Probing dispersion and re-agglomeration phenomena upon melt-mixing of polymer-functionalized graphite nanoplates

Abstract

A one-step melt-mixing method is proposed to study dispersion and re-agglomeration phenomena of the as-received and functionalized graphite nanoplates in polypropylene melts. Graphite nanoplates were chemically modified via 1,3-dipolar cycloaddition of an azomethine ylide and then grafted with polypropylene-graft-maleic anhydride. The effect of surface functionalization on the dispersion kinetics, nanoparticle re-agglomeration and interface bonding with the polymer is investigated. Nanocomposites with 2 or 10 wt% of as-received and functionalized graphite nanoplates were prepared in a small-scale prototype mixer coupled to a capillary rheometer. Samples were collected along the flow axis and characterized by optical microscopy, scanning electron microscopy and electrical conductivity measurements. The as-received graphite nanoplates tend to re-agglomerate upon stress relaxation of the polymer melt. The covalent attachment of a polymer to the nanoparticle surface enhances the stability of dispersion, delaying the re-agglomeration. Surface modification also improves interfacial interactions and the resulting composites presented improved electrical conductivity.

Effect of Graphite Nanoplate Morphology on the Dispersion and Physical Properties of Polycarbonate Based Composites

“…In several recent studies, the influence of the fabrication method and parameters as well as the GNP surface functionality was investigated, mostly for one or two GNP morphology types [23,24,25,26,27,28,29,30]. To use the full potential of the different respective GNP filler materials in polymer based composite applications [31,32,33,34,35,36,37], a more detailed and comprehensive understanding of their structure and processing behavior is needed.…”

Facile preparation of polyamide 6/exfoliated graphite nanoplate composites via ultrasound‐assisted processing

“…Melt processing is the most common method for fabricating polymer/xGNPs nanocomposites , and xGNPs are usually prepared by the exfoliation of low‐cost expanded graphite (EG) via a chemical technique before blending. However, the use of concentrated nitric acid and sulfuric acid in this method tends to give rise to defects in the carbon layers of the xGNPs , which may consequently decrease their strength and electrical and thermal conductivities.…”

Perspective: Outstanding theoretical questions in polymer-nanoparticle hybrids

“…245 While this methodology is pervasive, to our knowledge, there has not been a systematic means of modeling the role of shear fields on NP dispersion; an important exception is the recent work of Kalra et al who showed that nanoparticle aggregation is reduced in the presence of flow. 246 Questions that persist are as follows: can we predict morphology as a function of shear rate for NPs of different shapes (spheres, cylinders, and rods) and sizes?…”