A Shish-kebab superstructure in low-crystallinity elastomer nanocomposites: Morphology regulation and load-transfer

摘要

In this paper, a regulated morphology of multi-walled carbon nanotube bundles (CNTBs) in olefin block copolymer (OBC) is achieved via a facile method of short-time strong sonication and solution blending. Inside the CNTBs which consist of several to dozens of nanotubes, the nanotubes exhibit a well aligned structure. With the incorporation of CNTBs, a hybrid shish-kebab superstructure is formed that nanotubes in CNTBs form the central stems and OBC crystals form kebabs on the surface of nanotubes. Superior reinforcement is achieved, e.g., the tensile strength and Young's modulus can be both tripled with 2 wt% CNTB incorporation. A downshift of G'band of CNTBs in nanocomposites in in situ Raman Spectra can be strikingly 10.09 cm(-1), presenting remarkably effective load-transfer and leading to significant reinforcement. Additionally, unique morphology of CNTBs and the low compliance of rigid shish-kebab superstructure with large stereo hindrance could also contribute to the reinforcement of OBC/CNTB nanocomposites. In rheological tests, the nanocomposites exhibit quite low rheological percolation threshold of 0.34 wt% and gel point of 0.634 wt% as well as notable difference in terminal behavior in low frequency zone compared to that of neat OBC, revealing that the rigid bundle structure of CNTBs has remarkable effect on the viscoelastic behavior of OBC.