Paper Number
SR4
Session
Sustainable and Recyclable Polymers
Title
Partial-melting rheology in HDPE-iPP blends
Presentation Date and Time
October 10, 2022 (Monday) 10:50
Track / Room
Track 4 / Michigan AB
Authors
- Huang, Derek E. (National Institute of Standards and Technology)
- Kotula, Anthony (National Institute of Standards and Technology)
- Migler, Kalman (National Institute of Standards and Technology)
Author and Affiliation Lines
Derek E. Huang, Anthony Kotula and Kalman Migler
National Institute of Standards and Technology, Gaithersburg, MD 20899
Speaker / Presenter
Huang, Derek E.
Keywords
experimental methods; polymer blends; polymer melts; polymer sustainability; recyclable polymers
Text of Abstract
The processing of mixed polyolefins influences their morphology, crystallization kinetics, and material properties, with implications for manufacturing useful products from recycled plastics. High-density polyethylene (HDPE) and isotactic polypropylene (iPP) are prevalent in the waste stream, but their thermodynamic incompatibility restricts the usefulness of blended HDPE-iPP products, and the dependence of domain morphology and crystallization kinetics on composition, processing, and additives are not well understood. We employ the rheo-Raman microscope and phase contrast optical microscopy to study the transition between hierarchical, co-continuous and droplet morphologies using a partial-melting technique, where we crystallize HDPE-iPP blends and subsequently raise the temperature to melt the HDPE while the iPP remains crystalline. Transitions between domain structure are reflected in the rheology, and we evaluate the ability of an effective medium model to describe this transition from a continuous molten phase with suspended crystalline domains to a continuous semicrystalline phase with suspended liquid domains. Our results demonstrate the importance of processing on the structure and properties of mixed waste-stream crystallizing polymers and suggest that the usefulness of immiscible polyolefin blends may be increased by a better understanding of the processing parameters underlying co-continuous morphology.