Lecture-2SS - Material Properties Overview – Lecture...

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Unformatted text preview: Material Properties Overview – Lecture Slide Set 2 Lecture Dr. Anthony Brennan University of Florida Tel: 352.392.6281 Email: abrennan@mse.ufl.edu EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 1 Lecture 2 – Material Properties Overview Overview • Learning Objectives: – Standardized Test Methods – Materials • • • Synthetic: Polymers, Ceramics, Metals Natural Materials: Proteins, Peptides, Ceramics Composites: Synthetic, Synthetic/Natural – Mechanical Behavior Mechanical • • • Stress, Modulus, Strain Temperature Effects Time effects – Swelling Behavior EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 2 Standardized Test Methods Standardized • International Standards Organization International (ISO) (ISO) – Compilation of National Test Methods – Cooperative agreements between Cooperative regulatory and industrial groups regulatory • American Standards for Testing and American Materials (ASTM) Materials – Standardized test methods developed by Standardized committees – regulatory, industrial and academic members. academic EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 3 Importance of Chemistry Protein Tertiary Structure Conformational Structure Random Confirmation - Dilute Lamellar Configuration - Secondary Helical Configuration - Tertiary EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 4 Importance of Chemistry • Balance of Three Energies – Intermolecular – Intramolecular – Thermal (kT) • Structures – Linear – Branched EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 5 Characteristic Atomic Bonds Characteristic Bonding Energy Bonding Type Ionic Substance kJ/mol eV/Atom, Ion, Molecule Melting Temperature (ºC) NaCl 5.2 2800 450 4.7 1410 C (dia) 713 7.4 >3550 68 0.7 -39 Al 324 3.4 660 Fe 406 4.2 1538 W 849 8.8 3410 Ar 7.7 0.08 -189 Cl2 31 0.32 101 NH3 35 0.36 -78 H2O Hydrogen 1000 Hg van der Waals 801 Si Metallic 3.3 MgO Covalent 640 51 0.52 0 http://physics.uku.fi/studies/kurssit/MAT/laskarit/Exercise1-08.pdf Adapted from: Fundamentals of Materials Science and Engineering / An Introduction,” William D. Callister, Jr., John Wiley & Sons, NY, NY, 2001 or http://www.scribd.com/doc/8680373/Fundamentals-of-Materials-Science-and-Engineering-Callister EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 6 Mechanical Behavior Mechanical EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 7 Fundamental Mechanics Fundamental Stress F σ= A Strain l l − lo ε= lo Modulus σ E= ε EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 8 Stress - Strain Response • • • • A: Modulus-reversible A: strain strain B: Yielding-inelastic, B: irreversible strain, volume expansion expansion C: Strain HardeningC: plastic deformation plastic D: Failure-bond breakage EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 9 Stress - Strain Response • • • • A: High frequency (τ << t), Low temperature (T<<Tg,Tm), high crystallinity crystallinity B: Decreasing frequency, (τ ~t) (T~Tg, T<Tm) ~t) C: Decreasing frequency C: (τ >t), decreasing crystallinity, (T>Tg, T<Tm) crystallinity, D: Low frequency (τ >>t), high temperature (T>>Tg, T~Tm), low crystallinity T~Tm), EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 10 Four Parameter Model EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 11 Sinusoidal Test - DMTA τ ( t ) = τ o cos ω t γ ( t ) = γ o cos ω t Applied Stress Strain Response Ideally Viscous Liquid (Newtonian) π γ ( t ) = γ o cos (ω t − ) 2 EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 12 DMTA-Viscoelastic Behavior Input τ ( t ) = τ o cos ω t Response γ ( t ) = γ o cos (ω t − δ ) EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 13 DMTA-Viscoelastic Behavior τ (t) τ o e G= = γ (t) γ o τo = (cos δ + i sin δ ) γo = G ' + iG" * iδ EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 14 Tan δ Derived from DMTA Tan Derived G" tan δ = G' G * = G ' + iG" • The tan delta is a measure of the dispersion The of a network of • The diffusion times of each chain segment is The detected by the measurement. detected • We will see later the correlation to Mc – Molar We Mass between cross link junctions in networks networks EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 15 Williams-Landel-Ferry Equation Williams-Landel-Ferry •Doolittle Equation η = Ae •WLF Vo B V f ( B f )( T − T ) ∆ ln t = ( f α ) +(T −T ) o o f EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 o o 16 Stress Relaxation Stress t log t − log tref = log t ref = log aT EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 17 Williams-Landel-Ferry Shift Function Williams-Landel-Ferry • Semi Crystalline Semi Polymers Polymers η (T1 , t ) η (T2 , t ) ∝ log10 aT = − 8.86 (T − Tg ) 101 .6 + (T − Tg ) • Amorphous Amorphous Polymers Polymers η(T1 , t ) −17.4(T −Tg ) η(T2 , t )∝51.6+(T −Tg ) − 8.86 (T − Tref ) log aT = 101.6 + (T − T ) ref Polymer Processing Fundamentals, Tim A. Osswald (1998), H anser/Gardner Publications, Cincinnati, OH. EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 18 Stress Strain Behavior Comparison Comparison • Note Scales • Note Differences σ = ETensile ε E = 2 (1+ υ ) G E = 3 (1 − 2υ ) B σ yield = 0.028 ETensile Polymer Processing Fundamentals, Tim A. Osswald (1998), Hanser/Gardner Publications, Cincinnati, OH. EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 19 Typical Properties of Biomaterials Typical Material Elastic Modulus (GPa) Yield Stress (GPa) Tensile Stress Elongation to to Failure Failure (%) (GPa) Al2O3 350 - 1 to 10 <1 CoCr Alloy 225 0.53 0.74 10 316L SS 210 0.24 0.6 55 Ti6Al4V 120 0.83 0.9 18 Bone (Cortical) 15 to 30 0.3 to 0.7 0.7 to 0.15 0 to 8 PMMA 3 0.04∗ 0.05 15 HDPE 1 0.02 0.03 5 to 1000 Cartilage 0.001 - 0.007 20 PDMse 0.002 - 0.005 100 * Proportional limit EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 20 Strain Rate Dependence - PMMA Strain •Amorphous PMMA σ yield = 0.028 ETensile Polymer Processing Fundamentals,” Tim Osswald, (1998) Hanser/Gardner Publications, Cincinnati, OH 07/25/11 EMA 4666C - Polymer Processing Copyright Protected 21 Rubber Elasticity Ideal Elastomer Networks Ideal • Uniaxial Deformation σ 0x 1 = N v kT λ x − 2 λx • Biaxial Deformation: σ 0x 2 1 = G λ − 4 λ EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 22 Rubber Elasticity Deformation of Swollen Networks Deformation • Swollen Networks - Uniaxial: σ 0 x = N v kTϕ 1/ 3 1 λ x − 2 λx • But is more easily recognized as: σ 0 x = Gϕ 1/ 3 1 λ x − 2 λx EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 23 Swelling Behavior Hydrogel Semi-IPN Photoinitiated gel/Gamma Initiated IPN • 50 mmol – AAm • 500µ mol – N,N'methylenebisacrylamide (cross-linking methylenebisacrylamide monomer) monomer) • 10 mL distilled H2O • PNIPAAm was added in place of H2O to to form semi IPN form • Semi IPN was polymerized by Co60 radiation radiation EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 24 Swelling Behavior PNIPAAm/PAAm hydrogel EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 25 Equilibrium Force of Hydrogel PNIPAAm/PAAm EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 26 Elastic Modulus – Temperature Elastic Induced Phase Changes Induced EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 27 Summary • Mechanical Properties vary with time, Mechanical stress, strain rate, temperature and cycles. cycles. • Mechanical behavior of dissimilar Mechanical behavior can be equated by shift factors. factors. • Swelling directly impacts mechanical Swelling properties. properties. EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 28 Additional References • “Biomaterials Science – An Biomaterials Introduction to Materials in Medicine,” Ed. B. D. Ratner, A. S. Hoffman, F. J. Schoen, and J. E. Lemons, Academic Press, 1996, ISBN: 0-12-582460-2 Press, • Web resources listed in lecture EMA 6580 Science of Biomaterials - University of Florida Copyright 2009 EMA 29 ...
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