Crystallization kinetics and interfacial behaviors of polypropylene composites reinforced with multi-walled carbon nanotubes

177

In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs) reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1, 0.2, 0.3, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. Electric conductivity, dynamic mechanical analysis (DMA), three point bending tests and fracture tests were then performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of materials. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased from 1014 Ω•m of neat epoxy to 10 Ω•m with 0.4% CNT. The experimental results also indicate that the frequency dependent behavior of CNT/epoxy nanocomposite can be modeled by R-C circuit, permittivity of material increase with increasing of CNT content. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17°C increase in Tg. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite

Section: Thermal Propertiessupporting

confidence: 85%

mentioning

confidence: 99%

Improvement in electrical, thermal and mechanical properties of epoxy by filling carbon nanotube

Zhou¹,

Wu²,

Cheng³

et al. 2008

177

“…Hu et al [88] first used coagulation method to prepare MWNT/PET composites and found that the percolation threshold of the composite was 0.9 wt%. Seo et al [89,90] presented that the conductivity of CNT/PP composites was increased with increasing the CNT content and the electrical percolation threshold was formed between 1 and 2 wt% CNTs. Meincke et al reported that percolation threshold of CNT/PA6 composite at CNT loading 4~6 wt%.…”

Section: Cnt/polymer Functional Composites 321 Electrical Propertimentioning

confidence: 99%

The present status and key problems of carbon nanotube based polymer composites

Du¹,

Bai²,

Cheng³

2007

408

250

Abstract. The state-of-art and key problems of carbon nanotube (CNT) based polymer composites (CNT/polymer composites) including CNT/polymer structural composites and CNT/polymer functional composites are reviewed. Based on the results reported up to now, CNTs can be an effective reinforcement for polymer matrices, and the tensile strength and elastic modulus of CNT/polymer composites can reach as high as 3600 MPa and 80 GPa, respectively. CNT/polymer composites are also promising functional composite materials with improved electrical and thermal conductivity, etc. Due to their multi-functional properties, CNT/polymer composites are expected to be used as low weight structural materials, optical devices, thermal interface materials, electric components, electromagnetic absorption materials, etc. However, the full potential of CNT/polymer composites still remains to be realized. A few key problems, such as how to prepare structurecontrollable CNTs with high purity and consistently dependable high performance, how to break up entangled or bundled CNTs and then uniformly disperse and align them within a polymer matrix, how to improve the load transfer from matrix to CNT reinforcement, etc, still exist and need to be solved in order to realize the wide applications of these advanced composites.

“…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].…”

mentioning

confidence: 99%

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

Xiong

Gao²,

Li³

2007

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.