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Polymer Chemistry 2018
Polymer Sciences
ISSN: 2471-9935
Page 78
March 26-28, 2018
Vienna, Austria
3
rd
Edition of International Conference and Exhibition on
Polymer Chemistry
E
thylene-vinyl alcohol (EVOH) copolymers are semi-
crystalline materials composed of hydrophobic segments
of polyethylene (PE) and hydrophilic segments of polyvinyl
alcohol (PVOH). Due to its high barrier properties to gases,
hydrocarbons and organic vapours at drying state
[1]
, EVOH is
more and more used in food packaging applications, allowing
to extend the life span of the products
[2]
. Nevertheless, the
major disadvantage of EVOH is its moisture content sensitivity
that causes a significant decrease in the barrier properties in
high relative humidity environments
[3]
.
The main objective of this study is to get a better understanding
of the mechanism of water sorption molecules in these
copolymers determining the consequences on the mechanical,
thermal, water and oxygen barrier properties. Consequently,
these properties were analysed at several water activities (a
w
)
ranging from 0 to 1 on films elaborated from a 32% ethylene
containing copolymer with a crystallinity of 40%.
Water vapour sorption behaviour, corresponding to a BET II
sorption isotherm, reveals the sorption of water molecules on
polar sites (Langmuir contribution) at low activities and the
formation of water clusters at high activities
[4]
.
GAB modelized isotherm
[5]
combined with the use of the
clustering theory from Zimm & Lundberg
[6]
underline the
existence of a critical activity close to 0,5 corresponding to
the presence of one water molecule linked every nine PVOH
amorphous units. A strong modification of the properties
was observed starting from this critical point, showing
how important is the understanding of the water sorption
mechanism and the consequences on the properties.
References:
1. K. Khanah Mokwena, J.Tang, Food Science and
Nutrition, 2012, Vol 52, 640-650
2. J.M Lagaron, E. Giménez, B. Altava, V. Del-Valle,
R. Gavara, Macromolecular Symposia, 2003, Vol
198, 473-482
3. Z. Zhang, I.J. Britt, M.A. Tung, Journal of Applied
Polymer Science, 2001, Vol 82, 1866-1872
4. D. Cava, L. Cabedo, E. Gimenez, R. Gavara, J.M.
Lagaron, Polymer Testing, 2006, Vol 25, 254-261
5. S. Basu, U. S. Shivhare, A. S. Mujumdar, Drying
Technology, 2006, Vol 25, 917-930
6. J.L. Lundberg, Pure and Applied Chemistry, 1972,
Vol 31, 261-281.
Biography
A. Blanchard , in the final year of his phD, his researches taking place at the
IMP laboratory (Ingénierie des Matériaux Polymère) at Villeurbanne (France)
are focused on a FUI national project in collaboration with several indus-
trial partners (Polyone, Leygatech, Bobino) and scientific centres (CTCPA,
CNAM). This project named NOXY II, is dealing with the improvement of the
barrier properties of EVOH films for food packaging applications, in order to
extend the life span of the products.
anthony.blanchard@live.frEffect of humidity on mechanical, thermal and barrier
properties of EVOH films
A Blanchard
*
, F Gouanvé
and
E Espuche
Ingénierie des Matériaux Polymères, Université de Lyon, France
A. Blanchard et al., Polym Sci, Volume 4
DOI: 10.4172/2471-9935-C1-008