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A bone...

A bone. P. T. E. M. L. A. T. E. 3.082 FINAL PRESENTATION May 17, 2001. Bao-Yi Chang Elissa Robbins Elizabeth Immen Lisa Scoppettuolo. Thank you to Speed of Light for the Casting photograph. Injection Molding. www.biomet.com. Iron or Stainless Steel. Polymers: PLLA or PCL.

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A bone...

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  1. A bone...

  2. P T E M L A T E 3.082 FINAL PRESENTATION May 17, 2001 Bao-Yi Chang Elissa Robbins Elizabeth Immen Lisa Scoppettuolo

  3. Thank you to Speed of Light for the Casting photograph Injection Molding

  4. www.biomet.com

  5. Iron or Stainless Steel Polymers: PLLA or PCL

  6. Mission/Goals • To fabricate a bioresorbable bone plate • To fabricate a bone plate with a modulus close to that of bone through selection of materials and processing conditions

  7. Injection Molding • Used to fabricate plastic objects • -CD cases, water bottles, toys • Easy one step process • Ideal for mass production

  8. Hopper Mold Chamber Injection Molding Machine Plasticating Unit Control System Equipment Specifications Battenfeld 250

  9. 1. Begin Plastication 2. End Plastication screw nozzle 4. Begin Injection Mold 3. Close Mold 5. Eject Part Injection Mold Process

  10. Mold -Obtaining Mold Blank -Design Process -Machining -Adjustments Plate Dimensions(in)

  11. Experimental Runs Varying Parameters Establishing Ideal IM Conditions Product Testing….

  12. Instron Tensile Testing

  13. Results: Instron Testing

  14. IM Parameters  Mechanics IM3: high screw speed, low pressure IM1: low screw speed, low pressure Bone plate, not shaped for tensile testing IM4: high screw speed, high pressure IM2: low screw speed, high pressure

  15. Gel Permeation Chromatography • PCL degrades by hydrolysis • PCL was placed in water to simulate the body’s aqueous environment • Hydrolytic cleavage of PCL chains  Decrease in molecular weight

  16. Differential Scanning Calorimetry Melting point of PCL = 63.245 oC Polymers with low melting points are typically: • low molecular weight Tma Mw

  17. Decision Tree

  18. Fabricate bone plate from a completely bioresorbable COMPOSITE Bioglass Fibers Ceramic Particles: - Hydroxyapatite - b-tricalcium phosphate Possible Reinforcers b-tricalcium phosphate (Ca3(PO4)2, b -TCP) is a bioresorbable ceramic Future Plans ... Further Work and Study - Satisfy the mechanical requirements of bone plates - Mechanically superior to many bioresorbable homopolymers

  19. FTIR patterns of PDLLA, TCP, and a PDDLA/TCP composite (50 wt. % TCP) Possible Problems : Poor adhesion between polymer matrix and ceramic reinforcer Poor mechanical properties

  20. Methods of fabricating a PCL/b-TCP bone plate: -Melting and Hot Pressing - Twin Screw Extrusion - Pelletize Composite Mixture - Injection Molding: Viscosity (h) is an important parameter

  21. “To fabricate a bone plate with a modulus of 3 GPa, the composite would have to be 90 % TCP by volume!” Feasibility of a PCL/b-TCP Composite Ecomposite = XTCPETCP + (1-XTCP)EPCL (upper bound) Ecomposite = 1 / [(XTCP / ETCP) + (1-XTCP)/ EPCL] (lower bound) Source: Ashby, M. Engineering Materials I.

  22. TemPlate’s Composite Bone Plate By hot pressing a composite material of volume fraction 90% PCL / 10% -TCP, the modulus was increased by 60%.

  23. Cost Analysis

  24. Cost Analysis Polymer Injection Molding • Purchase Mold: (Master Unit Die) = $400 • Design ($60/hr * 30hr) = $1800 • Machining ($52/hr * 35hr) = $1820 ---------- Total for Mold $4060

  25. Cost Analysis

  26. Cost Analysis Processing • Battenfeld Machine Repair = $250 • Optimizing Initial Processing Conditions ($60/hr * 6hr) =$360 • Injection Molding 1000 plates ($60/hr * 40hr) = $2400 ---------- Total for IM $3010

  27. Cost Analysis

  28. Cost Analysis Material • Polycaprolactone (Polysciences, Inc. ($200/kg*20kg) = $4000

  29. Cost Analysis • Mechanical testing (Instron) ($60/hr*10hr) = $600 Product Analysis

  30. Cost Analysis Summary • Overhead ~ $7000 • Mold = $4060 • Injection Molding = $3010 • Materials = $4000 • Product Analysis = $ 600 • = $18,670 --------------- Total Cost of 1000 bone plates

  31. Cost Analysis competition * $168/bone plate $20/bone plate *Biomet.com

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