Ultrasonic properties of composites of polymers and inorganic nanoparticles

Abstract

The temperature dependencies of ultrasonic velocity and attenuation were measured in composites of inorganic nanoparticles with two types of polymers, poly(urea) elastomer with inorganic Mo 6 S 4 I 6 nanowires and poly(e-caprolactone) (PCL) with Mo 6 S 3 I 6 nanowires. Below room temperature large ultrasonic relaxation attenuation maxima and velocity dispersion were observed. It was found that the attenuation peak in the elastomer shifted to higher temperature after doping with nanoparticles and this behavior was related to the shift of glass transition temperature. The ultrasonic attenuation data was fitted to a relaxation equation with a single temperature dependent relaxation time. The thermal activation energy of the relaxation process, which was calculated from ultrasonic data, was found to increase in the poly(urea) elastomer doped with MoSI nanowires. The low temperature ultrasonic velocity increased in the poly(urea) with nanowires added and is determined by the increase in elastic modulus. Similar ultrasonic behavior was obtained for PCL composites with inorganic MoSI nanowires. In this case, the increase in elastic modulus was smaller in comparison to the composites of poly (urea) and nanowires. Therefore, reinforcement of PCL was less pronounced.

Ultrasonic and Dielectric Studies of Polyurea Elastomer Composites with Inorganic Nanoparticles

“…This shift is due to a change of polymer dynamics in the presence of nanoscale structures that affect the glass transition temperature [20][21][22]. For attractive interactions between the polymer and the nanoparticles, the chain relaxation time is increased and leads to higher T g values relative to the pure polyurea matrix [8][9][10][11]. It should be noted that the relaxation strength can be attributed mainly to the polymer matrix because the ultrasonic attenuation peaks are almost the same for all JSD nanocomposites.…”

“…The reinforcement of polyurea and polycaprolactone polymers by the addition of small amounts of inorganic nanoparticles (0.1 to 5 wt-%) was also observed by ultrasonic velocity measurements [11], confirming the results obtained in previous studies where ellipsoidal silica-coated hematite nanoparticles were dispersed into a polyurea matrix [12][13]. In this way, we present the temperature dependence of the longitudinal ultrasonic velocity and the ultrasonic attenuation of these new polyurea elastomer composites with inorganic nanoparticles.…”

“…Recently, it was shown by ultrasonic and mechanical spectroscopy experiments that small amounts of MoS 2 nanotubes or Mo 6 S 4 I 6 nanowires embedded in polyurea matrices shifted the ultrasonic attenuation peak. This behavior was related to the shift of the glass transition towards higher temperatures [8][9][10][11].…”

Composites of Inorganic Nanotubes and Polymers

“…An increased sensitivity to ammonia is reported. The fi nal contribution by Samulionis et al focuses on the ultrasonic properties of composites of poly(-caprolactone) with MoSI nanowires [14].…”

Phase Transitions in Smectic Bent-Core Main-Chain Polymer Networks Detected by Dielectric and Ultrasonic Techniques

“…The combination of such bent-core based molecules with polymers results on macromolecular structures which keep the properties of both components, and [7], which showed interesting dielectric and polarization switching properties under electric field. There are not so many ultrasonic measurements especially at high frequencies in polymeric materials [8]. It might also be of interest the detection of piezoelectric sensitivity in BCLC by ultrasonic method as for inorganic lamellar crystals of the CuInP 2 S 6 family [9][10][11].…”