Evaluating the Influence of Specific Mechanical Energy on Biopolymer Blends Prepared via High-Speed Reactive Extrusion

Abstract

This work studies, for the first time, the influence of specific mechanical energy (SME) on the reaction efficiency and blend's performance during reactive extrusion of biopolymer compounds. Poly(lactic acid) (PLA) and poly-(butylene succinate) (PBS) were compounded separately with poly(propylene carbonate) (PPC) and a premade maleic anhydride (MAH) compatibilizer to achieve functionalization. Different screw speeds (reaching 1000 rpm) and flow rates were tested. Results indicated that the grafting efficiency was directly proportional to the SME imparted in the system. The PBS blends compounded at shorter times and faster speeds experienced less degradation and better mechanical properties than blends compounded at longer times. The effect was similar but less pronounced for the PLA formulations. It is possible to optimize the reactive compatibilization of biopolymer blends by means of SME calculations and that better blend performance is achieved when conducting high-speed extrusion at short residence times.

Effect of exchange reactions and free radical grafting on the high‐speed reactive extrusion of poly(butylene succinate) and poly(propylene carbonate) blends

“…The tensile properties of the FRG blends and the samples made in a two‐step process using a premade compatibilizer from our previous study are depicted in Fig. .…”

“…Mechanical properties of the FRG and two‐step blend . [Color figure can be viewed at wileyonlinelibrary.com]…”

“…In the case of our previous FRG work, high speeds resulted in an enhancement of the properties due to the combined action of a finer dispersion morphology and grafting at the interface. Up to 360% strain at break was achieved for blends compounded at 1,000 rpm . The theory is that more reaction can be produced by the creation of more interfacial area between the phases and by increasing the melt temperature.…”

“…In the former, the MAH, peroxide, and polymers are added simultaneously in the extruder and the copolymer is formed in situ during blending; in the latter, a reactive polymer (premade copolymer) is prepared with MAH and the peroxide prior the blending of the polymers. The two‐step process was examined in our previous works in blends of poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS). Both polymers are biobased and biodegradable, polycondensates.…”

Morphology control and ionic crosslinking of pectin domains to enhance the toughness of solvent cast PVA/pectin blends

“…This leads to higher energy dissipation and hence delay in the failure of the matrix 19,20 . In the case of binary melt blends, control of domain size and inter‐domain distances are constrained by the limitations in the processing parameters 22,23 . However, during the preparation of solvent cast blends, it is possible to tune the phase morphology by controlling the solvent evaporation rate, in addition to other parameters such as, the type of solvent, substrate, and so forth 24,25 …”