Barbieri Thesis - BioMedical Materials program (BMM)
Barbieri Thesis - BioMedical Materials program (BMM)
Barbieri Thesis - BioMedical Materials program (BMM)
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Chapter 4 – Conntrol<br />
of mechanical<br />
and degraddation<br />
properties s in composites<br />
Measuremments<br />
with Ubbelohde<br />
decreasees<br />
in intrinsic viscosity for<br />
apatite coontent.<br />
In facct,<br />
in higher<br />
viscosity decrease (TTable<br />
3). Dyn<br />
indicated a significant increase in su<br />
content ( (ANOVA, p= 10<br />
decreasee<br />
in contact an<br />
than M255.<br />
The contact<br />
–8 viscometer sshowed<br />
sign nificant post– –extrusion<br />
the copolymmer,<br />
which wa as correlated with the<br />
apatite contaaining<br />
materia als there was a larger<br />
namic contacct<br />
angle mea asurements (F Figure 4)<br />
urface hydropphilicity<br />
with the increase of apatite<br />
, compar rison of initiaal<br />
values). The T sharp an nd larger<br />
ngle of M50 over o time indiccated<br />
that it absorbed a wate er quicker<br />
angle of M0 kept k stable inddicating<br />
no or little water abs sorption.<br />
4.3.3. In vvitro<br />
degradattion<br />
As expeccted,<br />
there wass<br />
larger fluid uptake when more apatite was present (Table ( 4),<br />
which ledd<br />
to polymer<br />
hydrolysis as indicated by intrinsic c viscosity changes.<br />
Unexpecttedly,<br />
larger fluid uptake correspondedd<br />
to smaller decrease in n intrinsic<br />
viscosity (Table 2). IIn<br />
filler–conta aining compoosites,<br />
i.e. M25<br />
and M50 0, apatite<br />
dissolutioon<br />
and/or releease<br />
of whole<br />
apatite paarticles<br />
occurr red as shown<br />
by the<br />
increasingg<br />
calcium andd<br />
phosphate ion concentraation<br />
in SPS over o time.<br />
As expeccted,<br />
M25 releeased<br />
signific cantly fewer ioons<br />
as compa ared to M50 due d to its<br />
lower apaatite<br />
content (FFigure<br />
5; Table<br />
4). The phaase<br />
content of o apatite (and polymer)<br />
remainedd<br />
relatively sstable,<br />
varyin ng within ±11–3%<br />
compa ared to their r starting<br />
counterpaarts<br />
(Table 1). .<br />
Figure 3. TTEM<br />
images of MM25<br />
at (a) low and<br />
(c) high magnification.<br />
TEM im mages of M50 at (b) low and<br />
(d) high maagnification.<br />
BSEEM<br />
images of cro oss–sections of ( (e) M25 and (f) M50 taken unde er the same<br />
conditions oof<br />
electron beamm<br />
voltage, workin ng distance, conttrast<br />
and brightn ness. Uniform dis stribution of<br />
apatite partticles<br />
in both commposites<br />
is observ ved. Due to the loower<br />
content of apatite, a M25 appears<br />
darker<br />
than M50 (ssee<br />
as reference BSEM images in n Chapter 3).<br />
78
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