Kinetics of nucleation and crystallization in poly(butylene succinate) nanocomposites

Differential fast scanning calorimetry (DFSC) was employed on poly(butylene succinate) nanocomposites containing silver nanoparticles and multi-walled carbon nanotubes (MWCNT), in order to identify the temperature range of heterogeneous nucleation caused by both nanofillers. The fast scanning rates also allow investigating self-nucleation by recrystallization experiments approaching the crystallization temperature from low temperatures. The recrystallization behavior of PBSu and its nanocomposites is distinct from all other polymers studied so far as only the previously crystallized part of the material is able to recrystallize, independently on the available large number of nuclei. Since full melting of small crystals at low temperatures is observed this highlights the importance of ordered structures remaining in the polymer melt. On cooling from the melt the neat polymer did not crystallize at rates higher than 70 K/s, while the nanocomposites needed rates of 500 K/s and 300 K/s for silver and MWCNT, respectively. Below 280 K the crystallization kinetics of the matrix was almost the same with the nanocomposite samples. The nucleation mechanism changes at 280 K from heterogeneous to homogeneous. The study further confirms that below the glass transition nucleation and crystallization appears only after approaching the enthalpy value of the extrapolated supercooled liquid by enthalpy relaxation. (C) 2014 Elsevier Ltd. All rights reserved.