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

• Published in: Journal of Raman spectroscopy Vol. 47; no. 11; pp. 1337 - 1342
• Main Authors: Lewandowska, A. E., Eichhorn, S. J.
• Format: Journal Article
• Language: English
• Published: Bognor Regis Blackwell Publishing Ltd 01-11-2016; Wiley Subscription Services, Inc
• Subjects: Agglomeration; Cellulose; cellulose nanocrystals; composites; Computer numerical control; Imaging; Nanocrystals; Polyethylenes; Raman imaging; Raman spectroscopy; thermoplastics
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.4966

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 cross‐sectional 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. Copyright © 2016 John Wiley & Sons, Ltd.
Raman imaging has been used as a non‐destructive method for the spatial quantification of the mixing process of cellulose nanocrystals (CNCs) in HDPE. A series of polyethylene‐based composites was prepared by melt compounding using freeze‐dried and spray‐dried CNCs as a nanofiller. The results confirmed that CNCs have a strong tendency to agglomerate. However, a certain degree of mixing between CNCs and HDPE is observed from Raman images and chemical images obtained by spectroscopy.