Density Polyethylene Nanocomposites Research Articles

Effective Utilization of Bast Fiber in High Density Polyethylene Nanocomposite Enriched by Alumina Nanoparticle: Mechanical Performance Evaluation

Effective Utilization of Bast Fiber in High Density Polyethylene Nanocomposite Enriched by Alumina Nanoparticle: Mechanical Performance Evaluation

Improved rheological, barrier, antibacterial, and electromagnetic interference shielding properties of graphene and graphene derivatives based linear low density polyethylene nanocomposites

AbstractMultifunctional polymer/graphene based lightweight and flexible nanocomposite films are increasingly being utilized in the packaging, electronics, and pharmaceutical industries together. Herein, two graphene derivatives: silver nanoparticle decorated reduced graphene oxide (G‐Ag) and chemically reduced graphene oxide (rGO) prepared by wet chemical method and graphene nanoplatelets (GNP) have been incorporated into linear low density polyethylene (LLDPE) thermoplastic matrix via melt compounding method. The incorporation of graphene derivatives affected the physico‐mechanical, electrical and thermal conductivity, and barrier properties (both oxygen and water vapor permeability) of the nanocomposite films. With 5 wt% of G‐Ag, rGO, and GNP loading, the thermal conductivity of these three nanocomposite films was enhanced by an average of 136.7%, 123%, and 143.3%, respectively. Graphene having high specific surface area and aspect ratio allow for a tortuous passage of oxygen and water molecules through the nanocomposite film, ultimately improving both oxygen and water vapor impermeability qualities for all LG‐Ag, LrGO, and LGNP nanocomposites. Moreover, the films have been tested against both gram‐positive and gram‐negative bacteria to ensure their bactericidal activity. The prepared composite films also showed Electromagnetic Interference (EMI) shielding effectiveness (−21, −17, and −19 dB) higher than the commercial cut‐offs. The thermoplastic nanocomposite films with promising thermal conductivity might be an excellent choice for bacteria‐resistant and barrier‐capable packaging and efficient thermal management EMI shields in electronics.

Mechanical and Morphological Properties of Fluted Pumpkin Stem Fiber (Telfaira occidentalis) Recycled High Density Polyethylene Nanocomposites

The outstanding characteristic properties of nanographene such as high aspect ratios and improved mechanical properties in comparison with other types of nanofillers like carbon nanotubes and clays has accelerated their use as nanosize filler in polymer matrix composites. The litter of agro-wastes is a critical issue which must be addressed for the preservation of the global environment. The effect of nanographene addition on the mechanical and morphological properties of nanocomposites prepared using fluted pumpkin stem fiber (FPF) and recycled high density polyethylene (R-HDPE) was investigated. Four weight levels of nanographene 0, 0.5, 1.5 and 2.5 wt % were mixed with 65 wt. % HDPE, 35wt. % FPF and 3wt% maleic acid anhydride produced using melt compounding and the extruded nanocomposites was shaped by injection molding machine for the mechanical tests. The results showed that addition of 0.5 wt % nanographene increased the flexural strength, flexural modulus and notched impact strength by 24.77MPa, 1800MPa and 32.61J/m2, compared to the control samples 20.5MPa, 1500MPa and 19.35J/m2 respectively. Although the addition of nanographene to the FPF/HDPE composite significantly improved the flexural strength, flexural modulus and notched impact strength, these improvements came at a unique nanographene loading of 0.5 wt %. The morphological images revealed that the samples with nanographene loading of 0.5 wt. % showed no fiber pullout/holes, whereas higher contents (1.5-2.5wt %) of nanographene exhibited fiber pullout/holes and were easily agglomerated. This study has shown that fluted pumpkin stem fiber could be used in composite formulation with good results comparable to wood-plastic-composites.

Effects of Hydrolytic and Oxidizing Agents on the Properties of Low Density Polyethylene/Halloysite Nanocomposites for Biomedical Applications

Low density polyethylene (LDPE) nanocomposites reinforced with natural halloysite nanotubes (HNTs) were synthesized and evaluated as a prospective material for biomedical applications via in vitro biostability studies in this work. A twin-screw extruder machine was used to fabricate the examined LDPE and LDPE/HNTs nanocomposites (NCs), followed by in vitro treatment of the prepared NCs via immersion in oxidizing and hydrolytic chemicals for four weeks at 37°C. The materials’ in vitro mechanical characteristics were evaluated under these harsh conditions. The analysis showed that the LDPE with 3 wt% HNTs exhibited the best nanofiller dispersion characteristics. This NC also presented smoother surface degradation characteristics compared to the plain LDPE and other LDPE NCs. Furthermore, as compared to plain LDPE, the LDPE NCs showed enhanced mechanical capabilities, and these qualities were less impacted by the in vitro conditions. The introduction of 3 wt% HNTs into the LDPE gave the best in vitro mechanical characteristics. Furthermore, the existence of a better-scattered nanotube structure was thought to offer a more sinuous pathway for the propagation of H2O and the oxidants, thereby reducing their penetration across the matrix chains. Hence, the kinetics of disintegration inside the LDPE molecular chains were slower, resulting in improved biostability.

ANN approaches to determine the dielectric strength improvement of MgO based low density polyethylene nanocomposite

This paper presents the modification occurred to the dielectric strength feature of low density polyethylene compounded with nano magnesia (LDPE/MgO). MgO nanoparticles were prepared using sol–gel technique, MgO filler surface was functionalized to improve the interfacial bonding. Specimen’s groups of composites with different filler concentrations were fabricated by mix blend method. Samples exposed to various salinity media by immersion, dielectric strength test was applied on each set according to relevant ASTM standard with identical testing technique. The results were statistically processed then compared to the pristine material. Tests results utilized to learn Artificial Neural Network in order to acquire the value of dielectric strength of compounds having similar composition but containing different doping amounts or influenced with various salinity level media. The dielectric strength is enhanced by the addition of MgO nanofiller. From the investigation of the obtained results, it is concluded that additives of 1.4% filler concentration by weight is the optimum MgO content for LDPE/MgO nanofiller material. We think that this paper may promote a good researching methodology that gather both empirical work and numerical tools in this field.

Enhanced mechanical and thermal properties of nanodiamond reinforced low density polyethylene nanocomposites

AbstractIn this study, the reinforcement effects of low‐content hydrophilic nanodiamond (ND) on linear low‐density polyethylene (PE) nanocomposites were investigated. ND was incorporated in PE via simple solution blending. The obtained PE/ND nanocomposites were characterized using scanning electron microscopy, ultraviolet–visible spectra, X‐ray diffraction, tensile test, thermogravimetry, and differential scanning calorimetry. Generally, PE/ND nanocomposites with poor interfacial interaction cause large agglomerates, resulting in brittle and poor mechanical properties. Owing to the different natures of non‐polar PE and polar ND, the higher the ND content, the larger the agglomerates formed in the nanocomposites. However, PE/ND nanocomposites show unique mechanical properties, that is, the Young's modulus, tensile strength, elongation at break, and toughness increased upon the incorporation of ND. The Young's modulus of the PE/ND nanocomposites exceeded the theoretical value calculated using the Halpin–Tsai model. In addition, the toughness increased by 18% at only 0.5 wt% ND loading. Furthermore, there was an increase in the thermal degradation temperature, melting temperature, and crystallization temperature.

Obtaining and evaluation of polyethylene nanocomposites with graphene nanoplatelets through in‐situ ethylene polymerization

AbstractIn‐situ polymerization of ethylene with graphene has been previously studied; however, the reported nanocomposites exhibit poor filler dispersion, even at low graphene loadings. In the present work, well dispersed and homogeneous graphene nanoplatelets (GNP)‐high density polyethylene (HDPE) nanocomposites were obtained in up to 12.5% weight content of graphene through an in‐situ polymerization of ethylene in graphene suspensions. The composites' potential as masterbatches was evaluated by melt mixing them with commercial HDPE. The obtained materials exhibited important physical‐mechanical properties increases when compared with those of commercial HDPE. To our knowledge, our materials' GNP concentration (≤0.82 wt.%) is the lowest reported, with the composites showing a 27% increase in their maximum tensile strength and a 41% increase in their flexural modulus when compared with blank HDPE. In addition, Raman spectroscopy and scanning electron microscope (SEM) analyses give evidence of the higher exfoliation degree of GNP obtained in the in‐situ ethylene polymerizations.

Tribological performance of high density polyethylene (HDPE) composites with low nanofiller loading

High density polyethylene (HDPE) nanocomposites were prepared by melt mixing of the polymer with 0.5–1.0 wt-% hydrophobic surface treated fumed silica and titanium nitride (TiN) nanopowders, fiber-shaped halloysite nanotubes (HNT), and graphene oxide (GO) nanoplatelets in the presence of trace amount of organic peroxide. Surface treatments of the nanofillers with hydrophobic vinyltrimethoxy silane (VTMS) were accomplished in boiling toluene solvents and in the case of fumed silica, most feasibly in ethanol solvent. Sliding friction and wear of the nanocomposites were characterized by pin-on-disk (POD) test against polished bearing steel disc. Microstructures of the nanocomposites, and the wear surfaces were characterized by scanning electron microscopy (SEM). Microindentation experiments were carried out to measure the surface hardness, elasticity and the plastic and elastic work of indentation. VTMS surface coverage was highest on fumed silica and GO powders, which also correlated with the most homogeneous and fine filler dispersion in HDPE polymer, and showed the best performance of the nanocomposites in the POD test. In all cases, the addition of silane treated nanopowders reduced the sliding wear of the HDPE against polished steel counter surface. Moreover, deviation of the wear rate data between parallel measurements was greatly reduced by the nanofiller addition indicating homogenous structure. The coefficient of friction (COF) of the neat polymer was reduced only in the case of TiN filler. Inverse linear trend was found between the specific wear rate of the nanocomposites and a parameter derived from micro-indentation data (HIT*total work of indentation)−1, which is formally similar to the well-known Ratner-Lancaster correlation.

Carbon Nanotube Reinforced High Density Polyethylene Materials for Offshore Sheathing Applications.

Multiwall carbon nanotube (CNT)-filled high density polyethylene (HDPE) nanocomposites were prepared by extrusion and considered for their suitability in the offshore sheathing applications. Transmission electron microscopy was conducted to analyse dispersion after bulk extrusion. Monolithic and nanocomposite samples were subjected to accelerated weathering and photodegradation (carbonyl and vinyl indices) characterisations, which consisted of heat, moisture (seawater) and UV light, intended to imitate the offshore conditions. The effects of accelerated weathering on mechanical properties (tensile strength and elastic modulus) of the nanocomposites were analysed. CNT addition in HDPE produced environmentally resilient nanocomposites with improved mechanical properties. The energy utilised to extrude nanocomposites was also less than the energy used to extrude monolithic HDPE samples. The results support the mass substitution of CNT-filled HDPE nanocomposites in high-end offshore applications.

Influence of graphene oxide on the morphological and mechanical behaviour of compatibilized low density polyethylene nanocomposites

Abstract The research work aims to analyze the effect of graphene oxide (GO) distribution on the morphological, physical, static and dynamic mechanical properties of polyolefin matrices. Polar polymer namely maleic anhydride grafted polyethylene (MA-g-PE) is used as a compatilizer to incorporate GO into low density polyethylene (LDPE). Preparation of polyolefin nanocomposite is carried out by melt-mixing technique. According to ASTM standard, the specimens are prepared through compression molding technique. Mechanical properties of pure and graphene oxide filled polymers are analyzed through universal testing machine. Storage modulus and tan delta characteristics are analyzed through dynamic mechanical analyzer. A series of characterization methods like the X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscopic (TEM) were performed on the prepared nanocomposites. The effects of compatibilizer and grapheme oxide on polyolefin nanocomposites were investigated by dynamic mechanical analysis (DMA), tensile test and percentage elongation. The XRD results showed increase in intergallery spacing of nanosheets proving the formation of GO from flake graphite. TEM images prove the improved distribution of GO sheets into the polymer matrix in presence of compatibilizer. Compatiblized nanocomposites show significant enhancement in Tensile strength, modulus of elasticity, storage modulus and subsequent decrease in tan delta peak implying minimum heat buildup compared to control. Polar-polar interaction between GO and compatibilizer leads to improved distribution of the nanofiller in the base polymer matrices. This indeed enhances the technical properties of the polymer.

Well-Dispersed Cellulose Nanofiber in Low Density Polyethylene Nanocomposite by Liquid-Assisted Extrusion.

Two different liquid assisted processing methods: internal melt-blending (IMB) and twin-screw extrusion (TWS) were performed to fabricate polyethylene (PE)/cellulose nanofiber (CNF) nanocomposites. The nanocomposites consisted maleic anhydride-grafted PE (PEgMA) as a compatibilizer, with PE/PEgMA/CNF ratio of 97/3/0.5–5 (wt./wt./wt.), respectively. Morphological analysis exhibited that CNF was well-dispersed in nanocomposites prepared by liquid-assisted TWS. Meanwhile, a randomly oriented and agglomerated CNF was observed in the nanocomposites prepared by liquid-assisted IMB. The nanocomposites obtained from liquid-assisted TWS exhibited the best mechanical properties at 3 wt.% CNF addition with an increment in flexural strength by almost 139%, higher than that of liquid-assisted IMB. Results from this study indicated that liquid feeding of CNF assisted the homogenous dispersion of CNF in PE matrix, and the mechanical properties of the nanocomposites were affected by compounding method due to the CNF dispersion and alignment.

Welding Behaviour of Graphene Oxide Reinforced High Density Polyethylene Nanocomposites

Welding is used to produce bonded joints with technical properties to the base material. The thermoplastic nanocomposites are more familiar in recent days due to their excessive automotive applications. The specimens were prepared by pure HDPE and various weight ratios HDPE with nanofiller composites by melt mixing method and required shape produced by using compression moulding. The nanofiller will be chosen in this study is Graphene oxide. The main scope of using Graphene oxide was to enhance the mechanical properties of the prepared specimens. In this work, Ultrasonic welding had been used to carry out the test on both pure HDPE and HDPE with grapheme oxide. Mechanical properties were analyzed for both pure HDPE and grapheme oxide filled HDPE of both body part and welded part joints are compared.The mechanical properties of tensile strength and youngs modulus and elongation of the body part for graphene oxide filled HDPE was substantially increased due to the presence of compatabilizer.Thus the result improves the weld strength of the nanofilled polymer matrix with compatabilizer

Permeation characterization and modelling of polyethylene/clay nanocomposites for packaging

The approach of upgrading barrier properties of polymer with nanofillers is effectual and well established now-a-days to manufacture films and quality packaging. This research deals with enhancement of barrier attributes of clay-based high density polyethylene nanocomposites against oxygen and water permeability. Na-Montmorillonite and two grades of kaolin clays were used for HDPE/clay nanocomposites preparation in twin-screw extruder with temperature profile of 160, 170, 180, 190 and 200 °C along the extruder at 110 rpm with clay loading up to 10 wt%. The extent of maximum reduction in water and oxygen vapors permeation was more prominent at 5 wt% sample of each clay. XRD analysis revealed no exfoliation in kaolin clay samples but indicated presence of exfoliation in Na-MMT samples. SEM and TEM micrographs revealed nano-level dispersion for both kaolin clays and Na-MMT and agglomerate formation at high wt% of clays. Experimental data for oxygen and water vapors permeation through nanocomposites were fitted on Nielsen, Cussler and Gusev–Lutsi models. Modelling of barrier performance was utilized for acquiring aspect ratio of filler for nanocomposites. Maximum and average aspect ratio of fillers and third-degree polynomial equation for nanocomposite, through curve fitting, were determined to predict improved barrier properties of nanocomposites.

Matrix morphology and the particle dispersion in HDPE nanocomposites with enhanced wear resistance

Abstract High density polyethylene nanocomposites were prepared by melt mixing of varying type of nanopowders in the presence of vinyltrimethoxysilane (VTMS) coupling agent. Three spherical/irregular-shaped nanopowders, fumed Al2O3, γ-Al2O3, cubic titanium nitride (TiN) (1.5 vol-%), and high aspect ratio graphene oxide platelets (GO) (0.5 vol-%) were investigated in a high molecular weight HDPE matrix. Significant differences in the dispersion quality between the nanopowders were found by TEM and AFM. Degree of crystallinity of the nanocomposites (DSC/XRD) was consistently lower than in the neat HDPE polymer. The particularly well dispersed fumed Al2O3, γ-Al2O3 and GO nanopowders induced significant modification on the micromechanical properties of the HDPE. For the first time, great enhancement in the sliding wear performance, and an improvement in the abrasive wear performance was found in the high molecular weight HDPE nanocomposites. DSC analyses showed elevations in the glass transition temperatures and the peak melting temperatures of the nanocomposites. XRD peak splitting in the HDPE + GO and the HDPE + γ-Al2O3 nanocomposites suggest the emergence of a concurrent orthorhombic HDPE phase. Formation of new phases was also supported by DSC analyses showing broad and multimodal melting peaks. Scherrer analyses of XRD data showed slightly increased HDPE crystalline thicknesses in the range of 15–20 nm in the nanocomposites, which was in line with the TEM and AFM observations. The great elevation in the melting temperatures of the HDPE nanocomposites with fumed Al2O3 and γ-Al2O3 could not be attributed to the polymer lamellar thickness, but rather to the altered properties of the solid amorphous phase stemming for the nanopowder additives.

Biological Activity and Nanostructuration of Fe3O4-Ag/High Density Polyethylene Nanocomposites

We report here the synthesis of uniform nanospheres-like silver nanoparticles (Ag NPs, 5–10 nm) and the dumbbell-like Fe3O4-Ag hybrid nanoparticles (FeAg NPs, 8–16 nm) by the use of a seeding growth method in the presence of oleic acid (OA)/oleylamine (OLA) as surfactants. The antibacterial activity of pure nanoparticles and nanocomposites by monitoring the bacterial lag–log growth has been investigated. The electron transfer from Ag NPs to Fe3O4 NPs which enhances the biological of silver nanoparticles has been proven by nanoscale Raman spectroscopy. The lamellae structure in the spherulite of FeAg NPs/High Density Polyethylene (HDPE) nanocomposites seems to play the key role in the antibacterial activity of nanocomposites, which has been proven by nanoscale AFM-IR. An atomic force microscopy coupled with nanoscale infrared microscopy (AFM-IR) is used to highlight the distribution of nanoparticles on the surface of nanocomposite at the nanoscale. The presence of FeAg NPs in PE nanocomposites has a better antibacterial activity than that reinforced by Ag NPs due to the faster Ag+ release rate from the Fe3O4-Ag hybrid nanoparticles and the ionization of Ag NPs in hybrid nanostructure.

High performance linear low density polyethylene nanocomposites reinforced by two-dimensional layered nanomaterials

Two-dimensional (2D) layered nanomaterials, including pristine α-zirconium phosphates (ZrP), amine-intercalated organophilic α-zirconium phosphates (OZrP) and organophilic montmorillonite (OMMT), are directly incorporated into linear low density polyethylene (LLDPE) by injection molding. ZrP and OZrP achieve good dispersion in the LLDPE matrices while OMMT forms agglomerations as observed by scanning electron microscope (SEM). The differential scanning calorimetry (DSC) analysis reveals that well-dispersed ZrP and OZrP could act as a nucleating agent to increase crystallinity of LLDPE while the agglomerated OMMT decreases the crystallinity of the polymer matrix. Tensile tests show that the strength and ductility of the LLDPE/ZrP nanocomposites can be enhanced simultaneously, due to the high modulus and parallel alignment along the injection direction for ZrP in matrix. The heat resistance of LLDPE, can also be enhanced by the addition of 2D nanoplatelets, among which ZrP perform the best, showing an increase of ∼16 °C in heat distortion temperature.

Electrically Conductive and Flame Retardant Graphene/Brominated Polystyrene/Maleic Anhydride Grafted High Density Polyethylene Nanocomposites with Satisfactory Mechanical Properties

Electrically conductive and flame-retardant maleic anhydride grafted high-density polyethylene (MA-HDPE) nanocomposites with satisfactory mechanical properties are fabricated by melt compounding MA-HDPE with polyethyleneimine (PEI)-modified reduced graphene oxide (PEI@RGO) as the conductive nanofiller and brominated polystyrene (BPS) as the flame retardant. The modification with PEI significantly improves the interfacial compatibility and dispersion of the RGO sheets in the MA-HDPE matrix, leading to electrically conductive nanocomposites with enhanced mechanical properties. Furthermore, the addition of 25 wt% of BPS makes the nanocomposite flame-retardant with a UL-94 V-0 rating. Thus, the multifunctional RGO/MA-HDPE nanocomposites with good electrical, flameretardant, and mechanical properties would have potential applications in construction and pipeline fields.

Thermal Stability of High Density Polyethylene-Clay Nanocomposites Produced by in situ Solvent Polymerization

High density polyethylene and high density polyethylene-clay nanocomposites were produced using direct solvent polymerization and a Ziegler catalyst system (TiCl4 and triethylaluminum in hexane). The produced polymer has a high average molecular weight and a multimodal molecular weight distribution composed of four distributions including a very high molecular weight component. The laboratory polymer has a thermal stability in inert atmosphere similar to the commercial high density polyethylene produced by Braskem. In oxidant atmosphere the produced polymer presents three thermal oxidation events above 400ºC due to the combustion of low, medium and high molecular weight molecules. The thermal oxidation of the nanocomposites is shifted and reduced for high temperatures indicating an improvement in the thermal stability of the polymeric matrix due to the clay barrier effect for gases and volatile compounds.

Effect of Particles Size on Dielectric Properties of Nano-ZnO/LDPE Composites.

The melt blending was used to prepare 3 wt% ZnO/low density polyethylene (ZnO/LDPE) nanocomposites in this article. The effect of different inorganic ZnO particles doping on the dielectrical property and crystal habit of LDPE matrix was explored. The nanoparticles size was 9 nm, 30 nm, 100 nm, and 200 nm respectively. Scanning electron microscope (SEM) was used to characterize ZnO nanoparticles whereas differential scanning calorimetry (DSC) was used to make thermal characterization of the samples. Besides, the AC (alternating current), DC (direct current breakdown characteristics and electrical conductivity of the nanocomposites was studied in this article. The experimental results showed that nano-ZnO/LDPE composites had the advantages such as small crystal size, high crystallization rate and crystallinity owing to nano-ZnO particles doping, when doping nano-ZnO particles size was 30 nm, the ZnO/LDPE nanocomposite crystallinity crest value 39.77% appeared. At the mean time, the DC and AC breakdown field strength values of composites were 138.0 kV/mm and 340.4 kV/mm respectively. They were the maximal values which improved 8.24% and 13.85% than LDPE. The AC breakdown field strength of samples decreased with specimen thickness increase. The DC breakdown field strength of LDPE and ZnO/LDPE composites were greater than AC breakdown field strength. From the conductivity experimental result it could be seen that when the experimental temperature and electric field intensity rose, the current density and conductivity of ZnO/LDPE composites increased with the enlargement of ZnO particles size. But the values were less than which of LDPE.

Preparation and antimicrobial assessment of zinc-montmorillonite intercalates based HDPE nanocomposites: A cost-effective and safe bioactive plastic

Zinc-montmorillonite intercalates based high density polyethylene (HDPE) nanocomposites were prepared by melt compounding route as an affordable and non-toxic substitute for silver based antimicrobial plastics, which are costly and sometimes toxic to human tissues. Zn is an essential trace element important for growth in humans and shows acceptable antimicrobial behavior, but its antimicrobial attribute has been largely unutilized. Zn ion exchanged montmorillonite (Zn-MMT) and ZnO nanoparticles (NPs) decorated MMT (ZnO-MMT) were synthesized in lab using a combination of simple ion exchange and reduction reactions. The synthesized intercalates were melt mixed in HDPE at different concentrations to obtain HDPE/Zn-MMT and HDPE/ZnO-MMT nanocomposites with uniform dispersion of incorporated nano-additive. For comparison, HDPE/ZnO nanocomposite without MMT was also synthesized. A mixture of intercalated and exfoliated microstructure at lower loadings and intercalated morphology at higher loadings was confirmed by both TEM and WAXD studies in the nanocomposites. The antibacterial properties and antifungal properties were evaluated against gram-negative E. coli, gram-positive S. aureus and black mold fungi A. niger. Remarkable reduction in bacterial colonies and significant zone of inhibition was obtained for the Zn-montmorillonite intercalates and HDPE nanocomposites at 5 wt% of loading. The nanocomposites demonstrated no lysis of human RBC cells in hemolytic assay and no effect in human dermal fibroblast cell proliferation in MTT assay asserting its non-toxic nature, in contrast with HDPE/ZnO nanocomposite which showed mild cytotoxic behavior.