Characterisation of formulated high-density poly(ethylene) by magic angle spinning nuclear magnetic resonance

Alyssa M Rose; Andrew R McLauchlin; George Wilson; Tom O McDonald; Frédéric Blanc

doi:10.1039/d4py00010b

Characterisation of formulated high-density poly(ethylene) by magic angle spinning nuclear magnetic resonance

Polym Chem. 2024 Mar 6;15(15):1511-1521. doi: 10.1039/d4py00010b. eCollection 2024 Apr 16.

Authors

Alyssa M Rose¹, Andrew R McLauchlin^{1

2}, George Wilson¹, Tom O McDonald^{1

2}, Frédéric Blanc^{1

3

4}

Affiliations

¹ Department of Chemistry, Crown Street, University of Liverpool L69 7ZD UK frederic.blanc@liverpool.ac.uk.
² Henry Royce Institute, Department of Materials and Department of Chemistry, University of Manchester M13 9PL UK.
³ Leverhulme Research Centre for Functional Materials Design, Crown Street, University of Liverpool L7 3NY UK.
⁴ Stephenson Institute for Renewable Energy, Peach Street, University of Liverpool L69 7ZD UK.

Abstract

High-density poly(ethylene) (HDPE) is an important class of polymer used extensively in plastic packaging as well as numerous other applications. HDPE has a structure that consists of crystalline (monoclinic and orthorhombic) and amorphous domains. Here, we exploit a range of approaches focusing on magic angle spinning (MAS) nuclear magnetic resonance (NMR) aimed at comparing the effect of the HDPE sample formulation (cutting, shaving and cryomilling), from the commercially available manufactured pellets, into these domains and their quantification. ¹³C cross polarisation (CP) experiments reveal that these formulated HDPEs are qualitatively different and ¹³C CP build-up curves and ¹³C direct excitation experiments enable the content of each domain to be obtained, pointing to an increase of monoclinic domain at the expense of the orthorhombic one upon increased processing. The crystallinity contents obtained compared, in some cases, favourably with those obtained by differential scanning calorimetry (DSC) data. These results provide evidence that the manner of preparation of HDPE pellets modifies the concentration of the various domains and suggest that care should be taken during processing.