Reinforced Ultra High Molecular Weight Research Articles

MoO3 reinforced Ultra high molecular weight PE for neutrons shielding applications

Structural, Morphological and neutron attenuation properties of ultrahigh molecular weight polyethylene (UHMWPE) reinforced with molybdenum trioxide composite material obtained by solid state mixing of pellets and powder components via hot pressing have been studied. In this work, Ultra high molecular weight polyethylene and MoO3 has been utilized with different concentration using a hot compression iron mold. The changes in the microstructure of the prepared polymer and its particulate composites were evaluated by SEM. In order to investigate the quantitative of all elements used in these samples, we utilized Energy-dispersive X-ray spectroscopy (EDX) to present the profiles of synthesized samples which show a clear peaks C (carbon), and Mo (Molybdenum). The X-ray diffraction of all samples was examined to study the modification of the phase and lattice for UHMWPE before and after the addition of molybdenum trioxide (MoO3). Raman analysis was utilized to explore the crystallinity, molecular interactions, phase, polymorphy, and chemical structure. This technique is based on non-destructive interaction between light with the chemical bonds inside a material. The Raman spectrum for the current work presented within the range of 150–1600 cm−1. In order to understand the neutron shielding performance for the fabricated UHMWPE with different concentrations of MoO3, 241Am/Be fast neutron source was used to determine the fast neutron radiation equivalent dose rate. The background absorbed dose rate was measured as 0.98 (±0.017) (μSv/h). It was seen that the addition of MoO3 into the UHMWPE enhances the neutron shielding. The dose released from the source was absorbed by 7.71 (±1.3) %, 18.48 (±2.9) %, 22.26 (±2.4) %, 24.07 (±1.8) % and 26.17 (±1.3) % from UHMWPE with 1, 2, 3, 4 and 5% of MoO3 respectively. Additionally, GEANT4 10.02. p01 version was used to calculate total macroscopic cross-sections (TMCS) for the MoO3 doped UHMWPE. According to the results obtained from GEANT4, it was observed that the TMCS values of the UHMWPE increase with increment of the mole fraction of the MoO3 in the structure of UHMWPE examined and that the 5.0% MoO3 sample has the best neutron shielding ability.”

Mechanical properties of graphene and nano-diamond reinforced ultra high molecular weight polyethylene

Nano-material reinforced ultra high molecular weight polyethylene (UHMWPE) composites are generally used as a joint replacement material. An investigation has been done on Hardness and 3-point bending of ultra high molecular weight polyethylene (UHMWPE) which was loaded with Nano-diamond (ND) and Graphene (Gr). In order to perform some mechanical tests a UTM test equipment and hardness test equipment were utilized. Due to the formation of a good molecular bonding, there is a significant increase in hardness from 51 HV for neat UHMWPE to 57 HV at 0.5 wt% ND loading of ND/UHMWPE nanocomposites and 54 HV at 0.3 wt% Gr loading of Gr/UHMWPE nanocomposites. At 0.5 wt% of Gr loading, the highest value of the flexural modulus (3750 N/mm2) is observed. When 0.5 wt% of Gr and 0.3 wt% of ND is added, then there is a significant increase in ultimate flexural strength and flexural modulus by loading of nano fillers. In this study the fabrication of ND/UHMWPE and Gr/UHMWPE nanocomposites exhibited good mechanical properties and they can be explode for total joint replacement.

The addition of acid treated carbon nanotube on the interfacial adhesion of carbon fiber reinforced UHMWPE composite

Carbon fiber reinforced Ultra High Molecular Weight Polyethylene (CF/UHMWPE) composites have been filled with acid treated carbon nanotube to enhance the adhesion. According to the modification, the interlaminar shear strength (ILSS) of composites has been greatly improved. Dynamic wetting method, XPS and SEM are used to examine the microscopic properties of resultant composites. The enhanced ILSS is attributed to the CNT interlock, which improves the wetting between carbon fibers and resins. Copyright © 2017 John Wiley & Sons, Ltd.

Carbon Nanotube Functionalization Decreases Osteogenic Differentiation in Aluminum Oxide Reinforced Ultrahigh Molecular Weight Polyethylene

Ultrahigh molecular weight polyethylene (UHMWPE) is one of the most preferred materials as an acetabular cup-liner for bone implant applications. The current work develops a correlation between wettability, protein adsorption with osteogenic differentiation upon reinforcement of functionalized carbon nanotube (f-CNT) and 10 wt % aluminum oxide (Al2O3) in compression molded UHMWPE composites. Phase characterization has confirmed the retention of CNTs after compression molding. The loading of 2 wt % f-CNT in UHMWPE has shown to increase the contact angle (CA, from 88.9° to ∼97.3°), decrease the surface free energy (SFE, 23.20 to ∼20.85 mJ/m2) and elicit enhanced adsorbed protein density (PD, from ∼0.26 to ∼0.32 mg/cm2) in comparison to that of virgin polymer. Similar trend also has observed with 5 and 10 wt % f-CNT reinforcement. Initially, a high density of L929 mouse fibroblast cells is observed for 10 wt % unfunctionalized CNT (u-CNT) loading (48 h of incubation) with high values of dispersion fraction of surface free energy (σd), i.e., 0.967, whereas a decrease in cell density after 48 h is attributed to significant apatite mineralization and low dispersion fraction (σd) of CNT-Al2O3-UHMWPE biocomposites. Interestingly, gene expression studies have corroborated low osteogenic differentiation (i.e., weaker intensity osteopontin and β-actin) in 2-10 wt % f-CNT reinforced Al2O3-UHMWPE biocomposites in comparison to that of similar wt % reinforcement of u-CNT. Thus, implant material can be engineered, (bulk or surface-modified), possessing osteoanalogous and cytocompatible properties based on f-CNT-Al2O3-reinforced UHMWPE nanocomposites.

Processing, Characterization and Fretting Wear of Zinc Oxide and Silver Nanoparticles Reinforced Ultra High Molecular Weight Polyethylene Biopolymer Nanocomposite

Ultra-high molecular weight polyethylene (UHMWPE) is the most widely used biopolymer for articulating surfaces, such as an acetabular cup liner interfacing with a metal/ceramic femoral head. However, the formation of wear debris leads to the aseptic loosening of implants. Thus, in order to improve the life span via enhancing the fretting wear resistance, UHMWPE is reinforced with ZnO/Ag nanoparticles. It is envisaged that the ZnO/Ag addition will also exhibit antibacterial properties. In the current study, the synergetic effect of the reinforcement of ZnO/Ag nanoparticles (0–3 wt.% combinations) on the fretting wear behavior of a UHMWPE matrix is assessed. The phase characterization of compression- molded UHMWPE-Ag-ZnO biopolymer nanocomposites has elicited the retention of starting phases. All samples were processed at >98% density using compression molding. Silver and ZnO reinforcement showed enhanced hardness ~20.4% for U3A and 42.0% for U3Z. Fretting wear performance was evaluated at varying loads (5–15 N), keeping in mind the weight at different joints, with constant frequency (5 Hz) as well as amplitude of oscillation (100 µm). Laser surface profilometry showed change of wear volume from 8.6 × 10−5 mm3 for neat polymer to 5.8 × 10−5 mm3 with 1 wt.% Ag + 1 wt.% ZnO reinforcement (at 15 N load). Consequently, the mechanics of resistance offered by Ag and ZnO is delineated in the UHMWPE matrix. Further, S. aureus viability reduction is ~28.7% in cases with 1 wt.% Ag addition, ~42.5% with 1 wt.% ZnO addition, but synergistically increase to ~58.6% and 47.1% when each of Ag and ZnO is added with 1 wt.% and 3 wt.%, respectively (when compared to that of the UHMWPE control sample). Increased wear resistance and superior bioactivity and enhanced anti-bacterial properties of 1 wt.% Ag + 1 wt.% ZnO and 3 wt.% Ag + 3 wt.% ZnO shows the potential use of ZnO-Ag-UHMWPE biopolymer composites as an articulating surface.

Nanodiamond reinforced ultra high molecular weight polyethylene for orthopaedic applications: dry versus wet ball milling manufacturing methods

Nanodiamonds (NDs) were investigated as reinforcement for ultrahigh molecular weight polyethylene (UHMWPE). Dry and wet mixing with planetary ball milling was compared and analysed by scanning electron microscopy (SEM), differential scanning calorimerty (DSC), X-ray diffraction (XRD) and contact angle measurements. The composites were mixed from one to four hours to study the dispersion of the nanoparticles. It was concluded that wet mixing is more effective at distributing nanodiamonds in comparison to dry mixing. It could also be concluded that dry mixing increases the temperature by 20°C more than wet mixing which resulted in a more distinct welding process of the UHMWPE powder.

Graphene reinforced ultra high molecular weight polyethylene with improved tensile strength and creep resistance properties

Reduced graphene oxide or graphene was dispersed in ultra high molecular weight polyethylene (UHMWPE) using two methods to prepare nanocomposite films. In pre-reduction method, graphite oxide (GO) was exfoliated and dis- persed in organic solvents and reduced to graphene before polymer was added, while reduction of graphene oxide was car- ried out after polymer addition for in situ reduction method. Raman spectroscopic study reveals that the second method results in better exfoliation of graphene but it has more amorphous content as evident from selected area electron diffraction (SAED) pattern, wide angle X-ray and differential scanning calorimetry (DSC). The nanocomposite film produced by pre- reduction method possesses higher crystallinity (almost the same as that of the pure film) as compared to the in situ method. It shows better modulus (increased from 864 to 1236 MPa), better strength (increased from 12.6 to 22.2 MPa), network hardening and creep resistance (creep strain reduced to 9% from 50% when 40% of maximum load was applied for 72 h) than the pure film. These findings show that graphene can be used for reinforcement of UHMWPE to improve its tensile and creep resistance properties.

Nanotribological behavior of graphene nanoplatelet reinforced ultra high molecular weight polyethylene composites

Nano-scratch behavior of ultrahigh molecular weight polyethylene (UHMWPE) reinforced with graphene nanoplatelet (GNP) in varying composition of 0, 0.1, 0.5 and 1wt% is reported. Hot pressed composite structures are characterized for their tribological behavior in scratch mode using a normal load of 100–300μN. Increasing GNP content from 0.1 to 1wt% results in lowering of the coefficient of friction due to easy shear of graphene nanoplatelets. Graphene reinforcement also increases the wear resistance by more than four times, which is a combined effect of lubrication as well as toughening offered by GNPs.

Mechanical and Antibacterial Properties of Treated and Untreated Zinc Oxide filled UHMWPE Composites

Treated and untreated zinc oxide (ZnO) particulate reinforced ultra high molecular weight polyethylene (UHMWPE) composites were prepared using hydraulic hot press. The effects of the ZnO filler loading on tensile and antibacterial properties of the composites were investigated. The ZnO surfaces were treated with silane coupling agent (3-APTES) and were characterized using FTIR. The influences of ZnO content on tensile behavior of the composites were investigated. The tensile fracture surfaces of the ZnO-filled UHMWPE composites were characterized using SEM. Antibacterial property was tested against two common human body bacteria, that is, Escherichia coli and Staphylococcus aureus. The results showed that the tensile modulus of the composites was enhanced with addition of ZnO with increased filler loading. The performance of tensile strength and elongation at break for treated and untreated ZnO-filled UHMWPE were found to decrease with increasing filler loading compared to pure UHMWPE. Both treated and untreated ZnO-filled UHMWPE showed active inhibition towards E. coli (Gram-negative bacteria) whereas slight inhibition for S. aureus (Gram-positive bacteria) from the test. Treated ZnO-filled UHMWPE showed better inhibition against bacteria.

The Addition of Acid Treated Carbon Nanotube on the Tribological Properties of Carbon Fiber Reinforced UHMWPE Composite

Carbon fiber reinforced Ultra High Molecular Weight Polyethylene (CF/UHMWPE) composites have been filled with acid treated carbon nanotube to enhance the tribological properties. According to the modification, the friction and wear properties of composites have been greatly improved. XPS and SEM are used to examine the microscopic properties of resultant composites. The enhanced tribological properties are attributed to the acid treated CNT interlock, which improves the wetting between carbon fibers and resins.

Mechanical Properties of Carbon Nanotubes Reinforced Ultra High Molecular Weight Polyethylene

Carbon nanotubes (CNT) have been shown to enhance the engineering properties of plastic fibers in ballistic-resistant garments enabling the garments to withstand very high impact forces while remaining to be lightweight. Previous study shows that by reinforcing ultra high molecular weight polyethylene (UHMWPE) fibers with a small amount of carbon nanotubes, the fibers are simultaneously toughened and strengthened. In this paper, we study the mechanical properties of carbon nanotube reinforced ultra high molecular weight polyethylene (UHMWPE) by using micromechanics-based Mori-Tanaka model. Results show that the addition of small amount of carbon nanotubes as reinforcement can substantially improve the mechanical properties of the UHMWPE fibers.

Synthesis and characterization of multiwalled carbon nanotube reinforced ultra high molecular weight polyethylene composite by electrostatic spraying technique

In the present work, multiwalled carbon nanotube (MWNT) reinforced UHMWPE composite films were prepared by electrostatic spraying followed by consolidation. X-ray diffraction and differential scanning calorimetry studies showed a decrease in the crystallinity of UHMWPE due to the nature of the fabrication process as well as addition of MWNT. Tensile test showed an 82% increase in the Young’s modulus, decrease in stress to failure from 14.3 to 12.4 MPa and strain to failure from 3.9% to 1.4% due to 5% addition of MWNT. Raman spectra showed the presence of compressive stresses in the nanotubes. Fracture surface showed presence of pullout like phenomena in the MWNT reinforced film. � 2007 Elsevier Ltd. All rights reserved.

Analysis and Characterization of Alumina Particles Reinforced Ultra High Molecular Weight Polyethylene Composite for Acetabular Cup

Composites of ultra high molecular weight polyethylene (UHMWPE) reinforced with 5, 10 and 15 percent of alumina were prepared by a technique of uniform mixing and moulding. Acetabular cups were produced by compression moulding methods. A new walk simulator was also developed in-house for testing the tribological performances of these cups. The results from walk simulator tests are encouraging. Using a human walk simulator machine we did in vitro wear testing. Characterizations were performed to analyse the microstructure, composition, phase purity and crystalline by using XRD, DSC/TGA. Biocompatibility test was done by cytotoxicity, hemocompatibility and MTT assay methods. Biocompatibility tests gave hemolysis counts with these polymer composites well within the acceptable range and the results indicate a significant improvement in biocompatibility of the polymer composites over the in parent polymers.

Carbon Fibre Reinforced Plastics for Load-Bearing Implants

Work is currently in progress concerning two distinct groups of carbon fibre composites for orthopaedic implants. This paper will emphasize the work on carbon fibre reinforced ultra high molecular weight polyethylene for which preliminary results have been reported (Bradley and Evans, 1977). Carbon fibre reinforced epoxy will be referred to only briefly owing to publication elsewhere (Bradley et al, 1980).

Carbon Fibre Reinforced Ultra-High Molecular Weight Polyethylene for Medical Application

Ultra-high molecular weight polyethylene (UHMWPE) has been reinforced with type I and type II carbon fibres by a compression moulding technique. The composite is found to have markedly improved tensile and flexural properties, suggesting that it would be useful both as an improvement to current polyethylene components and as an inducement to more elaborate designs using the composite material.

Anchorage of the femoral head prosthesis to the shaft of the femur.

Anchorage of the femoral head prosthesis to the shaft of the femur.