Study of the Thermal, Mechanical and Melt Rheological Properties of Rice Straw Filled Poly (Butylene Succinate) Bio-composites Through Reactive Extrusion Process

Efficiency of Twin-Screw Extrusion of Biodegradable Poly (Butylene Succinate)-Wheat Bran Blend

“…This suggests it originates from the melting process rather than water evaporation. The presence of an additional peak on the DCS curves that originates from the melting process was also reported for PBS composites with palm fibers [ 87 ], PBS with rice straw [ 74 ], PBS with hemp fibers and with hemp shives [ 46 ], as well as PBS blends with polylactide and poly(3-hydroxybutyrate- co -hydroxyvalerate) [ 88 ] and even for neat PBS [ 89 ]. As was stipulated in these reports, this first endothermic peak can result from the melting of less-perfect crystals of PBS.…”

“…However, the significant increase in the mass flow rate together with increasing rotational speed is undoubtedly associated with growing material feeding rate and transportation speed along the plasticizing system, but can also be partially related to the rheological properties. Previous work has demonstrated that both PBS and its biocomposites exhibit a non-Newtonian character with a tendency for shear thinning behavior, which has a positive impact on the material mass flow rate [ 61 , 74 ]. The statistical analysis also showed a significant negative impact of the interactions between the screw rotational speed and bran content on the mass flow rate.…”

“…The source literature stipulates that despite the general increase in the blend melt viscosity, increasing LCF content also means that PBS shear thinning behavior intensifies with increasing filler content. This is explained by decreased activation energy, which stands for the amount of energy required to set a polymer molecule in motion against the frictional forces of adjacent macromolecules [ 61 , 74 , 76 ]. The increasing amount of gases, especially water vapor, released from bran during processing, resulting in the porosity of the processed blend, can significantly reduce the activation energy.…”

“…This increase comes from enhancing both the mass flow rate of the extruded polymer blend (where a higher transport efficiency with the same cross-section of extrusion head channels results in an obvious increase in pressure) and its viscosity. The increase in the blend viscosity results from the shortened duration of its residence within a plasticizing system, as well as increasing bran content [ 51 , 61 , 74 ]. The highest pressure increase of 3.1 MPa (65%) is the end product of a fourfold increase in the screw speed.…”

“…The spectrum of neat PBS ( Figure 12 ) contains visible absorption bands that are characteristic for substances with an ester group within their chemical structure: an absorption band at 1713 cm −1 that comes from the vibrations of the –C=O group, as well as bands at 1265 cm −1 , 1156 cm −1 and 1044 cm −1 that correspond to the vibrations of the –C-O-C– and –O-(C=O) groups [ 81 ]. In addition, absorption bands at 2962–2857 cm −1 , 1472 cm −1 and 1329 cm −1 come from the vibrations of aliphatic methylene groups [ 74 ].…”