Rheology and pressurised gyration of starch and starch-loaded poly(ethylene oxide)

This work investigates the rheology and spinning of starch and starch-loaded poly(ethylene oxide) (PEO) by pressurised gyration in order to prepare nanofibres. The spinning dopeʹs rheological properties played a crucial role in fibre formation. Newtonian behaviour is observed in 1–20 wt% starch suspensions and non-Newtonian behaviour is found in all the PEO–starch mixtures. Pressurised gyration of the starch suspensions produced beads only but PEO–starch mixtures generated fibres. The fibre diameter of the PEO–starch samples is shown to be a function of polymer concentration and rotating speed of the gyration system. Fibre formation can only be facilitated below a certain working pressure. The concentration of starch in the PEO–starch mixtures is crucial in defining whether beaded or continuous fibres were generated and this is related to the composition of the spinning dope. FT-IR, XRD and microscopy studies indicated very good miscibility of starch and PEO in the nanofibres. The storage modulus of the PEO–starch were also studied as a function of temperature (30–150 °C) and showed interesting results but it was not possible to deduce general trends valid for the entire temperature range.