Effect of Carbon Nanofiber Structure on Crystallization Kinetics of Polypropylene/Carbon Nanofiber Composites

Abstract

Effect of heat treatment of carbon nanofibers (CNF) on electrical properties and crystallization behavior of polypropylene was reported. Two types of CNFs (untreated and heat treated at 2300 °C) were incorporated into polypropylene (PP) using intensive mixing. A significant drop in volume resistivity was observed with composites containing untreated 5 wt % and heat treated 3 wt % CNF. In non-isothermal crystallization studies, both untreated and heat treated CNFs acted as nucleating agents. Composites with heat treated CNFs showed a higher crystallization temperature than composites with untreated CNFs did. TEM results of CNF revealed that an irregular structure of CNFs can be converted into the continuous graphitic structure after heat treatment. Furthermore, STM showed that the higher carbonization temperature leads to the higher graphite degree which presents the larger carbon network size, suggesting that a more graphitic structure of CNFs led to a higher crystallization temperature of PP.

Carbon nanofiber type and content dependence of the physical properties of carbon nanofiber reinforced polypropylene composites

“…The incorporation of CNF into the polymer matrix is accompanied by an increase of crystallinity from 38% for the PP up to around 50% for the composites (Table ), related to the promotion of a more heterogeneous crystallization of the polymer by the fillers . This effect was observed even for the lower CNF concentrations, to be more specific, further addition above 0.5 vol% of CNFs does not lead to major improvement of the degree of crystallinity for PP/PR 19 LHT XT and PP/PR 25 PS XT composites.…”

“…Thermogravimetric analysis (TGA) was used to evaluate the thermal degradation of PP and nanocomposites and the filler matrix interaction .…”

Structural aspects of mechanical properties of iPP‐based composites. I. Composite iPP fibers with VGCF nanofiller

“…found an 18°C increase in the PP crystallization temperature with an addition of 5 wt % CNF . However, there was no significant effect of CNFs on the melting temperature and on the degree of crystallinity . Sandler et al .…”

“…Differential scanning calorimetry (DSC) and electron microscopy experiments have shown that carbon nanoparticles (CNT, CNF) can act as effective nucleating agents in PP matrix . In an isothermal crystallization study Lozano and Barrera observed, that the addition of 5 wt % CNF led to higher nucleation rate of PP and increased crystallization temperature by 8°C .…”