Reactive extrusion of partially crosslinked poly (butylene succinate) via novel vane extruder: thermal, mechanical and rheological properties

In this study, crosslinked poly (butylene succinate) (PBS) was prepared successfully by the reactions of the end hydroxyl groups of PBS with the isocyanate groups of hexamethylene diisocyanate prepolymer (HDIP) using a vane extruder (VE) followed by compression moulding. Torque and gel permeation chromatography showed that the PBS was successfully corsslinked by HDIP. The effects of varied HDIP on properties such as mechanical, thermal properties, and capillary rheological behaviours were also evaluated. The results indicated that HDIP crosslinked PBS with high efficiency. The gel fraction of the crosslinked PBS increased to 57% with the 1.5 wt-% HDIP loading. Differential scanning calorimetry revealed that the cross-link points in the crosslinked samples act as crystal nuclei and the crystallisation temperature increase. Dynamic mechanical analysis revealed that the glass transition temperature (Tg) increased with increase in gel fraction. This may be caused by the reduced molecular chain mobility for corsslinked samples. The capillary rheological properties showed that all samples exhibit non-Newtonian and shear thinning characteristics in the range of applied shear rates, and the apparent viscosity increased with the HDIP content. What's more, the crosslinked PBS also showed improved mechanical properties and thermal stability.