A rheotens-based criterion for melt spinnability of virgin, recycled, petrol-based, and bio-based polymers

Abstract

The development of a pragmatic laboratory criterion that can predict the spinnability of molten polymeric materials has the potential to reduce the necessity for costly industrial testing. The present study aims to compare the potential of existing conventional shear-based and extensional-based metrics with a proposed Rheotens-based metric in order to determine the most suitable method for material spinnability prediction. In this study, the characterization process encompassed virgin and reprocessed polyolefins (PE, PP), two PLA polymers (a spinning-grade polymer vs an extrusion grade), and two PLA/PHB blends (an industrially spinnable one vs an unspinnable one). So far, commonly used shear and classical extensional measurements incorporating the Beyreuther–Vogel criterion have been unsuccessful in differentiating between spinnable and unspinnable grades. We therefore refined the Rheotens test into a guided “impact” experiment at preset wheel speeds and defined a Rheotens Spinnability Index (RSI) from the force–take-up-speed curve. Within the present material set and experimental protocol, the RSI provided clear empirical decision ranges for the tested materials: RSI < 4 unspinnable, 4 ≤ RSI < 5 transition, and RSI ≥ 5 spinnable. The spinnability assignments were supported by melt-spinning trials on a Hills LBS-300 line, with additional verification of PLA and PLA/PHB materials on a ZDL-25 dry-melt line. Therefore, the proposed method offers a reference-free, single-material screening approach that outperforms shear-based metrics by directly probing extensional resistance and melt-strength build-up that influenced drawdown. The approach provides a practical tool for screening virgin, recycled, petrol-based, and biobased materials.