Influence of fly ash cenospheres on performance of coir fiber‐reinforced recycled high‐density polyethylene biocomposites

Recycled high‐density polyethylene (RHDPE)/coir fiber (CF)‐reinforced biocomposites were fabricated using melt blending technique in a twin‐screw extruder and the test specimens were prepared in an automatic injection molding machine. Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of fly ash cenospheres (FACS) in RHDPE/CF composites were investigated. It was observed that the tensile modulus, flexural strength, flexural modulus, and hardness properties of RHDPE increase with an increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % CF and 1 wt % MA‐g‐HDPE exhibited optimum mechanical performance with an increase in tensile modulus to 217%, flexural strength to 30%, flexural modulus to 97%, and hardness to 27% when compared with the RHDPE matrix. Addition of FACS results in a significant increase in the flexural modulus and hardness of the RHDPE/CF composites. Dynamic mechanical analysis tests of the RHDPE/CF/FACS biocomposites in presence of MA‐g‐HDPE revealed an increase in storage (E′) and loss (E″) modulus with reduction in damping factor (tan δ), confirming a strong influence between the fiber/FACS and MA‐g‐HDPE in the RHDPE matrix. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties in the composites when compared with RHDPE matrix. The main motivation of this study was to prepare a value added and low‐cost composite material with optimum properties from consumer and industrial wastes as matrix and filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42237.     

Utilizing discarded plastic bags as matrix material for composites reinforced with chicken feathers

High‐ density polyethylene (HDPE) in used plastic bags was reinforced with chicken feathers to develop composites in an effort to add value and reduce the amount of the plastics and feathers disposed in landfills. Feathers are biodegradable, derived from renewable resource, and are inexpensive and HDPE in plastic bags is mostly discarded in landfills. Utilizing feathers as reinforcement for HDPE composites will provide an opportunity to develop environmentally friendly composites. In this research, HDPE plastic bags were reinforced with chicken feathers and the flexural, tensile and acoustic properties were studied. It was found that incorporating feathers substantially improved the flexural properties and tensile modulus. At the optimum condition, the HDPE‐feather (50/50) composites had flexural strength of 13.9 MPa and stiffness of 0.45 N/mm compared to 9.8 MPa and 0.29 N/mm for 100% HDPE. The 50/50 HDPE‐feather composite had similar tensile strength but more than twice the tensile modulus of neat HDPE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation,structural development,and mechanical properties of microfibrillar composite materials based on polyethylene/polyamide 6 oriented blends

The preparation of microfibrillar composites (MFCs) based on oriented blends of polyamide 6 (PA6) and high‐density polyethylene (HDPE) is described. By means of conventional processing techniques, the PA6 phase was transformed in situ into fibrils with diameters in the upper nanometer range embedded in an isotropic HDPE matrix. Three different composite materials were prepared through the variation of the HDPE/PA6 ratio with and without a compatibilizer: MFCs reinforced by long PA6 fibrils arranged as a unidirectional ply; MFCs containing middle‐length, randomly distributed reinforcing PA6 bristles; and a nonoriented PA6‐reinforced material in which the PA6 phase was globular. The evolution of the morphology in the reinforcing phase (e.g., its visible diameter, length, and aspect ratio) was followed during the various processing stages as a function of the blend composition by means of scanning electron microscopy. Synchrotron X‐ray scattering was used to characterize selected unidirectional ply composites. The presence of transcrystalline HDPE was demonstrated in the shell of the reinforcing PA6 fibrils of the final MFCs. The impact of the compatibilizer content on the average diameter and length of the fibrils was assessed. The influence of the reinforcing phase on the tensile strength and Young's modulus of the various composites was also evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Catalytic grafting: A new technique for polymer/fiber composites. II. Plasma treated UHMPE fibers/polyethylene composites

In this paper, the catalytic grafting technique for preparation of polymer/fiber composites is extended to plasma treated ultra-high modulus polyethylene (UHMPE) fiber/high density polyethylene (HDPE) system. The OH groups introduced on the UHMPE fiber surface by oxygen plasma treatment were used to chemically anchor Ziegler-Natta catalyst which then was followed by ethylene polymerization on the fiber surface. The morphology and interfacial behavior, as well as the mechanical properties, of the HDPE composites reinforced by catalytic grafted or ungrafted UHMPE fibers were investigated by SEM, DSC, polarized light optical microscopy, and tensile testing. The experimental results show that the polyethylene grafted on the fibers acted as a transition layer between the reinforcing UHMPE fibers and a commercial HDPE matrix. The interfacial adhesion was also significantly improved. Compared with the composite reinforced by ungrafted UHMPE fibers, the composite reinforced by catalytic grafted UHMPE fibers exhibits much better mechanical properties.     

Mechanical and Tribological Properties of PET/HDPE MFCs

Microfibrillar reinforced composites (MFCs) were prepared from polyethylene terephthalate (PET) and high density polyethylene (HDPE). The mechanical and tribological properties of the MFCs were investigated. Static and dynamic mechanical tests revealed that the tensile strength, tensile modulus, and dynamic modulus of the HDPE matrix were improved greatly. Wear mechanism analysis demonstrated that the ability of HDPE to form transfer films on the counter rings was strengthened, which was responsible for the variation of friction and wear properties of the matrix.     

Processability,morphology and mechanical properties of wood flour reinforced high density polyethylene composites

Abstract

Wood flour reinforced high density polyethylene (HDPE) composites have been prepared and their rheological properties measured. The melt viscosity decreased as the processing temperature increased and the wood flour content decreased. A power law model was used to describe the pseudoplasticity of these melts. Adding wood flour to HDPE produced an increase in tensile strength and modulus. Composites compounded in a twin screw extruder and treated with a coupling agent (vinyltrimethoxysilane) or a compatibliser (HDPE grafted with maleic anhydride) exhibited better mechanical properties than the corresponding unmodified composites because of improved dispersion and good adhesion between the wood fibre and the polyalkene matrix. Scanning electron microscopy of the fracture surfaces of these composites showed that both the coupling agent and compatibiliser gave superior interfacial strength between the wood fibre and the polyalkene matrix.     

Studies on thermal,mechanical, morphological,and viscoelastic properties of polybenzimidazole fiber reinforced high density polyethylene composites

High density polyethylene (HDPE) and polybenzimidazole fiber (PBI) composites were prepared by melt blending in a twin screw extruder. The thermomechanical properties of PBI fiber reinforced HDPE composite samples (1%, 4%, and 8%) of fiber lengths 3 mm and 6 mm were investigated using differential scanning calorimeter (DSC), universal testing machine, rheometer, and scanning electron microscopy (SEM). The effects of fiber content and fiber lengths on the thermomechanical properties of the HDPE‐PBI composites were studied. The DSC analysis showed a decrease in crystallinity of HDPE‐PBI composites with an increase of fiber loading. SEM images revealed homogeneous distribution of the fibers in the polymer matrix. The thermal behavior of the composites was evaluated from thermogravimetric analysis and the thermal stability was found to increase with the addition of fibers. The evidence of homogeneous distribution was verified by the considerably high values of tensile strength and flexural strength. In the rheology study, the complex viscosities of HDPE‐PBI composites were higher than the HDPE matrix and increased with the increasing of PBI fiber loading. POLYM. COMPOS., 5–13, 2016. © 2014 Society of Plastics Engineers     

Effect of microfiber reinforcement on the morphology,electrical, and mechanical properties of the polyethylene/poly(ethylene terephthalate)/carbon nanotube composites

In situ microfiber reinforced conductive polymer composites consisting of high‐density polyethylene (HDPE), poly(ethylene terephthalate) (PET), and multiwalled carbon nanotube (CNT) were prepared in a twin screw extruder followed by hot stretching of PET/CNT phase in HDPE matrix. For comparison purposes, the HDPE/PET blends and HDPE/PET/CNT composites were also produced without hot stretching. Extrusion process parameters, hot‐stretching speed, and CNT amount in the composites were kept constant during the experiments. Effects of PET content and molding temperature on the morphology, electrical, and mechanical properties of the composites were investigated. Morphological observations showed that PET/CNT microfibers were successfully formed in HDPE phase. Electrical conductivities of the microfibrillar composites were in semi‐conductor range at 0.5 wt% CNT content. Microfiber reinforcement improved the tensile strength of the microfibrillar HDPE/PET/CNT composites in comparison to that of HDPE/PET blends and HDPE/PET/CNT composites prepared without hot stretching. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Mechanical,dynamic mechanical,and thermal characterization of fly ash and nanostructured fly ash‐waste polyethylene/high‐density polyethylene blend composites

Disposal of polyethylene used as carry bags is the greatest challenge increasing day by day. Composite materials were prepared by mixing Fly ash (FA) and nanostructured fly ash (NFA) from thermal power station as filler and blends of Waste polyethylene (WPE)(carry bags) collected from municipal solid waste (MSW) with virgin high‐density polyethylene (HDPE) as matrix. Different modifications were induced to improve the overall properties of these composites. At first, the WPE/HDPE blend matrix was modified by grafting with maleic anhydride (MA) and the composite prepared with FA/NFA. Then, the WPE/HDPE‐FA/NFA composite as a whole was treated with electron beam irradiation at 250 kGy radiation dose and finally the FA/NFA filler was treated with radiation dose of 250 kGy and the composite prepared. Significant enhancement in tensile strength, flexural strength, flexural modulus, and hardness are observed for MA modified and irradiated composites, the increase being more prominent in irradiated composites. Furthermore, an increase in storage/loss moduli with enhanced thermal stability was observed with the addition of FA/NFA and upon modifications. The analysis of the tensile fractured surfaces by scanning electron microscopy was in well correlation with the mechanical properties obtained. In summary, after analyzing the effects of the three different modifications on mechanical, dynamic mechanical and thermal properties, the irradiation on to the WPE/HDPE‐FA/NFA composites investigated was selected as the most appropriate for future applications. POLYM. COMPOS., 37:3256–3268, 2016. © 2015 Society of Plastics Engineers     

Morphological,mechanical, tribological,and thermal expansion properties of organoclay reinforced polyethylene composites

The morphological, mechanical, thermal, and tribological properties of high‐density polyethylene (HDPE) composites reinforced with organo‐modified nanoclay (3 and 6 wt%) were studied. A commercial maleic anhydride‐based polymeric compatibilizer (PEgMA) was used to improve the adhesion between the polyethylene and clay. Transmission electron microscopy (TEM) characterization of composites revealed that nanoclay exists mainly in a multilayered structure in the HDPE matrix. Mechanical testing of composites showed that Young's modulus and tensile strength increased with nanoclay content. Coefficients of the linear thermal expansion (CLTE) of HDPE–PEgMA–clay composites were slightly lower in the flow direction than those of HDPE–PEgMA. The tribological properties were measured in dry conditions against a steel counterface. The friction coefficient of the matrix was decreased by the addition of clay. Electron microscopic results suggested that the wear mechanism for HDPE and HDPE composites was mainly adhesive. Clay agglomerates were observed on the worn surfaces of the composites, which may partly explain decreased friction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effect of coupling agents on rice‐husk‐filled HDPE extruded profiles

Lignocellulosic composites are diversifying their applications into various fields as they can meet the requirements of the respective applications by changing the matrix, fiber resource and processing ingredients. In this research work we explored the potential of extruded rice‐husk‐filled high density polyethylene (HDPE) composite profiles for structural applications. The structure and the properties of the interface in fiber‐reinforced composites play a crucial role in determining the performance properties of the composites. An optimum degree of adhesion between the fiber and the matrix is required for efficient stress transfer from the matrix to the fiber. Generally, coupling agents are used to improve the adhesion between lignocellulosic filler and the polymer matrix in structural composite materials. In this study, four different coupling agents based on ethylene‐(acrylic ester)‐(maleic anhydride) terpolymers and ethylene‐(acrylic ester)‐(glycidyl methacrylate) terpolymers were used to enhance the performance properties of the composites. The results indicated that these coupling agents enhanced the tensile and flexural strength of the composites significantly, and the extent of the coupling effect depends on the nature of the interface formed. Incorporation of coupling agents enhanced the resistance to thermal deformation and the water absorption properties of the composite, whereas it reduced the extrusion rate significantly. Among the four coupling agents used, EGMA1—the one with a glycidyl methacrylate functional group and without any methyl acrylate pendant group on the polymer backbone—was found to be the best coupling agent for the rice‐husk‐filled HDPE composites. Copyright © 2004 Society of Chemical Industry     

Properties of rice husk‐HDPE composites after exposure to thermo‐treatment

Natural fiber reinforced thermo‐plastic composite, with its often‐excellent properties, is well known as a material for external flooring and landscaping. Thermo‐treatment is considered as a method to improve the mechanical properties of these composites; however, oxidation might occur. In this article, thermo‐treatment is applied to a rice husk reinforced high density polyethylene (RH‐HDPE) composite. Variations in the mechanical properties, color, mass, and chemical constituents of the RH‐HDPE composite after thermo‐treatment were investigated. The results indicated that, with the extension of thermo‐treatment time, the color of the composites darkened; the composites underwent a gradual mass loss; during the early stages of thermo‐treatment the composite's flexural properties increased, and then remained stable after 128 h of treatment. Fourier transform infrared (FTIR) spectroscopy analysis showed wood indices of the RH‐HDPE composite decreased, indicating thermo‐degradation occurred during thermo‐treatment. Wide angle X‐ray diffraction (WAXD) results indicated an increased crystallinity of the RH‐HDPE composite in the first 128 h of thermo‐treatment, and increased crystalline grain size in the first 64 h of thermo‐treatment. Appropriate thermo‐treatment is essential to improve the mechanical properties of RH‐HDPE composites. POLYM. COMPOS., 35:2180–2186, 2014. © 2014 Society of Plastics Engineers     

Industrially viable technique for the preparation of HDPE/fly ash composites at high loading: Thermal,mechanical, and rheological interpretations

This article describes an industrially viable melt blending approach for the preparation of high‐density polyethylene (HDPE)/fly ash composites having high loading of fly ash (FA) (up to 25 wt %). In this approach, solvent was used to enhance the mixing of FA in HDPE matrix. FA coated on the outer surface of HDPE granules using solvent is an economical technique for the incorporation of high loading of FA using conventional twin screw extruder. Herein, the effect of HDPE reinforced with FA on thermal, rheological, and mechanical properties has been investigated. Incorporation of FA in HDPE matrix resulted in higher storage modulus (E′), loss modulus (E″), and complex viscosity (η*) as compared to neat polymer. Tensile and flexural moduli were also found to increase (～47% and ～66%, respectively) with the addition of FA (25 wt %). However, the elongation at break of HDPE reduced as the rigid spherical FA particles do not undergo elongation. The dispersion of FA within the polymer matrix and interaction of FA with HDPE were investigated using scanning electron microscopy. Rheological and mechanical properties of the composites were also correlated with the morphology. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45995.     

Effects of PBO fiber and clay on the mechanical,morphological, and dynamic mechanical properties of NR/HDPE blends

Poly(p‐phenylene‐2,6‐benzobisoksazole) (PBO) and natural rubber (NR)/high density polyethylene (HDPE) composites were melt‐blended in a Haake internal mixer. The tensile strength, tensile modulus, and impact strength increased with fiber loading and optimized at 20%. Incorporation of clay into the NR/HDPE/PBO composites resulted in an improvement of tensile strength for NR/HDPE/PBO composites compared to the systems without clay. However, addition of clay was only effective at low contents (5–7.5%). Additional improvement of tensile strength, tensile modulus, and impact strength of the hybrid composite was observed on addition of liquid natural rubber (LNR). Scanning electron micrographs of the samples had indicated that the presence of clay decreased the domain size of the dispersed phase. Results on dynamic response showed that incorporation of clay and LNR into the composites had increased the storage modulus and reduced the tan δ. The shift of glass transition temperature (T_g) to higher values for composites also indicated good interaction between the fiber and the matrix. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.     

Preparation and properties of polyethylene terephthalate/polyethylene/near infrared reflective pigment composites

Polyethylene terephthalate/high density polyethylene (PET/HDPE) composites containing a near infrared reflective (NIR, nickel antimony titanium yellow rutile) pigment was prepared using ethylene‐glycidyl methacrylate‐vinyl acetate (EGMA‐VA) as a compatibilizer to increase the infrared reflection of PET/HDPE and limit the thermal heat accumulation in light of environmental and energy conservation concerns. HDPE was premixed with NIR to form N‐HDPE masterbatch. A good interfacial bonding between PET matrix and HDPE dispersed phase with the help of compatibilizer was confirmed through Fourier transform‐infrared spectra, scanning electron microscopy, and torque rheometer. For PET/N‐HDPE composites, the major X‐ray diffraction peaks and melting behaviors remained unchanged, indicating the limited alternation of crystalline structure for the composite systems with or without compatibilizer. The observed increment in the crystallization temperature of PET for the investigated PET/N‐HDPE composites was mainly due to the nucleation role of both inorganic NIR and HDPE. Tensile strength and elongation at break for compatibilized cases at various N‐HDPE contents conferred higher values than those of the corresponding counterparts without compatibilizer. Yet, Young's modulus for compatibilized systems was about 40% lower than that for systems without compatibilizer, attributed to the rubbery nature of EGMA‐VA. With the inclusion of NIR into HDPE to form PET/N‐HDPE composites with or without EGMA‐VA compatibilizer, the values of reflectance increased to a great degree. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40830.     

The effects of nanoclay on the extrusion foaming of wood fiber/polyethylene nanocomposites

This article presents the foaming behaviors of wood fiber/high density polyethylene (HDPE) composites with small amounts of nanoclay. Melt compounding is used to prepare two types of clay‐filled wood fiber composites: intercalated and exfoliated clay composites. Their respective morphologies are determined using wide‐angle X‐ray diffraction (XRD) and transmission electron microscopy (TEM). We subsequently conduct an extrusion foaming experiment of the composites using N₂ as the blowing agent. Varying the wood fiber content, as well as the processing parameters, such as temperature and pressure, the effects of different amounts of clay and the degree of exfoliation on the final cell morphology and the foam density of the wood fiber/HDPE/clay nanocomposite foams are studied. The results suggested that the addition of nanoclay improved the cell morphology of the wood fiber/HDPE composite foams as its content and degree of dispersion increased. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Characteristics of paper mill sludge‐wood fiber‐high‐density polyethylene composites

Paper mill sludge (PMS) is a waste material from pulping. In this article it was used to replace part of a wood fiber (WF) filler to reinforce high‐density polyethylene (HDPE). The properties of the PMS/WF/HDPE composites were investigated. When half of WF was replaced with PMS, the bending strength and modulus of WF/HDPE composites decreased by 16.08% and 29.91%, respectively, but their impact strength increased by 11.31%. Dynamic mechanical analysis demonstrated that with PMS addition, the storage modulus decreased and the loss tangent increased. Although the flexural properties of the PMS/WF/HDPE composites decreased compared to WF/HDPE composite, they still had satisfactorily high strengths. The 30:30:36 PMS/WF/HDPE composite presented bending and impact strengths of 61.00 MPa and 12.11 kJ m⁻², respectively. The 50:20:26 PMS/WF/HDPE composite presented bending and impact strengths of 55.02 MPa and 10.37 kJ m⁻², respectively. Rheological test proved that substituting part of WF with PMS would not affectmanufacture processing. This study indicated that paper mill sludge could be used in wood plastic composites, which would reduce pollution from paper manufacturing. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

The comparison of properties of (rubber tree seed shell flour)‐filled polypropylene and high‐density polyethylene composites

The effect of varied rubber tree seed shell flour (RSSF) filler loadings on processing torque, mechanical, thermal, water absorption, and morphological properties of polypropylene (PP) and high‐density polyethylene (HDPE) composites has been studied. The addition of RSSF in the composites increased the stabilization torque in both PP‐ and HDPE‐based composites. Tensile strength, elongation at break, flexural strength, and impact strength show significant reduction when higher loading of RSSF was incorporated, while tensile modulus and flexural modulus were improved. The phenomenon was noted for both matrices, PP and HDPE, but HDPE‐based composites showed clear effects on the reduction of the mechanical properties compared with RSSF‐filled PP. Scanning electron microscopy of tensile fracture specimens revealed the degree of dispersion of RSSF filler in the matrices. At higher filler loadings, agglomerations and poor dispersion of RSSF particles were spotted, which induce the debonding mechanism of the system. Thermogravimetric analysis thermograms showed that both PP‐ and HDPE‐based composite systems with higher RSSF content have higher thermal stability, initial degradation temperature, degradation temperature, and total weight loss. Water absorption ability of the composites increases as the filler loading increases for both matrices. J. VINYL ADDIT. TECHNOL., 22:91–99, 2016. © 2014 Society of Plastics Engineers     

From morphology of attrited copper/MWCNT hybrid fillers to thermal and mechanical characteristics of their respective polymer‐matrix composites: An analytical and experimental study

Synergistic effect of copper and multiwalled carbon nanotube on thermal and mechanical properties of high‐density polyethylene (HDPE)‐matrix composite was evaluated. Attrition mill was employed to prepare the hybrid powder. Reinforcing the polymer‐matrix was carried out using different contents of simultaneously (Sim) and separately (Sep) milled powders as hybrid fillers. X‐ray diffraction and microscopy results show different trends of particle size for Sep and Sim affected by both milling time and volume fraction ratio. Thermal characterization indicates that conductivity was enhanced by 90% and thermal expansion was reduced to 53% of neat HDPE. Young's modulus and tensile strength were improved by 7.8 and 1.22 times of neat HDPE, respectively. Also, characteristics of Sim‐reinforced composites exhibited better correlated relation with milling time compared with erratic behavior of Sep. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45397.     

Injection‐molded high‐density polyethylene–hydroxyapatite–aluminum oxide hybrid composites for hard‐tissue replacement: Mechanical,biological, and protein adsorption behavior

In this article, we report the mechanical and biocompatibility properties of injection‐molded high‐density polyethylene (HDPE) composites reinforced with 40 wt % ceramic filler [hydroxyapatite (HA) and/or Al₂O₃] and 2 wt % titanate as a coupling agent. The mechanical property measurements revealed that a combination of a maximum tensile strength of 18.7 MPa and a maximum tensile modulus of about 855 MPa could be achieved with the injection‐molded HDPE–20 wt % HA–20 wt % Al₂O₃ composites. For the same composite composition, the maximum compression strength was determined to be 71.6 MPa and the compression modulus was about 660 MPa. The fractrography study revealed the uniform distribution of ceramic fillers in the semicrystalline HDPE matrix. The cytocompatibility study with osteoblast‐like SaOS2 cells confirmed extensive cell adhesion and proliferation on the injection‐molded HDPE–20 wt % HA–20 wt % Al₂O₃ composites. The cell viability analysis with the 3(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay revealed a statistically significant difference between the injection‐molded HDPE–20 wt % HA–20 wt % Al₂O₃ composites and sintered HA for various culture durations of upto 7 days. The difference in cytocompatibility properties among the biocomposites is explained in terms of the difference in the protein absorption behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012