Novel permittivity gradient carbon nanotubes/cyanate ester composites with high permittivity and extremely low dielectric loss

Abstract

Novel permittivity gradient (3-G) composites based on surface treated multi-walled carbon nanotubes (eMCNTs) and cyanate ester (CE) resin were successfully developed by the gravity sedimentation method. The composites consisting of original multi-walled carbon nanotubes (MCNTs) and CE resin, coded as MCNT/CE, were also prepared for comparison. Each composite was cut into three slices in the direction of thickness for evaluating the difference of dielectric properties over a wide frequency range from 1 to 10 9 Hz between the whole composites and their slices. Results show that the surface treatment of MCNTs is necessary to form 3-G composites because the good dispersion of nanotubes in the resin matrix and the attractive interfacial adhesion between nanotubes and the matrix are key aspects for guaranteeing the gradient distribution of the concentration of nanotubes in the composites. Note that two interesting phenomena were discovered. First, the whole composites show different conductive and dielectric properties from their slices, specifically, the percolation effect does not appear in either whole eMCNT/CE or MCNT/CE composites, while it can be observed in their slices. In addition, the percolation threshold of the eMCNT/CE slice is about 25% lower than that of the MCNT/ CE slice. Second, with regard to the whole composite and its slice with the same content of nanotubes, they have a similar dielectric constant, but the dielectric loss factor of the former is remarkably larger than that of the latter; these differences in properties are attributed to the different space distribution of the concentration of nanotubes between the whole composites and slices. These attractive features of eMCNT/CE composites suggest that the method proposed herein is a new approach to develop high performance 3-G composites, especially those with high dielectric constant and extremely low dielectric loss for cutting-edge industries.

Preparation of POSS/Quartz fibers/cyanate ester resins laminated composites

“…The highly symmetrical crosslinked structure of triazine rings and a few polar groups result in good dielectric properties (dielectric constant of 3.0–4.0 and dielectric loss of 0.005–0.010), which reveals good stability in a wide range of temperature and electric field frequency. Furthermore, a large number of aromatic rings, aryl and heterocyclic linkages and the unique triazine rings make CE resins possess high mechanical strength, excellent heat resistance properties, and high dimensional stabilities . Therefore, CE resins display potential application in radomes and antenna system of aircrafts.…”

Thermal and water absorption properties of cyanate ester resins modified by fluoride‐containing and silicone‐containing components

“…To our best knowledge, the research on CE resins has been mainly focused on thermal and dielectric properties, and few have evolved moisture absorption performance. The water absorption properties of cyanate ester resins are related to temperature, humidity, chemical medium type and concentration, etc . Generally, the composition and structure of the material are the determinants of the water absorption behavior .…”

“…The water absorption properties of cyanate ester resins are related to temperature, humidity, chemical medium type and concentration, etc . Generally, the composition and structure of the material are the determinants of the water absorption behavior . According to literature reports, the introduction of silicon‐ and fluorine‐containing components could efficiently reduce the overall polarity and void content within the resin matrix, hence reducing the water absorption of the materials .…”

Enhancing the dielectric properties of highly compatible new polyimide/γ-ray irradiated MWCNT nanocomposites

“…Considering high mechanical strength, good solvent resistance, excellent thermal stability, and low dielectric loss, PIs gained preference over other polymeric dielectrics [36][37][38][39][40][41][42] . Various researchers reported the dispersion of CNTs in poly(methyl methacrylate) 35 , PVDF 29,37,[48][49][50] , cyanate ester [51][52][53][54] , and polyurethane 34,55 . The applicability of PIs as dielectric material can be enhanced by substantially increasing their dielectric constant while retaining their high tensile strength, thermal stability, and chemical resistance.…”