Biomedical Engineering Reference
In-Depth Information
O
O
O
H
2
catalyst
heat
OC C
O
n
O
Glycolide
PGA
O
CH
3
O
CH
3
O
catalyst
heat
O
OC C
n
H
H
3
C
O
Lactide
PLA
O
O
CH
3
O
CH
3
O
O
O
H
2
catalyst
heat
OC C
O
C
C
O
O
n
m
H
H
3
C
O
O
Glycolide
Lactide
PLG
8.6
Ring opening polymerization of PGA, PLA and PLG.
Table 8.2
Physical, mechanical and degradation properties of PGA, PLA and PLG
polymers
Polymer
Melting point
T
g
(°C)
Modulus
Elongation
Degradation
(GPa)
b
time (months)
c
(°C)
(%)
PGA
225-230
35-40
7.0
15-20
6-12
50/50
d l
-PLG
Amorphous
45-50
2.0
3-10
1-2
65/35
d l
-PLG
Amorphous
45-50
2.0
3-10
3-4
75/25
d l
-PLG
Amorphous
50-55
2.0
3-10
4-5
85/15
d l
-PLG
Amorphous
50-55
2.0
3-10
5-6
l
-PLA
173-178
60-65
2.7
5-10
> 24
d l
-PLA
Amorphous
55-60
1.9
3-10
12-16
a
Middleton and Tipton
58
b
Tensile or flexural modulus
c
Time to complete resorption
(37%) with a melting point of 175-178ºc and a
T
g
of 60-65ºc.
53, 54
on the
other hand, poly(
d
,
l
-lactide) (
d l
-PLA) is an amorphous polymer. it presents
a random distribution of both isomeric forms of lactic acid and accordingly
