Electrical properties of polyimide composite films containing TiO₂ nanotubes

Abstract

A study on the dielectric behavior of polyimide composite films containing different amounts of TiO 2 nanotubes (TNs) was performed. The films were prepared by casting solutions resulting from direct mixing of a poly(amic acid) and TNs onto glass plates, followed by thermal imidization. The influence of TNs content on the properties of polyimide composites was investigated. AFM and SEM analyses showed good compatibility between the filler and polymer matrix. Dynamic mechanical analysis and broadband dielectric spectroscopy were used to evidence relaxation processes into the films. The electrical properties were evaluated on the basis of dielectric constant and dielectric loss, and their variation with frequency and temperature. At moderate temperature a secondary b relaxation was observed while incorporation of TNs decreased the activation energy and facilitated the appearance of an additional b 1 process. An a relaxation and a conductivity process were evidenced at higher temperatures. The values of dielectric constant and dissipation factor increased with TNs amount, and the maximum of r relaxation peak shifted to higher temperatures. POLYM.

PI/TiC/TiO2 with Z-scheme heterostructure for the photocatalytic degradation of organic dyes

“…The CO asymmetric stretching vibration and bending peaks at 1776 cm −1 and 732 cm −1 , symmetric stretching vibration peak at 1716 cm −1 and stretching vibration peak at 1353 cm −1 of C–N are all characteristic peaks of PI. 30–32 The absorption band at 1550 cm −1 (–CO–NH asymmetric) attributed to the PAA precursor was not observed, confirming that the imidization reaction was complete. 33 Compared with PI, a broad band was observed at 457 cm −1 , which was attributed to the Ti–O–Ti bond.…”

“…PI showed a broad peak at 2y = 181, revealing its amorphous nature. 30,37 After adding TiO 2 , the new peaks at 25.31 and 48.01 in PI/TiO 2 corresponded to the (101) and (200) crystal planes of TiO 2 . 38 Compared with PI/TiO 2 , the new peaks at 2y = 35.91, 41.71, 62.41, 72.31 and 76.21 in PI/TiC/TiO 2 corresponded to the crystal planes of (111), ( 200), ( 220), (311) and (222) in TiC.…”

Thermally improved crystalline phase and intercalated PEO/OMMT nanocomposites for high to ultrahigh radio frequency range low‐permittivity nanodielectrics

“…Therefore, it can be concluded that the conductivity values of these PNC materials are dominated by the frequency as well as altered by filler concentration to some extent, which favors the literature values of conductivities reported for several other polymers and polymer-based composites in the radio frequency range. 29,37,41 It is noted that at the lower frequencies, the variation in conductivities of these PNCs is in the range of about one order magnitude which reduced gradually and overlapped at the higher frequencies. Additionally, the 1 and 3 wt% OMMT loaded PNC materials exhibited reduced conductivities than that of the PEO film at the lower frequencies whereas the 5, 10, and 20 wt% OMMT containing PNCs exhibited higher conductivities (see inset of Figure 5; σ 0 versus x (wt%) plot at 10 MHz).…”

A review on recent advances on improving polyimide matrix nanocomposites for mechanical, thermal, and tribological applications: Challenges and recommendations for future improvement

“…In recent years, various types of micro/nanoparticles, for example, alumina, silica, titanium dioxide, glass fibre, titanate nanotubes, carbon nanotubes, calcium carbonate, nano-clay, and graphite/graphene have been employed in the development of nanocomposites, such as polyimide nanocomposites, epoxy nanocomposites, polyester nanocomposites, and polypropylene composites, and so on for thermal, mechanical, tribological, and electrical applications. 9–32 Among these entire polymer based matrices, thermoplastic polyimide matrix has gained more attention as polymer matrix material in preparing composites for tribological, mechanical, and thermal application, owing to its good wear resistance, corrosion resistance, high strength to weight ratio, good interfacial bonding, better thermal stability, and had great applications in the field of aerospace and advance equipments. 33–37 As a result of this reported properties, polyimides (PIs) are widely accepted as a new generation of polymers with naturally rigid chains, which is of high commercial importance in the design of frictional components, such as soft seal, piston ring, gear, bear, and other tribological and/or constructive parts in demanding applications 38,39 as can been seen in Figure 1.…”