Institute of Carbon Chemistry CSIC

Zaragoza, Spain

Institute of Carbon Chemistry CSIC

Zaragoza, Spain
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Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Ashrafi B.,NRC Institute for Aerospace Research | Naffakh M.,CSIC - Institute of Polymer Science and Technology | Gonzalez-Dominguez J.M.,Institute of Carbon Chemistry CSIC | And 4 more authors.
Carbon | Year: 2011

Novel poly(ether ether ketone) (PEEK)/single-walled carbon nanotube (SWCNT)/glass fiber laminates incorporating polysulfone as a compatibilizing agent were fabricated by melt-blending and hot-press processing. Their morphology, mechanical, thermal and electrical properties were investigated and compared with the behavior of similar non-compatibilized composites. Scanning electron micrographs demonstrated better SWCNT dispersion for samples with polysulfone. Thermogravimetric analysis indicated a remarkable improvement in the thermal stability of PEEK/glass fiber by the incorporation of SWCNTs wrapped in the compatibilizer, ascribed to a significant thermal conductivity enhancement. Differential scanning calorimetry showed a decrease in the crystallization temperature and crystallinity of the polymer with the addition of both wrapped and non-wrapped SWCNTs. The laminates exhibit anisotropic electrical behavior; their conductivity out-of-plane is lower than that in-plane. Dynamic mechanical studies revealed an increase in the storage modulus and glass transition temperature in the presence of polysulfone. Mechanical tests demonstrated significant enhancements in stiffness, strength and toughness by the incorporation of wrapped nanofillers, whilst the mechanical properties of non-compatibilized composites only improved marginally. Samples with laser-grown SWCNTs exhibit enhanced overall performance. This investigation confirms that SWCNT-reinforced PEEK/glass fiber compatibilized composites possess excellent potential to be used as multifunctional engineering materials in industrial applications. © 2011 Elsevier Ltd. All rights reserved.


Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Martinez G.,CSIC - Institute of Polymer Science and Technology | Gonzalez-Dominguez J.M.,Institute of Carbon Chemistry CSIC | Anson A.,Institute of Carbon Chemistry CSIC | And 2 more authors.
Journal of Materials Chemistry | Year: 2010

A hydroxylated poly(ether ether ketone) (HPEEK) derivative has been covalently grafted onto the surface of acid-treated single-walled carbon nanotubes (SWCNTs) following two different esterification approaches. The hydroxylation degree of the HPEEK and the extent of the grafting reactions were determined by thermogravimetric analysis. Microscopic observations revealed an increase in the bundle diameter of the SWCNTs and the heterogeneous composition of the synthesized samples. Infrared, nuclear magnetic resonance and X-ray photoelectron spectra corroborated the grafting success, showing the appearance of signals associated with the ester group. The polymer-grafted SWCNTs display higher decomposition temperatures and a wider range of thermal degradation than the HPEEK. The esterification decreases the crystallization and melting temperature as well as the crystallinity of the HPEEK. The semicrystalline nature of the grafted samples was confirmed by X-ray diffraction analysis, which reveals a diminution in the crystal size of the polymer. Dynamic mechanical studies show an exceptional increase in the storage modulus and glass transition temperature of the polymer by the attachment to the SWCNTs. Slightly better thermal and mechanical properties are observed for the sample with the higher esterification degree. The HPEEK-grafted SWCNTs can be used as fillers to prepare PEEK nanocomposites with enhanced performance. © 2010 The Royal Society of Chemistry.


Diez-Pascual A.M.,CSIC - Institute of Polymer Science and Technology | Martinez G.,CSIC - Institute of Polymer Science and Technology | Martinez M.T.,Institute of Carbon Chemistry CSIC | Gomez M.A.,CSIC - Institute of Polymer Science and Technology
Journal of Materials Chemistry | Year: 2010

High-performance poly(ether ether ketone) (PEEK) nanocomposites have been prepared via melt-blending by the incorporation of a hydroxylated polymer derivative (HPEEK) covalently grafted onto the surface of single-walled carbon nanotubes (SWCNTs). Their morphology, thermal, mechanical and electrical properties have been investigated and compared with the behaviour of composites reinforced with similar non-grafted fillers. Microscopic observations reveal that the grafting of the HPEEK onto the SWCNTs facilitates their dispersion within the matrix. The crystallization and melting temperature of PEEK decrease upon incorporation of the HPEEK-grafted SWCNTs, ascribed to the restrictions on polymer chain mobility imposed by the strong CNT-matrix interactions. The addition of these fillers leads to an exceptional increase in the thermal stability, storage modulus and glass transition temperature of the matrix. Tensile tests show unprecedented improvements in the Young's modulus, strength and toughness of the composites by the polymer grafting, attributed to a very effective load transfer achieved through covalent and hydrogen bonding. Electrical conductivity measurements indicate that the typical percolation behaviour takes place at very low SWCNT contents. In contrast, the thermal conductivity increases almost linearly with the filler loading. This approach is a simple, scalable and efficient method to improve the overall performance of thermoplastic nanocomposites for potential lightweight structural applications. © 2010 The Royal Society of Chemistry.

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