Ultrahigh Molecular Weight Polyethylene/Graphene Oxide Nanocomposites: Wear characterization and Biological Response to wear particles

In the field of total joint replacements, polymer nanocomposites are being investigated as alternatives to ultra high molecular weight polyethylene (UHMWPE) for acetabular cup bearings. The objective of the present study was to investigate the wear performance and biocompatibility of UHMWPE/graphene oxide (GO) nanocomposites. This study revealed that low concentrations of GO nanoparticles (0.5 wt%) do not significantly alter the wear performance of UHMWPE. In contrast, the addition of higher concentrations (2 wt%) led to a significant reduction in wear. In terms of biocompatibility, UHMWPE/GO wear particles did not show any adverse effects on L929 fibroblast and PBMNC viability at any of the concentrations tested over time. Moreover, the addition of GO to a UHMWPE matrix did not significantly affect the inflammatory response to wear particles. Further work is required to optimise the manufacturing processes to improve the mechanical properties of the nanocomposites and additional biocompatibility testing should be performed to understand the potential clinical application of these materials

Ultra high molecular weight polyethylene and its reinforcement with Carbon Nanotubes in Medical Devices

This chapter discusses the advantages and complexities of ultra high molecular weight polyethylene(UHMWPE) when used as a bearing material for total joint arthroplasty (TJA) and total knee arthroplasty(TKA). The UHMWPE internal structure and its mechanical response depend strongly on a diversity offactors that include radiation crosslinking, fiber reinforcement, and the addition of antioxidants such asVitamin E or Vitamin C. All these manufacturing procedures induce morphological changes andsimultaneously alter the mechanical properties of UHMWPE. The importance of UHMWPE on arthroplasty,including the advantages, the limitations and the strategies devised to overcome the knowndrawbacks are discussed in the first section. The following sections revise and discuss thebiocompatibility, the manufacturing processes, the tribological behaviour, the aging by oxidation andirradiation of UHMWPE and UHMWPE-CNT nanocomposites. The last section analyses the viscoelasticbehavior of UHMWPE and its implications on the long-term survival of total joint arthroplasty

UHMWPE for biomedical applications: performance and functionalization.

According to a survey conducted by Grand View Research, the market demand for medical grade UHMWPE has raise remarkably from 60.9 kilotons up to 204.8 kilotons during 2015–2024 valued at $1.36 billion (USD) with a compound annual growth rate of 15%. There are various materials available for medical implants comprising of metals, ceramics and polymers among them UHMWPE has been used widely. The wide impact of UHMWPE in medical field is due it's superior biocompatibility, chemical resistance, low wear volume (0.68 mm3), ultimate tensile strength (41.3 MPa), low coefficient of friction [In dry condition (0.12–0.15)] and high crystallinity (more than 90%). However, wear debris, oxidative degradation due to generation of free radicals when subjected to irradiation with gamma rays and low ageing of implant are some critical problems observed in UHMWPE based implants in human body. These severe problems have been resolved using various innovative methodologies to enhance the properties of UHMWPE, comprising of surface modification techniques for pure UHMWPE as well as composite reinforced UHMWPE. The enhancement in properties of pure UHMWPE is achieved using electron beam or atmospheric cold plasma treatment. The reinforced composites are majorly developed by reinforcement of materials such as hydroxyapatite, Multi walled carbon nanotubes, Vitamin E (α-tocopherol), graphene oxide, DLC films, Gallic acid and Dodecyl gallate along with base UHMWPE matrix material. Based on the recent studies, Comparative study of these functionalization techniques along with the ameliorated surface or bulk properties along with it's diverse application in medical implant fields (Total hip arthroplasty, joint implants, bone tissue engineering) has been discussed extensively. Descriptive study of pure UHMWPE along with it's composite to functionalize the properties of the medical implants has been included in this review along with it's future scope succeeding the review

Rheological behavior of polymer/carbon nanotube composites: an overview

This paper reviews the current achievements regarding the rheological behavior of polymer-based nanocomposites containing carbon nanotubes (CNTs). These systems have been the subject of a very large number of scientific investigations in the last decades, due to the outstanding characteristics of CNTs that have allowed the formulation of nanostructured polymer-based materials with superior properties. However, the exploitation of the theoretical nanocomposite properties is strictly dependent on the complete dispersion of CNTs within the host matrix and on the consequent development of a huge interfacial region. In this context, a deep knowledge of the rheological behavior of CNT-containing systems is of fundamental importance, since the evaluation of the material’s viscoelastic properties allows the gaining of fundamental information as far as the microstructure of nanofilled polymers is concerned. More specifically, the understanding of the rheological response of polymer/CNT nanocomposites reveals important details about the characteristics of the interface and the extent of interaction between the two components, hence allowing the optimization of the final properties in the resulting nanocomposites. As the literature contains plenty of reviews concerning the rheological behavior of polymer/CNT nanocomposites, this review paper will summarize the most significant thermoplastic matrices in terms of availability and relevant industrial applications

Shape-memory polymers based on carbon nanotube composites

For the past two decades, researchers have been exploring the potential benefits of combining shape-memory polymers (SMP) with carbon nanotubes (CNT). By incorporating CNT as reinforcement in SMP, they have aimed to enhance the mechanical properties and improve shape fixity. However, the remarkable intrinsic properties of CNT have also opened up new paths for actuation mechanisms, including electro- and photo-thermal responses. This opens up possibilities for developing soft actuators that could lead to technological advancements in areas such as tissue engineering and soft robotics. SMP/CNT composites offer numerous advantages, including fast actuation, remote control, performance in challenging environments, complex shape deformations, and multifunctionality. This review provides an in-depth overview of the research conducted over the past few years on the production of SMP/CNT composites with both thermoset and thermoplastic matrices, with a focus on the unique contributions of CNT to the nanocomposite’s response to external stimuli

Mechanical and piezoresistive properties of GNP/UHMWPE composites and their cellular structures manufactured via selective laser sintering

In this study, we describe the development of composites comprising ultra-high molecular weight polyethylene (UHMWPE) reinforced with graphene nanoplatelets (GNP), specifically designed for additive manufacturing (AM) of self-sensing structures through selective laser sintering (SLS). We employed ball-milled GNP/UHMWPE powder feedstocks to fabricate standard test specimens and 2D cellular structures with varying GNP content. A comprehensive assessment of their mechanical and piezoresistive properties was carried out under uniaxial tensile loading. The incorporation of 1.5 wt% GNPs into UHMWPE demonstrated a notable increase in crystallinity by ∼28 % and a significant reduction in porosity by about 98 %. These enhancements contributed to a substantial improvement in both strength (∼21 %) and elastic modulus (∼40 %). Moreover, the introduction of 1.5 wt% GNPs resulted in the formation of electrically percolated composites characterized by prominent piezoresistive behavior. These composites exhibited gauge factors ranging from 9.6 to 18 under uniaxial tensile loading. During cyclic tensile loading, the GNP/UHMWPE composite displayed hysteresis in its piezoresistive response due to viscoelasticity, impeding an immediate return to its original state. Additionally, the gauge factors of the 2D cellular structures generally demonstrated lower values compared to those of the parent composite, scaling proportionally with the effective elastic modulus

Tailoring the electrical and thermal conductivity of multi-component and multi-phase polymer composites

The majority of polymers are electrical and thermal insulators. In order to create electrically active and thermally conductive polymers and composites, the hybrid-filler systems is an effective approach, i.e. combining different types of fillers with different dimensions, in order to facilitate the formation of interconnected conducting networks and to enhance the electrical, thermal, mechanical and processing properties synergistically. By tailoring polymer-filler interactions both thermodynamically and kinetically, the selective localisation of fillers in polymer blends and at the interface of co-continuous polymer blends can enhance the electrical conductivity at a low percolation threshold. Moreover, selective localisation of different filler types in different co-continuous phases can result in multiple functionalities, such as high electrical conductivity, thermal conductivity or electromagnetic interference shielding. In this review, we discuss the latest progress towards the development of electrically active and thermally conductive polymer composites, and highlight the technical challenges and future research directions