Work

A Straightforward Methodology for the Quantification of Long Chain Branches in Polyethylene by 13C NMR Spectroscopy

Year: 2025

Type: article

Abstract: Formation of long chain branches (LCB) in polyethylene (PE), via incorporation of in situ generated vinyl macromonomers, is known to affect material properties dramatically, making their detection and quantification of primary importance. 13C NMR spectroscopy is the archetypal technique for the analysis of polymer microstructure, yet it suffers from major limitations in the analysis of LCB in polyethylene, primarily in terms of resolution. Herein, we propose a simple and effective methodology for detecting and quantifying LCB based on the analysis of C atoms in β-position with respect to the branching point. By analyzing model ethylene/α-olefin copolymers bearing methyl, ethyl, butyl, hexyl or tetradecyl chain branches, we show how the Cβ resonances can be used to discriminate between shorter or longer branches. Importantly, the proposed method allows the most critical discrimination between hexyl-type branches and LCB, with an up to three-fold detection enhancement with respect to previously proposed procedures based on the analysis of the methine carbons. The proposed approach is then tested on a representative industrial sample of HDPE, proving that it is suitable to detect very small amounts of LCB.

Source: Polymers

DOI: 10.3390/polym17091274

Authors: Francesco Zaccaria, Andrea Pucciarelli, Roberta Cipullo, Vincenzo Busico

Institutions: University of Naples Federico II, Scuola Superiore Meridionale

Language: English

Topic: Polymer crystallization and properties

Subfield: Polymers and Plastics

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,258

Funders: Università degli Studi di Napoli Federico II, European Commission, Ministerio de Economía y Competitividad, NextGenerationEU