SFPI, glycerol, and water were mixed using a Perrier 32.
DMA spectra of SFPI films show two distinct tan[delta] peaks attributed to [alpha]- and [beta]-transitions .
Our first idea was so to investigate the extrusion of SFPI on a large range of temperature: from 85 to 160[degrees]C using a constant screw speed of 20 rpm.
Consequently, when die temperature reached the SFPI denaturation temperature (around 125[degrees]C) they were denatured while probe temperature just before the die was only 99[degrees]C.
But as moistened biopolymers tend to degrade over time and as SFPI extrusion was obtained with a low mechanical energy, we wanted to investigate a possible processing with an amount of added water as low as possible.
Forming of SFPI by extrusion is driven by an excessively complex phenomenon: denaturation.
In our case, we tried first using 20 parts of water and 50 parts of glycerol for 100 parts of SFPI to find the most appropriate temperature to film extrusion.
Effect of water content is then only a plasticizer effect, increase of plasticizer content involves a decrease of SFPI denaturation temperature .
Plasticization of SFPI is then more efficient at high temperature and with a high amount of external plasticizer.