Sonication-Induced Modification of Carbon Nanotubes: Effect on the Rheological and Thermo-Oxidative Behaviour of Polymer-Based Nanocomposites

Abstract

The aim of this work is the investigation of the effect of ultrasound treatment on the structural characteristics of carbon nanotubes (CNTs) and the consequent influence that the shortening induced by sonication exerts on the morphology, rheological behaviour and thermo-oxidative resistance of ultra-high molecular weight polyethylene (UHMWPE)-based nanocomposites. First, CNTs have been subjected to sonication for different time intervals and the performed spectroscopic and morphological analyses reveal that a dramatic decrease of the CNT’s original length occurs with increased sonication time. The reduction of the initial length of CNTs strongly affects the nanocomposite rheological behaviour, which progressively changes from solid-like to liquid-like as the CNT sonication time increases. The study of the thermo-oxidative behaviour of the investigated nanocomposites reveals that the CNT sonication has a detrimental effect on the thermo-oxidative stability of nanocomposites, especially for long exposure times. The worsening of the thermo-oxidative resistance of sonicated CNT-containing nanocomposites could be attributed to the lower thermal conductivity of low-aspect-ratio CNTs, which causes the increase of the local temperature at the polymer/nanofillers interphase, with the consequent acceleration of the degradative phenomena.

The Advances in Biomedical Applications of Carbon Nanotubes

“…There are two main methods for the polymer modification: noncovalent attachment (polymer wrapping and absorption) and covalent attachment ("grafting") [37]. There is a range of studies on the effect of polymer modification on the electrochemical, mechanical, thermal, and rheological properties of CNTs [38][39][40][41]. In addition, polymer modification and hybridization with CNTs have been also actively studied with regard to bio-medical applications, particularly for bio-sensing [42][43][44].…”

Quantification of carbon nanotube dispersion and its correlation with mechanical and thermal properties of epoxy nanocomposites

“…For SEM analysis of nanocomposites, the samples are first polished with abrasive papers (grade: 400, 800, 1500, 2000 sequentially) and then with diamond polishing (0.5 μm) to attain the required surface finish. SEM micrographs of nanocomposites are later used with QSMA tool to quantify the CNT dispersion in epoxy matrix.…”

Structure, properties, and applications of polyacrylonitrile/carbon nanotube (CNT) fibers at low CNT loading

“…Sonication breaks CNT bundles and clusters, and is also known to reduce CNT length. [37][38][39] CNT/DMF dispersion was added into the reactor containing PAN solution with desired PAN solid content while stirring at 70 C. Excess DMF solvent was evaporated using a vacuum distillation process at 70 C to 80 C. The addition process was continued until the desired concentration of CNT (10 wt% with respect to the weight of polymer + CNT) was achieved. The final solid content (PAN and CNT) was 11.5 g/dL confirmed by thermogravimetric analysis test (TGA: Q-500 TA instrument).…”