PHBV-graft-GMA via reactive extrusion and its use in PHBV/nanocellulose crystal composites

• Published in: Carbohydrate polymers Vol. 205; pp. 27 - 34
• Main Authors: Zheng, Ting, Zhang, Zhan, Shukla, Srishti, Agnihotri, Shubh, Clemons, Craig M., Pilla, Srikanth
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2019
• Subjects: Cellulose nanocrystal; Extrusion; Injection molding; Nanocomposite; PHBV; Injection molding; PHBV; Extrusion; Cellulose nanocrystal; Nanocomposite
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2018.10.014

•Systematically investigated andoptimized the reactive extrusion of GMA-g-PHBV.•PHBV/CNC bio-based nanocomposites were manufactured by melt extrusion.•GMA-g-PHBV improved the dispersion of CNC.•Enhanced CNC dispersion did not lead to an enhanced CNC reinforcing performance. Reactive extrusion was used for dicumyl peroxide (DCP)-initiated grafting of glycidyl methacrylate (GMA) to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The effects of GMA and DCP content and their weight ratio on the GMA grafting percentage (GP%), the polymer melt viscosity, and the PHBV molecular weight were investigated. FTIR spectroscopy determined that the DCP did indeed initiate GMA grafting. However, the changes in both the zero-shear viscosity (η0) and the molecular weight suggested the existence of crosslinking products in the extruded polymers. A negative correlation between the degree of crystallinity (χc) of the PHBV-g-GMA and the GP% suggested the influence of chain branching on crystallinity. In addition, the GMA content was found as a key factor determining the GP%. The PHBV-g-GMA was used as a matrix polymer in cellulose nanocomposites to evaluate its effects on CNC dispersion and CNC-matrix adhesion relative to the unmodified PHBV matrix. The SEM images and the change in crystallization temperature suggested enhanced dispersion of CNC in a PHBV-g-GMA matrix. However, little increase in strength properties were found with CNC addition suggesting inadequate stress transfer between the matrix and CNCs.