Fracture Characterization of High-Density Polyethylene Materials Using the Energetic Criterias

Impact behavior of polymers has received considerable attention in recent years,and much work based on fracture mechanic approaches has been carried out.In this paper,fracture behavior in large deformation of a high density polyethylene(HDPE)materials was investigated through experimental impact testing on single edge notched specimen(SENB)and by using theoretical and analytical fracture criteria concepts.Moreover,a review of the main fracture criteria is given in order to characterize the toughness of this polymer in the both cases(static and dynamic).The fractured specimens obtained from the Charpy impact test were characterized with respect to their fracture surfaces.Characteristic zones of the fracture surface can be assigned to different stages and mechanisms of the fracture process.Finally,for a better understanding of fracture and damage mechanisms and to provide the best estimation of fracture toughness in impact,an experimental approach based on microscopic observations(SEM)was used.

Micromechanical analysis on tensile properties prediction of discontinuous randomized zalacca fibre/high-density polyethylene composites under critical fibre length

In this research,the tensile properties'performance of compression moulded discontinuous randomized zalacca fibre/high-density polyethylene under critical fibre length was analysed by means of experimental method and micromechanical models.These investigations were used to verify the tensile properties models toward the effect of fibre length and volume fraction on the composites.The experimental results showed that the tensile properties of composites had significantly increased due to the enhancement of fibre length.On the contrary,a decline in the tensile properties was observed with the increase of volume fraction.A comparison was made between the available experimental results and the performances of Tsai-Pagano,Christensen and Cox-Krechel models in their prediction of composites elastic modulus.The results showed that the consideration of fibre's elastic anisotropy in the Cox-Krenchel model had yielded a good prediction of the composites modulus,nevertheless the models could not accurately predict the composites modulus for fibre length study.

Optimization of Process Parameter for Sawdust/Recycled Polyethylene Composites

In this paper, Okhuen wood sawdust and recycled polyethylene (RLDPE) were blended and then hot-pressed to produce sawdust/recycled polyethylene composite board. The optimum processing parameters for preparing the composite such as temperature, pressing time, sawdust/RLDPE content and pressure were investigated and optimized using L9 (34) Taguchi experimental design orthogonal array. The tensile strength of the various formulations was determined. The results show that those factors made different effects on the tensile strength of the composites. The optimized process conditions obtained are as follows: press time 7 min, press temperature 180°C, saw-dust/RLDPE 60:40%, press pressure 40kg/cm2. The average tensile strength of the optimized composite board was 13.991 MPa. The composite board met the standard for general purpose applications.

Characterization and Comparison of Rheological Properties of Agro Fiber Filled High-Density Polyethylene Bio-Composites

The rheological behavior of composites made with high-density polyethylene (HDPE) and different agro fiber by-products such as corncob (CCF), Rice hull (RHF), Flax shives (FSF) and Walnut shell (WSF) flour of 60 - 100 mesh were studied. The experimental results were obtained from samples containing 65 vol.% agro fiber and 3 wt.% lubricant. Particle sizes distribution of the agro fibers was in the range of 0.295 mm to ?0.125 mm. SEM showed evidence of complete matrix/fiber impregnation or wetting. The melt rheological data in terms of complex viscosity (η*), storage modulus (G'), loss modulus (G"), and loss tangent (tanδ) were evaluated and compared for different samples. Due to higher probability of agglomeration formation in the samples containing 65 vol.% of agro fillers, the storage modulus, loss modulus and complex viscosity of these samples were high. The unique change in all the samples is due to the particle size distribution of the agro fibers. The storage and loss modulus increased with increasing shear rates for all the composites, except for Walnut shell composite which exhibited unusual decrease in storage modulus with increasing shear rate. Damping factor (tanδ) decreased with increasing shear rate for all the composites at 65 vol.% filler load although there were differences among the composites. Maximum torque tended to increase at the 65 vol.% agro fiber load for all composites. Corncob and Walnut shell composites gave higher torque and steady state torque values in comparison with Flax shives and Rice hull composites due to differences in particle sizes distribution of the agro fibers.

Accurate detection method of high-density polyethylene fi lm leakage location based on secondary electric potential difference

High-density polyethylene(HDPE)film leakage location detection is frequently accomplished using the double-electrode technique.The electric potential and potential difference are the main physical parameters in the double-electrode approach.Due to the impact of the complex geoelectric environment,the electric potential and the electric potential difference are not sensitive enough to respond to minimal leakage.The tiny leaking area cannot be precisely located using the electric potential and electric potential difference.Using the COMSOL Multiphysics software,this study created a standard geoelectric model of the double-electrode method.We calculated a new parameter—the G parameter through secondary electric potential difference—based on the response characteristics of the electric potential and the electric potential difference while the HDPEfilm is leaking.The experiment demonstrates that the G parameter is more sensitive than the electric potential and electric potential difference for detecting the leaking area of HDPE film.The G parameter is more effective at detecting leakage than the electric potential and electric potential difference.The results of this study can be used to locate HDPEfilm leakage areas in a landfill.

A New Selective Neural Network Ensemble Method Based on Error Vectorization and Its Application in High-density Polyethylene (HDPE) Cascade Reaction Process

Chemical processes are complex, for which traditional neural network models usually can not lead to satisfactory accuracy. Selective neural network ensemble is an effective way to enhance the generalization accuracy of networks, but there are some problems, e.g., lacking of unified definition of diversity among component neural networks and difficult to improve the accuracy by selecting if the diversities of available networks are small. In this study, the output errors of networks are vectorized, the diversity of networks is defined based on the error vectors, and the size of ensemble is analyzed. Then an error vectorization based selective neural network ensemble (EVSNE) is proposed, in which the error vector of each network can offset that of the other networks by training the component networks orderly. Thus the component networks have large diversity. Experiments and comparisons over standard data sets and actual chemical process data set for production of high-density polyethylene demonstrate that EVSNE performs better in generalization ability.

Decorative Wood Fiber/High-Density Polyethylene Composite with Canvas or Polyester Fabric

Wood-plastic composite is an environmentally friendly material,due to its use of recycled thermoplastics and plant fibers.However,its surface lacks attractive aesthetic qualities.In this paper,a method of decorating wood fiber/high-density polyethylene(WF/HDPE)without adding adhesive was explored.Canvas or polyester fabrics were selected as the surface decoration materials.The influence of hot-pressing temperature and WF/HDPE ratio on the adhesion was studied.The surface bonding strength,water resistance,and surface color were evaluated,and observation within the infrared spectrum and under scanning electron microscopy was used to analyze the bonding process.The results showed that the fabric and WF/HDPE substrate could be closely laminated together depending on the HDPE layer accumulated on the WF/HDPE surface.The molten HDPE matrix penetrates canvas more easily than polyester fabric,and the canvasveneered composite shows a greater bonding strength than does the polyester fabric-veneered composite.A higher proportion of the thermoplastic component in the substrate improved the bonding.When the hot-pressing temperature exceeded 160°C,the fabric-veneered WF/HDPE panels had greater water resistance,although the canvas fabric changed more obviously in terms of fiber shape and color,compared with the polyester fabric.For the canvas fabric,140°C–160°C was a suitable hot-pressing temperature,whereas 160°C–180°C was more suitable for polyester fabric.The proportion of the thermoplastic component in the composite should be not less than 30%to achieve adequate bonding strength.

Effects of Palm Kernel Shell on the Microstructure and Mechanical Properties of Recycled Polyethylene/Palm Kernel Shell Particulate Composites

The effect of palm kernel shell on the microstructure and mechanical properties of recycled polyethylene (RLDPE) reinforced with palm kernel shell particulate composite was evaluated to assess the possibility of using it as a new material for engineering applications. The composites were produced by compounding and compressive moulding technique by varying the Palm kernel shell particle from 5-25vol% with particles size of 150, 300 and 400 μm. The microstructure (SEM/EDS) and the mechanical properties of the composites were investigated. The hardness of the composite increases with increase in palm kernel shell content and the tensile strength of the composite increased to optimum of 5vol%. Scanning electron Microscopy (SEM) of the composites surfaces indicates fairly interfacial interaction between the palm kernel shell particles and the RLDPE matrix. The composites produced with 150 μm particle size have the best properties of the entire grade. Hence this grade can be use for interior applications such as car seat, dash board, and car interior for decorative purposes or other interior parts of automobile where high strength is not considered a critical requirement.

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 Groundnut Shell Powder on the Mechanical Properties of Recycled Polyethylene and Its Biodegradability

Natural fiber reinforced composites have gained considerable attention particularly in the manufacturing industry owing to their light weight, corrosion resistance, abundance, and biodegradability. In this work, alkaline treated and untreated groundnut shell powder (GSP) was used to reinforce recycled polyethylene to produce GSP-recycled polyethylene composites with improved mechanical properties and biodegradability. GSP with particle sizes of 0 - 300 μm and 300 - 600 μm was used in different proportions: 5%, 10%, 15%, 20%, 25%, and 30% wt. The fiber was immersed for 5 hours in a 10 wt% NaOH solution. Tensile and hardness test data showed an improvement in mechanical properties of the treated fiber composites. Results of water absorption test also showed that treated GSP-recycled polyethylene composites had a lower rate of water absorption than the untreated GSP-recycled polyethylene composites. Through Fourier transform infrared spectroscopy, disappearance of characteristics peaks of hemicellulose and lignin was observed. Growth of fungi on the fiber-reinforced composites was observed, which was evidence that GSP-recycled polyethylene composite was biodegradable. Finally, SEM micrographs showed uniform distribution of treated fibers in the polymer matrix;this explained the observed improvement in the mechanical properties of treated GSP-recycled polyethylene composites.

High-Density Polyethylene Based on Exfoliated Graphite Nanoplatelets/Nano-Magnesium Oxide: An Investigation of Thermal Properties and Morphology

In this study, high-density polyethylene (HDPE)/exfoliated graphite nanoplatelet (xGnP) composites reinforced with a 2 wt.% concentration of nano-magnesia (n-MgO) were fabricated using an injection moulding machine. The thermal properties and morphological structures of the composites were investigated. The XRD results showed the peaks of xGnP and n-MgO, where the intensity of the xGnP peaks became stronger with adding increasing amounts of xGnP into the polymermatrix. In terms of morphology, some agglomeration of particles was observed within the matrix, and the agglomeration decreased the thermal properties of the composites. The nanocomposites showed less thermal stability than the pristine polymer. The reduction in the onset temperature compared to that of neat HDPE was attributed to less adhesion between the fillers and the matrix. In addition, the crystallinity was reduced by the addition of fillers.

Physical and Thermo-Oxidative Characterization of Asphalt Modified with High Density Polyethylene and Recycled Engine Oil

Modification of asphalt using polymers, oils and other additives has been an option to improve asphalt pavement performance and extend its lifespan. The present work aims to evaluate the influence of the addition of engine oil on the consistency and thermal properties of HDPE-modified asphalt. For this study, compositions containing asphalt, engine oil and high-density polyethylene (HDPE) were prepared, varying the concentration of engine oil by 2.5 wt%, 5 wt%, 7.5 wt% and 10 wt% and keeping the concentration of HDPE at 5 wt%. The samples were characterized by conventional tests of penetration, softening point and viscosity, aging in a Rotational Thin Film Oven (RTFO), Thermogravimetric Analysis (TGA). According to the results, the addition of HDPE to virgin asphalt causes an increase in the consistency of the virgin asphalt, which then decreases linearly as the engine oil is added into the matrix. Conventional tests showed improvements in the applicability of the asphalt in terms of resistance to cracks and permanent deformation. TGA showed a slight increase in stability for the modified asphalt samples at elevated temperatures. The RTFO showed mass gain and loss for samples with and without engine oil, respectively.

Molecular Dynamics-Based Simulation of Polyethylene Pipe Degradation in High Temperature and High Pressure Conditions

High-density polyethylene(HDPE)pipes have gradually become the first choice for gas networks because of their excellent characteristics.As the use of pipes increases,there will unavoidably be a significant amount of waste generated when the pipes cease their operation life,which,if improperly handled,might result in major environmental contamination issues.In this study,the thermal degradation of polyethylene materials is simulated for different pressures(10,50,100,and 150 MPa)and temperatures(2300,2500,2700,and 2900 K)in the framework of Reactive Force Field(ReaxFF)molecular dynamics simulation.The main gas products,density,energy,and the mean square displacement with temperature and pressure are also calculated.The findings indicate that raising the temperature leads to an increase in the production of gas products,while changing the pressure has an impact on the direction in which the products are generated;the faster the temperature drops,the less dense the air;both temperature and pressure increase impact the system’s energy conversion or distribution mechanism,changing the system’s potential energy as well as its total energy;the rate at which molecules diffuse increases with temperature,and decreases with pressure.The results of this investigation provide a theoretical basis for the development of the pyrolytic treatment of polyethylene waste materials.

Recycling Polyethylene Terephthalate （PET） Packaging as the Basis of Economic Projects and Solution of Social and Environmental Problems in Russia

In this article, based on the analysis of the current environmental situation in Russia and other countries, as well as of the problem of recycling plastic waste in the Russian Federation （RF）, the authors clearly show the effectiveness of investments in the processing of polymer debris on the example of polyethylene terephthalate （PET） waste （granulates, flakes）. In the frame of case study of social and environmental investment project on creating enterprise that will engage in collection, recycling, and sale of the consumer PET packaging in Russia, the authors demonstrate the economic feasibility of the creation of such kind of enterprises taking into account market conditions and the features of the existing system of taxation in Russia. The realization of the project will also help in solving environmental and social problems of large cities, in particular, will create more jobs （in terms of 6% of unemployment rate in the country）. The study also identifies the main obstacles in the way of waste recycling in Russia, and the recommendations for improvement of normative base of the industry are given.

Analytical Case Study on a Dedicated Pigment in Recycling Processes of Polyethylene

The ability to track & trace materials is a key feature in the entire chain, and it ensures circularity principles. Examples from plastic recycling show the enormous added value that analytical technology can have for the circular economy. During polymer production and recycling processes, pigments can be added for different purposes;e.g. as colouring agent of the polymeric product but also as tracer for tracking process development and control in the final recycle products versus possible by-products. An analytical method for tracking the pigment Solvent Blue 15 in input materials, in intermediates as well as in recyclates was developed by tracing and quantifying an indicator metal which is copper (Cu). Therefore, suitable digestion procedures and a quantification method by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) were developed and used for measuring the polymeric digests. The method was tested on relevant samples from chemical recycling processes. The background concentrations in base/raw material are in the range of 0.05 - 0.1 mg·kg-1 Cu. The processing concentrations are in the range of 4.2 to 28 mg·kg-1 Cu, while the pigment starting material (polyethylene, PE) has a concentration of around 50 mg·kg-1 Cu.

Effectiveness of Compatibilizer on Mechanical Properties of Recycled PET Blends with PE, PP, and PS

Recycled PET (R-PET) is well known to exhibit brittle behavior in the presence of notches and indicated the low heat distortion temperature. In addition, it is hard to prevent some impurities such as cap or label of the bottle that mixed into R-PET during the recycling process. In this paper, the effect of the amounts and kinds of compatibilizers on the morphological characteristics and mechanical performance of recycled poly(ethylene terephthalate) (R-PET) compounded with polyethylene (PE), polypropylene (PP), and polystyrene (PS) was investigated. From the results, with an increase in the glycidyl methacrylate modified PE (EGMA) additive contents, in the increment of the Izod impact strength of Composite-G was obtained. In addition, it was found that the miscibility of Composite-G was improved with increasing the amount of EGMA, which indicated from the result of SEM images.

EFFECT OF PAN-MILLING STRESS ON CRYSTAL STRUCTURES OF HIGH DENSITY POLYETHYLENE

A detailed study was performed on the crystal structures of pan-milled high-density polyethylene (HDPE) using differential scanning calorimetry (DSC) and X-ray diffraction. The crystallinity of HDPE first decreased slightly, followed by a gradual increase with increasing milling times. Monoclinic crystals appeared after 4 cycles of milling. With increasing times of milling, the proportion of monoclinic crystals increased significantly while the proportion of orthorhombic crystals decreased gradually. With increasing times of milling, the crystallite size of orthorhombic form decreased greatly, while the size of monoclinic crystallites kept almost constant during milling.

Utilization of waste polyethylene terephthalate as a reducing agent in the reduction of iron ore composite pellets

The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate （PET）, because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450℃ for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron （iron nuggets） were reduction at 1450℃ for 10 min using composite pellets containing 60% PET and 40% coke.

Effect of substrates on crystallization of high density polyethylene

The experimental observations about remarkable influence of the substrates on the isothermal crystallization rate of a high density polyethylene(HDPE) were presented.Two methods were used to characterize the crystallization rate:the change of turbidity of the HDPE specimen and the changes of the complex viscosity and storage modulus measured by a rotational rheometer,which gave consistent results showing that the isothermal crystallization rate decreased in sequence as the specimen contacted with aluminum,brass and stainless steel plates,respectively.As to the dominant influence factor,the chemical composition of the substrates can be excluded via insulating the plate by an aluminum foil.Instead,we propose the plate's ability of removing the latent heat of crystallization from the specimen.Rheological measurement is sensitive to the crystallization process.The colloid like model proposed by BOUTAHAR et al for the crystallization of HDPE gives reasonable predictions of the crystallized fraction from the measured storage modulus.

Analysis of Highway Asphalt Modified with Recycled Rubber and Waste Plastics

In this study,it is shown how recycled rubber and waste plastics can modify the softening point and penetration of asphalt traditionally used for highways.It is shown that the modified asphalt can meet the performance index requirements when the components are present with a certain proportion or relative ratio(1:3.5).The dispersion process of the masterbatch in base asphalt can effectively be implemented,with good results and a smaller mixing time.The proposed approach may be regarded as a good strategy to achieve energy savings and protection of the environment.