Quantification of the degree of mixing of cellulose nanocrystals in thermoplastics using Raman spectroscopy

Abstract

A combination of Raman imaging with image analysis has been used to quantify the degree of mixing of cellulose nanocrystals (CNCs) in melt compounded high density polyethylene (HDPE). Raman spectroscopy is shown to provide an accurate “fingerprint” of the composition of the crosssectional area of the end section of a formed composite. This information is then converted to a chemical image allowing spatial quantification of the mixing of CNCs in the HDPE. A degree of mixing between CNCs and HDPE is reported, with a strong tendency for the former to agglomerate with little dispersion. Freeze-dried CNCs show better mixing with HDPE and a lower tendency to agglomerate than spray-dried CNCs. This approach shows the potential to use Raman spectroscopy to quantify the degree of mixing of CNCs in a thermoplastic matrix.