Mechanical Properties Of High Density Polyethylene Research Articles

Effect of Cornshell Fibre Addition on Mechanical Properties of High-Density Polyethylene (HDPE) Composites with Aluminium Oxide (Al2O3) and Maleic Anhydride (MAH) as Coupling Agent

Effect of Cornshell Fibre Addition on Mechanical Properties of High-Density Polyethylene (HDPE) Composites with Aluminium Oxide (Al2O3) and Maleic Anhydride (MAH) as Coupling Agent

Radiation attenuation properties of chemically prepared MgO nanoparticles/HDPE composites

Sheets of high-density polyethylene (HDPE) loaded with magnesium oxide in micro and nano were synthesized with different weight percentages of micro-MgO (0,5,10,20 and 30% by weight) and nano-MgO (5 and 30%) and shaped in form of disc and dog bone shape. The morphological, mechanical, and attenuation characteristics of each concentration were determined. The linear attenuation coefficients (LAC) of the prepared discs were calculated using a well-calibrated scintillation detector and five standard gamma-ray point sources (241Am, 133Ba, 137Cs, 60Co and 152Eu). The LAC was theoretically calculated for HDPE/micro-MgO composites using XCOM software. A good agreement between the theoretical and experimental results was observed. The comparison between micro and nano-MgO as a filler in HDPE was evaluated. The results proved that the loaded nano-MgO in different proportions of HDPE produced greater attenuation coefficients than its micro counterpart. The addition of nano MgO with different weight percentage led to a significant improvement in the mechanical properties of HDPE, the ultimate force and ultimate stress increased as the concentration of nano MgO increased, and the young modulus of HDPE also increased with increasing concentration of micro and nano MgO.

Investigation on Constitutive and Ductile Damage Mechanism of High-Density Polyethylene under Tensile and Bending Conditions

High-density polyethylene (HDPE) is one of the most commonly used materials for manufacturing pipelines. In this paper, the deformation behavior of HDPE materials under uniaxial tensile stress was investigated by employing uniaxial tensile tests and macroscale/mesoscale morphology analysis. The experimental results indicated that the stress–strain relationship of HDPE is nonlinear, and the ductile fracture characteristics of necking and local failure appear in the sample after the engineering strain reaches 35%. Therefore, for the first time, a hyperelastoplastic constitutive model that describes the elasticity by the Marlow model and combined the isotropic plasticity-ductility damage correction is established, and a corresponding numerical approach is proposed. The simulation scheme was implemented in finite-element software, and the mechanical responses of HDPE under uniaxial tensile and bending loads were predicted. Obtained calculations were relatively consistent with experimental observations. Hence, the proposed model and approach have a good simulation effect on the mechanical properties of HDPE and can be employed for the process prediction of such materials. This study is beneficial to the in-depth understanding of the hyperelastoplasticity and failure mechanism of HDPE and provides ideas for the deformation and failure study of other polymer materials.

Additive Effects of Solid Paraffins on Mechanical Properties of High-Density Polyethylene

In this work, two types of solid paraffins (i.e., linear and branched) were added to high-density polyethylene (HDPE) to investigate their effects on the dynamic viscoelasticity and tensile properties of HDPE. The linear and branched paraffins exhibited high and low crystallizability, respectively. The spherulitic structure and crystalline lattice of HDPE are almost independent of the addition of these solid paraffins. The linear paraffin in the HDPE blends exhibited a melting point at 70 °C in addition to the melting point of HDPE, whereas the branched paraffins showed no melting point in the HDPE blend. Furthermore, the dynamic mechanical spectra of the HDPE/paraffin blends exhibited a novel relaxation between -50 °C and 0 °C, which was absent in HDPE. Adding linear paraffin toughened the stress-strain behavior of HDPE by forming crystallized domains in the HDPE matrix. In contrast, branched paraffins with lower crystallizability compared to linear paraffin softened the stress-strain behavior of HDPE by incorporating them into its amorphous layer. The mechanical properties of polyethylene-based polymeric materials were found to be controlled by selectively adding solid paraffins with different structural architectures and crystallinities.

A study on the synergetic effects of self/induced crystallization and nanoparticles on the mechanical properties of semi-crystalline polymer nanocomposites: experimental and analytical approaches

This work investigates the effects of nanoparticle content, aggregation/agglomeration, polymer/particle interphase, and crystallinity on the mechanical properties of high-density polyethylene (HDPE) nanocomposites. Different samples of HDPE nanocomposites, containing 0.5, 0.75, and 2 wt% of pure and surface-modified silica nanoparticles were prepared by melt-mixing method. The pure silica nanoparticles (PSN) and surface-modified silica nanoparticles with (3-aminopropyl) tri-ethoxy-silane (AMS) were characterized with field emission scanning electron microscopy (FESEM) and Fourier-transform infrared (FTIR) spectra. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to estimate the crystallinity and crystal size of the nanocomposite samples. Finally, tensile testing was performed on the nanocomposites to establish the relationship between mechanical properties and nanoparticle loading, and surface modification. The results indicate that the crystallinity and elastic modulus of the nanocomposites increased with increasing nanoparticle content. Moreover, the Gutzow–Dobreva theory was applied to approximate the degree of the induced crystallinity in each sample. A mechanical model based on two equivalent box models (EBM) was proposed to determine the crystalline, amorphous phase modulus, thickness and tensile modulus of the polymer/particle interphase region, which showed a decreasing trend with the nanoparticles content and indicated that this region was thicker for the HDPE/AMS relative to HDPE/PSN. Also, it was found that nanoparticles affected both crystalline and amorphous sections, which their effect on the crystals was more significant and presence of the well-dispersed nanoparticles in the amorphous section substantially enhanced their performance against the exerted stress.

Morphology, rheological, thermal, and mechanical properties of high-density polyethylene toughened by propylene-ethylene random copolymers

Morphology, rheological, thermal, and mechanical properties of high-density polyethylene toughened by propylene-ethylene random copolymers

HDPE 기반의 나노다이아몬드 복합소재의 물성 예측을 위한 인공신경망 연구

The mechanical performance of the nanocomposite depends on the processing conditions of the samples. Therefore a predictive model is essential to proceed the combination of processing conditions into account, for accurately predicting the mechanical properties is a critical requirement in manufacturing industries. The current investigation explores the prediction of mechanical properties of high-density polyethylene (HDPE)-based nano-diamond nanocomposite (i.e., HDPE/0.1 ND) using an artificial neural network (ANN) model under various processing conditions of temperature and pressure. A 2-10-2 (2 input, 10 hidden and 2 output layer) neural network model with Levenberg–Marquardt algorithm is developed to predict Young

Improving comprehensive properties of high-density polyethylene matrix composite by boron nitride/coconut shell carbon reinforcement

Simultaneously enhancing the thermal conductivity, insulation, and mechanical properties of high-density polyethylene (HDPE) composites is highly desired for electronic and electrical applications. In this research, HDPE/boron nitride (BN)/coconut shell charcoal (CSC) composites were prepared. Benefit from the synergistic effect between the multi-dimensional hybrid fillers, the prepared HDPE/BN/CSC composites exhibited enhanced comprehensive properties compared to the HDPE/BN composites and pure HDPE. In particular, as for HDPE/25BN/3CSC (25 wt% BN, 3 wt% CSC) nanocomposites compared to the pure HDPE, enhancements in in-plane thermal conductivity of 980.89%, normal thermal conductivity of 138%, and tensile strength of 18.91% were obtained, while higher volume resistivity and decomposition temperature were achieved. This work provides a simple but effective way for improving the thermal conductivity and comprehensive physical properties of HDPE composites.

Biochar from food waste as a sustainable replacement for carbon black in upcycled or compostable composites

This study investigates biochar, a carbon-based material produced via pyrolysis, as a filler in two plastics: biodegradable plastic polylactic acid (PLA) and recycled high-density polyethylene (HDPE). Specifically, we examine biochar derived from post-consumer food waste as a method to reuse this large waste stream. We find that pyrolysis of this inhomogeneous waste at 900 °C forms biochar with a graphitic structure and electrical conductivity similar to carbon black. Biochar addition impacts the properties of HDPE and PLA differently, with reduced thermal stability in PLA and only minor impacts on the thermal and mechanical properties of HDPE. In both polymers, agglomeration of biochar particles results in low electrical conductivity of the composites. This study highlights a loss of thermal stability in PLA with the addition of biochar as a critical roadblock to applying biochar as a filler in PLA. We propose that inorganic compounds in the biochar catalyze the thermal degradation of PLA, resulting in shorter PLA chains and reducing the composite’s mechanical properties. An important finding of this work is that food-waste-derived biochar increased the degradation rate of PLA under composting conditions, with almost twice the mass loss after 40 days in samples with high biochar loading compared to neat PLA. This study highlights both the promise and challenges of utilizing biochar as a filler in PLA and HDPE. If particle dispersion and thermal stability with PLA can be addressed, biochar has the potential for reuse of a high environmental impact waste stream for a wide range of applications.

Effects of an industrial graphene grade and surface finishing on water and oxygen permeability, electrical conductivity, and mechanical properties of high-density polyethylene (HDPE) multilayered cast films

Graphene-based composites are promising candidates to improve properties in flexible packaging to protect electronic devices. However, the literature hardly addresses the industrial scale requirements. In this context, high-density polyethylene (HDPE), a common packaging material, and an industrial grade graphene (G) were used to prepare multilayered composites by cast film coextrusion, a flexible-packaging-industry compatible technique. The effects of G content and surface finishing on HDPE films’ properties were investigated. Experimental results showed that a maximum permeability reduction of 43% at 0.5 wt% of G was achieved. Such result was associated with a good dispersion efficiency and with the filler’s aspect ratio. However, as the concentration of G increased both barrier and mechanical properties worsened due to a poor dispersion of G within the composite. Additionally, it was found that surface finishing induced defects increasing permeability despite improvements in visible light transmittance and reduction of surface roughness. These defects can be successfully prevented using a proper design of layers during coextrusion. In summary, the present study showed the feasibility of G-based flexible packaging film applications at an industrial scale. The importance of G dispersion and of layer design to achieve improved barrier properties should be emphasized.

Study of wear performance and mechanical properties of HDPE on addition of CNT fillers

Carbon nanotube (CNT)/High-Density Polyethylene (HDPE) nanocomposite specimens were prepared with varying concentrations of 0, 0.04, 0.12 wt% by using ethanol as solvent followed by sonication and magnetic stirring for homogeneous distribution of CNT throughout the composite. To find variation in different mechanical properties like the modulus of elasticity, yield strength, tensile test was conducted and observed that the addition of nanofillers enhances the modulus of elasticity by 24.4 percent, and Yield Strength by 5.19 percent, with 0.12 percent CNT Toughness was evaluated by Charpy and Izod tests and found that it was improved by adding CNT nanofillers. Toughness improvement by the Izod test was 35 percent and by Charpy test, it was 4.76 percent with 0.12 percent CNT. The pin on the disc wear test exhibits depletion on the wear of nanocomposites. Even compared with the available theoretical model and found maximum 2.43 percent error in results for modulus of elasticity.

Radiation-Based Crosslinking Technique for Enhanced Thermal and Mechanical Properties of HDPE/EVA/PU Blends.

Crosslinking of polyolefin-based polymers can improve their thermal and mechanical properties, which can then be used in various applications. Radiation-induced crosslinking can be done easily and usefully by irradiation without a crosslinking agent. In addition, polymer blending can improve thermal and mechanical properties, and chemical resistance, compared to conventional single polymers. In this study, high-density polyethylene (HDPE)/ethylene vinyl acetate (EVA)/polyurethane (PU) blends were prepared by radiation crosslinking to improve the thermal and mechanical properties of HDPE. This is because HDPE, a polyolefin-based polymer, has the weaknesses of low thermal resistance and flexibility, even though it has good mechanical strength and machinability. In contrast, EVA has good flexibility and PU has excellent thermal properties and wear resistance. The morphology and mechanical properties (e.g., tensile and flexure strength) were characterized using scanning electron microscopy (SEM) and a universal testing machine (UTM). The gel fraction, thermal shrinkage, and abrasion resistance of samples were confirmed. In particular, after storing at 180 °C for 1 h, the crosslinked HDPE-PU-EVA blends exhibited ~4-times better thermal stability compared to non-crosslinked HDPE. When subjected to a radiation dose of 100 kGy, the strength of HDPE increased, but the elongation sharply decreased (80%). On the other hand, the strength of the HDPE-PU-EVA blends was very similar to that of HDPE, and the elongation was more than 3-times better (320%). Finally, the abrasion resistance of crosslinked HDPE-PU-EVA was ~9-times better than the crosslinked HDPE. Therefore, this technology can be applied to various polymer products requiring high heat resistance and flexibility, such as electric cables and industrial pipes.

The effect of artificial weathering and hardening on mechanical properties of HDPE with and without UV stabilizers

Outdoor applications of polymers are increasing rapidly. So, the ability of polymers to withstand environmental degradation became very important for many researchers. The effect of artificial weathering and hardening on the stability of high-density polyethylene (HDPE) with and without stabilizers has been studied. HDPE samples were prepared with UV absorbers (UVA) and hindered amine light stabilizers (HALS) at different concentrations. The results indicated that non-stabilized HDPE was mechanically dead after 300 h of exposure, where it lost almost 98% of its toughness, and the percentage of elongation at break reduced from 1223% to 21%. It was clear that stabilizers sustain the mechanical properties of samples efficiently until 900 h. However, the best performance was observed by samples containing a specific concentration of HALS and UV absorber, which retain most of its properties until 1300 h. The hardening test was performed by heating the samples to 125 °C then suddenly cooled at 0 °C, 25 °C, and 50 °C. The mechanical properties of HDPE were significantly affected by hardening.

One-pot preparation of hydrophobic lignin/SiO2 nanoparticles and its reinforcing effect on HDPE

Nano silica (SiO2) is usually used as a common reinforcing agent in polymer materials, in which the interfacial interaction greatly affects the mechanical properties of the composites. The reinforcement effect of silica on non-polar polymer is restricted due to their poor compatibility. In this work, amphipathic lignin modified by quaternization and alkylation was used as a modifier for silica to prepare hydrophobic lignin/SiO2 nanoparticles by in-situ one-pot co-precipitation method. In alkaline solution, hydrophobic lignin and SiO2 (from Na2SiO3) were self-assembled to form nanospheres through electrostatic and hydrophobic interactions. The results showed that the lignin/SiO2 nanoparticles were highly hydrophobic nanospheres with macropores in the surface. When the lignin/SiO2 nanoparticles (10 wt%) were added to reinforce high-density polyethylene (HDPE), the mechanical properties of HDPE were improved with the strength of 24.5 MPa and the elongation of 1096%, which were increased by 10.4% and 14.3% compared with the control HDPE, because of the good compatibility and large bonding area. This work puts forward a new solution for the application of lignin in reinforcement of non-polar polymers.

Investigation on mechanical properties of sugarcane bagasse ash reinforced with incorporation of HDPE - montmorillonite composite materials

Natural Composite are the materials that have more variety of real time product usages and also many industries realize the benefits of these materials, as it offers for light-weight composite structures. The nano-composites are also the composite materials, in which the nano particles have been reinforced into a base matrix material. The result of inclusion of nano particles will have considerable improvements in the mechanical properties, like higher tensile strength, better toughness, higher hardness, etc. In this research, High-Density Polyethylene (HDPE) has been used as matrix material and nano-clay Cloisite-30B as the reinforcement material with sugarcane bagasse ash. A compatibilizer, HDPE grafted with Maleic anhydride (HDPE-g-MA) has also been used to provide a better blending of polymers that will increase their stability and better interaction between the high density polyethylene and nano-clay and montmorillonite minerals with sugarcane bagasse ash. Sample specimen of nano-composite materials had prepared by at different zone temperatures. Also the distribution of these particles such as nano clay, montmorillonite minerals and Sugarcane bagasse ash are in the range of (0-4 wt%) with HDPE in equal proportion. Various mechanical tests like flexural, tensile, hardness and impact using respective dies as per ASTM standard were prepared. In prior to the samples were tested, the investigation of four different wt. % of nano-clay-montmorillonite minerals on the mechanical properties of HDPE had examined to verify the most effective wt % of nano-clay-montmorillonite minerals for improving the strength of nano-composites. The experimental results on mechanical properties of HDPE/Cloisite-30B nano-clay montmorillonite and sugarcane bagasse ash has been analyzed and improvement of strength of materials have also been studied with various wt% (0 to 4%) of nano-clay-montmorillonite and experimental results proved that the sugarcane bagasse ash on HDPE nano-montmorillonite mineral composite yield better strength and desirable mechanical properties.

Influence of Thermal Ratcheting on the Creep and Mechanical Properties of High-Density Polyethylene

Abstract The objective of this research is to describe the consequence of thermal ratcheting on the long-term creep property of the high-density polyethylene (HDPE) material. The thermal ratcheting phenomenon increases significantly the creep strain of HDPE. The magnitude of the creep strain of HDPE increases by 8% after just 20 thermal cycles between 28 and 50 °C. The creep modulus, which is inversely proportional to the creep strain, depletes further under thermal ratcheting. Both the properties change significantly with the number of thermal cycles. The coefficient of thermal expansion (CTE) of HDPE varies with the applied compressive load, with successive thermal cycles, and with the thermal ratcheting temperature. The impact of thermal ratcheting diminishes with an increase in initial steady creep exposure time period, but still the magnitude cumulative deformation induced is noteworthy. The magnitude of growth in creep strain drops from 8% to 2.4% when thermal ratcheting is performed after 1 and 45 days of steady creep, respectively. There is a notable change in the thickness of the material with each heating and cooling cycle even after 45 days of creep; however, the thermal ratcheting strain value drops by 80% in comparison with the thermal ratcheting strain after 1 day of creep and under similar test conditions.

HDPE/SILICA COMPOSITES-PART II: EFFECT OF SILICA PARTICLE SIZE AND SILICA MODIFICATION ON THE THERMAL AND MECHANICAL PROPERTIES

In this work, the effect of silica particle size and organosilane type used in the silica organofunctionalization on the thermal and mechanical properties of high-density polyethylene (HDPE)/silica composites were evaluated. HDPE/silica composites were prepared by the extrusion method using two types of silica: fumed silica, with nanometric particle size and silica gel, micrometric, modified with organosilanes containing methyl or octyl functional groups. Silicas were added to the HDPE at 1% v/v concentration. The addition of the silicas to the HDPE did not influence the melt (Tm) and the crystallization (Tc) temperatures of the resulting composites but influenced its crystallinity. The mechanical property of Izod impact strength, the dynamicmechanical rheological test (DMTA) and the surface contact angle analysis showed improvements in relation to pure HDPE when used methyl-modified pyrogenic silica as filler. This result suggests that the surface modification of pyrogenic silica with methylsilane groups results in a stronger interaction of this silica with the HDPE matrix. This effect was not observed for micron-sized silica gel, where modification with organosilanes was not sufficient to guarantee interfacial interaction with the HDPE matrix.

Studies on the Effects of Bentonite (Nanoclay) on the Mechanical Properties of High-Density Polyethylene

In this work, the effect of Bentonite (Nanoclay) on the mechanical and mor-phology properties of HDPE/Nanoclay composite pipe material was investi-gated. This led to the development of a composite material with improved me-chanical properties. The HDPE/nanoclay composites were produced using an injection moulding machine at 200?C and rotor speed of 50 rpm. The compati-bilizer used in this study was Polyethylene-graft-Maleic Anhydride. Different compositions of nanoclay reinforcements were prepared and added to HDPE resin. A particle size of 425 μm was used in proportions of 0%, 5%, 10%, 15%, and 20% on weight fraction basis. All the composites samples were characterized by Zwick Roell tensile testing machine and Scanning Election Microscopy (SEM). Experimental results obtained showed improvements in the tensile strength, and modulus at the expense of elongation. The maximum tensile strength and modulus was obtained at 10% filler composition. These enhanced properties are due to the homogenous dispersion of nanoclay in HDPE matrix, which is evident from the structure that was evaluated using SEM.

Effect of carbon black distribution on the properties of polyethylene pipes - Part 1: Degradation of post yield mechanical properties and fracture surface analyses

In this study, we investigated the effect of carbon black distribution on the degradation of mechanical properties of high-density polyethylene in the form of plastic pipes used in water distribution networks. Polyethylene pipes with similar carbon black concentrations but different carbon black distributions were produced with industrial scale compounding and extrusion equipment. Tensile specimens were directly prepared from extruded pipe samples and elongated to fracture at different strain rates. Carbon black distributions of bulk samples and fracture surfaces were investigated using stereo and scanning electron microscopy (SEM). It was found that the carbon black distributions, fracture surfaces and fracture modes were significantly different in these pipes. Although the yield properties were similar, the post-yield properties of samples were significantly different, dramatically decreasing with the increasing inhomogeneity of carbon black distribution. Pipes with a certain level of heterogeneity in the carbon black distribution showed ductile and brittle fractures in the same fracture plane, whereas homogenous black and natural polyethylene (without carbon black) showed ductile fractures only.

Evaluation of mechanical properties of polyethylene for pipes by energy approach during tensile and fatigue tests

Since its introduction in pipe applications more than 40 years ago, polyethylene (PE) has been taking a growing place in gas and water distribution due to its low cost, lightness and good corrosion resistance. Besides, long-term properties have been steadily rising due to the development of novel PE-based materials. The present highest standard is the PE100 class. Several laboratory tests are used to extract design data for long-term failure-type prediction based on stress and time to failure relationship. It remains difficult to assess the relation between creep and fatigue loadings on the one side. On the other side, the manufacturing process of the test specimens influences considerably the obtained performance for viscoelastic materials subjected to working conditions. In present paper, the mechanical properties of high-density polyethylene (HDPE), PE 100 class, for pipes were investigated using experimental techniques. Thermographic technique was used during the static tests in order to identify the maximum stress zone and also during the fatigue tests to study the temperature evolution of the specimen. The aim of this study is the application of the Thermographic Method for the fatigue assessment of PE100.