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

Ting Zheng; Zhan Zhang; Srishti Shukla; Shubh Agnihotri; Craig M Clemons; Srikanth Pilla

doi:10.1016/j.carbpol.2018.10.014

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

Carbohydr Polym. 2019 Feb 1:205:27-34. doi: 10.1016/j.carbpol.2018.10.014. Epub 2018 Oct 10.

Authors

Ting Zheng¹, Zhan Zhang², Srishti Shukla³, Shubh Agnihotri⁴, Craig M Clemons⁵, Srikanth Pilla⁶

Affiliations

¹ Clemson University, Department of Automotive Engineering, 4 Research Drive, Greenville, SC, 29607, USA; Clemson University, Clemson Composites Center, Greenville, SC, 29607, USA. Electronic address: tzheng@g.clemson.edu.
² Clemson University, Department of Automotive Engineering, 4 Research Drive, Greenville, SC, 29607, USA. Electronic address: zhanz@g.clemson.edu.
³ Clemson University, Department of Automotive Engineering, 4 Research Drive, Greenville, SC, 29607, USA; Department of Mechanical Engineering, Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh, 221005, India. Electronic address: srishti.shuklacd.mec14@itbhu.ac.in.
⁴ Clemson University, Department of Automotive Engineering, 4 Research Drive, Greenville, SC, 29607, USA; Department of Mechanical Engineering, Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh, 221005, India. Electronic address: shubh.agnihotri.mec14@iitbhu.ac.in.
⁵ Clemson University, Department of Automotive Engineering, 4 Research Drive, Greenville, SC, 29607, USA; USDA Forest Service, Forest Products Laboratory, Madison, WI, 53726, USA. Electronic address: cclemons@fs.fed.us.
⁶ Clemson University, Department of Automotive Engineering, 4 Research Drive, Greenville, SC, 29607, USA; Clemson University, Clemson Composites Center, Greenville, SC, 29607, USA; Clemson University, Department of Material Science and Engineering, Clemson, SC, 29602, USA. Electronic address: spilla@clemson.edu.

PMID: 30446104
DOI: 10.1016/j.carbpol.2018.10.014

Abstract

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 (χ_c) 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.

Keywords: Cellulose nanocrystal; Extrusion; Injection molding; Nanocomposite; PHBV.