Chemical Bonding in Polyethylene−Nanotube Composites:  A Quantum Mechanics Prediction

Abstract

To make full use of the strength of carbon nanotubes in a composite, it is important to have a high-stress transfer at the matrix−nanotube interface via strong chemical bonding. This paper investigates the possible polyethylene−nanotube bonding with the aid of a quantum mechanics analysis. The polyethylene chains were represented by alkyl segments, and the nanotubes were modeled by nanotube segments with H atoms added to the dangling bonds of the perimeter carbons. The study predicts that covalent bonding between an alkyl radical and a nanotube is energetically favorable, and that the tubes of smaller diameters have higher binding energies. Hence, a high-stress transfer can be realized in polyethylene-based carbon nanotube composites in the presence of free-radical generators.

Structural orientation and tensile behavior in the extrusion-stretched sheets of polypropylene/multi-walled carbon nanotubes' composite

“…Although the oriented degrees of crystalline structure in the samples with different CNTs' contents are almost identical, the added MWCNTs may significantly impact the modes of nucleation and crystallization of basal polymer. According to the past literature [32,37,39] and our recent study [32], an interesting character of polymer crystallization nucleated by oriented CNTs was that the preferentially aligned CNTs could act as a template for generation of oriented, anisotropic cylindrulites. In this work, the template effect of MWCNTs for anisotropic crystalline superstructure could be also effective for the stretched PP/MWCNTs' composite sheets, which can be evident through re-crystallization observation using PLM.…”

“…It provides the possibility that the formation of PP/CNTs' co-crystallized structure similar to ''hybrid shish-kebab''. In this way, an efficient stress transfer is ensured from the nanotubes to the polymer matrix analogous to the case that strong chemical bonding existed at the polymer/nanotube interface [39]; on the other hand, selfreinforcement effect is expected in the oriented crystalline superstructure because rigid nanotubes acted as nuclei to reinforce the whole anisotropic crystal. Consequently, the oriented crystalline superstructure composed of rigid CNTs as nucleus and PP lamellae as kebabs possesses better mechanical performances than the oriented crystalline structure in the pure PP sheet.…”

Shear enhanced interfacial interaction between carbon nanotubes and polyethylene and formation of nanohybrid shish–kebabs

“…For polymer/CNT composites, the well dispersion of CNTs and the polymer/CNTs' interfacial adhesion are two main issues for warranting excellent mechanical properties [7]. Due to high aspect ratio of nanotubes, large interfacial areas are available for matrixto-fillers' stress transfer, but an adequate interfacial adhesion is necessary in order to achieve a good load transfer [8].…”

A Cohesive Law for Carbon Nanotube/Polymer Interface Accounting for Chemical Covalent Bonds

“…One method is the non-covalent attachment of molecules on the CNTs, or wrapping of the CNTs, and the other method is the chemical functionalization of the CNTs' surfaces. These treatments will alter the nature of the CNT's surface and make it more com- patible with the polymer matrix [13][14][15][16][46][47][48]. For example, the atoms surrounding the atoms forming covalent bond or the attached molecules may undergo local deformation.…”