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

Thermal conductivity of carbon nanotubes and their polymer nanocomposites: A review

Recently, polymer nanocomposites reinforced with lower volume fraction of nanoceramics and carbon nanotubes have attracted steadily growing interest due to their peculiar and fascinating properties as well as their unique applications in commercial sectors. The incorporation of nanoceramics such as layered silicate clays, calcium carbonate or silica nanoparticles arranged on the nanometer scale with a high aspect ratio and/or an extremely large surface area into polymers improves their mechanical performances significantly. The properties of nanocomposites depend greatly on the chemistry of polymer matrices, nature of nanofillers, and the way in which they are prepared. The uniform dispersion of nanofillers in the polymer matrices is a general prerequisite for achieving desired mechanical and physical characteristics. In this review article, current development on the processing, structure, and mechanical properties of polymer nanocomposites reinforced with respective layered silicates, ceramic nanoparticles and carbon nanotubes will be addressed. Particular attention is paid on the structure–property relationship of such novel high-performance polymer nanocomposites.

Structural and mechanical properties of polymer nanocomposites

Polylactide (PLA)-based nanocomposites

Advances in understanding alkali-activated materials

The commercial grade of isotactic polypropylene was modified by a specific β-nucleating agent in a broad concentration range. The supermolecular structure of the specimens prepared by injection molding was characterized by X-ray scattering and correlated with mechanical behavior. It was found that at a critical nucleant concentration of 0.03 wt % the content of the β-modification virtually reaches a saturation level. With further addition of the nucleant, the β-phase content increases only slightly. The long period passes through a distinct maximum at the same nucleant concentration. This singularity in structure remarkably correlates with a minimum of the yield stress and maxima of strain at break and fracture toughness. Such general behavior is also reflected in the correlation between the β-phase concentration and fracture toughness profiles along the injection-molded bars. It is suggested that in the critically nucleated material an optimum thickness of the amorphous interlayer with connecting chains between the β-crystallites is established, rendering the material the highest possible ductility and toughness. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1174–1184, 2002

The effect of specific β‐nucleation on morphology and mechanical behavior of isotactic polypropylene

Tensile behaviour of isotactic polypropylene modified by specific nucleation and active fillers

Effect of clay treatment on structure and mechanical behavior of elastomer-containing polyamide 6 nanocomposite

We have studied an effect of three types of modifications of carbon nanotubes (CNTs) on dispersion and mechanical properties of final epoxy-amine based nanocomposites. First approach includes end-walled covalent chemical modification at the ends of nanotubes. The second one is side-walled covalent chemical modification along the whole length of nanotubes. The third procedure is noncovalent, physical modification done by the CNT surface coating with polyaniline. The modification of nanotubes was determined by X-ray photoelectron spectroscopy. The prepared epoxy-amine nanocomposites were characterized by dynamic-mechanical analysis, tensile testing, light microscopy, transmission electron microscopy, and thermogravimetry. We observed an improvement of the mechanical properties and the thermal stability by addition of the carbon nanotubes to the epoxy matrix. The strong interactions between the nanotube and the polymer matrix were discovered in the nanocomposites with physically modified nanotubes. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Modification of Carbon Nanotubes and Its Effect on Properties of Carbon Nanotube/Epoxy Nanocomposites

Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0.6μm), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering.

Jiří Kotek

Papers

The effect of specific β‐nucleation on morphology and mechanical behavior of isotactic polypropylene

Tensile behaviour of isotactic polypropylene modified by specific nucleation and active fillers

Effect of clay treatment on structure and mechanical behavior of elastomer-containing polyamide 6 nanocomposite

Modification of Carbon Nanotubes and Its Effect on Properties of Carbon Nanotube/Epoxy Nanocomposites

Strong synergistic effects in PLA/PCL blends: Impact of PLA matrix viscosity.