Small but strong: A review of the mechanical properties of carbon nanotube–polymer composites

Materials with good flexibility and high conductivity that can provide electromagnetic interference (EMI) shielding with minimal thickness are highly desirable, especially if they can be easily processed into films. Two-dimensional metal carbides and nitrides, known as MXenes, combine metallic conductivity and hydrophilic surfaces. Here, we demonstrate the potential of several MXenes and their polymer composites for EMI shielding. A 45-micrometer-thick Ti3C2Tx film exhibited EMI shielding effectiveness of 92 decibels (>50 decibels for a 2.5-micrometer film), which is the highest among synthetic materials of comparable thickness produced to date. This performance originates from the excellent electrical conductivity of Ti3C2Tx films (4600 Siemens per centimeter) and multiple internal reflections from Ti3C2Tx flakes in free-standing films. The mechanical flexibility and easy coating capability offered by MXenes and their composites enable them to shield surfaces of any shape while providing high EMI shielding efficiency.

Electromagnetic interference shielding with 2D transition metal carbides (MXenes)

We review the present state of polymer nanocomposites research in which the fillers are single-wall or multiwall carbon nanotubes. By way of background we provide a brief synopsis about carbon nanotube materials and their suspensions. We summarize and critique various nanotube/polymer composite fabrication methods including solution mixing, melt mixing, and in situ polymerization with a particular emphasis on evaluating the dispersion state of the nanotubes. We discuss mechanical, electrical, rheological, thermal, and flammability properties separately and how these physical properties depend on the size, aspect ratio, loading, dispersion state, and alignment of nanotubes within polymer nanocomposites. Finally, we summarize the current challenges to and opportunities for efficiently translating the extraordinary properties of carbon nanotubes to polymer matrices in hopes of facilitating progress in this emerging area.

Polymer Nanocomposites Containing Carbon Nanotubes

Carbon nanotubes (CNTs) hold the promise of delivering exceptional mechanical properties and multi-functional characteristics. Ever-increasing interest in applying CNTs in many different fields has led to continued efforts to develop dispersion and functionalization techniques. To employ CNTs as effective reinforcement in polymer nanocomposites, proper dispersion and appropriate interfacial adhesion between the CNTs and polymer matrix have to be guaranteed. This paper reviews the current understanding of CNTs and CNT/polymer nanocomposites with two particular topics: (i) the principles and techniques for CNT dispersion and functionalization and (ii) the effects of CNT dispersion and functionalization on the properties of CNT/polymer nanocomposites. The fabrication techniques and potential applications of CNT/polymer nanocomposites are also highlighted.

Dispersion and functionalization of carbon nanotubes for polymer-based nanocomposites: a review

Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

This paper reviews recent studies conducted on carbon nanotube/polymer composites. Carbon nanotubes are promising new materials for blending with polymers with potential to obtain low-weight nanocomposites of extraordinary mechanical, electrical, thermal and multifunctional properties. The size scale, aspect ratio and properties of nanotubes provide advantages in a variety of applications, including electrostatically dissipative materials; advanced materials with combined stiffness, strength and impact for aerospace or sporting goods; composite mirrors; automotive parts that require electrostatic painting and automotive components with enhanced mechanical properties. The various processing methods for producing these nanocomposites are discussed, in particular melt mixing, solution processing and in-situ polymerization. Some key results are summarized, relating to the mechanical, electrical, thermal, optical and surface properties. Finally, the challenges for the future are discussed in terms of processing, characterization, nanotube availability, nanotube tailoring, and the mechanisms governing the behavior of these remarkable nanoscale composites. Polym. Compos. 25:630–645, 2004. © 2004 Society of Plastics Engineers.

Big returns from small fibers: A review of polymer/carbon nanotube composites

Electromagnetic interference shielding mechanisms of CNT/polymer composites

A review of vapor grown carbon nanofiber/polymer conductive composites

This study shows that a limiting dispersed phase particle size exists at very low concentrations for polymer blends mixed in an internal batch mixer and two types of twin-screw extruders. The Taylor limit for breakup of a single drop in a matrix underpredicts the limiting particle size; this discrepancy is attributed to viscoelastic effects. For uncompatibilized blends, the final particle size increases with the dispersed phase concentration due to increased coalescence. The particle size distribution also broadens at higher concentrations. Using in-situ reaction during blending or adding premade diblock copolymers suppresses coalescence resulting in smaller particle size and narrower particle size distribution. Using premade block copolymers is not as efficient in stabilizing morphology as using reactive polymers. It is shown that the main advantage of using compatibilizers in polymer blends is the suppression of coalescence achieved through stabilizing the interface, not a reduction in the interfacial tension. There is a critical shear rate in polymer systems where a minimum particle size is achieved. A qualitative explanation of why this occurs is given based on droplet elasticity

Uttandaraman Sundararaj

Papers

Big returns from small fibers: A review of polymer/carbon nanotube composites

Electromagnetic interference shielding mechanisms of CNT/polymer composites

A review of vapor grown carbon nanofiber/polymer conductive composites

Drop Breakup and Coalescence in Polymer Blends - The Effects of Concentration and Compatibilization

EMI shielding effectiveness of carbon based nanostructured polymeric materials: A comparative study