Nonisothermal crystallization kinetics of carbon nanotubes containing segmented polyurethane elastomer

Abstract

Nanocomposites of the segmented polyurethane (SPU) elastomer with different concentrations of multiwall carbon nanotubes (MWCNTs) have been prepared. Scanning electron microscopy has been used to visualize the surface morphology and distribution of the nanotubes inside the matrix. Differential scanning calorimetry has been utilized to investigate the effects of MWCNTs on the crystallization characteristics of the SPU by collecting data at four cooling rates namely 5, 10, 15, and 20°C/min in the temperature range between 200°C to ambient. The results reveal that MWCNTs act as effective nucleating agent for crystallization of the hard segment of SPU and advance the onset and peak temperatures of crystallization by 38 and 23°C, respectively. The associated enthalpy and extent of crystallization are also increased by 34%. Different crystallization kinetic parameters have been calculated using both modified Avrami and combined Ozawa‐Avrami models to suggest a three dimensional growth of crystallization of SPU and its nanocomposites. The activation energy has been calculated using Kissinger method, which indicates that activation energy decreases with increasing concentration of MWCNTs. The calorimetric results have further been correlated with thermomechanical analysis and glass transition temperature of the nanocomposites corresponding to soft segment is found to increase by 20°C. POLYM. ENG. SCI., 56:1248–1258, 2016. © 2016 Society of Plastics Engineers

Formulation of micro‐phase separation kinetics of polyurethane nanocomposites

“…Moreover, the crystallinity of the TPU/MWCNT nanocomposites has been noticeably increased comparing pristine TPU due to positive nucleating effect of MWCNTs. Gupta et al have reported that incorporation of the MWCNTs into the PU matrix increases the onset and peak temperatures of crystallization, whereas decreases the activation energy of the nanocomposites due to heterogeneous nucleation effect of the MWCNTs . Song et al have proposed that the incorporation of clay nanoplates into the PU matrix decreases the size of the spherical aggregates, corroborating the key role of clay nanoplates on the aggregation performance of the hard domains …”

Micro‐phase separation kinetics of polyurethane nanocomposites with neural network

“…Gupta et al have reported that nucleation effect of the MWCNTs into the polyurethane matrix increases the onset and peak temperatures of crystallization .…”

Effect of nanofiller content and confined crystallization on the microphase separation kinetics of polyurethane nanocomposites

“…Due to the extremely high surface area in nanocomposites, an improvement of the mechanical, barrier and thermo-mechanical properties, and conductivity can be achieved at low filler contents which marks the main advantage of these materials over the microphase reinforced composites (less than 5 wt%) [8][9][10]. Crystallization behavior of polymer such as nucleation rate, crystallite size, crystallization temperature, and rate of crystal formation are altered by the presence of nanofillers [11,12]. Most of the relative crystallinity analyses are based on the Avrami equation which can describe the kinetics of polymer crystallization.…”