Protein materials oxygen permeability

The gas barrier properties (O2, CO2 and ethylene) of protein-based materials are highly attractive since they are minimal under low RH conditions. Oxygen permeability (around 1 amol/m/s/Pa) is comparable to ethylene vinyl alcohol (EVOH) properties (0.2 amol/m/s/Pa) and much lower than the properties of LDPE (1,000 amol/m/s/Pa) [61] (Table 11.12). The O2 permeability of protein films is about 10-fold higher that EVOH-based films, mainly due to the high plasticiser content of protein-based films. 

Film forming materials, plasticizer type and amount and other additives affect film properties differently. Table 1 and 2 show the water vapor permeability (WVP) and oxygen permeability (OP) of different polysaccharide-, protein-, composite- and frait and vegetable-based films with various plasticizers using different processes. Comparisons among them are difficult because of different film compositions, test conditions (RH, temperature), methodology, and number of replications were used in each woik. 

Biomedical Applications Due to their excellent blood compatibility (low interaction with plasma proteins) and high oxygen and moisture permeabilities, siloxane containing copolymers and networks have been extensively evaluated and used in the construction of blood contacting devices and contact lenses 376). Depending on the actual use, the desired mechanical properties of these materials are usually achieved by careful design and selection of the organic component in the copolymers. 

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