background image
- Practical Guide -
Page 67 of 153
Table 3.2.1
Ranges of parameters for the applicability of the migration model for PS and
respectively HIPS.
Polymer
T (
o
C)
c
P,0
(%)
K
P/F
PS
< 70
< 1 for all PS
1 for high solubility
HIPS
< 70
of migrant in food,
1000 for low solubility
of migrant in food
For PS and HIPS the actual values of A'
p
and could be determined empirically from the data
base of diffusion coefficients and verified by well defined migration experiments reported in
recent years by internationally recognized laboratories /1, 2/. Applying these values of A'
P
and
t (see table 3.2.2) in Eqs. (4) and (5) results in "upper limit" diffusion coefficients, D
P
*
.
These D
P
*
when introduced in Eq. 2, lead to overestimations (in most cases largely) of the
experimental migration data available.
Table 3.2.2: Parameters for PS and HIPS
Polymer
A'
p
J
J
J
J
PS
0
0
HIPS
1.0
0
3.3
Polyesters
The polyesters used for food packaging applications are polyethylene therephthalate (PET),
polybutylene therephthalate (PBT) and polyethylene naphthalate (PEN). Using product
knowledge of these polyesters the temperature range for the applicability of migration
modelling, as required by the general requirements given before, is listed in Table 3.3.1. In
these cases the migration process in these polyesters follows the generally accepted physical
law of diffusion, Eq. (1), with the solution given in Eq. (2).
Table 3.3.1.
Ranges of parameters for the applicability of the migration model for PET and
PEN.
Polymer
T (
o
C)
c
P,0
(%)
K
P/F
PET
< 175
< 1 for all Polyesters
1 for high solubility
of migrant in food,
PEN
< 175
1000 for low solubility
of migrant in food
For PET and PEN the actual values of A'
p
and
t from Eq. (5) were determined empirically
using migration data from well defined migration experiments reported in recent years by
internationally recognized laboratories /1, 2/. Using these values of A'
P
and
t (see table
3.3.2) in Eqs. (4) and (5) results in "upper limit" diffusion coefficients, D
P
*
, which,
introduced in Eq. (2), lead to overestimations (in most cases largely) of the experimental
migration data.
Table 3.3.2:
Parameters for PET and PEN