properties of microfibrillated cellulose/high density polyethylene composites

AbstractMicrofibrillated cellulose (MFC) was uniformly dispersed in high‐density polyethylene (HDPE) using a large amount of surfactant, and composites were prepared after removing the surfactant at different contents. The structural, morphological, thermal, and tensile properties of these composites were systematically investigated. The results demonstrated an asymptotic relationship between the amount of surfactant removed and the number of removal cycles. A negative linear correlation was observed between the surfactant content and the tensile strength, tensile modulus, and storage modulus at −20 °C of the composites, while a positive linear correlation was found with the loss modulus at −20 °C. Excessive surfactant adversely affected the dispersion of MFC, as well as the mechanical properties and thermal stability of the composites. However, when the surfactant content was below 2.8%, its impact on the composite properties was minimal, and the tensile strength, modulus, and thermal stability of the composites were significantly improved compared to neat HDPE. These findings indicate that surfactant pretreatment is an effective strategy for dispersing MFC in non‐polar polymers, and controlling the surfactant content in the final product can effectively tailor the properties of the resulting composites.Highlights Confirms the relationship between surfactant content and MFC/HDPE composite properties. Surfactant content showed an asymptotic relationship with removal cycles. Surfactant content and mechanical properties exhibited a negative linear correlation. Surfactant content and thermal stability exhibited a negative relationship. Surfactant content had minor impact when below 2.8%.

Potentialities of cellulose nanofibers (CNFs) in low density polyethylene (LDPE) composites

Potentialities of cellulose nanofibers (CNFs) in low density polyethylene (LDPE) composites

Recycled from waste tires carbon black/high‐density polyethylene composite: Multi‐scale mechanical properties and polymer aging

AbstractThis study addresses the global issue of recycling vehicle rubbish tires by a vacuum pyrolysis process, exploring a novel environmentally responsive approach for thermal decomposition and recovery of the carbon black particles contained in tires (25–30 wt%). Carbon black is typically used for its UV protection in plastics and abrasion resistance in composites and rubbers. This research aims at providing an eco‐responsible alternative to commercial carbon black of fossil origin by recycling the carbon black (rCB) from end‐of‐life tires. A particle reinforced composite material was developed containing rCB and high‐density polyethylene. For comparison purposes, an identical composite was manufactured using commercial carbon black (CB). Accelerated aging studies have been carried out on the materials. Topographic evolution of the samples with aging and oxidation kinetic of the surface and through the thickness were studied. Multiscale mechanical properties have been evaluated for a more comprehensive understanding of the mechanisms involved in the degradation. A comparison of the different materials properties was carried out in order to highlight the various elements linked to the degradation and UV protection of materials. This work helps demonstrating the feasibility of using recycled carbon black particles from waste tires as a high‐performance filler for plastics and composites.Highlights Recycled carbon black (rCB) is an eco approach of revalorizing tire waste. Vacuum pyrolysis successfully allows recovery of reusable rCB. The rCB acts as a photon absorber, limiting degradation of HDPE. The rCB limits the cross‐linking responsible of embrittlement of HDPE. A critical carbonyl index of 20 marks the occurrence of cracks and degradation.

Effect of lignocellulosic corn stalk on mechanical, physical, and thermal properties of injection moulded low density polyethylene composites: An approach towards a circular economy

Escalating concern over global warming, which is mostly associated with deforestation, has led to the development of new classes of materials that can replace wood and better utilise natural resources. Presently, waste is a significant factor in recycling. In this regard, one of the leading contributors to waste is agricultural waste, which includes dried branches, leaves of trees, plants, and other organic materials. In the current study, waste from corn agriculture was utilised as a potential reinforcement for the fabrication of corn stalk-low density polyethylene (CS-LDPE) composites via an injection moulding technique at 170 °C. The different parameters were assessed to develop composites using CS, including physico-chemical, macromolecular, mineralogical, elemental, and morphological analysis. The amount of corn stalk (CS) was varied from 10 to 50 wt% with respect to the polymer. The mechanical, physical and thermal performance of the composites was examined. The density and water absorption of the composites were found to remain within the ranges of 1.00–1.11 g/cm3 and 0.22–1.01 %, respectively, whereas these parameters increased as the proportion of CS increased. The thermal conductivity decreases with the addition of CS from 0.36964 ± 0.020 to 0.22388 ± 0.002 W/mK. It was observed that adding CS to the composites increased their tensile and flexural properties, but decreased their impact strength. The maximum flexural strength of 14.40 ± 1.558 MPa, flexural modulus of 752.53 ± 180.409 MPa, tensile strength of 10.49 ± 0.946 MPa and tensile modulus of 539.79 ± 91.044 MPa were observed with a 50 % CS content. The results suggest that these materials have considerable potential to serve as a cost-effective substitute for the conventional lignocellulosic fillers in the manufacturing of wood-plastic composites.

Tribological performance analysis of sustainable basalt micro-filler loaded bio-based polypropylene and high density polyethylene composites

The current research work involves the fabrication and tribological properties analysis of constant basalt filler reinforced (30 wt %) bio-based polypropylene (PP) and high density polyethylene (HDPE) thermoplastic composites. Compression molding technique is used after an internal mixing process in order to produce composite samples. The physical and hardness properties have been evaluated for both neat polymers and composite samples. In order to study the coefficient of friction (COF) and specific wear rate (SWR) of PP and HDPE composite samples, the Taguchi and Analysis of Variance (ANOVA) methodologies were applied. For PP samples, the optimum parameters in response to COF are found to be 0 wt% basalt (rank 3), 9 N load (rank 1), 200 r/min speed (rank 4), and 100 m distance (rank 2); for the SWR output, the optimum parameters are 30 wt% basalt (rank 1), 6 N load (rank 4), 100 r/min speed (rank 2), and 200 m distance (rank 3). For HDPE samples, the optimum parameters in response to COF are 0 wt% basalt (rank 1), 6 N load (rank 3), 100 r/min speed (rank 4), and 100 m distance (rank 2); for the SWR output, the optimum parameters are 30 wt% basalt (rank 1), 6 N load (rank 3), 100 r/min speed (rank 4), and 150 m distance (rank 2). Consistently, it has been shown that incorporating basalt fillers to PP and HDPE composites has more dramatically decreased SWR than COF. The depth of wear constantly rises according to increasing load, irrespective of the processing variables, as shown in 2D depth profiles. It is discovered that the confirmation tests carried out for the optimum parameters are within statistically acceptable bounds. The depth profile plots revealed that the worn track edges are found with polymer bumps because of deep grooves and softened polymer debris, which commonly observed more with HDPE samples due to low softening temperature. Moreover, the worn surfaces of the composites have plowed lines and cracks that are brought about by the micro-cutting and micro-plowing activity of the erosive asperities counterface. In addition to surface characteristics, the transfer films created during sliding also significantly influenced the mode of sample wear.

The Functional and Biodegradation Characteristics of High-Density Poly-ethylene, Poly-caprolactone and Poly-ethylene Maleic Anhydride Composites

The goal of this research is to develop environmental friendly polymer composites in order to reduce the use of current polymers and promote global security. High density poly-ethylene (HDPE) and poly-caprolactone (PCL) composites were mixed with varying amounts of poly-ethylene joined maleic anhydride (PE-g-MA) as a strong compatibilizer. The different composites were prepared using the conventional infusion shaping approach. Mechanical properties were accounted for to have good increase for the diverse compositions and the strength and pliable strain% (stretching) rate at break were improved in comparison to unadulterated HDPE. Examining electron magnifying lens (SEM) morphology revealed that the expansion of PE-g-MA increased the compability and so aided in the achievement of a synergistic mix of superior qualities. The manure internment test yielded favorable bio-corruption results and demonstrated the fertilizer's ability to enable bio-debasement of various composites, allowing their utilization as key polymers in the assembly of single-use products and also protecting nature and acting as a decent waste administration of HDPE polymer.

Thermal buckling behavior of 3D printed foams: Plain, graded, and sandwich variants

The present work focuses on the experimental investigation of the thermal buckling response of 3D printed functionally graded glass micro balloon (GMB) reinforced high density polyethylene (HDPE) composites and their respective sandwiches under non-uniform heating conditions. The influences of GMB loading and its graded composition on temperature distribution are analyzed. The reinforcement of hollow GMB rendered lower thermal conductivity due to enhanced thermal resistance with an increase in filler percentage. An increased thermal buckling strength is also observed. Due to their non-uniform thermal expansion, functionally graded sandwich beams exhibited less deflection than plain beams. Among the cases of three heating conditions (One end heating: case-1, Center heating: case-2, both end heating: case-3), maximum deflection is observed in case 2 while the minimum deflection is noted in case 1. These printed foams can be utilized for lightweight thermal insulating pipes.

Effect of different modifiers on tobacco stalk fiber/high‐density polyethylene composites

AbstractAgricultural waste fiber has huge utilization potential due to its abundant sources, renewability, and low recycling costs. In this process, up to 30 wt% tobacco stalk fiber (TSF) was compounded with high‐density polyethylene (HDPE) and interfacial modifiers using a grinder, melting‐blending mixer, and injection molding machine to prepare environmentally friendly TSF/HDPE composites, which have excellent mechanical properties and good water resistance. On this basis, the interfacial compatibility between TSF and HDPE was enhanced by adding a silane coupling agent KH550, titanate coupling agent 201, and maleic anhydride grafted polyethylene (MA‐g‐PE), which led to the improvement of mechanical properties of composites. The mechanical properties of the composites with 2% MA‐g‐PE were the best, while the tensile strength and flexural strength increased by 72% and 38%, respectively, compared with the unmodified composites. Fourier transform infrared (FTIR) spectroscopy showed that TSF was modified by different coupling agents and new chemical bonds were formed. The scanning electron microscopy images showed that the interfacial compatibility between TSF and HDPE was improved by the interface modifiers. This work confirms that it is possible to use TSF to prepare composites and provides a new way for resource utilization of tobacco stalk fiber.Highlights TSF was incorporated into composites, boosting material sustainability. The interface compatibility between TSF and HDPE was greatly improved. Thermal and water absorption analysis can be used for composites design. Composites modified by 2 wt% MA‐g‐PE had optimal comprehensive properties.

Novel method of mechanical alignment for chopped carbon fiber/high density polyethylene composites: Processing, modeling, and characterization

In this study, we investigated a novel method of mechanical alignment to enhance the tensile properties of chopped carbon fiber (CCF)/high-density polyethylene (HDPE) composites. By utilizing a novel extruder and take-up system based on the melt spinning technique, we successfully controlled the alignment of CCF at various thicknesses using mechanical tension. This facilitated the production of extruded profiles with controlled tensile conditions. Experimental measurements were conducted to evaluate the tensile strength and modulus of the composites. The results demonstrate the effectiveness of the proposed CCF alignment method, which involves adjusting the thickness of the extruded profiles, in controlling the mechanical properties of the composites. As a result, the ultimate tensile strength increased by 50%, and the tensile modulus increased by 130%. Additionally, we developed a numerical model that predicts the tensile modulus based on randomly generated fibers and the Mori-Tanaka model for property estimation. The fiber orientation distribution was influenced by the fiber shape and manufacturing conditions. Scanning electron microscope (SEM) images revealed that the fibers aligned more along the extrusion direction with increased draw ratio. The orientation distribution of the randomly generated fibers varied significantly based on the fiber length and draw ratio, indicating a narrowed distribution range along the extrusion direction with increased fiber length or draw ratio. These findings demonstrate that the proposed CCF alignment method, which involves changing the thickness of the extruded profiles, can effectively control the mechanical properties of the composite.

The evaluation of waste engine oil/old newspaper in recycled low density polyethylene composites

AbstractThe study investigates changes in the mechanical, thermal, morphological and physical properties of recycled low density polyethylene (LDPE) composites made with percentages (10 wt%, 20 wt%, 30 wt.%) of old newspaper fiber (ONF) and waste engine oil (WEO) (1 wt.%). The composites were manufactured by a single screw extruder. Adding WEO up to 20 wt% of ONF had a positive effect on the flexural properties, while the incorporation of WEO up to 10 wt % of ONF showed an affirmative effect on the tensile properties of the composites. The highest flexural strength was achieved in A3 (13.19 MPa) and B3 (12.3 MPa) samples for ONF added composites and ONF/WEO composites, respectively. Adding to the WEO decreased the water absorption values of the recycled low density polyethylene composites. Differential scanning calorimetry analysis showed that the addition of 1% WEO, the crystallinity of the composites decreased to about 30%. In the light of the results, the WEO could be successfully used with old newspaper in a polyethylene matrix.Highlights The highest tensile strength was achieved in the B3 sample (with WEO). The highest flexural strength was achieved in the B3 sample (with WEO). The highest tensile was obtained from the A3 sample (without WEO). The highest flexural strength was obtained from the A3 sample (without WEO). The crystallinity of the composites decreased to about 30%.

The experiment and simulation of enhanced mechanical performance for polyethylene terephthalate/high‐density polyethylene composites via domain size control

AbstractSolid‐state shear milling (S3M) equipment is proficient for achieving room‐temperature ultrafine grinding of multicomponent polymers, demonstrating significant potential in polymer blending and waste plastic recycling. However, a systematic investigation of S3M's ability to control the domain size of multicomponent polymer is currently lacking, which was of great potential for the high‐value recycling of waste plastics that are difficult to separate and thermodynamically incompatible. As the raw material of beverage bottle, polyethylene terephthalate/high‐density polyethylene (PET/HDPE) system with tremendous production was hard to be recycled together. Therefore, in this study, we chose PET/HDPE for the study of domain size control efficiency of S3M on mechanical properties of polymer blend. We also measured the processing parameters during the fabrication of PET/HDPE blended powder to determine the optimal manufacturing parameters for the polymer composite with outstanding mechanical property. After 30 milling cycles, the powder size of PET/HDPE gradually decreased from 849.8 μm (2 cycles) to 43.2 μm, which related to PET domain size of 71.9 and 5.2 μm, respectively. Meanwhile, at 24 milling cycles, the PET/HDPE composites reached the highest tensile strength of 27.6 MPa, meeting the most proper milling condition for PET/HDPE system. Finite element computer simulation was introduced to further investigate the domain size influence on mechanical property of PET/HDPE composites, which acquired similar results with the experimental value before excessive milling cycles. Based on both the experimental results and simulation support, a theoretical basis for the domain‐size‐control analysis of S3M in multicomponent waste polymer recycling was established.

Effect of the melt flow index of compatibilizer on the melt processing and properties of highly filled magnesium hydroxide/linear low density polyethylene composites

AbstractThe application of highly filled composites is limited by their poor processing and rheological properties due to the high loading of fillers. One possible solution to this problem is to use maleic anhydride grafted polypropylene (MAPP) with high melt index as compatibilizer and lubricant. Herein, magnesium hydroxide (MH)/linear low‐density polyethylene (LLDPE) composites with 60 wt% of MH were prepared using MAPP with three different melt flow indexes (MFI). The equilibrium torque and melt flow index tests show that the addition of MAPP with high MFI significantly improves the processability and flowability of MH/MAPP/LLDPE composites. The rheological studies show that it also leads to a substantial reduction in the viscosity and therefore MH/MAPP/LLDPE composites exhibit more solid‐like responses. The scanning electron microscopy shows that a transition layer is formed at the MH‐LLDPE interface. The flame retardancy test shows that the addition of MAPP slightly reduces the flame retardancy of the composites as evidenced by the reduced limiting oxygen index and increased total heat release. Cone calorimeter test shows that the simultaneous addition of MH and MAPP has a synergistic smoke suppression effect.

Reinforcing the mechanical properties of bamboo fiber/low density polyethylene composites with modified bamboo-woven structure

Reinforcing the mechanical properties of bamboo fiber/low density polyethylene composites with modified bamboo-woven structure

Low cost and easily scalable microwave absorbing material based on three-layer honeycomb sandwich structures

The present work describes a new three-layer structure for developing lightweight and low-cost microwave absorbing material using available honeycomb (HC) structures sandwiched by high density polyethylene (HDPE) composites loaded with a 3% of hybrid mixture of carbon black (CB) and graphite (GF) as dielectric filler (HDPE/HB) or 5% of granitic quarry waste (HDPE/GQW) as magnetic material. The microwave absorbing properties was studied in the X-band frequency range, which is useful for military purpose. Uncoated HC structure presented reasonable microwave absorbing properties, which could be improved by a proper choice of the thickness and cell size. The three-layer structure constituted by HC (4 mm thick) sandwiched by HDPE composites (1 mm thick) with HDPE/GQW composite as the matching layer resulted in minimum reflection loss of − 30.0 dB, which corresponds to electromagnetic wave attenuation higher than 99.9%. The present work illustrates the possibility of developing low cost and lightweight microwave absorbing material with easy and scalable fabrication procedures, for applications in both civil and military fields. The results also provide useful application of the waste generated from crushed gneiss rock during the production of fine aggregates, which is important for the environmental sustainability purpose.

Characterization of cellulose acetate/low density polyethylene fibre reinforced composite

Three different compatibilizers were used; namely: Fusabond (FSB) which is a maleic anhydride grafted polyethylene, montanic acid (E wax), and used engine oil (UEO) were incorporated into cellulose acetate/low density polyethylene (CA/LDPE) composites at three fiber contents: 5, 15 and 30 phr. Three series of samples consisting of treated composites using coupling agents were prepared, while one group was left untreated as a reference composite. To assess the performance of the composites, different testing techniques were used. These include attenuated total reflectance spectroscopy(FTIR-ATR), thermogravimetric analysis(TGA), differential scanning calorimetry(DSC), tensile test, dynamic mechanical thermal analysis(DMTA), and scanning electron microscopy(SEM). The presence of ethylene vinyl acetate (EVA) in LDPE enhanced the adhesion at the polymer/fiber interface, as reflected by the increase of Young’s modulus by 75, 166, and 245% respectively compared to neat LDPE, an increase of the storage modulus and a reduction of the damping factor value. Incorporating Fusabond was also found to affect slightly the mechanical properties with high fiber contents compared to the composites without the coupling agent by 13%. On the other hand, the use of montanic acid and used engine oil affected the cellulose acetate fibers distribution within the matrix. The UEO enhanced the dispersion but acted as a plasticizer resulting in a slight reduction of the crystallinity. Moreover, the interaction between the LDPE matrix and the CA fibres was indicated by the resulting fracture surface morphology. The results obtained suggest that the CA/LDPE composites would be suitable for packaging or used in automotive applications.

Construction of high-strength aligned bamboo fibre/high density polyethylene composites

Construction of high-strength aligned bamboo fibre/high density polyethylene composites

Comparative Evaluation of the Stiffness of Abaca-Fiber-Reinforced Bio-Polyethylene and High Density Polyethylene Composites

The use of bio-based matrices together with natural fibers as reinforcement is a strategy for obtaining materials with competitive mechanical properties, costs, and environmental impacts. However, bio-based matrices, unknown by the industry, can be a market entry barrier. The use of bio-polyethylene, which has properties similar to polyethylene, can overcome that barrier. In this study, composites reinforced with abaca fibers used as reinforcement for bio-polyethylene and high density polyethylene are prepared and tensile tested. A micromechanics analysis is deployed to measure the contributions of the matrices and reinforcements and to measure the evolution of these contributions regarding AF content and matrix nature. The results show that the mechanical properties of the composites with bio-polyethylene as a matrix were slightly higher than those of the composites with polyethylene as a matrix. It was also found that the contribution of the fibers to the Young's moduli of the composites was susceptible to the percentage of reinforcement and the nature of the matrices. The results show that it is possible to obtain fully bio-based composites with mechanical properties similar to those of partially bio-based polyolefin or even some forms of glass fiber-reinforced polyolefin.

Evaluation of crystallinity, thermal, mechanical and morphological features of high density polyethylene composites reinforced with crosslinked semifluorinated acrylate polymer microspheres

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.

Time‐dependent properties of high‐density polyethylene with wood/graphene nanoplatelets reinforcement

AbstractThe effect of graphene nanoplatelets (GNPs) on the long‐term performance of wood fiber/high‐density polyethylene (HDPE) composite is investigated by using short‐term creep tests with an efficient, faster data analysis approach. Previously, it was shown that the addition of GNPs at 15 wt% into HDPE reduces the viscoplastic (VP) strain developed during 2 h creep by ~50%. The current study shows that 25 and 40 wt% wood content in HDPE reduce the VP strains developed during 2 h creep time by >75% with no noticeable effect of the increased wood content. However, further addition of GNPs results in more than 90% total reduction in the VP strains. The current study shows that the development of the VP strains in the hybrid composites follows Zapas model. Viscoelastic (VE) response of these composites is nonlinear and thus is described by Schapery's model. Parameters for VP and VE models are obtained from the creep experiments and were validated in a separate loading‐unloading test sequence. Results show a very good agreement between experiments and predictions for the studied materials as long as the micro‐damage is not present.

Low density polyethylene composites based on flax fibers modified by a combination of coupling agent

AbstractThis investigation proposes a natural fiber surface modification approach based on the use of a system of coupling agents (CAs) to improve the mechanical properties of polymer composites made of flax fibers and low‐density polyethylene. This system combines the coating of the NaOH treated (mercerized) flax fibers by a CA (Epolene C18 [M‐C18]) in a solution under moderated heat (70°C–80°C), followed by the addition of 1% or 3% wt. of another CA (Epolene E43 [M‐E43]) during the injection molding. The comparison between the solution modified and the neat and mercerized flax fibers using scanning electron micrograph (SEM), thermogravimetric analysis (TGA), and density underscored some differences ascribed to the presence of M‐C18 onto the modified fibers. The mechanical properties showed that the combination of solution modification and direct introduction during the injection‐molding step of 1% of M‐E43 was efficient as the corresponding composites exhibited an improvement of 9.1%, 15.9%, and 11.1% of his tensile, flexural, and impact strengths respectively compared to the neat fiber composite. Due to their good impact and flexural strengths, these composites can be suitable for automotive parts such as keyboard.