- 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