Miguel López-Manchado - Academia.edu (original) (raw)

Papers by Miguel López-Manchado

The Journal of Physical Chemistry C, 2010

Macromolecules, 2005

www.chemie.uni-freiburg.de/makro/kays.

The reinforcing effect of carbon nanofibres on rubber compounds, namely nitrile rubber (NBR) in r... more The reinforcing effect of carbon nanofibres on rubber compounds, namely nitrile rubber (NBR) in relation to conventional carbon fibres has been compared in this work. The carbon fibres exhibit a weak with the rubber matrix, however, the addition of carbon nanofibres sensibly improve the tensile properties respect to pristine elastomer, due mainly to its nanometer size and high surface-to-volume ratio. In order to improve the interaction filer-rubber at the interface and then, to increase the mechanical properties of these compounds, the superficial of carbon nanofibres was modified by using chemical and gas plasma treatments. The carbon nanofibres modified by plasma exhibit a great number of reactive groups on the surface, improving the compatibility with the rubber matrix, which is reflected in an increase of the final properties of the material. However, the chemical treatment of the carbon nanofibres hardly varies the properties of the compound, due to the degradation that the na...

European Polymer Journal, 2018

A comparative study on the mechanical, electrical and piezoresistive properties of polymer compos... more A comparative study on the mechanical, electrical and piezoresistive properties of polymer composites using carbon nanostructures of different topology

Composites Part B: Engineering, 2016

Graphene materials often are obtained through thermal reduction of graphite oxide. This is due to... more Graphene materials often are obtained through thermal reduction of graphite oxide. This is due to the fact that other synthesis methods are more difficult and generally render lower yield. The structure and morphology of these graphene materials could affect their performance in different applications. Herein, thermally reduced graphite oxide (TRGO) was obtained from thermal reduction of graphite oxide prepared by using the methods reported by Brodie and Hummers. The oxidation method greatly affects the structure and morphology of the resulting TRGO. TRGO obtained by the Brodie's method generates a morphology comprised of rather exfoliated galleries while that obtained by the Hummers method presents randomly distributed sheets. The influence of structural differences on the dispersion of TRGOs in natural rubber latex (NR) and on the resulting mechanical and electrical properties of the TRGO/NR nanocomposites is studied. The TRGO prepared by the Brodie's method (TRGO-B) showed a more homogeneous dispersion in the polymerematrix, rendering enhanced mechanical and electrical properties of their nanocomposites. TRGO-B/NR nanocomposites showed higher electrical conductivity, which is attributed to the formation of an electrically conducting filler network through the polymerematrix. This is consequence of the morphology presented by TRGO produced by the Brodie's method.

Journal of the Chilean Chemical Society, 2014

Inorganic fillers such as CaCO 3 and clays are widely used as fillers to improve the mechanical a... more Inorganic fillers such as CaCO 3 and clays are widely used as fillers to improve the mechanical and physical properties of polypropylene (PP). With the aim of improving simultaneously the stiffness and yield stress of PP, hybrid nanocomposites comprising PP/CaCO 3 /clay (montmorillonite) were prepared and their thermal and mechanical properties were investigated and compared with those of PP/CaCO 3 and PP/clay composites. Morphological characterizations of the composites were performed by SEM and XRD analyses. The results showed exfoliated clay in the hybrid composite with a much higher degree than in PP/ clay composite. Increase in modulus and yield stress and better thermal stability was attained for hybrid composites as a result of the clay exfoliation. The toughening effect of two different types of CaCO 3 particles was also observed in hybrid composites, where an effective enhancement of the mechanical and thermal properties were achieved depending on the origin, specific area, particle and pore size of the CaCO 3 used.

Soft Matter, 2009

Fully dispersed layered silicate nanoparticles (nanoclay) in a polymer matrix have provided a new... more Fully dispersed layered silicate nanoparticles (nanoclay) in a polymer matrix have provided a new class of multi-functional materials exhibiting several performance improvements over conventional composites. Yet challenges with miscibility and interfacial strength might prevent nanocomposites from realizing their full potential. In this paper we demonstrate the effect of the chemical characteristics of the nanoclay on the miscibility and dispersion in the polymer matrix as well as on the interfacial strength of the bound polymer and the nanoclay mobility, all of which determine the macroscopic properties of the nanocomposite.

Reactive and Functional Polymers, 2005

An ethylene-propylene copolymer (EPR) was functionalized in the melt by grafting with itaconic ac... more An ethylene-propylene copolymer (EPR) was functionalized in the melt by grafting with itaconic acid and its monoand di-methyl esters by using dicumyl peroxide as radical initiator. Grafting reactions were carried out in a Brabender-Plasticorder at 180°C under a nitrogen flow at a speed of 75 rpm for 6 min. Fourier transform infrared spectroscopy (FTIR) was used to confirm the existence of grafted monomers. The absorption bands characteristic of each monomer grafted were observed in the FTIR spectrum of the modified EPR and were taken as evidence of grafting. The percentage of grafting attained was also followed by FTIR analysis, where the amount of monomer incorporated in EPR was estimated from a calibration curve established for the monomers used in this work. The degree of grafting obtained was 1.1% by weight of EPR for itaconic acid, 1.2% for monomethyl itaconate and 2.5% for dimethyl itaconate. Rheological and contact angle measurements indicate that the polarity of EPR is increased by grafting reaction.

Polymer Engineering & Science, 2003

The mechanical properties and morphology of ternary composites based on PP-EPDM blends reinforced... more The mechanical properties and morphology of ternary composites based on PP-EPDM blends reinforced with natural flax fibers are analyzed. In order to evaluate the simultaneous effect of the incorporation of both elastomer and fibers, an experimental design based on a Doehlert Uniform Net has been employed. The tensile, flexural and impact behaviors of the composites are investigated, and the results show that flax fibers behave as an effective reinforcing agent in these systems. In fact, a considerable increase in the studied properties in the presence of the fibers was observed. It is interesting to note that the reinforcing effect is more noticeable as the EPDM content in the blend increases. Morphological studies by scanning electron microscopy (SEM) were also carried out.

Macromolecules, 2010

H low-field NMR spectroscopy and equilibrium swelling experiments. Multiple-quantum (MQ) NMR expe... more H low-field NMR spectroscopy and equilibrium swelling experiments. Multiple-quantum (MQ) NMR experiments provide detailed quantitative molecular information on the cross-link density of the elastomer matrix in a variety of filled systems, indicating generally weak filler effects on the overall cross-link density and on the network homogeneity. Swelling experiments, as well as mechanical data, are additionally influenced by the matrix-filler and filler-filler interactions. Our approach is based on comparing crosslink densities from NMR and (Flory-Rehner) swelling experiments, for which a masterline is always found in unfilled elastomers. In filled elastomers two different scenarios are observed. If there are no interactions between the polymer chains and the filler surface, no deviations from the masterline are detected because the swelling capacity of the composite is governed by the bulk polymer. Deviations from the masterline (reduced swelling) are exhibited by those composites that have strong rubber-filler interactions. In these cases, some fraction of the polymer is connected to the filler surface, which thus behaves like a giant cross-link, and the overall degree of swelling is thus reduced as compared to the bulk polymer. The novel experimental approach was used to evaluate filler-elastomer interactions in different composites and nanocomposites.

Macromolecular Materials and Engineering, 2003

Macromolecular Chemistry and Physics, 2001

Journal of Applied Polymer Science, 2003

... PDF (226K). Keywords: rubber; clay; nanocomposites; vulcanization kinetics. Abstract. ... vul... more ... PDF (226K). Keywords: rubber; clay; nanocomposites; vulcanization kinetics. Abstract. ... vulcanization reaction. However, until now, no studies on the vulcanization behavior ofrubberclay nanocomposites have been reported in the literature. ...

Composites Part B: Engineering, 2014

Composites Science and Technology

In this article, we examine the effects of two different nanostructured carbons when they are inc... more In this article, we examine the effects of two different nanostructured carbons when they are incorporated in a rubber matrix in terms of mechanical and electrical properties as well as the icephobic behaviour of the nanocomposites when swollen. Nitrile butadiene rubber composites reinforced with thermally reduced graphene oxide or multiwalled carbon nanotubes or both of them were prepared and characterized. At a particular hybrid filler loading, tensile and electrical tests showed a significant improvement of the composite. From the swelling studies, after the immersion, the nanocomposites experienced a reduction of the cross-link density that promotes weakening of ice adhesion, being this effect more evident for those samples prepared with hybrid fillers. In view of the composite formulations, that utilize commercially available elastomers and fillers, these findings would be applicable to the automotive and aviation sectors, where the demand for multifunctional rubbers is increasing.

Journal of applied …, 2003

... 6 Gupta, AK; Srinivasan, KR; Krisha Kumar, P. J Appl Polym Sci 1991, 44, 4415. 7 Gupta, AK; R... more ... 6 Gupta, AK; Srinivasan, KR; Krisha Kumar, P. J Appl Polym Sci 1991, 44, 4415. 7 Gupta, AK; Ratnan, BK; Srinivasan KR J Appl Polym Sci 1992, 45, 1303. ... 16 Oliveira, MG; Soanes, BG; Santos, CM; Diniz, MF; Dutra, RC Macromol Rapid Comm 1999, 10, 526. ...