Influence of dry grinding in a ball mill on the length of multiwalled carbon nanotubes and their dispersion and percolation behaviour in melt mixed polycarbonate composites

Abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractBall milling of carbon nanotubes (CNTs) in the dry state is a common way to produce tailored CNT materials for composite applications, especially to adjust nanotube lengths. For Nanocyl TM NC7000 nanotube material before and after milling for 5 and 10 hours the length distributions were quantified using TEM analysis, showing decreases of the mean length to 54 and 35%, respectively. With increasing ball milling time in addition a decrease of agglomerate size and an increase of packing density took place resulting in a worse dispersability in aqueous surfactant solutions. In melt mixed CNT polycarbonate composites produced using masterbatch dilution step the electrical properties, the nanotube length distribution after processing, and the nano-and macrodispersion of the nanotubes were studied. The slight increase in the electrical percolation threshold in the melt mixed composites with ball milling time of CNTs can be assigned to lower nanotubes lengths as well as the worse dispersability of the ball milled nanotubes. After melt compounding, the mean CNT lengths were shortened to 31%, 50%, and 66% of the initial lengths of NC7000, NC7000-5h, and NC7000-10h, respectively.

Influence of shear-induced crystallization on the electrical conductivity of high density polyethylene carbon nanotube nanocomposites

“…There are several literature reports regarding the influence of melt-mixing time on the final CNT length [12,26,32,33,42]. It is frequently invoked to explain loss of conductivity in literature.…”

“…shear stress) may lead to a decrease of CNT aspect ratio, and hence increase of resistivity [31][32][33][34]. For example, it was recently shown and quantified by Krause et al [33,34] that melt processing of CNT-polymer composites can lead to significant CNT shortening, which influences the properties of the composites. On the other hand, the influence of processing related crystalline structure on electrical conductivity has been rarely studied.…”

Functionalisation of MWCNTs with poly(lauryl acrylate) polymerised by Cu(0)-mediated and RAFT methods

“…The bulk density was reported to be 66 kg m -3 (44) and the oxygen to carbon ratio reported to be 0.0045 45 . Filter paper was obtained from Fisher (cellulose) with a pore size of 20-25 m. Isotactic poly(propylene) (iPP) with a melt-flow rate of 52 g/10 min (230 °C/ 2.16 kg) (grade H734-52RNA) was purchased from Braskem and used as received.…”

Sonication-assisted dispersion of carbon nanotubes in aqueous solutions of the anionic surfactant SDBS: The role of sonication energy

“…However, the poor solubility of CNTs in water-aggregates form because of the highly attractive van der Waals (vdW) forces (e.g. 500 eV/μm of tube length for SWCNTs) between tubes-significantly limits their applications [3,4].…”