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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May 17, 2001
Bao-Yi Chang Elissa Robbins
Elizabeth Immen Lisa Scoppettuolo
PLLA or PCL
-Obtaining Mold Blank
Establishing Ideal IM Conditions
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
• 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
Melting point of PCL = 63.245 oC
Polymers with low melting points are typically:
• low molecular weight
- b-tricalcium phosphate
b-tricalcium phosphate (Ca3(PO4)2, b -TCP) is a bioresorbable ceramic
... Further Work and Study
- Satisfy the mechanical requirements of bone plates
- Mechanically superior to many bioresorbable homopolymers
Possible Problems :
Poor adhesion between polymer matrix and ceramic reinforcer Poor mechanical properties
-Melting and Hot Pressing - Twin Screw Extrusion
- Pelletize Composite Mixture
- Injection Molding:
Viscosity (h) is an important parameter
“To fabricate a bone plate with a modulus of 3 GPa, the composite would have to be 90 % TCP by volume!”
Feasibility of a
Ecomposite = XTCPETCP + (1-XTCP)EPCL (upper bound)
Ecomposite = 1 / [(XTCP / ETCP) + (1-XTCP)/ EPCL] (lower bound)
Source: Ashby, M.
Engineering Materials I.
By hot pressing a composite material of volume fraction 90% PCL / 10% -TCP, the modulus was increased by 60%.
Polymer Injection Molding
Total for Mold $4060
Total for IM $3010
Total Cost of 1000 bone plates