Heart valve prostheses have become common since their introduction in the 1
960s. Although prostheses work well in situ at the physiological site they
are not designed for other applications such as conduits. Research at Notti
ngham Trent University has led to the design of a conduit valve prosthesis
to allow for correct arterial and valvular flow. Requirements are to have a
porous internal structure to incur tissue in-growth, improve heamodynamic
performance and longevity of the prosthesis. Powder reaction moulding techn
ology has been implemented to create such a prosthesis from medical grade a
luminium oxide. Methyl methacrylate and cyanoacrylates were investigated as
binders with aluminium oxide as the powder constituent. The production of
samples with a small L/D ratio and analysis of reaction kinetics provided v
aluable evidence to support the role of these binders. It was found that me
thyl methacrylate can only mix to a powder volume fraction of 0.33, whilst
cyanoacrylate can bind with alumina to a higher volume fraction of 0.45. Wi
th cyanoacrylate binding the largest fraction, samples were moulded from cy
anoacrylate/alumina utilising a hand extrusion unit. The mould design repre
sented the conduit heart valve and was manufactured from polytetraflouroeth
ylene (PTFE). Investigation of the moulded bodies leads to two observations
. Firstly, cyanoacrylate requires a surface initiation to polymerise within
a mould cavity and secondly, mould release agents are needed to extract th
e part. Preliminary investigation into thermal de-binding of cyanoacrylate
from alumina has been completed with promising results, proving that cyanoa
crylate is a useful constituent for reaction moulding. (C) 2001 Elsevier Sc
ience B.V. All rights reserved.