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Papers by Javier Cañavate

Polymers, Mar 27, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Philosophy of engineering and technology, 2015

The inclusion of competences related to social context in engineers’ education has been recommend... more The inclusion of competences related to social context in engineers’ education has been recommended by several organizations and authors. Among these abilities appears the development of reflective and behavioral skills or the awareness of public debate in engineering. In order to create an engineer profile with expanded social commitment, some criteria have been implemented by accreditation boards.

Polymers, May 25, 2020

The amount of elastomeric waste, especially from tires is constantly increasing on a global scale... more The amount of elastomeric waste, especially from tires is constantly increasing on a global scale. The recycling of these residua should be considered a priority. Compounding the waste rubbers with other polymers can be an excellent alternative to reuse waste materials. This procedure requires solving the issue of the lack of compatibility between the waste rubber particles and other polymers. Simultaneously, there is a claim for introducing biodegradable plastics materials to reduce their environmental impact. In this work, reclaimed rubber/poly(ε-caprolactone) (RR/PCL) blends are proposed to enhance the recycling and upcycling possibilities of waste rubbers. The results show that the addition of PCL to the RR allows obtaining blends with improved mechanical properties, good thermal stability, and enhanced interfacial compatibility between the used components. Structure and properties of the proposed RR/PCL have been studied by means of static and dynamic mechanical testing, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA)-FTIR analysis.

Journal of Biological Chemistry, 2002

Zinc is present at high concentrations in the photoreceptor cells of the retina where it has been... more Zinc is present at high concentrations in the photoreceptor cells of the retina where it has been proposed to play a role in the visual phototransduction process. In order to obtain more information about this role, the study of the effect of zinc on several properties of the visual photoreceptor rhodopsin has been investigated. A specific effect of Zn 2؉ on the thermal stability of rhodopsin, obtained from bovine retinas and solubilized in dodecyl maltoside detergent, in the dark is reported. The thermal stability of rhodopsin in its ground state (dark state) is clearly reduced with increasing Zn 2؉ concentrations (0-50 M Zn 2؉). The thermal bleaching process is accelerated in the presence of Zn 2؉ with k rate constants, at 55°C, of 0.028 ؎ 0.002 min ؊1 (0 M Zn 2؉) and 0.056 ؎ 0.003 min ؊1 (50 M Zn 2؉), corresponding to t1 ⁄2 values of 24.4 ؎ 1.6 min and 11.8 ؎ 0.1 min, respectively. Thermodynamic parameters derived from Arrhenius plots show a significant E a increase at 50 M Zn 2؉ for the process, with ⌬G ‡ decrease and increase in ⌬H ‡ and ⌬S ‡ possibly reflecting conformational rearrangements and reordering of water molecules. The stability of the metarhodopsin II intermediate is also decreased and changes in the metarhodopsin II decay pathway are also detected. The extent of rhodopsin regeneration in vitro is also reduced by zinc. These effects, specific for zinc, are also seen for rhodopsin in native disc membranes, and may be relevant to the suggested role of Zn 2؉ in normal and pathological retinal function.

Fibers, 2016

This paper studies the addition of fibers from end-of-life tires to commercial mortar mixtures. T... more This paper studies the addition of fibers from end-of-life tires to commercial mortar mixtures. Two different types of mortar, one lime-plastic and other cement-fluid, are mixed with different percentage of fibers ranging from 0% to 1%. The changes in bulk density, consistency, compressive and flexural strength, dynamic Young modulus and water absorption are studied. According to the results, consistency is the property that shows more relevant changes for an addition of 0.25% fibers. Consistency is related to workability and affects the water absorption and the Young modulus values. On the contrary, bulk density and mechanical properties did not change with the addition of fibers. The results prove that this fiber, considered a waste from recycling of end-of-life tires, can be used in commercial mixtures without losing strength. On the other hand, mortar workability limits the amount of fibers that can be included in the mixture and this parameter determines the performance of the mortar.

Polymers

The environmental degradation of the films used in packaging is a key factor in their commercial ... more The environmental degradation of the films used in packaging is a key factor in their commercial use. Industrial and academic research is aimed at obtaining materials that have degradation features that ensure their eco-sustainability but, at the same time, preserve their use properties during storage and distribution periods. This study analyzes the degradability behavior over time of commercial packaging that meets the requirements of the UNE 13432 standard and the prEN 17427 (2020) home composting certification requirements under standard storage conditions. The study attempts to provide insight into the durability of the films under standard storage conditions, verifying that this type of packaging has a useful life of more than 12 months and that after this storage period it still retains the usability properties for which it was conceived. The analyzed sample has been manufactured using a three-layer technology under some commercial formulations based on PBAT + STARCH + PLA an...

Journal of Composite Materials, Mar 15, 2011

Thermoplastic vulcanizates (TPVs) are a specific group of the so called thermoplastic elastomers.... more Thermoplastic vulcanizates (TPVs) are a specific group of the so called thermoplastic elastomers. The main characteristic is the existence of a crosslinked rubber phase obtained by dynamic vulcanization in the presence of the thermoplastic matrix. This article studies TPVs based on ground tyre rubber (GTR), high-density polyethylene, and ethylene propylene diene monomer rubber. Vulcanization is performed by a new peroxide developed to resist high temperatures and an standard one. The aim of this study is optimize the formulation in order to include GTR, while maintaining a good balance of properties in the final TPV material. The use of GTR would improve the possibilities of recovering tyre waste. A detailed study regarding the influence of each component in the final mechanical properties has been carried out. The swelling properties, ATR infrared spectroscopy, TGA, and DSC analysis indicated a high degree of crosslink and good adhesion between the matrix and the rubber phase. Morphology of the composites was assessed by scanning electron microscopy. A composite containing a combination of peroxides and 40/30/30 of HDPE, EPDM, and GTR was found to show a good balance of characteristics regarding mechanical properties, crosslinking, and adhesion between phases.

Polymer-plastics Technology and Engineering, Nov 25, 2000

... The decrease of end epoxy rings during the reaction can be measured by quantitative analysis ... more ... The decrease of end epoxy rings during the reaction can be measured by quantitative analysis using FTIR spectroscopy [4]4. Ishida, H. and Koenig, J. 1978. Colloid Interf. ... This type of analysis has been successfully used in kinetic [5]5. Antoon, M. and Koenig, J. 1981. J. Polym. ...

Materials, Jan 22, 2022

Polymer Bulletin, Apr 20, 2000

This paper studies polymer composites formed by a polystyrene matrix (PS) and a block copolymer o... more This paper studies polymer composites formed by a polystyrene matrix (PS) and a block copolymer of poly(styrene-butadiene) (SBS). Two series of polymer composites with different compositions have been prepared: the first by extrusion followed by injection and the second by dissolution and evaporation of the solvent from the injected samples. The comparison of the FTIR spectra of the polymer composites with those simulated by addition of the spectra of the component polymers allows the detection of differences attributed to the existence of interactions between both polymers that cause partial miscibility between them. The results obtained are corroborated by differential scanning calorimetry.

In this paper, ground tire rubber (GTR) was mechano-chemically modified with road bitumen 160/220... more In this paper, ground tire rubber (GTR) was mechano-chemically modified with road bitumen 160/220 and subsequently treated using a microwave radiation. The combined impact of bitumen 160/220 content and microwave treatment on short-term devulcanization of GTR were studied by thermal camera, wavelength dispersive X-ray fluorescence spectrometry (WD-XRF), static headspace and gas chromatography-mass spectrometry (SHS-GC-MS), thermogravimetric analysis combined with Fourier transform infrared spectroscopy (TGA-FTIR), oscillating disc rheometer and static mechanical properties measurements. The obtained results showed that bitumen plasticizer prevent oxidation of GTR during microwave treatment and simultaneously improves processing and thermal stability of obtained reclaimed rubber.

RSC green chemistry series, 2018

This chapter deals with the study of different approaches to improve the compatibility of waste r... more This chapter deals with the study of different approaches to improve the compatibility of waste rubber with polymeric matrixes of high density polyethylene (HDPE) by using surface treatments to increase adhesion. Different surface treatments such as etching with sulphuric and nitric acids, the use of a silane as a coupling agent and chlorination with trichloroisocyanuric acid (TCI) have been applied. The modification of waste rubber by grafting has also been studied. This process is based on the dynamical crosslinking of ethylene propylene diene monomer (EPDM) with peroxides. The mechanical properties of the resulting materials were studied and compared. The chemical modifications that occurred on the waste rubber were monitored by Fourier-transform infrared spectroscopy (FTIR). The behaviour of the materials at the fracture was assessed by means of scanning electron microscopy (SEM). The results of treated and untreated samples were compared with neat HDPE. Waste rubber, added to HDPE in small quantities, acts as a filler, improving the stiffness and providing a more brittle behaviour. Treatment with TCI gave poor mechanical properties obtaining lower values than neat HDPE in some cases, and in general worst properties than the other methods. The most interesting mechanical properties have been obtained by a grafting process based on EPDM dynamically crosslinked with a mixture of peroxides T-311 and dicumyl peroxide (DCP).

Materials, Feb 22, 2023

Express Polymer Letters, 2019

Environmentally-friendly microwave heating is increasingly used in polymer chemistry and technolo... more Environmentally-friendly microwave heating is increasingly used in polymer chemistry and technology. The selectivity and highly efficiency in the heat transfer present a huge advantage in systems based on recycling, improving their productivity and economic competitiveness. In case of the industrial recycling of waste rubbers, especially end-of-life tires, microwave-induced devulcanization and pyrolysis are nowadays considered as promising approaches. This work aims to report the recent progress in microwave treatments of vulcanized rubbers with different compositions. Special attention is focused on the correlation between microwave processing parameters and devulcanization/pyrolysis efficiency, which have a significant impact on the structure-property relationships of the obtained products. Moreover, the main challenges affecting the future of the industrial application of the microwave technology in rubber recycling are also discussed.

Afinidad, 2011

La gestion de los neumaticos al final de su ciclo de vidaprecisa soluciones para potenciar su reu... more La gestion de los neumaticos al final de su ciclo de vidaprecisa soluciones para potenciar su reutilizacion y reciclado.Un paso previo consiste en la pulverizacion de losneumaticos por parte de empresas especializadas. La incorporacionde este granulado como refuerzo en matricestermoplasticas se ha propuesto como metodo de valorizaciondel polvo de neumatico. Este sistema se ve limitadopor la incompatibilidad entre matriz y refuerzo. Recientemente,un nuevo polvo de neumatico, denominado comercialmente “desvulcanizado” ha aparecido en el mercado.En este articulo se comparan materiales compuestosformulados con polvo de neumatico desvulcanizado conlos obtenidos con el mismo material sin tratamiento enmatriz de polietileno de alta densidad. Tambien se estudiael efecto de distintos metodos de mezclado, del uso deaditivos dispersantes y del tamano de particula.

Materials, Sep 16, 2021

The dynamic development of the automotive industry resulted in a significant increase in rubber w... more The dynamic development of the automotive industry resulted in a significant increase in rubber wastes, especially end-of-life tires, which are a serious threat to the natural environment and human health. This situation has enforced the industry and academic research groups to search new and cost-effective methods for recycling waste tires. In this field of research, reactive processing and functionalization seem to be a very promising approach to extend recycling and the ‘up-cycling’ of ground tire rubber. This chapter presents recent progress in the modification of waste rubber and valorization strategies with special attention on structure-properties relationships of the products obtained.

Afinidad, Jul 1, 2019

espanolLa creciente cantidad de neumaticos utilizados en la industria ha inducido a los investiga... more espanolLa creciente cantidad de neumaticos utilizados en la industria ha inducido a los investigadores a encon-trar alternativas para el reciclaje de los neumaticos al final de su vida util. Varias alternativas propuestas para este fin incluyen la incorporacion de caucho tri-turado de neumatico GTR como relleno en materia-les compuestos. El principal inconveniente que pre-senta este metodo es la falta de compatibilidad entre el GTR y la matriz de polimero. Con el fin de resolver este problema, la desvulcanizacion por microondas se ha revelado un procedimiento interesante puesto que cuando el GTR tratado con microondas se in-corpora a una matriz elastomerica, puede conseguir-se mejorar la reticulacion posterior si se realiza un vulcanizado. En este articulo, una mezcla formada por caucho natural NR y caucho de nitrilo NBR se ha propuesto como matriz para materiales compuestos que incluyen GTR. Para mejorar la compatibilidad, el GTR ha sido tratado con microondas antes de su aplicacion como refuerzo en la matriz elastomeri-ca. Los resultados indican que el tratamiento previo de GTR por microondas mejora la reticulacion y la co-vulcanizacion de los elastomeros usados, lo que tiene una influencia positiva en el comportamien-to mecanico y la microestructura de los materiales compuestos NR/NBR/GTR. Los materiales han sido evaluados mediante ensayos de traccion, ensayo de hinchamiento, Analisis TGA, FTIR y SEM. catalaLa creixent quantitat de pneumatics utilitzats en la industria ha impulsat els investigadors a trobar alternatives per al reciclatge Existeixen diverses al-ternatives proposades per a aquest fi, incloent la incorporacio de cautxu triturat de pneumatic GTR com a farciment en materials compostos. El prin-cipal inconvenient que presenta aquest metode es la manca de compatibilitat entre el GTR i la matriu de polimer. Per tal de resoldre aquest problema, la desvulcanitzacio per microones sembla un proce-diment interessant, ja que quan el GTR tractat amb microones s’incorpora a una matriu elastomerica, es pot aconseguir una major reticulacio posterior si a continuacio es realitza un vulcanitzat. En aquest ar-ticle, una barreja formada per cautxu natural NR i cautxu de nitril NBR s’ha proposat com a matriu per a materials compostos que inclouen GTR. Per mi-llorar la compatibilitat, el GTR ha estat tractat amb microones abans de la seva aplicacio com a reforc a la matriu elastomerica. Els resultats indiquen que el tractament previ de GTR per microones millora la reticulacio i la co-vulcanitzacio dels elastomers usats i te una influencia positiva en el comportament me-canic i la microestructura dels materials compostos NR/NBR/GTR. Els materials han estat avaluats mit-jancant assajos de traccio, assaig d’inflament, analisi TGA, FTIR i SEM. EnglishThe increasing amount of tires used in the indus-try induces the researchers to find alternatives to the recycling of the end-of-life tires. Several alter-natives in order to application of ground tire rubber GTR include their incorporation as a filler in com-posites. The main issue in this approach is the lack of compatibility between GTR and polymer matrix. In order to solve this problem the devulcanization by microwaves has been proposed as an interest-ing approach in order to improve the subsequent crosslinking when the GTR is incorporated to an elastomeric matrix and subsequently co-vulcaniza-ted. In this article a blend formed by natural rubber NR and nitrile butadiene rubber NBR has been pro-posed as a suitable matrix for composites including GTR. In order to improve the compatibility, the GTR was treated by microwaves prior to its application as semi-reinforcement in rubber matrix. The results in-dicate that the pretreatment of GTR by microwaves improves the cross-linking and co-vulcanization of used elastomers, what have a positive influence on the mechanical behaviour and microstructure of the NR/NBR/GTR composites evaluated by tensile tests, equilibrium swelling, Thermo Gravimetric Analysis (TGA), Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM).

Journal of Reinforced Plastics and Composites, Jul 1, 2000