Authors Du, M. ; Jariyavidyanont, K. ; Kühnert, I. ; Boldt, R. ; Androsch, R.
Title Effect of molar mass on critical specific work of flow for shear-induced crystal nucleation in poly (l-lactic acid)
Date 13.04.2021
Number 59981
Abstract The concept of specific work of flow has been applied for the analysis of critical shearing conditions for the formation of crystal nuclei in poly (l-lactic acid) (PLLA). Systematic variation in both time and rate of shearing the melt in a parallel-plate rheometer revealed that these parameters are interconvertible regarding the shear-induced formation of crystal nuclei; that is, low shear rate can be compensated for by increasing the shear time and vice versa. This result supports the view that critical shearing conditions can be expressed by a single quantity, providing additional options for tailoring polymer processing routes when enhanced nuclei formation is desired/unwanted. Analysis of PLLA of different mass-average molar masses of 70, 90, 120, and 576 kDa confirmed improved shear-induced crystal nucleation for materials of higher molar mass, with critical specific works of flow, above which shear-induced nuclei formation occurs, of 550, 60, 25, and 5 kPa, respectively.
Publisher Polymers
Citation Polymers 13 (2021) 1266

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