Environmental Engineering Reference
In-Depth Information
Figure 6.22
Twin-screw extruder, pellets and film blowing of caseinates-based plastic. Courtesy
of F. Prochazka.
Casein is the name of a family of proteins that are commonly found in mam-
malian milk. It was used to produce galalithe by reaction with formaldehyde, one
of the first declared plastics. Nowadays new processes exist to produce biodegrad-
able, edible and water-soluble packaging [35]. The process involves sodium
caseinates, obtained from the extraction of cow milk, and consists of a classical
double-step operation: compounding of glycerol-plasticised transparent pellets
and film blowing (Figure 6.22).
Other types of proteins such as keratin, for example from feathers or extracted
from blood, have also been tested to produce biodegradable biomaterials in the
last decades.
6.3.6.5
Animal Fibres
Animal fibres, for example silk or wool, consist largely of proteins. As for textile
applications, these fibres can be used like vegetal fibres to produce various kinds
of materials.
Applications for keratin, the fibrous structural protein constituting human hair
and wool, include composites [36], biocomposites or biomedical applications
[37], but also in the construction sector.
