Biomass is one of the main alternatives to the use of oil in plastics field. Due to their various functional properties, caseinates are considered as an interesting raw material for making biodegradable and water-soluble packaging. The transformation of sodium caseinate by the processes used for synthetic plastics industry has been demonstrated. A corotating twin-screw extruder was used to get glycerol plasticized caseinate pellets. The physicochemical properties of the obtained material have confirmed the thermal stability of this protein and demonstrated the influence of surrounding moisture on material behavior. With the Relative Humidity varying from 40 to 90% and increasing the glycerol content, an hydrous plasticizer, the mechanical properties of sodium caseinate based materials changed from those of glassy (rigid) to rubbery (soft) plastics. The pellets were then taken over to make film using a blown-film extruder. The water vapour permeability of blown film was studied and showed that sodium caseinate based films are a poor moisture barrier. The second part dealt with the sodium caseinate blend. Sodium caseinate/calcium caseinate and sodium caseinate/PBAT blends was performed. Adding calcium caseinate, started from 50%, improved the mechanical properties and delayed hydrous transfer through the film. Concerning the sodium caseinate/PBAT blends, adding PBAT increased until twice more the material’s Young modulus but decreased the moisture transfer resistance because of the incompatibility between the two polymers
Synthesis of a thermoplastic biodegradable and water soluble material based on a milk protein