Properties Of High Density Polyethylene Research Articles

Influence of flame retardant magnesium hydroxide on the mechanical properties of high density polyethylene composites

The effects of incorporating magnesium hydroxide as a flame retardant on the mechanical properties of high density polyethylene which include tensile, flexural, compressive, shear and fracture toug...

A study on the Environmental Stress Cracking (ESC) Properties of Polyethylene Materials

In this study, the environmental stress cracking (ESC) properties of high-density polyethylene (HDPE)and low-density polyethylene (LDPE) were investigated. In order to clarify the effects of the chemical structures of polyethylene on ESC properties in various alcohols, the bent strip test was carried out. From the result of the bent strip test as well as the tensile test of these samples, it was found that ESC of HDPE occurred significantly just after a short period in butanol,propanol, and ethanol. In contrast, no ESC phenomenon in LDPE was observed. From DMA result,it was found that stress cracking properties caused the appearance of the β relaxation peak,which corresponds to the molecular motion of amorphous region of PE and the intensity of the relaxation increases with soaking time. As for the LDPE, however, no significant change was observed. Therefore, the difference of the morphology of PE (especially in amorphous region) affects the ESC properties of PE materials. Moreover, we attempted a Sonic-IR method to detect the cracks of inner-cap of PET bottle. When applying ultrasonic to inner-cap having cracks, slight temperature increase was detected at the points of cracks, indicating that there was a possibility that Sonic-IR method could be one of the promising candidates to detect the ESC for a nondestructive inspection.

Analysis of Mechanical Properties of High Density Polyethylene, Fly ash and Carbon nanotubes reinforced Hybrid Composite

Analysis of Mechanical Properties of High Density Polyethylene, Fly ash and Carbon nanotubes reinforced Hybrid Composite

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.

Optical Properties of HDPE in Injection Molding and Injection Press Molding for IR System Lenses Part II: Mold Temperature and Surface Roughness Effects on Injection Molding

Abstract An experimental investigation of injection molding was conducted to assess the high infrared radiation (IR) transmittance with an opaque state (low visibility ray (VR) transmittance) necessary for IR system lenses as a target high-density polyethylene (HDPE) IR transmission material. In our earlier investigation, experimental investigations of injection molding and injection press molding were conducted using the mold cavity of a disk-shaped finished mirror-like surface. For high mold temperature and long cooling time, the increased core-layer thickness improved the IR transmittance. Simultaneously, the VR transmittance decreased because the crystallinity became higher. Furthermore, when injection press molding was done, the VR transmittance decreased because the crystallinity increased. Using a 0.5-mm-thick mold cavity with disk shapes having different surface roughness, an injection molding experiment was conducted for this study while changing only the mold temperature of 20 to 80°C. Results show that when the mold surface roughness became high, the surface roughness of molded parts became high, too. Thereby the IR and VR transmittance were decreased. However, when the mold temperature was high, the influences of the so-called skin-core structure and crystallinity were stronger than the influence of the surface roughness of molded parts. The IR transmittance increased because of the decrease of the skin layer. Furthermore, the VR transmittance decreased because of a simultaneous rise of the crystallinity. The minimum value of obtained VR transmittance was 9.3% at mold temperature of 80°C using a mold of the highest surface roughness. This molded part reached an opaque state. Furthermore, a higher IR transmittance of 64.9% was obtained. When injection molding was conducted using a mold of a mirror-like surface with the same conditions as those in this investigation in our earlier investigation, the obtained IR and VR transmittances were 65.4% and 0.6%, respectively. Consequently, when the mold temperature was high, a few differences were found with transmittance of the molded parts using the mold of the mirror-like surface. Results showed that no difficulty arises when a mold having higher surface roughness is used at a higher mold temperature.

The alterations in high density polyethylene properties with gamma irradiation

In the present investigation, high density polyethylene (HDPE) polymer has been used to study the alterations in its properties under gamma-irradiation. Physico-chemical properties have been investigated with different spectroscopy techniques, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), biocompatibility properties, as well as, mechanical properties change. The FT-IR analysis shows the formation of new band at 1716cm−1 that is attributed to the oxidation of irradiated polymer chains, which is due to the formation of carbonyl groups (C˭O). XRD patterns show that a decrease in the crystallite size and increase in the Full Width at Half Maximum (FWHM). This means that the crystallinity of irradiated samples is decreased with increase in gamma dose. The contact angle measurements show an increase in the surface free energy as the gamma irradiation increases. The measurements of mechanical properties of irradiated HDPE samples were discussed.

Effect of Cloisite 30B nanoclay on the mechanical properties of HDPE nanocomposites

In the past decades the study of nanocomposites has held the interest of researchers due to their better mechanical properties by the addition of small amounts of filler material called nanoclay. In this study, high-density polyethylene (HDPE) was chosen as matrix material and nanoclay as reinforcement material, i. e., Cloisite 30B. HDPE grafted with maleic anhydride (HDPE-g-MA) with 3 wt.-% compatibilizer was used to provide better adhesion between the high-density polyethylene and nanoclay. The nanocomposite materials were prepared by melt compounding in a twin screw extruder with a spindle speed of 50 rpm with zone temperatures. The addition of nanoclay to HDPE was in the range of 0 to 4 wt.-%. The specimens were prepared according to ASTM standard for various mechanical tests like flexural, tensile, hardness, and impact tests using respective dies in the injection molding machine. The scanning electron microscope analysis was used to characterize the ditribution of particles in the nanocomposites. In addition, the effect of five different amounts of nanoclay (0 to 4 wt.-%) on the mechanical properties of HDPE was examined to identify the most effective amount of nanoclay for improving the strength of nanocomposites.

On the friction stir welding, tool design optimization, and strain rate-dependent mechanical properties of HDPE–ceramic composite joints

Friction stir welding is a recently developed technique for joining low-melting metals and polymers. In the present work, friction stir welded joints of high-density polyethylene (HDPE) sheets were produced using a newly designed tool with a concave shoulder and a grooved conical pin. The joints were produced with and without the additions of ceramic particulates including silicon carbide (SiC), alumina, graphite, and silica. The effect of strain rate on the tensile properties of base material and plain welded joints was examined. In addition to tensile properties of composite joints, hardness profiles across the weld nugget were analyzed. It was observed that the increasing strain rate improved both the tensile strength and the ductility of the plain welded joints. The tool was able to yield a joint efficiency of around 84% in the plain welded samples. Although, in terms of joint efficiency, the composite joints were less efficient than the plain welded HDPE, SiC additions were found to yield better material properties relative to other reinforcements. Finally, it was concluded that an SiC–HDPE composite joint can be of practical importance in high strain rate applications, provided the optimum tool design and stir welding parameters are available.

Hybrid modification of high‐density polyethylene with hyperbranched polyethylene‐functionalized multiwalled carbon nanotubes and few‐layered graphene

ABSTRACTHerein, a facile method has been reported to efficiently prepare debundled multiwalled carbon nanotubes (MWCNT) and few‐layered graphene using a hyperbranched polyethylene (HBPE), and as hybrid fillers, their modification effects on high‐density polyethylene (HDPE) are well demonstrated. Stable dispersions of debundled MWCNT and graphene in chloroform were respectively obtained by sonication using the HBPE as stabilizer, and MWCNT/graphene/HDPE ternary nanocomposites were then fabricated by solution‐assisted premixing and subsequent melt mixing, at a fixed mass ratio of MWCNT/graphene of 3:1 and serially changed filler loadings. It is found that the MWCNT and graphene have good dispersibility in the composites, and as hybrid fillers, they can effectively form composite net‐like structure, which makes them show better modification effects on both the electrically and thermally conductive properties of HDPE, as compared to the single MWCNT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44848.

Influences of matrix viscosity on alignment of multi-walled carbon nanotubes in one-dimensional confined space

The effects of matrix viscosity on alignment of multi-walled carbon nanotubes (MWCNTs) and physical properties of high density polyethylene (HDPE)/MWCNTs composite nanofibers via nanolayer coextrusion are studied. The alignment states are altered depending upon the matrix viscosity of the composite nanofibers. The morphology and nano-sized diameter of the nanofibers are observed on scanning electron microscope. To characterize the prioritized alignment and dispersion of MWCNTs in the matrix, transmission electron microscopy, polarized Raman spectra, and high resolution optical microscopy are used. It is found that the alignment of MWCNTs in higher viscosity matrix of the nanofibers is better than that in lower viscosity. The aligned MWCNTs composite nanofibers have smaller slope variations of rheological curves with increasing content of MWCNTs. In addition, the higher aligned HDPE/MWCNTs composite nanofibers exhibit higher decomposition temperature and enhanced mechanical properties. However, the poorly aligned nanofibers have higher electrical and thermal conductivities due to the easily formed three-dimensional network.

무어링 로프용 메탈로센 촉매 고밀도 폴리에틸렌 모노 필라멘트의 물성에 미치는 연신비의 영향

This study examined the effect of draw ratio on the properties of high density polyethylene (m-HDPE) prepared using a metallocene catalyst as mooring rope material for 20,000-30,000 ton ships (small and medium class ships). The density, crystallinity, crystallite size, crystalline orientation, melting enthalpy, and tensile modulus increased with increasing draw ratio from 8 to 14; however, the elongation at break decreased. The tensile strength of the m-HDPE filament increased significantly with increasing draw ratio up to 12 and then decreased a little. The reduction in tensile strength for the filament with draw ratio of 14 might be due to stress whitening. The various properties of the m-HDPE mono-filament with draw ratio of 14 prepared in this study (tensile strength: 8.0 g/d, elongation at break: 10.0%, tensile modulus: 104.5 g/d, water absorption: 0.19%, color fastness to sea water (grade): 4-5, chemical resistance: 82-94%) were found to pass the mooring rope material criteria for 20,000-30,000 ton ships (tensile strength: > 8 g/d, elongation at break: 10% <, tensile modulus: > 100 g/d, water absorption: 0.7% <, color fastness to sea water (grade): > 4, chemical resistance: > 80%).

On the Injection Molding Processing Parameters of HDPE-TiO₂ Nanocomposites.

In recent years, the development and use of polymeric nanocomposites in creating advanced materials has expanded exponentially. A substantial amount of research has been done in order to design polymeric nanocomposites in a safe and efficient manner. In the present study, the impact of processing parameters, such as, barrel temperature, and residence time on the mechanical and thermal properties of high density polyethylene (HDPE)-TiO2 nanocomposites were investigated. Additionally, scanning electron microscopy and X-ray diffraction spectroscopy were used to analyze the dispersion, location, and phase morphology of TiO2 on the HDPE matrix. Mechanical tests revealed that tensile strength of the fabricated HDPE-TiO2 nanocomposites ranged between 22.53 and 26.30 MPa, while the Young’s modulus showed a consistent increase as the barrel temperature increased from 150 °C to 300 °C. Moreover, the thermal stability decreased as the barrel temperature increased.

Rheological properties of HDPE and LDPE at the low-frequency range under supercritical CO2

The effects of temperature, pressure (using helium as the pressurizing medium) and dissolved CO2 concentration on the rheological properties of linear high-density polyethylene (HDPE) and branched-chain low-density polyethylene (LDPE) were carefully investigated using a high-pressure rheometer. The results showed that at low pressure, the rheology of the PEs was sensitive to pressure increase. As the pressure increased to higher values, the rheology leveled off for HDPE and increased for LDPE. Under supercritical CO2, the plasticization of the dissolved gas contributed primarily to the thickening effect of pressure. Furthermore, the loss factors decreased with increasing pressure and increased with increasing CO2 pressure. Lastly, the effect of gas concentration was described by the Fujita-Kishimoto model on the assumption that the coupled effect of pressure and CO2 concentration could be separated.

Mechanical Properties of Pineapple Leaf Powder Filled High Density Polyethylene

The effects of pineapple leaf powder (PALP) on the mechanical properties of high density polyethylene (HDPE) composites were studied. HDPE and PALP composites were prepared by injection moulding technique. The filler (PALP) contents investigated were 2, 4, 6, 8, and 10 wt% for each formulation. Results of the mechanical tests carried out on the HDPE/PALP composites showed that the tensile strength, tensile modulus, flexural strength, abrasion resistance, and hardness of the composites increased with increases in filler content for all the filler contents investigated while the elongation at break (EB) for PALP/HDPE composites was found to decrease with increases in filler content for all the filler contents investigated. The tensile strength of PALP/HDPE composites was increased by 6.49% at 2 wt% filler content, and 30.39% at 10 wt% filler content. It was also observed, from the results, that the elongation at break of PALP/HDPE composites was decreased by 2.40% at 2 wt% filler content, and 10.24% at 10 wt% filler content. The present study has highlighted the utility of pineapple leaf powder (PALP) as reinforcing filler in HDPE compounding. Pineapple leave which is an agricultural waste has been shown to have potential as a cheap, more readily available and more environmentally friendly filler.

Mechanical Properties of Pineapple Leaf Powder Filled High Density Polyethylene

The effects of pineapple leaf powder (PALP) on the mechanical properties of high density polyethylene (HDPE) composites were studied. HDPE and PALP composites were prepared by injection moulding technique. The filler (PALP) contents investigated were 2, 4, 6, 8, and 10 wt% for each formulation. Results of the mechanical tests carried out on the HDPE/PALP composites showed that the tensile strength, tensile modulus, flexural strength, abrasion resistance, and hardness of the composites increased with increases in filler content for all the filler contents investigated while the elongation at break (EB) for PALP/HDPE composites was found to decrease with increases in filler content for all the filler contents investigated. The tensile strength of PALP/HDPE composites was increased by 6.49% at 2 wt% filler content, and 30.39% at 10 wt% filler content. It was also observed, from the results, that the elongation at break of PALP/HDPE composites was decreased by 2.40% at 2 wt% filler content, and 10.24% at 10 wt% filler content. The present study has highlighted the utility of pineapple leaf powder (PALP) as reinforcing filler in HDPE compounding. Pineapple leave which is an agricultural waste has been shown to have potential as a cheap, more readily available and more environmentally friendly filler.

Tribological modification of high-density polyethylene by using carbon soot from diesel combustion

Purpose The purpose of this paper is to explore the tribological properties of high-density polyethylene (HDPE) modified by carbon soot from the combustion of No. 0 diesel. Design/methodology/approach Carbon soot is characterized using X-ray diffraction, transmission electron microscopy and scanning electronic microscopy. The tribological properties of HDPE samples with carbon soot are investigated on a materials surface tester with a ball-on-disk friction pair. Findings The collected carbon soot mainly comprises amorphous carbon nanoparticles of 50-100 nm in diameter. The main wear behaviours of pure HDPE include abrasive wear and plastic deformation. After adding carbon soot nanoparticles to HDPE, HDPE wear decreases. The appropriate carbon soot content is 8 per cent in HDPE under the selected testing conditions. Compared with other HDPE samples, HDPE with 8 per cent carbon soot has higher melting temperature, lower abrasive wear and better wear resistance. The lubrication of HDPE with carbon soot is due to the formation of a transferring film composed of HDPE, amorphous carbon and graphite carbon. Originality/value The paper reveals the HDPE modification and lubrication mechanisms by using carbon soot from the combustion of diesel. Related research can perhaps provide a potential approach for the treatment of carbon soot exhaust emission.

The effect of CH4/H2 ratio on the surface properties of HDPE treated by CHx ion beam bombardment

The surface of high density polyethylene (HDPE) substrate was bombarded by the CH[Formula: see text] group ion beam, which was generated by the mixture of CH4/H2. Varying the CH4/H2 ratio, HDPE surfaces with different chemical bond structures and properties were obtained. Raman and XPS results show that [Formula: see text] and [Formula: see text] bond structures are formed at HDPE surface bombarded by CH[Formula: see text] group ions. The [Formula: see text] bond fraction at bombarded HDPE surface depends on the H2 ratio in CH4/H2 mixture, because the H ion/atom/molecule can improve the growth of [Formula: see text] bond structure. For HDPE surface bombarded by CH4/H2 = 50/50, [Formula: see text] bond fraction reaches the maximum of 30.5%, the surface roughness decreases to 17.04 nm, and the static contact angle of polar H2O molecule increased to 140.2[Formula: see text].

Optical Properties of HDPE in Injection Molding and Injection Press Molding for IR System Lenses

Abstract To obtain the “high infrared radiation (IR) transmittance and low visible ray (VR) transmittance” necessary for a high-performance IR lens, cavity thickness and molding conditions were investigated experimentally for disk-shaped high-density polyethylene (HDPE). When injection molding and injection press molding were done using different cavity thicknesses, results showed that the molded part using the thinner cavity thickness maintained a semitransparent state. Simultaneously, they showed that higher IR transmittance was obtained. For high mold temperature and long cooling time, the increased core-layer thickness improved the IR transmittance. The VR transmittance decreased because crystallinity became higher. Furthermore, when injection press molding was conducted, the VR transmittance decreased because crystallinity became higher. IR transmittance and VR transmittance were obtained respectively as 65.4% and 6.4% when injection press molding was conducted at higher mold temperatures with longer cooling times.

Morphological, thermal, mechanical, and rheological properties of high density polyethylene reinforced with Illite clay

In this work, Illite (natural Moroccan clay) was selected to reinforce high density polyethylene (HDPE) and to determine the efficiency of styrene‐(ethylene‐butene)‐styrene triblock copolymer grafted with maleic anhydride (SEBS‐g‐MA) as a coupling agent. The composites were prepared by extrusion followed by injection molding of various clay contents (5–40 wt%). From the samples produced, the morphological, thermal, mechanical, and rheological properties were measured. The results showed that interfacial adhesion was improved with coupling agent addition leading to increased Young's modulus, as well as higher tensile strength, and strain at yield. Nevertheless, the maximum value for the composites without SEBS‐g‐MA (57% modulus increase) was obtained at 20 wt% compared to 15 wt% for the composites with SEBS‐g‐MA (45% modulus increase). The thermal stability of the composites also increased with clay content, especially when the coupling agent was added. Finally, water absorption tests revealed that the composites have a higher tendency to absorb water with increasing clay content, but the use of a coupling agent substantially reduced this problem. POLYM. COMPOS., 39:1522–1533, 2018. © 2016 Society of Plastics Engineers

Effect of Molecular Structure Parameters on Crystallinity and Environmental Stress Cracking Resistance of High‐Density Polyethylene/TiO2 Nanocomposites

AbstractThe correlation between molecular microstructure with crystallization behavior and environmental stress cracking resistance (ESCR) for three commercial grades of high‐density polyethylene and their nanocomposites has been investigated. Molecular architecture was characterized using high‐temperature gel permeation chromatography (GPC) test. Qualitative comparison of crystallinity and side chain branches of neat high‐density polyethylenes (HDPEs) has been performed using FTIR test and results were in good accordance with GPC results. Investigation of crystallinity and effect of side chain branches on the crystallite's dimensions has been carried out by DSC and XRD tests. Moreover, it was found that addition of nano‐TiO2 to HDPE causes an increase in crystal content and a decrease in crystal size, simultaneously. It was concluded from ESCR characterization that molecular weight and side chain branches are the most important structural parameters affecting ESCR properties of HDPE. The significance of side chain branches is higher compared to molecular weight.