Morphological interpretations and their correlation with biphasic rheological networks and subsequent segmental relaxation, and electrical conductivity were comprehensively addressed for polyamide‐12/polypropylene‐multi‐walled carbon nanotubes (PA‐12/PP/MWNT) based ternary nanocomposites fabricated by melt mixing route. The partial migration of MWNT from PP to PA‐12 phase is evident from the spreading coefficient estimations based on interfacial dynamics and transmission electron microscopy (TEM) analysis. Melt rheology measurements based on scaling parameters associated with various viscosity models such as, Cross model, Carreau‐Yasuda model, and Berzin model indicated systematic variation in network rigidity that is in tune with dispersion‐selective nano‐morphology of the nanocomposites. The phase inversion was attained for composition in the range of 50 to 60 wt% of PP‐MWNT content as indicated by Han plot and van‐Gurp Palmen plots which is in direct correspondence to dispersed‐phase‐volume‐fraction range of ~0.3‐0.36. Broadening of loss‐peaks vis‐a‐vis enhanced storage moduli in dynamic mechanical analysis (DMA) signifies the reduced mobility (of polyamide chains) and hence the enhanced stiffness. The electrical conductivity of the nanocomposites post‐annealing decreased at temperatures above 100°C demonstrating the temperature‐sensitive morphology disruption (of the conductive PP‐MWNT channels) in the nanocomposites.
The effect of multi-walled carbon nanotubes (MWCNT) loading on the crystallization behavior of matrix polyamide 12 (PA-12), in PA-12/polypropylene-MWCNT (PP-MWCNT)-based nanocomposites were analyzed for their non-isothermal crystallization behavior at various cooling rates of 2.5–20 °C/min in differential scanning calorimetry (DSC). Several kinetic models such as Jeziorny (modified-Avrami), Mo and Tobin models were employed to analyze the crystallization behavioral trend with respect to time and temperature of the nanocomposites. The crystallization rate increased half-time of crystallization with MWCNT content as estimated from the Jeziorny theory. The linear agreement between Jeziorny model and experimental relative crystallinity outperforms the Tobin analysis where the coefficient of linear regression was found to be considerably trailing behind and off the satisfactory mark. The Mo model accounts for the percentage crystallinity and thereby successfully explained the crystallization behavior of PA-12 where the kinetic parameters increased with crystallinity indicating higher cooling rate for higher crystallinity. The MWCNT induced crystallization (nucleation activity) values were close to zero irrespective of MWCNT loading which reiterates the enhanced crystallization (rate) of PA-12 in the nanocomposites. Estimations based on Friedman approach showed inter-relationship between activation energy and crystallinity where the later was found to be governed by major (matrix) PA-12 phase.
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