Properties Of High Density Polyethylene Research Articles

The Effect of Graphene on the Mechanical Properties of High Density Polyethylene (HDPE)/Zinc Borate Polymer Composite

Bu çalışmada; yüksek yoğunluklu polietilen (YYPE) içerisine %5 oranında çinko borat ve farklı oranlarda grafen tozları katılarak bir kompozit üretilmiştir. Kompoziti oluşturan malzemeler çift vidalı ekstrüzyon makinesinde karıştırılarak beş farklı grup elde edilmiştir ve enjeksiyon makinası kullanılarak standart test numuneleri üretilmiştir. Mekanik değerleri belirlemek için çekme, sertlik ve darbe testleri yapılmıştır. Ayrıca çinko borat ve grafenin dağılımlarını belirlemek için taramalı elektron mikroskobisi (SEM) ile fotoğrafları çekilmiştir. Analizler sonucunda YYPE içerisinde çinko borat ve grafen toz ilavesiyle; elastiklik modülü, çekme mukavemeti, kopma mukavemeti ve sertlik değerlerinin arttığı diğer taraftan darbe mukavemeti kopma uzaması ve kopma uzaması değerlerinin ise düştüğü tespit edilmiştir. SEM inceleme sonucu çinko borat ve grafen tozlarının homojen dağıldığı tespit edilmiştir.

Effect of functionalized graphene addition on mechanical and thermal properties of high density polyethylene

Abstract High density polyethylene (HDPE)/graphene nanocomposites were successfully synthesized by compounding of HDPE, as polymer matrix, with hexamethylenediamine functionalized graphene. The resulting nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and thermal gravimetric analysis (TGA) techniques. SEM characterization confirmed the good dispersion (homogeneous and uniform) of graphene in the polyethylene matrix. The TGA technique revealed a slight improvement in thermal resistance. Functionalized graphene improved a better thermal stability of HDPE (up to 6 °C) than non-functionalized graphene (up to 2 °C). Mechanical tensile and torsion tests showed that HDPE/functionalized graphene nanocomposites exhibit high tensile strength and low torsional strength compared to HDPE/non-functionalized graphene nanocomposites. Compared to pure HDPE, the Young’s modulus increased by 80% and 30%, whereas, the torsion modulus increased by about 34% and 44% for the HDPE/functionalized and HDPE/non-functionalized graphene, respectively. Regardless of this increase, it can be seen that the torsion modulus of HDPE/non-functionalized graphene is much higher than that of HDPE/functionalized graphene.

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.

Assessing the weathering-induced degradation on the structural integrity of high-density polyethylene

Marine plastic pollution is a growing environmental concern, with plastic debris in the ocean having negative impacts on marine life and human health. One of the major challenges in addressing this problem is the slow degradation rate of plastics in the marine environment. In this study, the degradation of high-density polyethylene (HDPE), being extremely common in marine debris, is investigated when exposed to either (a) marine or (b) atmospheric environmental exposure. The weathering effects for this type of plastic were examined through ultraviolet spectrophotometer and tensile investigations. A chain-breaking activity in the microstructure of the weathered HDPE specimens was revealed. During the investigated eight (8) months of atmospheric and sea weathering, an approximate 10 % and 6 % decrease in ultimate tensile strength σUTS was noticed for the two different environments, respectively. Higher decrease was noticed for the respective elastic modulus E (Young’s modulus) that was approximate 23 % and 21 %, respectively. Based on the available experimental test results, a linear decrease rate equation of all the investigated mechanical properties was proposed, to give valuable information regarding the residual tensile mechanical properties of HDPE after weathering exposure.

Effect of gamma rays on some electrical properties of high density polyethylene (HDPE) dissolved in tetrahydrofuran (THF)

يتضمن هذا البحث دراسة بعض الخواص الكهربائية لمادة بولي اثيلين عالي الكثافة المذابة في رباعي هيدرو الفوران قبل وبعد تشعيعها بإشعاع كاما وبجرعة إشعاعية مقدارها (4000 rad) وبمعدل إشعاعي (181.8181 rad /min) ولمدة (22 min) واشتملت الخصائص الكهربائية على قياس كل من التوصيلية الكهربائية وسعة المتسعة الكهربائية المملوءة بمحاليل (HDPE) ذات التراكيز المختلفة, وحساب كل من التوصيلية المولارية وثابت العزل الكهربائي,وقد وجد بأن التوصيلية الكهربائية وسعة المتسعة وثابت العزل يزداد بزيادة التركيز وكذلك بعد التشعيع أما التوصيلية المولارية فأنها تقل بزيادة التركيز وتزداد قيمتها بعد التشعيع. لقد تمت جميع القياسات بدرجة حرارية ثابتة وهي درجة حرارة الغرفة (25°c) تقريبا. إن سبب التغير في قيم الخصائص قد يكون ناتجا من تشابك السلاسل البوليمرية ومن ثم زيادة المعدل اللزوجي للوزن الجزيئي للمادة البوليمرية المستخدمة في هذا البحث.

AFM Measurements and Testing Properties of HDPE and PBT Composites with Fillers in the Form of Montmorillonite and Aluminum Hydroxide.

This paper presents the effect of the addition of fillers such as aluminum hydroxide or montmorillonite on the structure and properties of polymers such as high-density polyethylene (HDPE) and polybutylene terephthalate (PBT). Both types of specimens were obtained by injection molding. X-ray diffraction examinations were performed on the materials obtained to determine the effect of the addition of the fillers used on the degree of crystallinity of the composites. The density and hardness of the composites were evaluated, and the static tensile test and the analysis of the structure parameters using atomic force microscopy (AFM) were also carried out. It was shown that the addition of powder fillers to polymers such as high-density polyethylene and polybutylene terephthalate affects the structure parameters such as surface roughness, mean grain size, anisotropy ratio, fractal dimension, the corner frequency of the composites, and mechanical properties such as Young's pseudo-modulus, average adhesion force, hardness, and tensile strength.

The Effects of Pin Profile on HDPE Thermomechanical Phenomena during FSW.

Friction stir welding (FSW) of polymeric materials has recently attracted significant attention. Herein, we present the effect of the tool pin profile on the FSW of high-density polyethylene (HDPE) joints through joint experimental analysis and thermomechanical simulations. For analysis of pin profile effects on the thermomechanical properties of HDPE joints, frustum (FPT), cubic (CPT), and triangular (TPT) pin shapes were selected in this study. This research investigated the heat generation of the parts of the different tools as well as heat flux (internal and surface). The results revealed that the heat generation in pins with more edges (cubic (96 °C) and triangular (94 °C)) was greater than in pins with a smooth shape (frustum (91 °C)). The higher heat generation caused the heat flux on the surface of the HDPE from the cubic pin profile to be greater than for other joints. Due to the properties of HDPE, higher heat generation caused higher material velocity in the stirring zone, where the velocity of the materials in TPT, CPT, and FPT pins were 0.41 m/s, 0.42 m/s, and 0.4 m/s, respectively. The simulation results show sharp-edged pins, such as triangular and cubic, lead to over-stirring action and internal voids formed along the joint line. Furthermore, the simulation results indicated that the size of the stirred zones (SZs) of the FPT, TPT, and CPT samples were 17 mm2, 19 mm2, and 21 mm2, respectively, which is around three times the corresponding values in the HAZ.

Assessing the Downstream Contamination of Chemically Recycled Ethylene Feed Streams on the Kinetic Behavior of Ziegler‐Natta Catalysts and Microstructural Properties of HDPE and LLDPE

AbstractThe sustainability of consumer materials, such as plastics, belongs to the most important aspect of eco‐efficiency analyses. Besides mechanical recycling, chemical recycling represents an interesting waste management pathway. In theory, this technique does not rely on single‐grade feedstock to maintain product quality. However, cross‐contamination of feedstocks potentially leads to above‐specification impurities in obtained pyrolysis oils. This study investigates the potential downstream poisoning of a fourth‐generation Ziegler‐Natta catalyst, using selected model poisons at high (worst‐case) concentrations. With experimental and computational analysis, economic feasibility factors such as catalyst activity and microstructural properties are evaluated during the synthesis of high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE). Noticeable effects on the catalyst activity can be observed when the poison interacts with the co‐catalyst, whereas a lower impact is observed for interactions with the activated catalyst‐co‐catalyst complex. Molecular weight distribution (MWD) and comonomer composition distribution (CCD) modeling highlighted marginal to no polymer property changes caused by contaminants. Combined with the applicability of pyrolysis post‐treatments, these observations show that chemical recycling can be a promising technique for post‐consumer plastic waste treatment.

Effects of freeze–thaw cycles on the properties of polyethylene geomembranes

High-density polyethylene (HDPE) geomembranes (GMs) are frequently used as fluid barrier components of cover systems for mine site reclamation in regions that are prone to freeze–thaw cycles (FTCs). However, HDPE GMs are more susceptible to stress cracking than linear low-density polyethylene (LLDPE) GMs. Hence, LLDPE GMs are increasingly considered as alternatives to HDPE GMs in cover systems. Nevertheless, little information is available on LLDPE compared to HDPE GMs. Moreover, little is known about the changes in the fluid barrier properties (the equivalent hydraulic conductivity and the oxygen sorption and diffusion coefficients) for these two materials with FTCs. The purpose of this study is therefore to compare the effects of FTCs on the tensile, hydraulic, and oxygen sorption and diffusion properties of HDPE and LLDPE GMs. To do so, GM sheets were subjected up to 300 FTCs. Mechanically, both GMs got stiffer and their tensile break properties increased with increasing number of FTCs. However, although the GM fluid barrier properties changed with FTCs, the equivalent hydraulic conductivity and the oxygen permeation coefficient remained within an order of magnitude of 10−14 m/s and 10−13 m2/s, respectively. Up to 300 FTCs would therefore have no adverse effects on HDPE and LLDPE GMs.

Influence of surface modification of zinc oxide on physical properties of high density polyethylene

Inorganic nanofillers have sparked important research in the field of polymer nanocomposites because they can improve the properties of polymers. Hydrophobic ZnO nanoparticles modified by oleic acid (OA) were designed and prepared to accelerate the dispersion state of ZnO in the high viscosity polyethylene (HDPE), and enhance the performance of HDPE. HDPE/ZnO nanocomposites with different kinds and fractions of ZnO were further prepared via melt mixing method. The result showed the hexagonal and spindle-like ZnO nanoparticles with size distribution of 150–300 nm was acquired in the absence and presence of OA. Compared with surface untreated ZnO (U-ZnO), ZnO nanoparticles modified by OA (O-ZnO) can disperse evenly into HDPE at the fraction of O-ZnO below 5 wt%. TG data showed the presence of nanosized U-ZnO and O-ZnO in HDPE can significantly enhance the thermal stability of HDPE through raising the activation energy of HDPE in thermal decomposition process. The thermal decomposition order (n) for HDPE/ZnO nanocomposites was mostly bigger than that of HDPE, demonstrating the decomposition mechanism for HDPE became more complicated because of the addition of ZnO nanoparticles. DSC data showed U-ZnO nanoparticles cannot accelerate nucleation of HDPE and seemed to postpone the crystallization process, and O-ZnO nanoparticles was heterogeneous nucleating agent for HDPE. Moreover, the tensile and impact strength of HDPE was improved by the addition of O-ZnO, and connected with the dispersion state of ZnO nanoparticles in HDPE. The improvement in thermal stability, crystallization and mechanical properties by adding ZnO into HDPE matrix significantly enhance the potential of HDPE in food packaging, electronic packaging, drug and pharmaceutical bottles.

Impact of Hybrid Fillers on the Properties of High Density Polyethylene Based Composites.

The main objective of this work is to develop a variety of hybrid high-density polyethylene (HDPE) micro- and nanocomposites and to investigate their thermal, mechanical, and morphological characteristics as a function of number of fillers and their contents percentage. In this study, 21 formulations of the composites were prepared using fillers with different sizes including micro fillers such as talc, calcium carbonate (CaCO3), as well as nano-filler (fumed silica (FS)) though the melt blending technique. The morphological, mechanical, and thermal properties of the composite samples were evaluated. The morphological study revealed negligible filler agglomerates, good matrix–filler interfacial bonding in case of combined both CaCO3 and FS into the composites. Sequentially, improvements in tensile, flexural and Izod impact strengths as a function of fillers loading in the HDPE matrix have been reported. The maximum enhancement (%) of tensile, flexural and impact strengths were 127%, 86% and 16.6%, respectively, for composites containing 25% CaCO3 and 1% FS without any inclusion of talc filler; this indicates that the types/nature, size, quantity and dispersion status of fillers are playing a major role in the mechanical properties of the prepared composites more than the number of the used fillers.

Tensile and Microscopic Properties of High-Density Polyethylene Geonet for Rainwater Scour Resistance

In order to study the tensile properties of a high-density polyethylene (HDPE) geonet for rainwater scour resistance and the micro properties of HDPE after tensile failure, a series of tensile tests on the HDPE geonet were carried out by the material testing system (MTS) tensile device. In this study, a correlation has been proposed to analyze the relationship between elongation and tensile strength of geonet material. The microscopic characteristics of the HDPE geonet were observed by using a scanning electron microscope SU8000. The high-density polyethylene geonet for rainwater scour resistance was evaluated based on mechanical performance and microstructure. The rainwater scour resistance properties of the high-density polyethylene geonet were estimated. It is determined that the geonet improved the rainwater scour resistance of the soil slope. The mechanical test results indicated that the longitudinal mechanical properties of the geonet are better than the transversal. The scanning electron microscope images of the geonet results confirmed that the polyethylene polymer produces fine and neat radial cracks during the tensile process of the geonet. The findings of this work are essential for the fundamental understanding, design, and application of the geonet.

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.

Surface modification of phosphogypsum and application in polyolefin composites.

Phosphogypsum (PG) is one of solid wastes with large amount of yield and serious pollution, which has attracted wide attention. The aim of this study is to investigate filling performance of PG on polypropylene (PP) or high-density polyethylene (HDPE) matrix. In this work, PG was calcined initially to improve whiteness and fix impurities. X-ray diffraction (XRD) results showed that after calcined at 500°C, the PG phase changed from CaSO4·2H2O to CaSO4. The modification effects of the three modifiers were evaluated by Fourier transform infrared spectra (FTIR), oil absorption value, water floatability, and contact angle analysis. The effects of weight fraction of PG in PP and HDPE matrix on mechanics and morphology were observed by tensile test, impact test, and scanning electron microscope. Scanning electron microscope (SEM) showed that modified PG can be dispersed uniformly in the matrix at low filling content. With the increase of PG filling content, the analysis of mechanical properties showed that the tensile strength of HDPE matrix increased, while the tensile strength of PP matrix decreased gradually. The impact strength of HDPE matrix would decrease, but the impact strength of PP matrix increased first and then decreased. Compared with calcium carbonate (CC), the mechanical properties of HDPE filled with PG performed better. The apparent density showed that polymer composites filled with PG have the characteristics of light weight.

Enhanced effect of thermal expansion process in rotational shear technology for high performance HDPE pipes

The purpose of this paper is to study the effect of thermal expansion process and rotational shear on the structure and properties of high-density polyethylene (HDPE) pipes. In this paper, HDPE pipes with excellent properties were prepared by the rotational shear system (RSS) and the thermal expansion process. The morphology study results showed that shish-kebab crystals appeared in the pipes. And with the application of thermal expansion process, the interlocking degree of the shish-kebab crystals was further deeper. The thickness of kebab increased greatly and a certain degree of tilt occurred. With the increase of the tensile ratio, the mechanical properties were improved. When the tensile ratio was 1.25, the hoop tensile strength of the pipes increased by 31.50%, and the creep rate also increased by 67.44%. The better mechanical properties at the tensile ratio of 1.25 are mainly attributed to the tighter Shish-Kebab structure after tube expansion.

Plasma-Induced Modifications on High Density Polyethylene and Polyethylene Terephthalate

This work presents comprehensive study of high density polyethylene (HDPE) and polyethylene terephthalate (PET) surface properties after exposed to 1.5, 3, 4.5 and 6 min oxygen (O2) plasma. The polymer surface structure is analyzed by Raman spectroscopy, which revealed surface restructuring modifications. The contact angle of HDPE and PET decreased gradually, and the work of adhesion is improved with O2 plasma. The water contact angle is reduced from 61.6° to 36.3° for HDPE and from 72.4° to 37.5° for PET by increasing plasma time from 1.5 to 6 min. The surface free energy is enhanced from 27.8 mJ m−2 to 69.0 mJ m−2 for HDPE and from 29.8 mJ m−2 to 67.2 mJ m−2 for PET, when the plasma time increased from 0 to 6 min. The polar groups significantly reduced the hydrophobicity of the irradiated films, and consequently the surface wettability is improved. The results showed observed improvement in surface properties of HDPE and PET polymeric films to be use in different applications such as printings, coatings and optoelectronics.

Effects of residual wax content on the thermal, rheological, and mechanical properties of high‐density polyethylene

AbstractThe influence of residual wax content on the thermal, rheological, and mechanical behavior of two high‐density polyethylene (HDPE) samples from different lots of the same supplier was characterized. HDPE with a low wax content presented a higher melting temperature and a wider melting endotherm. A decrease in the degree of crystallinity and thermal stability of HDPE with a higher wax content was observed. Thermograms obtained by DSC indicated a small additional exothermic transition associated with the exclusion of residual wax. A higher wax content in HDPE produces a decrease in its viscosity due to a lubricating effect, which allows the sliding of HDPE chains of high molecular weight. In contrast, HDPE with lower wax content achieves greater elongational viscosity and melt strength. The mechanical testing results show that HDPE with higher wax content presented lower Young's modulus, tensile strength, elongation at break, and Izod impact strength than HDPE with lower wax content. The results obtained show that a relatively slight difference in wax content significantly affects HDPE properties.

Comparative analysis of wear behaviour of commercial polymeric pipe materials under different sliding environments

ABSTRACT The friction and wear behaviour of three commonly used commercial polymeric materials, namely, Acrylic, high density polyethylene (HDPE) and unplastisised polyvinyl chloride (uPVC), was studied experimentally under normal ambient conditions. More specifically, the wear rate and coefficient friction of the materials were evaluated against a mild steel counter disc under three different sliding conditions realised by dry, wet (water) and 5% bentonite-clay water environments, which were then analysed as a function of sliding distance as well as the applied load on the sample. Moreover, in order to visualise the results of the present investigation in a comprehensive manner, the associated major physical and mechanical properties of the materials were also investigated. The vertical pin-on-disc method was used to conduct the study. Both the wear and friction characteristics were strongly linked to the structure of the polymers; HDPE samples being fully crystalline show best wear and friction characteristics, whilst the amorphous Acrylic shows the worst. Optical microscopic analysis of the specimens, particles from the worn surfaces (wear debris) and the counter disc also indicated that Acrylic was most affected by wear, whilst HDPE was least affected. SEM and EDX observations showed that uPVC was most affected by oxidation followed by HDPE and Acrylic. The excellent wear and frictional properties of HDPE, especially, in particle-dense fluid transportation, make it ideal for dynamic applications, particularly with mine debris flows and transporting of slurry.

Mechanical, thermal and rheological properties of thermoplastic polymer nanocomposite reinforced with nanodiamond, carbon nanotube and graphite nanoplatelets

ABSTRACT The current exploration is oriented towards mechanical, thermal and rheological properties of high density polyethylene (HDPE) reinforced with the equivalent weight percentage (i.e. 0.1 wt.%) of nanodiamonds (NDs), carbon nanotube (CNTs) and graphite nanoplatelets (GNPs) nanofillers. The highest Young’s of 1.24 GPa is shown by 0.1 ND, which decreased by 4.03, 12.09 and 18.54% for 0.1 CNT, 0.1 GNP and pure, respectively. A similar trend was observed during hardness and fracture stress results; however, the highest yield stress is perceived for the 0.1 CNT composite. The improvisation in percentage of crystallinity value is noted for 0.1 ND composites that augmented the results of hardness value. The rheological investigation recorded the shear-thinning behaviour for all the samples from 10−1 to 102 rad/s and the highest viscosity offered by 0.1 ND composite, which is in line with the results of the melt flow index. The results suggested that the addition of ND nanoparticles improvise mechanical, thermal and rheological properties and can be adapted as a suitable material for immediate application in the relevant industry.

Investigation on Physical and Mechanical Properties of High Density Polyethylene (PE100) Using Novel Catalyst

Novel catalyst called super active catalyst for the production of high density polyethylene (HDPE) pipes grade 100 was prepared and localized for the first time in Iran. The purpose of this paper is to evaluate the performance of the new catalyst and compare it with Finix-112 catalyst which is a commercial catalyst for the production of HEPE grade 100. Extensive experiments were performed on the physical and mechanical properties of the product using both catalysts including melt flow index, particle size distribution, volatility, density, bulk density, scanning electron microscope-energy dispersive x-ray analysis, charpy impact strength. Comparison of the results showed that the hydrogen responsibility performance of the product with super active catalyst is 19%, charpy impact is 16.7% and pressure condition in first reactor about 28% was better than product with Finix-112 catalyst. Home-made super active catalyst can be a good alternative to imported finix-112 catalyst and save a considerable amount of foreign currency.