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Polymer Matrix Nanocomposites: Recent Advancements and Applications
Published in Kaushik Pal, Hybrid Nanocomposites, 2019
Current opportunities for polymer nanocomposites in the biomedical arena arise from the multitude of applications and the vastly different functional requirements for each of these applications. For example, the screws and rods that are used for internal bone fixation bring the bone surfaces in close proximity to promote healing. This stabilization must persist for weeks to months without loosening or breaking. The modulus of the implant must be close to that of the bone for efficient load transfer [95, 96]. The screws and rods must be noncorrosive, nontoxic, and easy to remove, if necessary. Thus, a polymer nanocomposite implant must meet certain design and functional criteria, including biocompatibility, biodegradability, mechanical properties, and, in some cases, aesthetic demands. The underlying solution to the use of polymer nanocomposites in vastly differing applications is the correct choice of matrix polymer chemistry, filler type, and matrix–filler interaction [97].
Polymers
Published in Bryan Ellis, Ray Smith, Polymers, 2008
Applications: Polymethacrylate sheet has applications in glazing (windscreens, diffusers, mirrors, aircraft canopies); in meter cases, furniture, sanitary ware and in protective casing. Rods, tubes and fibres have uses in medical instruments, optics, and in electrical parts. Other uses of soln., and emulsion polymerised products include coatings; as a modifier (oils, impact modifier, to improve flow); in inks and in coating and processing applications. Many methacrylic homo- and copolymers have applications in the imaging industry, e.g., in litho coatings and other photoresists. A major use for methacrylic polymers is the medical industry (manufacture of contact lenses, artificial joints, dental products, bone cements; and in instrument and equipment parts). Long-chain methacrylates are used as performance-improving additives to lubricating oils and hydraulic fuels. Solns. of methacrylic polymers are used in ceramic transfer lacquers; in coatings (for concrete, fibrous cement, household appliances, non-ferrous metals, plastics, rubber, wood); in coil coatings, heat sealing, masonry paints, primers for building structs., corrosion protective coatings, PVC finishing, sterilisable coatings, stoving lacquers. Also used in the production of enstatite-free forsterite for the laser industry
Hard Tissue Replacements
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Sang-Hyun Park, Adolfo Llinás, and Vijay K. Goel
FIGURE 37.1 Radiographs of (a) an internal and external xation of the wrist shows the entire xation apparatus; (b) a total hip joint replacement in a patient who sustained a femoral fracture and was treated with double bone plates, screws, and surgical wire (arrows); (c) application of screws (pedicle screw) and rods in spine fusion.
Critical analysis of in vitro stability testing of spinal implants and proposal for standardization
Published in Expert Review of Medical Devices, 2022
Zoltán Csernátony, Sándor Manó, Zsolt Tiba, Géza Husi, Zoltán Jónás, Tímea Váradi, Loránd Csámer, Ágnes Éva Kovács
Lubrication is one of the key aspects of tribology. A lubricant is usually used to keep a distance between two solid materials, consequently preventing direct mechanical contact with each other. The lower the lubricity, the greater the wear of the examined material. The lubricity of a substance cannot be measured directly, moreover it is significantly influenced by other factors such as the shape, microgeometry and extent of the surfaces, viscosity and density of the lubricant, and temperature and pressure [5]. Lubricants can play a key role in the instability of assembled spinal implants in human bodies. Posterior spinal implants are composed of different pedicle screws and hooks, which are connected to two longitudinal rods. Spinal implants mounted on rods are subjected to significant strain after the correction of deformities, and this is compensated by the clamping force of the set screws securing the implant parts together. In the surgical field, both the loosening of the securing set screws and the sliding of the implants on the rods are facilitated by the undesired lubricity of the environment [6] and can be associated with implant failures due to set-screw loosening [7].