Công nghệ vật liệu trong y sinh học biom aterials chapter 2 phần 2 8

Chap.2 – 2.8 Composites ng c om Important Note: Reaction of the tissues to implant materials ! co Principle for material selection Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.8 Composites Composite: Composite materials are those that contain two or more distinct constituent materials or phases, on a microscopic or macroscopic size scale u •Matrix: phase which is continuous and surround the other phases cu •Dispersed phase: discontinuous phases reinforcement, filler •Examples: - reinforced plastics (artificially made) - wood, bone, cartilage, skin, tendon etc (natural composite): often exhibit hierarchical structure Note: alloys (brass) or metals (steel with carbide particles): are not composite •Properties depend very much upon structure In particular, properties depend on the shape of heterogeneities, volume fraction and interface Properties of composite depend on: - Properties of Matrix - Properties of dispersed materials - Interface adhesion - Biocompatibility (for biomaterials) •Classification: based on the form of reinforcement (particulate, fibrous composite, laminates) CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.8 Composites ng c om Chap.2 – co Simplest classification of composite materials Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 2.8 Composites cu u du o Chap.2 – Other more detailed classification of composites CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.8 Composites co ng c om Morphology of composites Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.8 Composites Reinforcements (Reinforcing systems) u Main reinforcements used in biomedical composite are carbon fibers, polymer fibers, ceramics and glasses cu Carbon fibers •Carbon fibers - Light, flexible, high-strength, high-tensile-modulus (d = 1.7-2.1 g/cm3, strength up to 4.5 GPa, elastic modulus up to 900 GPa) - Poor shear strength - Production: by pyrolysis of organic precursor fiber (rayon, PAN, and pitch) in innert environment Note: different between carbon and graphite fibers (93-95% carbon and more than 99%) •Composite: Lightness & high mechanical properties for load-bearing medical devices •Examples: - Short carbon fiber reinforced UHMWPE: for orthopedic application - In the 1980s: carbon fiber have been used for develop scaffolding device to indice tendon or ligament repair CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.8 Composites Polymer fibers Mainly aramid, UHMWPE fiber (strong and stiff), PET for some applications (biocompatibility, high strength and fatigue resistant), certain degradable fibers •Aramid (Kevlar, Nomex, Twaron) - Aramid fibers: light (d=1.44 g/cm3), stiff (modulus can go up to 190 GPa), strong (tensile strength about 3.6 GPa), resist impact and abrasion damage, but poor compressive and absorb moisture - Composite: high tensile strength and stiffness, damage resistance, resistance to fatigue and stress rupture; in medicine mainly for dentistry and ligament prostheses c om •UHMWPE (Spectra, Dyneema, Toyobo): Mw > 106 - Fibers: produced by gel-spinning technique from 2-8%w solution (in decalin) at 130140oC; highest specific strength of all commercial fibers available to date; high modulus; light weight (d=0.97 g/cm3), high energy dissipation ability; resist abrasion and not absorb water; but poor surface properties for other resins to adherence; low-temperature fabrication co ng - Bulk composite: extensive application in bearings for joint prostheses (excellent compatibility but with life time restrict by its wear resistance); PE reinforced acrylic resins: in dentistry, for intervertebral disc prostheses, fabrication of ligament augmentation devices Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.8 Composites •PET – Poly(ethylene terephthalate) cu u - PET Fibers (Dacron): have several biomedical uses, most in cardiovascular surgery for arterial grafts, proposed in orthopedics for fabrication of artificial tendon or ligaments and ligament augmentation devices (as fiber alone or in composite), proposed for soft tissue prostheses, intervertebral discs •PLA & PGA and their copolymers (biodegradable) - Biodegradable fibers: for biodegradable sutures, properties depend on several factors - Combination of fibers and tissue: proposed for ligament construction, scaffold for tissue engineering - Composite: in combination with parent matrix: for intramedullary biodegradable pins and plates, biodegradable scaffold for bone regeneration Ceramics - many different ceramics are used for reinforcing biomedical composite, in form of particulate - relative week & brittle compared to metals (in tension or shear loaded) - various calcium phosphates: most intensively studied system, particular those with Ca/Phosphorus ratio of 1.5-1.67; tricalcium phosphates Ca3(PO4)2 (whitlockite) and hydroxyapatite Ca10(PO4)6(OH)2 are used clinically for dental & orthopedic applications Advanced Program Biomedical Engineering – HUST, Vietnam CuuDuongThanCong.com https://fb.com/tailieudientucntt Chap.2 – 2.8 Composites - aluminum- and zinc-based phosphates, glass and glass-ceramics, and bone minerals Glasses - Glass fibers: widely used for forming structural and molding compounds, high strength-toweight ratio, good dimension stability, good resistance to heat, cold, moisture and corrosion, good electrical insulation properties, easy to fabrication, relative low cost - In biomedical application: dentistry (reinforcing acrylic resin for higher mechanical properties), degradable matrix reinforced by calcium phosphate glass fibers as implant materials For biomedical use: mostly thermoplastics polymeric matrix •Synthetic nondegradable polymers & composites c om Matrix system and their composites (Note: see 2.2.Polymers) - PEEK – poly(ether ether keton), UHMWPE, PTFE-polytetraflourethylene, PMMA, hydrogels: most common used ng - Usually reinforced with carbon fibers, PE fibers and ceramics, or reinforced with paticulate or choped fibers: used for prosthetic hip stems, fracture fixation devices, artificial joint bearing surfaces, artificial tooth roots, bone cements co - Generally used to provide specific mechanical properties unattainable with homogeneous materials Advanced Program Biomedical Engineering – HUST, Vietnam ng th an du o Chap.2 – 2.8 Composites - Total joint replacement: important application, can get a large range of mechanical properties by using different matrix reinforced with carbon fibers cu u (Note: cases of carbon fiber/polysulfone and epoxy/carbon fibers) 10 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.8 Composites Absorbable polymers and their composites: - From PLA, PGA, copolymer from them: implants for the repair of variety of osseous and soft tissues, satures; DMTMCs-dimethyltriethylene carbonates, polydioxanone, polycaprolactone, poly(amino acids) - Fracture fixation Note: disadvantages of rigid fixation devices (metals and alloys) and problems during healing (stress protection atrophy, very different elastic modulus between bone & metals/alloys, corrosion…) Degradable mechanically with time, reducing stress protection and the accompanying osteoporosis c om No need to secondary surgical procedure to remove absorbale devices From PLLA, PGA, polydioxanone (unreinforced: tension: 36%, bending: 54%, stiff: 3% compared with that of stainless steels; higher with reinforcement) co ng Self-reinforced PLLA(SR-PLLA) and self-reinforced PGA (SR-PGA): using sintering technique, commercial available; for treatment of fracture and osteotomies Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 11 2.8 Composites cu u du o Chap.2 – 12 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.8 Composites co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 13 du o Chap.2 – 2.8 Composites Fabrication Hand-lay-up u Spray up cu Compression molding Resin transfer molding Injection molding, extrusion Filament winding Pultrusion • For particle-reinforced composites: compression molding, injection molding, extrusion most common; in some applications in situ (dental restorative composites & particlereinforced bone cements • For fiber-reinforced composites: vacuum bag-autoclave process, filament winding, closedmold presses 14 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.8 Composites co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 15 du o Chap.2 – 2.8 Composites Mechanics of composites cu u * Mechanical properties in many composite materials depend on structure in a complex way, however for some structures the prediction of properties is relatively simple by using Voigt and Reuss models 16 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.8 Composites Calculate the stiffness of materials with Voigt and Reuss structures: c om Young modulus E of the Voigt composites is (neglecting restrain due to Poisson’s ratio: This is less than that of Voigt model co ng The Voigt and Reuss formulae constitute upper and lower bounds, respectively, upon the stiffness of the composite of arbitrary phase geometry Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 17 du o Chap.2 – 2.8 Composite cu u Calculate the properties of several composite material structures structures 18 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.8 Composites Rule of mixtures: Ec = EfV f + EmVm = EfVf + Em(1-Vf) Properties of some composites co ng c om - In orthopedic implant Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 19 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics Ceramics, glass and glass-ceramics: - include a broad range of inorganic/nonmetallic compositions cu u - essential for eyeglasses, diagnostic instruments, chemical ware, thermometer, tissue culture flasks, fiber optics for endoscopy; insoluble porous glasses: as carrier for enzymes, antibodies and antigens - Advantages: resistant to microbial attack, pH changes, solvent conditions, temperature Bioceramics •Ceramics are refractory, polycrystalline compounds, usually inorganic, including silicates, metal oxides, carbides and various refractory hydrides, sulfides and selenides •Ceramics can be classified according to their structural compounds, of which A mXn is an example (A;metal, X:nonmetal) 20 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics •Ceramics are generally hard, have high melting temperatures and low conductivity of electric and heat co ng c om •Ceramics are difficult to shear plastically (due to the ionic nature of bonding) brittle, creep at room temperature almost zero and very sensitive to notches or microcracks, low tensile strength compared to compressive strength Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 21 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics Types of bioceramics - tissue attachment cu u There are four types of tissue response and four different mean of attaching prostheses to skeletal system: 22 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.9 Ceramics, glasses, and glassglass-ceramics co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 23 2.9 Ceramics, glasses, and glassglass-ceramics cu u du o Chap.2 – 24 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.9 Ceramics, glasses, and glassglass-ceramics co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 25 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics Characteristics & processing of bioceramics cu u Characteristics & properties of the materials differ greatly, depending on processing methods used 26 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics Categories of microstructures: Glass Cast or plasma-sprayed polycrystalline ceramics Liquid-phase sintered (vitrified) ceramics Solid-state sintered ceramics co ng c om Polycrystalline glass-ceramics Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 27 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics cu u The interrelation between microstructure and thermal processing of various bioceramics 28 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.9 Ceramics, glasses, and glassglass-ceramics co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 29 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics Nearly inert crystalline ceramics Representative: Al2O3 bioceramics u •High-density, high-purity (>99.5%) alumina: cu - is used in load bearing hip prostheses and dental implant (excellent corrosion resistance, good biocompatibility, high wear resistance and high strength), knee prostheses, bone screw, corneal replacement, segmental bone replacement… - Most Al2O3 devices are very fine-grained polycrystalline < α-Al2O3 produced by pressing and sintering at T = 1600-1700oC - 0.5% MgO is used to aid sintering and limit grain growth during sintering - Role of grain size: strength, fatigue resistance and fracture toughness are a function of grain size and percentage of sintering aid (i.e., purity) The superb tribiologic properties (friction and wear) occur only when grain size are very small ( 100 àm) ãDegree of interconnectivity of pores is also very important co ng c om •Two sources of commercial available porous ceramics: hydroxyapatite converted from coral (e.g Pro Osteon) or animal bone (e.g Endibon) Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 33 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics Bioactive glass and glassglass-ceramics •Glass-ceramics are polycrystalline ceramics made by controlled crystallization of glasses cu u - In formation: to growth very small crystals and the size distribution of these crystals: use metallic agents such as Cu, Ag, Au, Pt groups, TiO2, ZrO2 and P 2O5 a - The glass-ceramics for implantation are SiO2- CaO-Na2O-P2O5 and Li2O-ZnO-SiO2 •Glasses, ceramics, glass-ceramics which can bond to bone have become known as bioactive ceramics - Common characteristics is time-dependent, kinetic modification of the surface that occur upon implantation (Note: see figure in the next page) - Specific proportion of composition is very important for bonding to bone (surface reactivity) (Note: explanation of the example in table and figure later pages) 34 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.9 Ceramics, glasses, and glassglass-ceramics co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 35 2.9 Ceramics, glasses, and glassglass-ceramics cu u du o Chap.2 – 36 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt 2.9 Ceramics, glasses, and glassglass-ceramics co ng c om Chap.2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 37 2.9 Ceramics, glasses, and glassglass-ceramics cu u du o Chap.2 – 38 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics co ng c om Surface chemistry and surface reactivity Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 39 du o Chap.2 – 2.9 Ceramics, glasses, and glassglass-ceramics cu u Clinical applications of bioactive glass and glass-ceramics 40 CuuDuongThanCong.com Advanced Program Biomedical Engineering – HUST, Vietnam https://fb.com/tailieudientucntt ... implant materials For biomedical use: mostly thermoplastics polymeric matrix •Synthetic nondegradable polymers & composites c om Matrix system and their composites (Note: see 2. 2.Polymers) -... https://fb.com/tailieudientucntt 2. 8 Composites co ng c om Chap .2 – Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 13 du o Chap .2 – 2. 8 Composites Fabrication Hand-lay-up u Spray up cu Compression.. .2. 8 Composites ng c om Chap .2 – co Simplest classification of composite materials Advanced Program Biomedical Engineering – HUST, Vietnam ng th an 2. 8 Composites cu u du o Chap .2 – Other