Novel route to fatigue-resistant fully sintered ultrahigh molecular weight polyethylene for knee prosthesis.
The role of entanglements in obtaining a homogeneous product of ultrahigh molecular weight polyethylene (UHMW-PE) has been explored. Studies performed in this report show that a disentangled state before melting is a prerequisite to obtain homogeneous products of an intractable polymer like UHMW-PE. The disentangled state is obtained directly from the reactor by controlling the polymerization conditions or in the solid state when there is enhanced chain mobility along the c axis of a unit cell. The disentangled state is maintained in the melt over a period of time, invoking implications in polymer rheology. This approach is applicable to polymers in general. The homogeneous fully sintered UHMW-PE, obtained for the first time, shows a considerable decrease in oxygen permeability and an increase in toughness and fatigue resistance. Such homogeneous products of UHMW-PE are beneficial in highly demanding applications, especially in knee prosthesis, where the polymer is used as an inlay between the human bone and a metal or ceramic part, which slides against the polyethylene component during normal gait.
Rastogi
S
S
Department of Chemical Engineering, Dutch Polymer Institute/Eindhoven University of Technology, Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. s.rastogi@tue.nl
Kurelec
L
L
Lippits
D
D
Cuijpers
J
J
Wimmer
M
M
Lemstra
P J
PJ
D007720:Knee Prosthesis / Q000592:standards*; D008422:Materials Testing; D019563:Mechanics; D008970:Molecular Weight; D010100:Oxygen / Q000737:chemistry; D010539:Permeability; D020959:Polyethylene / Q000138:chemical synthesis* / Q000737:chemistry / Q000627:therapeutic use; D011475:Prosthesis Failure
D020959:Polyethylene; D010100:Oxygen