Thermal Properties Of High Density Polyethylene Research Articles

Investigation of the usability of laurel waste in thermoplastic composite production

In this study, the usability of laurel waste in thermoplastic composite production was investigated. After the laurel branch waste and leaf waste were ground and sieved, they were added to high-density polyethylene (HDPE) at a rate of 0-10-20-40% by weight and mixed in an extruder. Then, boards with dimensions of 250x250x3 mm were produced from the mixtures according to the hot press molding technique. As a result of adding branch and leaf flour to neat HDPE, tensile strength decreased. The tensile strength was determined as 22.28 MPa in the HDPE board and 8.6 MPa in the 40% leaf flour added board. As a result of adding branch and leaf flour to neat HDPE, bending strength first increased and then decreased. The highest flexural strength was determined as 30.3 MPa with 10% leaf flour additive, and the lowest bending strength was determined as 21.68 MPa with 40% leaf flour additive. According to Shore D test results, branch flour and leaf flour increased the hardness of neat HDPE. According to the thermal analysis results, it was seen that the effect of branch flour and leaf flour on the thermal properties of HDPE was limited. In addition, scanning electron microscope (SEM) images showed that HDPE and branch flour mixed better.

The effect of chemical crosslinking on the properties of Rotomolded high density polyethylene

AbstractIn this study, high density polyethylene (HDPE) was combined with dicumyl peroxide (DCP) to produce crosslinked parts via rotational molding. The effect of DCP content (0.1–2.5 phr) on the crosslinking degree was investigated to determine its effect on the chemical, mechanical, physical, and thermal properties of HDPE. The gel content and crosslink density was found to increase with DCP content. These trends led to a reduction in the degree of crystallinity, melting, and crystallization temperature. Thermogravimetric analysis (TGA) showed that crosslinked HDPE (xHDPE) has higher thermal stability than the neat matrix in both air and nitrogen atmosphere. In addition, a direct relationship was observed between improved thermal resistance and higher impact strength. Finally, relationships between the tensile properties of xHDPE and the degree of crystallinity were observed, which were all controlled by the level of crosslinking. These results have the potential to advance the manufacturing of high performance materials suitable for a wide range of applications such as automotive parts, agricultural products, chemical storage tanks, large waste containers, and fuel tanks in general.

Effect of Mass and Temperature Rate on the Thermal Properties of High-Density Polyethylene Using Differential Scanning Calorimetry

Mass and heating rates alter the thermal properties, molecular structure, and phase changes of the materials. This study aimed to investigate the influence of sample mass (10-30 mg) and heating rate (4-15 °C/min) on the thermal characteristics of high-density polyethylene (HDPE) using differential scanning calorimetry (DSC). The experiments were conducted in two cycles. In the first cycle, samples of different masses (10-30 mg) were heated to 180 °C followed by cooling at a constant heating rate of 10 °C/min with a mass flow rate of 20 ml/min of purging gas (nitrogen). In the second cycle, a sample mass of 15 mg was used to investigate the thermal characteristics while varying the temperature rates (4, 6, 8, 10, and 15 °C/min). It was concluded that the variation in sample mass significantly affected the thermal properties of HDPE, leading to a slight increase in the melting temperature and latent heat, which shifted towards higher temperatures. In contrast, the temperature rate caused a reduction in the latent heat and crystallization temperatures. The thermograms obtained from the experiments provided insight into the thermal behavior of HDPE under different conditions, and the findings emphasized the importance of carefully considering the effects of mass and temperature rate when measuring the thermal properties of HDPE.

Effect of Vegetable Oil on the Properties of Asphalt Binder Modified with High Density Polyethylene.

Economic development results in increased traffic and higher traffic loads that often cause serious asphalt pavement problems, such as permanent deformation, fatigue cracking, and reduced lifetime. Polymers are seen as viable asphalt additives to minimize these problems. However, their incorporation reduces the workability of the material due to the increase in the viscosity of the blend. This study evaluates the effect of the addition of soybean oil on the physical, rheological, and thermal properties of high-density polyethylene (HDPE)-modified asphalt binder. The HDPE was kept at 5 wt.% and the soybean oil the asphalt was varied from 1 to 7 wt.%. A series of tests was conducted to evaluate the binders, comprising conventional tests (penetration, softening point, and ductility) rheological performance tests (dynamic viscosity and short-term aging (RTFO), and thermogravimetric analysis (TGA). The addition of HDPE reduced the penetration and increased the softening point and viscosity. The oil reduced steadily the viscosity, improved the workability and the thermal susceptibility of the modified asphalt up to 3 wt.% of oil, and reduced about 92% mass gain after aging. Hence, the oil is considered a good modifier agent for the improvement of polymer-modified asphalt's workability under service conditions.

Effects of Blending Tobacco Lignin with HDPE on Thermal and Mechanical Properties.

Depletion of fossil fuels and the detrimental environmental impacts of synthetic plastics have prompted a global interest in bio-based polymers. Lignin is an abundant, unused, and low-value byproduct of pulping and biochemical operations that has the potential to decrease the need for plastics derived from petroleum. Melt blending is one of the easiest strategies for expanding the commercial applications of lignin. Concerns remain, however, regarding the negative effects of lignin on the final composite material’s performance, and the increase in manufacturing costs. This study investigates the effects of blending lignin extracted from tobacco using a novel one-step processing technique on injection molding parameters, and the mechanical, physical, and thermal properties of high-density polyethylene (HDPE). By extruding HDPE pellets and lignin powder, varying blend concentrations (0, 5, 10, 15, and 30% wt.) were produced. Scanning electron microscopy (SEM) and optical microscopy were used to investigate the compatibility of the blend morphology. Results indicated that interfacial interactions were achieved as particles of tobacco lignin were well dispersed and uniformly distributed throughout HDPE. Intermolecular interactions between HDPE and lignin were also discovered through Fourier-transform infrared (FTIR) spectral analyses. The tensile test results showed that increase in lignin content up to 15% wt. had little effect on tensile strength, but at 30% wt., a 19% reduction was observed. With the addition of 5, 10, 15, and 30% wt. of lignin, the tensile modulus increased by 4%, 29%, 25%, and 8%, respectively. TGA results demonstrated that at 15% and 30% wt., tobacco lignin acted as a thermal stabilizer. The processability study revealed that tobacco lignin could be processed easily using injection molding without requiring significant changes to the process parameters. Overall, tobacco lignin showed great promise as a biodegradable HDPE filler.

Effects of Al2O3 and BaO nano-additives on mechanical characteristics of high-density polyethylene

Fabrication of polymer doped with metal oxides has been recently aimed to improve the physical, chemical, structural, morphological, thermal and mechanical characteristics. Therefore, the current study is directed to dope two nano-metal oxides into high density polyethylene (HDPE) using the roll-mixing and thermal-pressing techniques. The weight fractions of nanofillers were varied from 2.0% to 8.0% in the resulting composite. The FT-IR along with XRD and SEM were used to examine the structural properties of the new nanocomposites. Images from the scanning-electron microscopy demonstrated that Al2O3 and BaO nanoparticles were properly dispersed in the HDPE's polymeric material without essential aggregations. TGA as well as DSC were used to test the effects of Al2O3-NPs and BaO-NPs incorporation on the thermal properties of HDPE. Tensile tests were carried out to detect how the mechanical behavior of the polymeric matrix was affected by the weight fraction of the nanofiller. Elastic modulus, tensile strain (extension) at yield (%), tensile stress at break, ultimate tensile strength, tensile strain (extension) at break (%), and yield stress were determined in this research. It was concluded that the elastic modulus was found to increase with increasing the nanofiller content up to 4.0 wt% for BaO-NPs and 6.0 wt% for Al2O3-NPs to reach 229% and 208% increment, respectively with respect to the hosting matrix. The values of tensile stress at break, yield stress, tensile strain (extension) at break and tensile strain (extension) at yield of the synthesized nanocomposites decreased, as the content of both fillers increased from 2.0 to 8.0 wt%. Finally, a comparison between BaO-NPs and Al2O3-NPs, when added to the HDPE matrix, showed that the BaO nanofiller led to distinct improvements in the mechanical parameters of HDPE than Al2O3-NPs, for the same weight percentage.

Green composites based on high density polyethylene and recycled coffee gunny: Morphology, thermal, and mechanical properties

In this study, recycled coffee gunny (RCG) was used to reinforce high density polyethylene (HDPE). Maleic anhydride grafted polyethylene (MAPE) was added as a compatibilizer. Moreover, the RCG was chemically treated to enhance the compatibility between fiber and HDPE matrix. A series of RCG reinforced composites were prepared and the effects of MAPE and chemical modification of RCG on the mechanical and thermal properties of HDPE were investigated. The results of thermal and mechanical properties of composites revealed that the increments of heat deflection temperature, tensile strength, and impact strength of HDPE were 16[Formula: see text]C, 19.64% and 43.63% by the addition of modified coffee gunny, respectively. It reveals that the HDPE was reinforced with the coffee gunny, and thus can effectively reuse the discarded resources.

Effect of Cellulosic Waste Derived Filler on the Biodegradation and Thermal Properties of HDPE and PLA Composites

Composites with high density polyethylene (HDPE) and poly(lactic) acid (PLA) matrix have been tested to analyze the effect of natural fillers (wood flour, recycled wastepaper and a mix of both fillers) and temperature on polymer degradation. Composting tests have been performed in both mesophilic (35 °C) and thermophilic (58 °C) conditions. Degradation development has been evaluated through mass variation, thermogravimetric analysis and differential scanning calorimetry. HDPE, as expected, did not display any relevant variation, confirming its stability under our composting conditions. PLA is sensibly influenced by temperature and humidity, with higher reduction of Mw when composting is performed at 58 °C. Natural fillers seem to influence degradation process of composites, already at 35 °C. In fact, degradation of fillers at 35 °C allows a mass reduction during composting of composites, while neat PLA do not display any variation.

Evaluation of mechanical and thermal properties and creep behavior of micro- and nano-CaCO3 particle-filled HDPE nano- and microcomposites produced in large scale

The influence of the interfacial area and the particle size of CaCO3 filler particles on the mechanical and thermal properties of high-density polyethylene (HDPE) was studied in this work. The HDPE-based nano- and microcomposites were manufactured by using an industrial compounder system. The tensile, impact, creep, flexural and hardness properties of the filled and unfilled HDPE samples were investigated. The experiment revealed that the addition of both micro- and nanoparticles increased the tensile and flexural modulus of unfilled HDPE. However, it was observed that the addition of these particles did not have a significant effect on the tensile and flexural strength of unfilled HDPE. On the other hand, the presence of these particles decreased the elongation of break of unfilled HDPE. The impact strength of filled HDPE composites decreased slightly with both micro- and nanoparticle contents. The nanoparticle at high stress level (16 MPa) is more effective on the creep behavior of unfilled HDPE than on microparticles. However, microparticles were found to be more effective at low stress levels (8 and 12 MPa). It was found that the particle size has a profound effect on the thermal and physical properties of unfilled HDPE, such as density, melt flow index and vicat softening temperature. The results showed that the size of filler particles has a significant effect on the mechanical and thermal properties of the unfilled HDPE. Therefore, the size selection of constituent materials of nano- and microcomposites is an important consideration because it directly affects the functional performance of particle-filled HDPE nano- and microcomposites.

Morphological, electrical, mechanical and thermal properties of high-density polyethylene/multiwall carbon nanotube nanocomposites: effect of aspect ratio

The effects of the aspect ratio and the addition of multiwall carbon nanotubes (MWCNTs) on the morphological, electrical, mechanical and thermal properties of high-density polyethylene (HDPE)-based nanocomposites are investigated. The HDPE nanocomposites with various amounts up to 18.74 wt% of MWCNTs that have two different aspect ratios (AR) (200–400 (M58) and 500–3000 (M12)) were prepared by a melt mixing method, followed by compression molding. The results demonstrate that the addition of MWCNTs enhances the electrical, mechanical and thermal properties of the HDPE/MWCNTs nanocomposites. The HDPE nanocomposites with higher aspect ratio MWCNTs demonstrated a slightly better enhancement in the morphological and electrical properties than the other ones with lower aspect ratio MWCNTs. Additionally, Young’s modulus and the thermal stability increased with increasing aspect ratio of MWCNTs.

Investigation of Thermal Properties of High-Density Polyethylene/Aluminum Nanocomposites by Photothermal Infrared Radiometry

In this study, thermal properties of high-density polyethylene (HDPE) filled with nanosized Al particles (80 nm) were investigated. Samples were prepared using melt mixing method up to filler volume fraction of 29 %, followed by compression molding. By using modulated photothermal radiometry (PTR) technique, thermal diffusivity and thermal effusivity were obtained. The effective thermal conductivity of nanocomposites was calculated directly from PTR measurements and from the measurements of density, specific heat capacity (by differential scanning calorimetry) and thermal diffusivity (obtained from PTR signal amplitude and phase). It is concluded that the thermal conductivity of HDPE composites increases with increasing Al fraction and the highest effective thermal conductivity enhancement of 205 % is achieved at a filler volume fraction of 29 %. The obtained results were compared with the theoretical models and experimental data given in the literature. The results demonstrate that Agari and Uno, and Cheng and Vachon models can predict well the thermal conductivity of HDPE/Al nanocomposites in the whole range of Al fractions.

The effect of thermal and thermo-oxidative degradation conditions on rheological, chemical and thermal properties of HDPE

This research evaluates the effect that thermal and thermo-oxidative degradation conditions exert on the rheological, chemical and thermal properties of high-density polyethylene (HDPE). To that end, dynamic oscillatory rheology, solubility tests in xylene, TGA, DSC and FTIR were conducted on HDPE samples subjected to different degradation conditions: atmosphere (air or nitrogen), temperature (150, 175, 200, 225 or 250 °C) and time (10, 30 or 60 min). Thus, under nitrogen atmosphere, chain scission mechanism prevails over the formation of long chain branching/crosslinking phenomena, which is reflected in a decrease in complex viscosity (|η*|) and an increase in crystallinity (χc). Interestingly, under air atmosphere, two rheological responses were observed: a) a well-developed rubbery region, at degradation temperatures of 225 and 250 °C and, b) a so-called second “plateau” in G′ and G″, for lower degradation temperatures. Solubility tests in xylene point out that the rubbery region is consequence of both branching phenomena and the presence of crosslinking; however, the second “plateau” should be solely ascribed to the increase in the branching mechanism. In this case, the decrease in χc is consequence of both increase in branching and formation of degradation products (accordingly supported by FTIR results). Finally, TGA results reveal that thermal and thermo-oxidative degradation shift the characteristic temperatures (T5% and Tmax) to lower values, compared to virgin HDPE.

Fabrication of high-density polyethylene/multiwalled carbon nanotube composites via submerged friction stir processing

The focus of this work was to study the effect of multiwalled carbon nanotubes (MWCNTs) on morphology, mechanical, and thermal properties of high-density polyethylene (HDPE) nanocomposites. MWCNTs/HDPE nanocomposites were prepared using submerged friction stir processing (SFSP) technique. The pristine MWCNTs without any pretreatment were blended with HDPE at a fixed traverse speed of 30 mm min−1 and various rotational speeds ranging from 1200 r min−1 to 2100 r min−1. The effect of rotational speed on MWCNTs dispersion in HDPE matrix was assessed using scanning electron microscopy. The experimental results showed the rotational speed affected the disperision of the MWCNTs. The mechanical properties of the composites were measured, and the results indicated that the tensile strength increased at first and then decreased with the increase of the rotation speed. The thermal properties of MWCNTs-filled HDPE nanocomposites were studied by differential scanning calorimetry, and the crystalline content of the prepared composites by the SFSP technology was increased. From the experimental research, it was found that the SFSP technique was a practical way to fabricate polymeric composites.

Influence of γ-ray modified MWCNTs on the structural and thermal properties of high-density polyethylene

Abstract This study aims to investigate the influence of adding 100 kGy γ-irradiated multi wall carbon nano tubes (MWCNTs) on the structural and thermal properties of high-density polyethylene (HDPE). The effects of further γ-irradiation in the presence of γ-MWCNTs on aforementioned properties have also been investigated. FTIR spectroscopic measurements of HDPE and HDPE/γ-MWCNTs composites reveal that modification of MWCNTs with ≤100 kGy of γ-dose reduces its efficiency as free radical quencher. This behavior is found to increase further with the increase in the concentration of γ-MWCNTs. Wide angle X-ray diffraction (WAXD) data shows a decrease in percent crystallinity and shifting of crystalline peaks toward lower values of 2θ angles. This behavior is mainly attributed to the oxidation induced due to residual free radicals. Thermal analysis reveals that addition of γ-MWCNTs decreases the thermal stability as far as onset thermal degradation temperature, percent crystallinity, and melting temperature of UHMWPE/γ-MWCNTs. In addition to this, gel content measurements show that insoluble percentage of UHMWPE is higher with the incorporation γ-MWCNTs and further irradiation. The gel contents are found to improve up to 29% and 60%, respectively with the incorporation of γ-MWCNTs and further irradiation.

Thermal, physico‐mechanical, and morphological properties of HDPE graft‐copolymerized with polystyrene

In this study, polystyrene was graft‐copolymerized onto high‐density polyethylene (HDPE) by in situ polymerization of styrene monomer to change the physico‐mechanical and thermal properties of HDPE. The grafting was carried out in a Brabender‐type static mixer by injecting styrene monomer directly into the molten HDPE in the presence of a free‐radical initiator (lauroyl peroxide or LP). The effect of wt% of styrene and initiator concentrations on thermal, physico‐mechanical, and morphological properties of HDPE was investigated. The neat and modified HDPE was characterized by differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and also by tensile strength and contact angle measurements. It was found that the increase in wt% of styrene and LP dosage reduced elongation at break, hygroscopic expansion and also the melting, and the crystallization temperatures of HDPE but increased its tensile strength. The tensile strength was increased from 14.6 MPa for the neat HDPE to 20.6 MPA for the 10 wt% of styrene grafted onto HDPE using 0.8% LP. Scanning electron microscopy results show that there was no phase separation, and the grafted polystyrene became integral part of HDPE. The results demonstrate that styrene could be used in melt compounding to improve various properties of HDPE. Copyright © 2015 John Wiley & Sons, Ltd.

Mechanical and Thermal Properties of Bamboo Pulp Fiber Reinforced Polyethylene Composites

The purpose of this study was to investigate the mechanical and thermal properties of high-density polyethylene (HDPE) composites reinforced by bamboo pulp fibers (BPF). Using a twin-screw extruder, polymer composites were fabricated using BPF and bamboo flour (BF) as the reinforcement and HDPE as the matrix. Tensile and flexural tests of the HDPE composites were performed to determine the mechanical properties under different conditions. The thermal properties of HDPE composites were characterized by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The results showed that BPF improved the mechanical and thermal properties of the polymer composites more than did BF. The tensile and flexural strength of composites with 30 wt% BPF were increased by 61.46% and 22.94%, respectively, while the tensile and flexural modulus were increased by 84.52% and 27.30%, respectively. Compared to composites with 50 wt% BF, the T5% of composites with 50 wt% BPF increased by 20.18 °C. As the BPF content increased, the storage modulus (E’) and loss modulus (E”) initially increased, followed by a decrease. Compared to the BF/HDPE composites, BPF/HDPE composites reinforced at 30 wt% had a higher storage modulus (E’) and loss modulus (E”) and lower damping parameter (tanδ).

Thermal properties of carbon nanofiber reinforced high-density polyethylene nanocomposites

Reinforcing polymers with the appropriate nanofillers is an effective way to obtain a variety of enhanced material properties. In this paper, high-density polyethylene nanocomposites reinforced with either pristine or silane-treated carbon nanofibers at various weight percentages (0.5 wt%, 1 wt%, and 3 wt%) were fabricated through melt-mixing and compressive processing. Silane coatings with two thicknesses, 2.8 nm and 46 nm, were applied on the oxidized carbon nanofibers to improve the interfacial bonding between the carbon nanofibers and the matrix. Scanning electron microscopy and transmission electron microscopy demonstrated the dispersion of carbon nanofibers and the strongly improved interfacial adhesion between the carbon nanofibers and high-density polyethylene matrix due to the silane coating. The thermal properties of high-density polyethylene / carbon nanofiber nanocomposites were characterized and compared with those of the neat high-density polyethylene. The measurement results showed that the thermal conductivity of the high-density polyethylene /carbon nanofiber nanocomposites increased with the carbon nanofiber loading. The enhancement of thermal conductivity was not only due to the high thermal conductivity of carbon nanofibers but also due to the interfacial quality between the carbon nanofibers and the high-density polyethylene matrix. The interfacial thermal contact resistance between the carbon nanofibers and the matrix was determined to be in the range of [Formula: see text] to [Formula: see text]. Furthermore, the coefficient of thermal expansion of the nanocomposite was found to be reduced by the incorporation of carbon nanofibers.

The effects of weathering exposure on the physical, mechanical, and thermal properties of high-density polyethylene and poly (vinyl chloride)

This paper presents results describing the physical, mechanical, and thermal properties (melt flow index - MFI and oxidative induction time - OIT) of high density polyethylene and poly (vinyl chloride) after weathering exposure (6, 12, 18, and 30 months). The materials exposed were geomembranes of two thicknesses: 1.0 and 2.0 mm (PVC) and 0.8 and 2.5 mm (HDPE). The climate parameters (average) obtained were 25 ºC (temperature), 93 mm (precipitation), 66% (relative humidity), and 19 MJ/m².day (intensity of global radiation). Some results showed, for instance, that the behavior of the geomembranes changed after the exposures. A few minor variations in physical properties occurred. The density and thickness, for instance, varied 0.5-1.0% (average) for both the PVC and HDPE geomembranes. The mechanical properties changed as a function of the period of exposure. In general, some decreases were verified by the deformation of PVC. The samples became more rigid. In contrast, HDPE geomembranes became more ductile. Despite the variations in elasticity, some increases in deformability were verified. An MFI test showed some degradation in HDPE geomembranes. OIT tests revealed small values for both intact and exposed samples.

Electron-Beam-Induced Modifications in High-Density Polyethylene

Post-irradiation studies have been carried out to elucidate the effects of electron beam irradiation on the structural, optical, dielectric, and thermal properties of high-density polyethylene (HDPE) films. The experimental results showed that both the optical band gap and activation energy of HDPE films decreases with an increase in the doses of electron radiation. The electrical measurements showed that dielectric constant and the ac conductivity of HDPE increases with an increase in the dose of electron radiation. The thermal analysis carried out using DSC and TGA revealed that the melting temperature, degree of crystallinity, and thermal stability of the HDPE films increased, obviously, due to the predominant cross-linking reaction following high doses of electron irradiation.

Studies on the morphology and the thermal properties of high-density polyethylene filled with graphite

Studies on the morphology and the thermal properties of high-density polyethylene filled with graphite