TABLE OF CONTENTS In terms of conclusions about the effect of the functional barrier, two facts of importance can be looked upon, either by estimating the time of protection provided by the presence of this virgin polymer layer or by considering the decrease in this time of protection resulting from the advancement of the profiles of concentration of the contaminant which takes place during the process of co-extrusion or co-moulding.
The interest of the functional barrier is obvious, as it appears in the various figures depicting the kinetics of release of the contaminant in the liquid food. In each case, there is a time of full protection. Moreover, after this time, the amount of contaminant in the liquid food (as well as the concentration) increases rather slowly, bringing another partial protection. On the contrary, without a functional barrier, the kinetics of release of the contaminant into the liquid food exhibits a high rate, especially at the beginning of the process.
Quantitative results are given in the following three Tables (Tables 4.1 , 4.2 and 4.3 ).
| Mono-layer | M t/M in | |||
|---|---|---|---|---|
| R | 0.0001 | 0.001 | 0.01 | 0.1 |
| 1 | 1.00 10 ?4 | 1.02 10 ?3 | 1.08 10 ?2 | 0.1281 |
| 5 | 2.01 10 ?5 | 2.11 10 ?4 | 2.37 10 ?3 | 3.50 10 ?2 |
| 10 | 1.00 10 ?5 | 1.08 10 ?4 | 1.28 10 ?3 | 2.22 10 ?2 |
| 50 | 2.00 10 ?6 | 2.35 10 ?5 | 3.49 10 ?4 | 1.10 10 ?2 |
| ? | - | 7.50 10 ?7 | 7.86 10 ?5 |
