Recycled High Density Polyethylene Research Articles

Mechanical, Dynamic Mechanical and Thermal Properties of Banana Fiber/Recycled High Density Polyethylene Biocomposites Filled with Flyash Cenospheres

This study presents the preparation of Natural fiber-reinforced biocomposites based on Recycled High Density Polyethylene (RHDPE)/Banana Fiber (BF)/Fly ash Cenospheres (FACS) and aims to increase the economic value of these waste materials. Maleic anhydride grafted HDPE (MA-g-HDPE) was used as a compatibilizer to increase the dispersion of fibers into the polymer matrix as well as to increase the compatibility between the matrix and fillers. Variation in mechanical, thermal and dynamic mechanical properties with the addition of FACS in RHDPE/BF composites was investigated. It was observed that 7.5 wt% FACS, 30 wt% BF and 3 wt% MA-g-HDPE within RHDPE matrix resulted in an increase in tensile strength to 17%, tensile modulus to 188%, flexural strength to 38%, flexural modulus to 159% and hardness to 37% as compared with the RHDPE matrix. Significant enhancement in the thermal stability of the RHDPE/BF biocomposites was also observed in presence of FACS under thermogravimetric analysis. The morphology of the prepared biocomposites has been examined by using scanning electron microscopy. Dynamic mechanical analysis tests revealed an increase in storage and loss modulus of the biocomposite system. The use of such recycled material, agricultural and industrial wastes increased the properties of the final product suggesting their use to be a good alternative in the production of polymeric composites.

Effect of Nanographene on Physical, Mechanical, and Thermal Properties and Morphology of Nanocomposite Made of Recycled High Density Polyethylene and Wood Flour

The effects of the amount of nanographene on physical, mechanical, and thermal properties and morphology of the wood-plastic composites were investigated. This wood-plastic was made using recycled high density polyethylene (HDPE), nanographene, and wood flour. Four weight levels, 0, 0.5, 1.5, or 2.5 wt.% of nanographene, were combined with 70% polymeric matrix and 30% lignocellulosic material with an internal mixer. The results showed that by increasing the amount of nanographene up to 0.5% by weight, the flexural strength, flexural modulus, and notched impact strength of the composite increased. After adding 2.5 wt.% nanographene, these properties were reduced. By increasing the amount of nanographene, both the amount of residual ash and the thermal stability increased. Study of the images from scanning electron microscope (SEM) showed that the samples containing 0.5% of nanographene had less pores and were smoother than other samples.

Effect of Fibre Content on Mechanical Properties and Water Absorption Behaviour of Pineapple/HDPE Composite

The present study investigates the effect of varying content of pineapple fibre in pineapple/HDPE composite on the tensile strength, tensile modulus, hardness (Shore-D)and water absorption behaviour. The content of pineapple fibres is kept as 5%, 15% and 25% (by wt.) and the HDPE matrix is taken as 50-50 mixture of fresh and recycled HDPE. The results obtained for 25% pineapple/HDPE composite are compared with those obtained for pineapple-sisal (each 12.5%)/HDPE composite. Prior to the fabrication of composite, the fibres were subjected to chemical treatments with NaOH and maleic anhydride coupling agent for enhancing their adhesion with HDPE matrix. It is observed that the tensile strength and hardness of pineapple/HDPE composite decrease with increasing fibre content. Though, the tensile modulus increases with the increase in fibre content. The pineapple-sisal/HDPE composite exhibits higher tensile strength and hardness, thought lower tensile modulus, as compared to pineapple/HDPE composite, when the total fibre content is 25% in both the composites.The 48 hours water absorption study indicates that amongst all the composites, the water absorption is the minimum for 5%pineapple/HDPE composite. SEM examination of the tensile fractured surface reveals that fibre pull-out, fibre delamination and fibre breakage are the primary mechanisms responsible for tensile failure of the specimen.

Physical and Mechanical Properties of WPC Board from Sengon Sawdust and Recycled HDPE Plastic

Wood Plastic Composite (WPC) is a composite material made from sawdust and plastic as polymer bonding, that used in a variety of structural and non-structural applications. Nowadays, In Indonesia WPC is made from Sengon sawdust and recycled HDPE plastic. This research was conducted in order to investigate the physical and mechanical properties of WPC from Sengon sawdust in accordance with ASTM D7031. From the physical test, due to its water restrains, WPC has low moisture content, water absorption and swelling. For the mechanical properties, the bending strength and shear strength are around 40.49 MPa and 27.35 MPa, respectively. However, the WPC tensile strength is lower than common tropical wood, which is only 5.54 to 12.75 MPa, due to the absence of grain in WPC. Furthermore, the modulus of elasticity is only 2113 to 3398 MPa or around one tenth of that wood or concrete modulus of elasticity. From the withdrawal test shows that sheet metal screw type has the highest withdrawal strength compared to cut thread wood, and fine thread drywall screw. Hence, for structural application it is suggested that the WPC board is used for structural element with high moment inertia such as shear wall as its lower modulus of elasticity but has high shear strength.

Thermoplastic composite beam structures from mixtures of recycled HDPE and rubber crumb for acoustic energy absorption

The use of recycled rubber crumb in the design and production of thermoplastic-rubber composites as sound absorbers can provide solutions to noise pollution and for the recovery of post-consumer materials from both packaging and waste tyres. The work of this study is concerned with the effect of rubber crumb incorporation in high-density polyethylene (HDPE) and also in HDPE glass fibre composites on acoustic, mechanical and physical properties. Recycled HDPE compounds containing variable concentrations of cured rubber crumb particles were prepared by twin screw extrusion. Thermal analysis has revealed a significant increase in the level of crystallinity of the HDPE component by increasing the rubber content in the mixes. Standard three-point bending and notched impact test specimens were manufactured by injection moulding, and large-scale beam samples were produced by compression moulding using an ad hoc method that allows variation of the through-thickness elastomer content as a means of obtaining composition gradients. The flexural modulus and impact strength varied monotonically with rubber crumb concentration. A fast Fourier transform technique was used to determine the acoustic performance of the beams over a wide frequency range. The graded structures produced large improvements in acoustic absorption properties in the frequency range of 2–6 kHz, notably from composite beams containing 20% rubber and also in some multilayer beams with rubber concentration gradients.

Characterization of green rHDPE biocomposites filled with natural filler: Rheological and thermal studies

Palm kernel shell filled recycled high density polyethylene (rHDPE/PKS) biocomposites were produced in order to reduce the waste product from palm oil production. The biocomposites at various filler loading were prepared by melt mixing at 180 °C. Ultra Plast TP0' was selected as coupling agent in rHDPE/PKS biocomposites, in order to modify the properties of biocomposites. It was found that the higher filler loading had reduced the melt flow index (MFI) values. However, with the increasing of testing temperature from 180 to 210 °C, the MFI values of the biocomposites were increased. The presence of Ultra Plast TP01was capable to increase MFI values of the biocomposites. The thermal studies showed that thermal stability of the biocomposites was affected by PKS loading and coupling agent. Though the thermal stability of biocomposites was reduced by PKS, it can be improved by Ultra Plast TP01. Hence, Ultra Plast TP01 can serve as an effective coupling agent for rHDPE/PKS.

Erratum to: Rheological and Mechanical Properties of Silica-Based Bagasse-Fiber-Ash-Reinforced Recycled HDPE Composites

The rheological and mechanical properties of a recycled high-density polyethylene biocomposite with silicabased bagasse fiber ash as a reinforcing filler were investigated. The bagasse fiber ash (BFA) was surface-treated using a silane coupling agent (vinyltrimethoxysilane). Composites with BFA whose particle size was varied in the range of 3 to 25wt.% (37, 53, and 105mm), were prepared and examined.

Life Cycle Economic and Environmental Implications of Pristine High Density Polyethylene and Alternative Materials in Drainage Pipe Applications

A life cycle assessment (LCA) and cost analysis were conducted to compare the environmental and economic performance of nanocomposite polymers that use pristine and recycled high density polyethylene (HDPE) polymer with pristine, and pristine/recycled HDPE polymeric materials in drainage pipe. We evaluate three performance metrics; (a) non-renewable energy consumption (NRE); (b) greenhouse gas (GHG) emissions; and (c) production costs of the three pipe material alternatives. Original life cycle inventory data for the production of nanoclay from the mineral Montmorillonite were collected for this case study in the United States. Life cycle inventory models were developed for the cradle-to-gate production of drainage pipe used in highway construction that consider the sensitivity of model parameter inputs on the life cycle impact and cost results for the three material options. The GHG emissions for the nanoclay composite pipe are 54 % lower than those for pristine HDPE pipe, and 16 % lower than those for pristine/recycle HDPE pipe. With a slight difference in GHG emissions between the pristine/recycled and nanoclay composite, the production of nanoclay does not introduce a significant environmental burden to the pipe material. On average, the pristine HDPE pipe is 13 and 17 % higher in cost than the pristine/recycled HDPE and nanoclay composite pipes, respectively. Results of the LCA and cost analysis support using recycled HDPE as a substitute for pristine HDPE due to its low energy requirements and production costs. The uncertainty in GHG emissions of manufacturing pristine HDPE causes the largest variation of GHG emissions in nanoclay composite pipe (+3/−2 %). The production cost of the nanocomposite pipe is most influenced by the energy cost of PCR-HDPE (+25/−11 %). Our study suggests that a nanocomposite design that replaces part of the pristine HDPE with recycled HDPE and nanoclay reduces certain environmental risks and material cost of corrugated pipe.

Measurements and Comparison to Predictions of Viscosity of Heavily Filled HDPE with Natural Fibers

AbstractComposites of rice hulls at various levels of loadings in recycled HDPE were characterized rheologically using a conical extrusion die and small amplitude oscillatory shear (SAOS) measurements. Although the results do not match, due to the invalidity of the Cox–Merz rule for such composites, both types of measurements indicate that increasing the filler concentration results in significantly higher viscosities and increased shear thinning. The errors associated with the use of a conical die due to viscous dissipation are assessed through computer simulations. They are small for relatively small throughputs (small pressure drops). The experimental results for viscosity are compared to predictions of the Einstein–Batchelor equation for suspensions of spherical particles, the Guth–Simha equation, and the empirical Krieger–Dougherty correlation, for filler loadings of up to 70% by weight. The comparison indicates that reasonable approximations of the consistency index of the power law viscosity model are possible through using the above expressions for loadings up to perhaps 40–50% by weight.

Waste management by recycling of polymers with reinforcement of metal powder

Abstract Recycling of plastics/polymers is one of the waste management techniques which have been followed by many researchers. In past 20 years large number of applications in this field has been highlighted. But hither to very few have reported on plastic waste management by recycling of polymers with reinforcement of metal powder. In the present work an effort has been made to perform recycling of waste plastic/polymer with reinforcement of metal powder by controlling the melt flow index (MFI). The present study of recycling of waste plastic has been performed on single screw extruder machine by considering various input parameters (namely: barrel temperature, die temperature, and screw speed/rpm). Investigations were performed for the parametric optimization of single screw extruder machine for different mechanical/metallurgical properties (like: porosity, peak elongation, break strength, Shore D hardness) with the help of case study of recycled high density polyethylene (HDPE)100%, HDPE90% + Fe10%, low density polyethylene (LDPE)100% and LDPE94 + 6% (by wt.). As HDPE and LDPE do not decompose naturally, this nature makes these polymers suitable for structural applications (like in beams and reinforced concrete cements (RCC) structures).

Physical Characterization and Pre-assessment of Recycled High-Density Polyethylene as 3D Printing Material

3D printing has received lots of attention due to its limitless potential and advantages in comparison to traditional manufacturing processes. This study focuses on the most popular type of home 3D printers, namely fused filament fabrication (FFF) printers, which use plastic filaments as the feedstock. The rather high material cost and large amount of plastic waste generated by FFF 3D printers have driven the need for plastic filaments produced from recycled plastic waste. This study evaluates, in terms of physical characterization, the feasibility of using recycled high-density polyethylene (HDPE), one of the most commonly used plastics, as the feedstock for 3D printers, in comparison with the common acrylonitrile butadiene styrene plastic pellets. In-house extrusion using recycled HDPE pellets and flakes is possible. The diameter consistency and extrusion rate results, along with other physical characterization results, including differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and water absorption, suggest that making filaments from recycled HDPE pellets is a viable option, as the obtained filament has favorable water rejection and comparable extrusion rate and thermal stability. Existing methods for overcoming the warping and adhesion problems in 3D printing with HDPE were also reviewed. In order to increase the market competitiveness of waste-derived filaments, optimization of the extrusion process, studies on the mechanical and aging properties, and development of a standard characterization methodology and database are crucial.

Potential Use of Hazelnut Husk in Recycled High-Density Polyethylene Composites

Hazelnut husk was considered as a potential filler for thermoplastic composites. Different amounts of hazelnut husk flour and the recycled high-density polyethylene (R-HDPE) were used as the filler and polymer matrix, respectively. The composite compounds were produced using single-screw extrusion compounding, and then composite panels were prepared by hot-press compression molding. The morphological, physical, mechanical, and thermal properties, as well as the biological durability of the composites, were evaluated. The flexural and tensile modulus of the composites improved with increasing hazelnut husk filler content, whereas the physical properties, biological durability, and the flexural and tensile strengths were reduced. With the addition of a maleic anhydrite-grafted polyethylene (MAPE), the hazelnut husk filler was more finely dispersed within the polymer matrix and the degree of crystallinity was lower than that of the R-HDPE. This research revealed that hazelnut husk flour has potential for use as a filler in R-HDPE composites.

Rheological and Mechanical Properties of Silica-Based Bagasse-Fiber-Ash-Reinforced Recycled HDPE Composites

Rheological and Mechanical Properties of Silica-Based Bagasse-Fiber-Ash-Reinforced Recycled HDPE Composites

Effects of different filler types on decay resistance and thermal, physical, and mechanical properties of recycled high-density polyethylene composites

In this study, flexural properties, impact strength, thermal performance, water absorption, biological durability, and morphology of wood-plastic composites (WPCs) filled with different filler types were investigated. Six different formulations of WPCs were fabricated from mixtures of carpenter waste and recycled high-density polyethylene (R-HDPE). The carpenter waste was derived from wood and particle board wastes, and R-HDPE was used as the polymer matrix, with and without addition of maleic anhydrite grafted polyethylene (MAPE). All formulations were compression moulded in a hot press for 3 min at 170 °C. Investigations on the compression moulded specimens revealed that water absorption values in the particleboard waste flour specimens were lower than in the wood-waste flour WPCs. However, the wood-waste flour-filled composites exhibited higher mechanical property values than the particleboard waste flour WPCs. Statistically, only the wood-waste flour-filled composites with MAPE were significantly different. The use of MAPE (3 wt%) had a positive effect on the water absorption, crystallinity degree, and flexural properties of the WPCs. In addition, the peak temperatures of the composites did not show any variation, while thermal decomposition of the composites showed minor variations under the thermogravimetric analysis. Furthermore, the decay resistance of the composites improved with the use of particleboard waste flour. The obtained results demonstrate that particleboard waste flour, such as wood-waste flour, is potentially suitable as a raw material in WPCs.

General model for comparative tensile mechanical properties of composites fabricated from fly ash and virgin/recycled high-density polyethylene

The present work on the mechanical properties of ≤10 wt% fly ash additions in 2.5 wt% increments to recycled high-density polyethylene (RHDPE) synthesizes experimental data from three similar published reports. The present work shows, as a function of increasing fly ash addition level, maxima at the initial fly ash addition level of 2.5 wt% for the tensile elastic modulus (+25%) and tensile strength (+10%); a slight general increase in the yield stress (+6%); and significant general decreases in the yield strain (−61%), elongation at break (−92%), and Charpy impact strength (−55%). Combining these data with data for higher-level additions of fly ash (≤40 wt%/23 vol%) and cenospheres (≤39 vol%) to HDPE or RHDPE provides the basis for design parameters and a generalized model for the interpretation of failure of composites of hard brittle spherical dispersant additions in ductile polymeric matrices. The relevant load-extension plots are characterized by three behavioral regions: ductile deformation (dispersion strengthening and stress concentration), crazing (debonding and cavitation), and brittle failure (fibril failure). The locations of these regions and their transitions are a function of five dependent variables: dispersant volume, dispersant particle size, intrinsic flaw size (viz., dispersant size), generated flaw size (viz., void size), and interfacial bond strength and associated load transfer. POLYM. ENG. SCI., 56:1096–1108, 2016. © 2016 Society of Plastics Engineers

Palm Kernel Shell Filled Recycled High-Density Polyethylene: Effect of Filler Loading

Palm kernel shells (PKS) filled recycled high density polyethylene (rHDPE) biocomposites were produced using melt mixing. The biocomposites were prepared on Brabender Plasticorder at temperature of 185 °C and rotor speed of 50 rpm by varying filler loading (0 to 40 phr). In this study, the effect of PKS loading on rheological properties and thermal stability of rHDPE/PKS were investigated. Rheological study of the biocomposites was carried out by means of capillary rheometer under temperature of 190 °C, 200 °C and 210 °C. Thermal properties of biocomposites were studied by using thermo gravimetric analysis (TGA). The rheological results showed that the flowability of the composite increased with increasing temperature. Meanwhile, the result of TGA showed that at higher PKS loading, rHDPE/PKS biocomposites had lower total weight loss. The thermal stability of the biocomposites was reduced due to the addition of filler loading.

Mechanical properties of concrete reinforced with recycled HDPE plastic fibres

This work investigates potential engineering benefits of the pioneering application of simply extruded recycled high-density polyethylene (HDPE) plastic fibres in structural concrete. Mechanical and serviceability properties of concrete are studied through the testing of seven series of specimens: one made of the plain concrete and, for each of the two fibre diameters Ø1=0.25mm and Ø2=0.40mm, three series with 0.40%, 0.75% and 1.25% volume fraction of fibres. While the compressive strength and the elastic modulus of concrete were unaffected, the tensile strength and flexural (rupture) modulus were marginally increased, between 3% and 14% in the presence of HDPE fibres. Fibres mainly contributed by providing the post-cracking flexural ductility and through improving serviceability properties of concrete such as the reduced plastic shrinkage cracking, drying shrinkage and water permeability. The durability of HDPE fibres was assessed by means of the scanning electron microscope (SEM) imaging that showed no signs of their chemical deterioration in concrete. All findings suggest that recycled HDPE fibres can be instrumental in creating a new value chain in construction industry while also positively contributing to its environmental performance.

Thermal conductivity enhancement of recycled high density polyethylene as a storage media for latent heat thermal energy storage

In the context of reducing CO2 emissions and balancing energy supply and demand across the electricity grid, energy storage has become an important topic. Therefore, new energy policies are looking for more efficient and environmental friendly technologies. The aim of this research is to assist in the implementation of the renewable energies technologies and to improve the energy efficiency in well-known and established processes by recovering and storing heat. Moreover, the use of a recycled material as a storage media for thermal energy storage applications shows a more sustainable use of resources reducing at the same time the overall cost.In this research a novel composite, a recycled high density polyethylene (HDPE)/graphite(Cg) mixture, for medium temperature thermal energy storage application has been formulated and characterized. One common characteristic of polymers is their low thermal conductivities. This causes a slow thermal response when the PCM is used in high power applications. In this study the thermal conductivity properties of the HDPE/Cg were enhanced by the optimization of its manufacturing process and composition. Graphite content was added in different mass fractions into the PCM, and thermal properties were measured by means of Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Laser Flash Analysis (LFA). The experimental results showed that the thermal conductivities are improved by the higher mass fraction of graphite. When the graphite content was in the ratio of 20wt%, the thermal conductivity of the PCM increased from 0.51Wm−1K−1 up to 1.31Wm−1K−1. The secondary electron microscopy confirms a good homogeneity of the manufacturing process. Further chemical stability analysis was performed by means of charging and discharging processes. The cycled samples present good thermal property reliability at temperatures up to 250°C.

Rheological characterization of EVA and HDPE polymer modified bitumens under large deformation at 20 °C

Large amplitude oscillatory shear (LAOS) coupled with Fourier transform rheology (FTR) was used for the first time to characterize the large deformation behavior of selected bituminous binders at 20°C. Two polymer modified bitumens (PMB) containing recycled EVA and HDPE and two unmodified bitumens were tested with LAOS-FTR. The LAOS-FTR response of all binders was compared at same frequency, at same Deborah number (by tuning the frequency to the relaxation time of each binder) and at same phase shift angle δ (by tuning the frequency to the one corresponding to δ=50° in the SAOS response of each sample). In all the approaches, LAOS-FTR results allowed to differentiate between all the nonlinear mechanical characteristics of the tested binders. All binders show LAOS-FTR patterns reminiscent from colloidal dispersions and emulsions. EVA PMB was less prone to strain-induced microstructural changes when compared to HDPE PMB which showed larger values of nonlinear FTR parameters for the range of shear strains tested in LAOS.

The potential of deinking paper sludge for recycled HDPE reinforcement

This article studies the potential of deinking paper sludge (DPS) and recycled high density polyethylene (RHDPE) for biocomposites (DPS/RHDPE). Different DPS loadings (0 to 20 wt%) and compatibilizer content (0 to 4 wt%) were used in (DPS/RHDPE) formulations. A commercial paper wet‐strength agent polyamideamine‐epichlorohydrin resin (PAE) was used as DPS binder. The effects of DPS composition and PAE content on RHDPE/DPS biocomposites performance were studied. First, the chemical composition, morphology and thermal behavior of DPS were characterized using X‐ray diffraction, scanning electron microscopy, fiber quality analyser, and thermogravimetric analyses. The effect of the chemical treatment was evaluated using infrared spectroscopy (FTIR). Finally, crystallization behavior and tensile properties of DPS based biocomposites were discussed. Results revealed that DPS have a nucleating effect thanks to the presence of minerals such as calcium carbonate and talc. DPS increased the stiffness and the tensile strength of RHDPE. PAE could also serve as a compatibilizer between fibers and RHDPE. POLYM. COMPOS., 39:616–623, 2018. © 2016 Society of Plastics Engineers