Crystallization Kinetics in an Immiscible Polyolefin Blend

Published

December 12, 2022

Author(s)

Derek Huang, Anthony Kotula, Chad R. Snyder, Kalman Migler

Abstract

Motivated by the problem of brittle mechanical behavior in recycled blends of high density polyethylene (HDPE) and isotactic polypropylene (iPP), we employ optical microscopy, rheo-Raman, and differential scanning calorimetry (DSC) to measure the composition dependence of their crystallization kinetics. Raman spectra are analyzed via multivariate curve resolution with alternating least-squares (MCR-ALS) to provide component crystallization values. We find that iPP crystallization behavior varies strongly with blend composition. Optical microscopy shows that three crystallization kinetic regimes correspond to three underlying two-phase morphologies: HDPE droplets in iPP, the inverse, and cocontinuous structures. In the HDPE droplet regime, iPP crystallization temperature decreases sharply with increasing HDPE composition. For cocontinuous morphologies, iPP crystallization is delayed, but the onset temperature changes little with the exact blend composition. In the iPP droplet regime, the two components crystallize nearly concurrently. Rheological measurements are consistent with these observations. DSC indicates that the enthalpy of crystallization of the blends is less than the weighted values of the individual components, providing a possible clue for the decreased iPP crystallization temperatures.

Citation

Macromolecules

Volume

55

Issue

24

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.macromol.2c01691

Local Download

Keywords

polymers, rheology, Raman spectroscopy, crystallization, polyethylene, polypropylene

Citation

Huang, D. , Kotula, A. , Snyder, C. and Migler, K. (2022), Crystallization Kinetics in an Immiscible Polyolefin Blend, Macromolecules, [online], https://doi.org/10.1021/acs.macromol.2c01691, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935129 (Accessed April 18, 2024)