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Garate H.,CONICET | Garate H.,CEA Saclay Nuclear Research Center | Pietrasanta L.I.,CONICET | Goyanes S.,LPandMC | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2017

Hierarchical assembly of hard/soft nanoparticles holds great potential as reinforcements for polymer nanocomposites with tailored properties. Here, we present a facile strategy to integrate polystyrene-grafted carbon nanotubes (PSgCNT) (0.05-0.3 wt %) and poly(styrene-b- [isoprene-ran-epoxyisoprene]-b-styrene) block copolymer (10 wt %) into epoxy coatings using an ultrasound-assisted noncovalent functionalization process. The method leads to cured nanocomposites with core-shell block copolymer (BCP) nanodomains which are associated with carbon nanotubes (CNT) giving rise to CNT-BCP hybrid structures. Nanocomposite energy dissipation and reduced Young's Modulus (E∗) is determined from force-distance curves by atomic force microscopy operating in the PeakForce QNM imaging mode and compared to thermosets modified with BCP and purified carbon nanotubes (pCNT). Remarkably, nanocomposites bearing PSgCNT-BCP conjugates display an increase in energy dissipation of up to 7.1-fold with respect to neat epoxy and 53% more than materials prepared with pCNT and BCP at the same CNT load (0.3 wt %), while reduced Young's Modulus shows no significant change with CNT type and increases up to 25% compared to neat epoxy E∗ at a CNT load of 0.3 wt %. The energy dissipation performance of nanocomposites is also reflected by the lower wear coefficients of materials with PSgCNT and BCP compared to those with pCNT and BCP, as determined by abrasion tests. Furthermore, scanning electron microscopy (SEM) images taken on wear surfaces show that materials incorporating PSgCNT and BCP exhibit much more surface deformation under shear forces in agreement with their higher ability to dissipate more energy before particle release. We propose that the synergistic effect observed in energy dissipation arises from hierarchical assembly of PSgCNT and BCP within the epoxy matrix and provides clues that the CNT-BCP interface has a significant role in the mechanisms of energy dissipation of epoxy coating modified by CNT-BCP conjugates. These findings provide a means to design epoxy-based coatings with high-energy dissipation performance. © 2016 American Chemical Society.

Fama L.M.,LPandMC | Fama L.M.,CONICET | Fama L.M.,University of Buenos Aires | Pettarin V.,CONICET | And 4 more authors.
Carbohydrate Polymers | Year: 2011

In this work, novel starch based nanocomposites containing very small quantities of multi-walled carbon nanotubes (MWCNTs) (0.027 wt% and 0.055 wt%) were developed. These materials exhibited highly improved tensile and impact properties as a consequence of wrapping the MWCNTs with a starch-iodine complex composed by the same starch of the matrix. Thus, good dispersion of the filler in the matrix and excellent adhesion between phases (as shown in FE-SEM micrographs) were achieved. Increments up to almost 70% in stiffness and 35% in ultimate tensile strength, keeping deformations higher than 80% without break were found. Therefore, tensile toughness also increased up to ∼50%. Enhancements of up to ∼100% in biaxial impact parameters (thickness related perforation energy and disc maximum strength values) were also observed. The significant improvements in all uniaxial tensile and biaxial impact properties obtained for such significantly low contents of filler, as a result of the type of functionalization used, have not been already reported in the literature and point out these biodegradable composites as a very appealing alternative to traditional materials for different applications. © 2010 Elsevier Ltd. All rights reserved.

Felisberto M.,LPandMC | Sacco L.,LPandMC | Mondragon I.,University of the Basque Country | Rubiolo G.H.,LPandMC | And 3 more authors.
Materials Letters | Year: 2010

A new approach to chemical vapour deposition (CVD) growth of carbon nanotubes (CNTs) using commercial magnetite nanoparticles, avoiding its in situ synthesis, is reported. Commercial magnetite nanoparticles were used as catalyst material to growth multiwalled carbon nanotubes by chemical vapour deposition onto a silicon substrate of several square centimeters in area. It is shown that the application of an alternating electric field during the deposition of catalytical nanoparticles is an effective technique to avoid their agglomeration allowing nanotube growth. Scanning electron microscopy showed that the nanotubes grow perpendicularly to the substrate and formed an aligned nanotubes array. The array density can be controlled by modifying the deposited nanoparticle concentration. © 2010 Elsevier B.V. All rights reserved.

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