Non-isothermal crystallization kinetics of syndiotactic polystyrene polystyrene functionalized SWNTs nanocomposites

Abstract

Carbon nanotubes (CNTs) are unique nanostructured materials with remarkable physical, mechanical and electronic properties [1][2][3][4]. These properties make them attractive for applications in many scientific and technological fields such as electronic structures [5], polymer composites [6], and biological systems [7]. Among these potential applications, the prospect of obtaining high-performance CNT based polymeric nanocomposites has attracted the efforts of researchers in both academia and industry [8]. The combination of organic polymer components with CNT fillers in a single material has extraordinary significance for the development of advanced materials with remarkable mechanical, electrical, thermal and multifunctional properties [9][10][11][12]. Moreover, polymer/CNT nanocomposites challenge traditional filled polymers (loadings of 20 wt% or more) in many of these areas by providing similar physical enhancements but with as little as about 1 wt% addition of dispersed nanotubes [13]. Previous CNT based polymeric nanocomposites reports include increased modulus, impact strength, heat distortion temperature, and barrier properties with decreased thermal expansivity [14][15][16]. In addition, these nanocomposites are finding potential applications such as electrostatically dissipative materials and aerospace materials [17]. Currently, several processing methods, including melt mixing, solution process and in-situ polymerization [18][19][20] Abstract. Non-isothermal crystallization kinetics were characterized by using differential scanning calorimetry (DSC) analysis on neat semicrystalline syndiotactic polystyrene (sPS) and its nanocomposites with polystyrene (PS) functionalized full-length single walled carbon nanotubes (SWNT-PS), which was prepared by copper (I) catalyzed click coupling of alkyne-decorated SWNTs with well-defined, azide-terminated PS. The crystallization behavior of neat sPS polymer was compared to its SWNT based nanocomposites. The results suggested that the non-isothermal crystallization behavior of sPS/SWNT-PS nanocomposites depended significantly on the SWNT-PS contents and cooling rate. The incorporation of SWNT-PS caused a change in the mechanism of nucleation and the crystal growth of sPS crystallites, this effect being more significant at lower SWNT-PS content. Combined Avrami and Ozawa analysis was found to be effective in describing the non-isothermal crystallization of the neat sPS and its nanocomposites. The activation energy of sPS determined from nonisothermal data decreased with the presence of small quantity of SWNT-PS in the nanocomposites and then increased with increasing SWNT-PS contents.

Structure–property relationships in isotactic polypropylene/multi-walled carbon nanotubes nanocomposites

“…For the iPP/MWCNT nanocomposites the T c,1 peak shifts gradually to higher temperatures, as the amount of MWCNT increases, indicating that carbon nanotubes act as nucleating agents. This behavior has been reported previously in literature for polypropylene [24,[28][29][30] and other semicrystalline matrixes, such as polyamide [31][32][33][34] and polystyrene [35]. The observed increase of T c,1 is more pronounced at low nanotubes contents (T c,1 is increased by 13°C on addition of only 0.5 wt.% MWCNT) and becomes weaker as the amount of CNT increases (Table 1).…”

Morphological, Thermal, and Electrical Characterization of Syndiotactic Polypropylene/Multiwalled Carbon Nanotube Composites

“…The addition of the MWCNT causes a large initial increase of the crystallization temperature (T c ) (from 65.4 • C to 91.6 • C on addition of 0.5 wt.%) and then a gradual shift to higher temperatures (up to 100.6 • C for the highest amount of MWCNT), indicating the action of CNT as nucleating agents (Table 1). This behavior has been reported previously in the literature for iPP [20,21] and other semicrystalline matrixes, such as polyamide, [22][23][24][25] polystyrene, [26] and so on. It is noted that the nucleation ability of CNT usually leads to an increase in crystallization temperature by about 10 • C upon addition to the polymeric matrices (see [24] and references therein).…”

Kinetics and thermodynamics of adsorption of congo red on cellulose

“…To study the kinetics parameters for adsorption process the Avrami equation [18][19][20][21] is used to fit experimental results. This equation is as follows: (13) The linearized form of this equation is presented as: (14) where k a is the Avrami kinetic constant and is a measure of adsorption of adsorbate and n a is the Avrami exponent of time, which is related to the adsorption mechanism changes.…”