Dispersion Of Carbon Nanotubes In Polymers Research Articles

Progress on carbon nanotube filled polymer-based thermal conductive composites

<p indent="0mm">In the 5G era, the effective thermal management has become more demanding due to the ever-rising integration of electronic devices. High thermal conductivity materials play a crucial role in the field of thermal management, for example, thermal interface materials (TIMs) are used to fill the gap between the electronic chip and the heat sink to improve thermal transfer. In recent years, polymers have become a popular choice for thermal conductive materials because of their light, economical and excellent insulation and processability. To improve the thermal conductivity of materials, inorganic fillers with high thermal conductivity are generally composited with polymers. With the merits of high thermal conductivity, desirable chemical stability, carbon nanotubes (CNTs) are considered to have broad application potential in thermal conductive composites. Simple composition methods failed to increase thermal conductivity of composite materials to expected levels due to the large interfacial thermal resistance between CNTs and polymers and the disorderly distribution of CNTs in polymers. Therefore, reasonable design of polymer composites filled with CNTs is the key to achieving high thermal conductivity. This review mainly introduces the application of CNTs in thermal conductive polymer composites. Based on the existing theoretical research on thermal conductivity of composites and the application of molecular dynamics, more feasible strategies for improving the thermal conductivity of polymer composites filled with CNTs have been proposed. The approaches that improve the thermal conductivity of composites are mainly introduced from three aspects. (1) The intrinsic thermal conductivity of CNTs is an important factor affecting the thermal conductivity of polymer-based composites. CNTs and their macroscopic bulk materials both have excellent thermal conductivity. However, the thermal conductivity test results of the macroscopic materials of CNTs (such as CNTs fibers, arrays, and films) showed that the thermal conductivity of the macroscopic materials of CNTs was much smaller than that of single CNTs due to impurities, defects and inter-tube contact thermal resistance. Studies have shown that purification of CNTs and reduction of intertubular contact thermal resistance can improve the intrinsic thermal conductivity of CNTs. (2) From a microscopic perspective, phonons, the quantized energy of lattice vibration, are the main mechanism of heat conduction in most carbon fillers and polymers. Phonon scattering occurs in the process of phonon transfer, including the scattering between phonons and the scattering at the interface caused by defects and impurities, resulting in thermal resistance. The bonding strength of fillers and polymer interfaces are the crucial factors affecting the transmission of phonons. Hence, the thermal conductivity of composites could be effectively enhanced by surface treatment of CNTs, including covalent functionalization and non-covalent functionalization. Studies have shown that the functionalization can enhance the interfacial interaction between CNTs and polymers, while improving the dispersion of CNTs in polymers. (3) According to the thermal conduction network theory, the key to improving the thermal conductivity is whether the fillers can form a large number of continuous thermal conduction paths in the polymers and maintain a stable existence. However, high CNTs content usually affects the comprehensive properties of composites. To solve this problem, the arrangement and distribution of CNTs in the polymer should be improved to construct more heat conduction pathways, which can achieve high thermal conductivity at a low filling content. Here we introduce some effective methods, including the synergy effect, field orientation and the construction of 3D network structures. In this review, the characteristics and improvement effects of different technical approaches are summarized, which provides a reference for the research and application of CNT-filled polymer-based composites with high thermal conductivity. Finally, the future development prospects of carbon nanomaterial-filled polymer composites are discussed from perspectives of theoretical research, experimental design and engineering application.

Study of structural morphology, thermal degradation and surface charge decay in PU + PSF + CNTs polymer hybrid nanocomposite

Abstract Polyurethane (PU)/Polysulfone (PSF)/Multi Wall Carbon Nanotubes (CNTs) hybrid nanocomposite films were prepared by solution grown method with different wt% of functionalized CNTs. The structural and thermal properties of PU, PSF and PU + PSF + CNTs nanocomposite films were studied by various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR and TGA/DTG. The dispersion of CNTs in polymer was studied by SEM spectra, which indicates the presence of CNTs on the surface of the polymeric material. XRD results show the increases of crystallinity with different weight percentage of CNTs in polymer matrix. FTIR spectra reveal the position of different chemical bonds in pure and hybrid nanocomposite films. TGA and DTG show that the thermal stability of hybrid nanocomposite is better than PU and PSF due to reinforcement of CNTs in PU–PSF matrix. Surface charge decay study represents the charge stability in hybrid nanocomposite is due the localization of charge carriers in deeper traps.

Wear Characterization of Carbon Nanotubes Reinforced Polymer Gears

In last decade, polymeric gears have found wide applications in industrial fields. This is due to their advantages like noise reduction, self-lubricating features, weight reduction, cost savings as well as lower tribological characteristics in term of friction and wear. The main objective of this paper is to study the wear behavior of spur gears that makes polymer blended by carbon nanotubes (CNTs) (acetal). This was made by using appropriate adhesive oil (Paraffin) during injection moulding practice to produce thick flanges with diameter 134 mm and thickness 29 mm. The CNTs were produced by a fully automatic system using arc-discharge technique multi-electrodes. The synthesizing CNT/acetal flanges contain 1% CNTs by weight. The flanges were machined using CNC milling machine to produce spur gears. The dispersion of CNTs in polymer were examined by scanning electron microscope. The experiments were performed at a running speed of 1420 r/min and at torques of 13 and 16 N·m. In addition, the mechanical properties of CNT/acetal have been tested. The results showed that the wear resistances of the CNTs/acetal spur gears increased with the addition of CNT. The strength, Young's modulus and stiffness also increased while the hardness was not affected by the addition of CNT.

Polymer/Carbon Nanotube Composites

The unique geometry and extraordinary mechanical, electrical, and thermal conductivity properties of carbon nanotubes (CNTs) make them ideal candidates as functional fillers for polymeric materials. In this paper we review the advances in both thermoset and thermoplastic CNT composites. The various processing methods used in polymer/CNT composite preparation; solution mixing, in-situ polymerization, electrospinning, and melt blending, are discussed. The role of surface functionalization, including ‘grafting to’ and ‘grafting from’ using atom transfer radical polymerization (ATRP), radical addition–fragmentation chain transfer polymerization (RAFT), and ring-opening metathesis polymerization (ROMP) in aiding dispersion of CNTs in polymers and interfacial stress transfer is highlighted. In addition the effect of CNT type, loading, functionality and alignment on electrical and rheological percolation is summarized. We also demonstrate the effectiveness of both Raman spectroscopy and oscillatory plate rheology as tools to characterize the extent of dispersion of CNTs in polymer matrices. We conclude by briefly discussing the potential applications of polymer/CNT composites and highlight the challenges that remain so that the unique properties of CNTs can be optimally translated to polymer matrices.