Effects of carbon nanotubes on glass transition and crystallization behaviors in immiscible polystyrene/polypropylene blends

Abstract

Functionalized multiwalled carbon nanotubes (FMWCNTs) have been introduced into immiscible polystyrene/polypropylene (PS/PP) blends. Not only the change in glass‐transition temperatures of PS and PP but also the crystallization and melting behaviors of PP have been investigated. The results show that FMWCNTs exhibit dual effects in the blends. One is that FMWCNTs, as a plasticizer for both PS and PP, induce the change in glass‐transition behaviors in both PS and PP. The other is that FMWCNTs, as a heterogeneous nucleating agent for PP, change the crystallization behavior of PP from homogeneous/bulk crystallization process to only bulk crystallization process. Further results show that the presence of FMWCNTs also induces the morphology change of the immiscible blends to a certain degree. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

The effect of MWNTs concentration and nanofiber orientation on mechanical properties of PAA nanocomposite nanofibrous web

“…The reduction of T g in PAA/MWNTs nanofibers can be attributed to the easy movement of molecular chains of PAA because of the gap created by nanotubes and resulting in the increase of free volume between PAA molecular chains . Moreover, MWNTs can play the role of plasticizer and it enhances the polymer chain mobility to a certain extent .The broad endotherm peak at 180–280°C range in DSC curve for PAA nanofibers is due to dehydration of the adjacent carboxylic groups to form anhydrides which was associated with the weight loss of 23% in TGA curve. The reduction of the temperature range in this area for PAA/MWNTs sample indicates that nanotubes facilitate dehydration.…”

Mechanical and rheological response of polypropylene/boehmite nanocomposites

“…In particular, PP is extensively utilized not only for its balanced thermal and mechanical properties, but also due to its environmental friendliness and easy processability at a relatively low cost (Karger-Kocsis, 1999). PP has also been widely used in association with various types of nanofillers, such as carbon nanotubes and nanofibre (Ma et al, 2010;Wu et al, 2011;Rex J. Kuriger 2002), layered silicates (Ardanuy and Velasco, 2011;Olewnik et al, 2010;Perrinsarazin et al, 2005) and graphites (Kalaitzidou et al, 2007b;Kalaitzidou et al, 2007a;Li and Wu, 2012), nanoparticles such as silica (Pedrazzoli and Pegoretti, 2013;Sengupta et al, 2011) and calcium carbonate (Karamipour et al, 2011;Wang et al, 2010). An important role is played by such inorganic nanofillers, which can be usually dispersed at nanometric level without the addition of compatibilizers.…”

Electrical conductivity, phase behavior, and rheology of polypropylene/polystyrene blends with multi-walled carbon nanotube

“…With the incorporation of MWNT into PP/PS blend, crystallization peak of the blends shifts to the higher temperature. This observation is quite common to the general understanding of the role of nanofiller towards polymer crystallization (Ray et al 2007;Wu et al 2011). Moreover, the heat of crystallization of the PP estimated from DSC thermogram slightly decreases after use of PPMB and PSMB indicating that the degree of crystallinity of the PP is decreased.…”

“…Carbon nanotube has been proved to be an efficient nucleating agent for polymer crystallization because of their high aspect ratio, small size and good ability to reduce the nucleation activation energy of polymers (Wu et al 2011). Figure 12 shows the DSC cooling thermogram for PP/PS blend with and without MWNT.…”

“…This is known as a critical weight or volume percentage of fillers required for building up a continuous electrically conductive network throughout the polymer matrix and actually depends on the aggregation structure, porosity, average size, and size distribution of the conducting particles (Sircar and Lamond 1978), and on the polymer rheology (Sumita et al 1986) and processing conditions as well. Among the electrically conductive fillers, carbon nanotube-based composite tends to have higher conductivity and lower percolation threshold than either carbon black or carbon fiber based one (Antonucci et al 2007;Hwang et al 2010;Wu et al 2011;Wu and Shaw 2006). It is attempting to attribute this and other low thresholds simply to the high aspect ratio of the conductive filler.…”