Barium titanate‐based nanodielectrics of two chemically recyclable thermosets

Abstract

In this work was investigated the effect of the addition of barium titanate (BaTiO3) on electrical properties of two chemically recyclable thermosets, polyhemiaminal (PHA) and polyhexahydro‐s‐triazine (PHT), both fabricated from 4,4′‐oxydianiline (ODA), an ether derivative of aniline and paraformaldehyde. Thermal and mechanical properties as well as chemical recyclability of the two polymers and their nanocomposites/nanodielectrics were also investigated. In addition, a quantitative analysis was conducted of the nanoparticle dispersion in the PHA‐/PHT‐based BaTiO3‐containing nanocomposites using transmission electron microscopy imaging and the nearest‐neighbor distance index and this index was used to analyze the investigated properties in connection with the proper mechanisms. Regarding the electrical properties for both neat polymers, conductivity values of the order of 10−8 S m−1 at 100 Hz were observed and dielectric constant values close to 2.80 for both polymers at 1 kHz. The addition of 0.5 wt% of BaTiO3 ferroelectric nanoparticles increased by about 44% the dielectric constant (1 kHz) and conductivity (102 Hz) of the PHA‐based nanocomposite. PHA and PHT exhibited glass transition temperature (Tg) values in the range 125–180 °C. An increase of 7 °C in Tg was observed after the incorporation of 0.5 wt% of BaTiO3 into PHA. Concerning the mechanical properties, values in the range 4.00–4.45 GPa for reduced modulus and 0.30–0.43 GPa for nanohardness for PHA and PHT polymers were observed. Independently of filler content or polymer matrix, both mechanical properties were enhanced after the addition of BaTiO3. The chemical recycling of PHA/PHT and all nanocomposites in the initial ODA reagent after sulfuric acid treatment was successfully characterized using the NMR and Fourier transform infrared spectroscopic techniques. © 2018 Society of Chemical Industry

Hydrophilic and hydrophobic silica‐based nanocomposites of chemically recyclable thermoset

“…While García et al 3 . and Bello et al 10 . performed PHT synthesis using the ODA monomer and verified T g values of 222 and 180 °C, respectively.…”

“…The two techniques are different; however, the values obtained for the elasticity modulus are similar to those reported in this work. Bello et al 10 . carried out the synthesis of PHT using the monomer ODA and obtained a reduced modulus of 4.5 GPa by nanoindentation.…”

“…It should be noted that there are additional signals in the spectra of neat polymers and nanocomposites when compared to the spectrum of the BAPP monomer. These additional signals are related to depolymerization byproducts 3,4,10 …”

Nanohydroxyapatite embedded blends of ethylene‐co‐vinyl acetate and millable polyurethane as piezoelectric materials: dielectric, viscoelastic and mechanical features

“…Different research programmes have been reported in connection with the fabrication of flexible polymeric materials with enhanced dielectric and piezoelectric features. [5][6][7][8] Flexible piezoelectric materials are exploited as pressure sensing devices in biomedical applications. 9 Developing piezoelectric materials compatible with biological systems is an interesting area of research.…”

“…Developing a smart material with good flexibility and electronic properties is a challenge for material scientists. Different research programmes have been reported in connection with the fabrication of flexible polymeric materials with enhanced dielectric and piezoelectric features 5–8 . Flexible piezoelectric materials are exploited as pressure sensing devices in biomedical applications 9 .…”