THERMOPLASTIC EXTRUSION - THE MECHANISM OF THE FORMATION OF EXTRUDATESTRUCTURE AND PROPERTIES

Systems processed by thermoplastic extrusion can be regarded as hetero phase polymer melts of incompatible water-plasticized biopolymers. In the process of thermoplastic extrusion, proteins and polysaccharides a re melted at high pressure and temperature below the temperature regio n of their thermal decomposition. Dispersed particles of these systems can be deformed in flow. The mixed-melt anisotropic structure, formed in flow, is fixed by rapid conversion of the melt jet that lets the e xtruder die from a viscous state to a rubber-like state and then to a glassy state caused by cooling and drying. Incompatibility of proteins and polysaccharides in their water-plasticized melt mixtures impacts on structure formation and texturization during thermoplastic extrusio n.