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This research project explores the properties resulting from the combination of nylon 5,6 with natural rubber. The results underline the challenges involved in obtaining a homogeneous blend, highlighting the complexities of interactions between the components. A satisfactory blend was achieved by obtaining a Brabender. To briefly describe the main methods employed, analysis by Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) confirmed the semi-crystalline nature of nylon 5,6 and the amorphous nature of rubber. In addition, thermogravimetric analysis (TGA) identified degradation residues, suggesting the possible commercial origin of the polymer. Mechanical tests revealed that, although nylon alone resisted higher stress, the blend offered greater deformability. Polarized light microscopy revealed morphological changes, while the addition of natural rubber decreased the crystallization rate of nylon 5,6. Overall, this study makes a significant contribution to our understanding of polymer blends, offering innovative perspectives for a variety of industrial applications., Incoming

En l'actualitat, el desenvolupament de tecnologia sostenible de calefacció/refrigeració, juntament amb el reciclatge revesteixen una importància cabdal. En les últimes dècades, gran part de la inversió mundial s'ha dedicat a reduir els residus de cautxú o plàstic i desenvolupar materials respectuosos amb el medi ambient. El cautxú natural (NR) és un material prometedor per a aquestes aplicacions, contràriament als cautxús sintètiques. Això es deu a la seva suavitat, la seva font biobasada juntament amb la seva capacitat de cristal·lització induïda per soca (SIC) i les seves propietats elastocalòriques. Aquest treball té com a objectiu dissenyar mescles de cautxú elastocalòric combinant NR i cautxú de pneumàtics mòlts (GTR) com a farciments de reforç. Això s'ha fet mitjançant la preparació de mescles NR/GTR utilitzant dos sistemes de vulcanització diferents (a base de sofre i peròxid), amb diverses concentracions d'agents vulcanitzants i diversos tipus de partícules GTR (de diverses mides i diversos tractaments). Un estudi que combina termogravimetria, difracció làser, FTIR i proves d'inflamació va suggerir que les partícules GTR més petites on s'ha aplicat un tractament per microones d'1 minut a 800 watts, mostren el grau més alt de desvulcanització (ruptura de reticulats químics). El 20% de les partícules GTR tractades es van barrejar en una matriu NR fresca i la mescla es va revulcanitzar utilitzant 1,5 phr d'agents de sofre (després d'una optimització). Els resultats de les proves de tracció acoblades amb una càmera infraroja van mostrar que els materials NR/GTR tenen la major capacitat SIC i, en conseqüència, la major resposta elastocalòrica (calefacció de 8 °C, refredament de 8 °C). Aquests sistemes NR / GTR curats amb sofre podrien ser materials prometedors i sostenibles per ser utilitzats en prototips d'EC., Hoy en día, el desarrollo de tecnologías sostenibles de calefacción/refrigeración, junto con el reciclaje, son de suma importancia. En las últimas decadas, la mayor parte de la inversión mundial se ha dedicado a reducir los residuos de caucho o plástico y a desarrollar materiales inocuos para el medio ambiente. El caucho natural (NR) es un material prometedor para estas aplicaciones, a diferencia de los cauchos sintéticos. Esto se debe a su suavidad, su fuente bio-basada junto con su capacidad de cristalización inducida por esfuerzo (SIC), y propiedades elastocalóricas. El objetivo de este trabajo es diseñar mezclas de caucho elastocalórico que combinen NR y caucho de neumáticos de tierra (GTR) como reforzadores. Por eso, se han preparado mezclas de NR/GTR utilizando dos sistemas de vulcanización diferentes (basados en azufre y peróxido), con diversas concentraciones de agentes vulcanizantes y varios tipos de partículas GTR (diferentes tamaños y diferentes tratamientos). Un estudio combinando termogravimetría, difracción láser, FTIR y hinchazón sugirió que las partículas GTR más pequeñas que habían sido sometidas a un tratamiento de microondas de 1 minuto a 800 vatios mostraban el mayor grado de desvulcanización (ruptura de enlaces químicos). El 20 % en peso de las partículas GTR tratadas se mezclaron en una matriz NR fresca y la mezcla se revulcanizó con 1,5 phr de agentes sulfurosos (después de una optimización). Los resultados de los ensayos de tracción combinadas con una cámara infrarroja mostraron que los materiales NR/GTR tienen la mayor capacidad de SIC y, en consecuencia, la mayor respuesta elastocalórica (calentamiento de 8°C, enfriamiento de 8°C). Estos sistemas NR/GTR curados con azufre podrían ser materiales sostenibles prometedores para su uso en prototipos de eC., Nowadays, the development of sustainable heating/cooling technology together with materials recycling, are of utmost importance. In the last decades, an important part of the global investment has been dedicated to reducing rubber or plastic waste and develop eco-friendly materials. Natural rubber (NR) is a promising material for heating/cooling applications. This is due to its softness, its bio-based source together with its strain-induced crystallization (SIC) ability, and elastocaloric properties. This work aims to design elastocaloric rubber blends combining NR as the matrix and ground tyre rubber (GTR) as reinforcing fillers. This has been done by preparing NR/GTR blends using two different vulcanization systems (based on sulphur and peroxide), at various concentrations and several types of GTR particles were used (of different sizes and treated by microwave devulcanization). A study combining thermogravimetry, laser diffraction, FTIR and swelling tests suggested that the smallest GTR particles where a microwave treatment of 1 minute at 800 Watts has been applied, show the highest degree of devulcanization (rupture of chemical crosslinks expected to recycle the material). 20 wt.% of the treated GTR particles were blended in a fresh NR matrix and the mixture was revulcanized using 1.5 phr of sulphur agents (after an optimization of its concentration). Results of tensile tests coupled with an infrared camera showed that the NR/GTR materials have the highest SIC ability and consequently the highest elastocaloric response (heating of 8°C, cooling of 8°C). These sulphur-cured NR/GTR systems might be promising for sustainable applications such as heating/cooling prototypes., Incoming

The influence of the type of mechanical recycling of waste rubber particles on the tensile properties of waste/natural rubber blends has been investigated. The wastes originating from ground tyre rubber (GTR) had been treated by two distinct processes: cryo-grinding and high shear mixing (HSM). For both processes, the resulting composites show enhanced stiffness and strength for all strain rates and temperatures tested. This is attributed to both the reinforcing effect of the waste as well as the nucleation ability of the wastes on strain induced crystallization (SIC) in the natural rubber (NR) matrix. Cryo-grinding was shown to provide the finest particle size with an average diameter of 34 µm, while the HSM process was found to show an elastic modulus of aggregated GTR powder of 7 MPa at 1 Hz at room temperature. Within these characteristics, the NR/GTR blends using the HSM process show the best tensile performance under single loading, with the highest strength and highest ability to crystallize under strain. Under cyclic loading, NR/GTR blends using cryo-ground GTR particles show the best performance, which we ascribed to their ability to better distribute and accommodate the stress from one cycle to another owing to their finest size. Both explored recycling techniques provide the natural/waste rubber blends interesting properties such as mechanical reinforcement and strain-induced crystallization ability under various testing conditions., Peer Reviewed, Postprint (published version)

Ethylene Propylene Diene rubber (EPDM), is present in many applications. However, its crosslinked structure makes difficult its recycling. The use of devulcanized EPDM, (dEPDM) as a component of elastomeric composites, is a real possibility to reuse EPDM scraps. In this study, three matrices (natural rubber (NR), styrene butadiene rubber (SBR) and EPDM rubber) have been tested including devulcanized EPDM as a recycled component. The EPDM previously was devulcanized using a thermomechanical process followed by microwave irradiation. The resulting devulcanized EPDM was blended with the matrixes and then the new compound was vulcanized again. The samples showed a general increase of their mechanical properties and their thermal stability specially marked for NR and SBR. Compositions including about 40 phr dEPDM within the EPDM matrix exhibited a difference in their general behavior that it was manifested by a general decrease in properties compared with lower amounts of dEPDM. In order to further understand this behavior, the samples were analyzed in terms of cross-link density, swelling degree, and scanning electron microscopy. The study of the microstructure of the samples indicated that microagglomerates of dEPDM are formed inside the samples. In case of NR or SBR the agglomerates were very linked to the matrix through the covalent bonds established in the crosslinking process. In the case of the EPDM matrix, the agglomerates presented less interfacial cross-links. The cross-linking takes place preferentially within the dEPDM microdomains and this results in a relative decrease in mechanical properties and thermal stability when compared to NR and SBR, Authors thank the financial support from Ministerio de Ciencia e Innovación, project reference PID2021-126165OB-I00, corresponding to the 2021 call for Knowledge Generation Projects 2021, Postprint (published version)

In this work, ground tire rubber (GTR) was thermo-mechanically treated in the presence of styrene-butadiene-styrene (SBS) copolymers. During preliminary investigation, the effects of different SBS copolymer grades, the variable content of SBS copolymer on the Mooney viscosity, and the thermal and mechanical properties of modified GTR were determined. Subsequently, GTR modified by SBS copolymer and cross-linking agents (sulfur-based system and dicumyl peroxide) was characterized by assessment of rheological, physico-mechanical, and morphological properties. Rheological investigations showed that linear SBS copolymer, with the highest melt flow rate among studied SBS grades, was the most promising modifier of GTR, considering processing behavior. It was also observed that an SBS improves the thermal stability of the modified GTR. However, it was found that higher content of SBS copolymer (above 30 wt%) does not bring any effective changes and, for economic reasons, is inefficient. The results showed that samples based on GTR modified by SBS and dicumyl peroxide have better processability and slightly higher mechanical properties compared to samples cross-linked by a sulfur-based system. This is due to the affinity of dicumyl peroxide to the co-cross-linking of GTR and SBS phases, The authors are grateful for the research foundation of project WPC 2/SUSDEV4REC/2021, supported by the National Centre for Research and Development (Poland), and project 2021YFE0105200, supported by the Ministry of Science and Technology (China), Postprint (published version)

Millora de sistema de premsat i modelat per a terra de cautxú utilitzat en parcs infantils. Què és i quina és la funció? L'objectiu d'aquest TFG és crear un sistema que optimitzi la cadena de producció d'una empresa especialitzada en l'emmotllament de cautxú per a terra de parcs infantils. Per optimitzar aquest procés el que es busca és l'automatització del sistema, ja que actualment segueixen sent operaris els qui s'encarreguen manualment d'aquesta tasca. Una automatització del sistema pot comportar diversos avantatges com un benefici més gran per a l'empresari, en obtenir més hores de producció, o una reducció de lesions en l'àmbit laboral en evitar treballs d'elevada càrrega física. Per complir el nostre objectiu dissenyarem un sistema 3D, recreant el procés que s'ha de dur a terme. Un cop creat el disseny, es comparen el sistema automatitzat dissenyat en aquest TFG amb el sistema manual actual i se'n buscaran conclusions., Mejora de sistema de prensado y moldeado para suelo de caucho usado en parques infantiles. ¿Qué es y cuál es su función? El objetivo de este TFG es crear un sistema que optimice la cadena de producción de una empresa especializada en el moldeado de caucho para suelo de parques infantiles. Para optimizar este proceso lo que se busca es la automatización del sistema, ya que en la actualidad siguen siendo operarios quienes se encargan de esta tarea manualmente. Una automatización del sistema puede conllevar diversas ventajas como un mayor beneficio para el empresario, al obtener más horas de producción, o una reducción de lesiones en el ámbito laboral al evitar trabajos de elevada carga física. Para cumplir nuestro objetivo diseñaremos un sistema 3D, recreando el proceso el cual se ha de llevar a cabo. Una vez creado el diseño, se comparan el sistema automatizado diseñado en este TFG con el sistema manual actual y se buscarán conclusiones al respecto., Improvement of the pressing and molding system for rubber flooring used in playgrounds. What is it and what is its function? The objective of this final project is to create a system that optimizes the production chain of a company specialized in molding rubber for playground floors. To optimize this process what is sought is the automation of the system. In the actual industries it is still operators who are in charge of this task manually. Automation of the system can bring various advantages such as a greater benefit for the employer, by obtaining more hours of production, or a reduction in injuries in the workplace by avoiding jobs with a high physical load. To meet our objective we will design a 3D system, recreating the process which has to be carried out. Once the design is created, the automated system designed in this final project is compared with the current manual system and conclusions will be sought in this regard.

The characterization of the mechanical behavior of elastocaloric materials is essential to identify their viability in heating/cooling devices. Natural rubber (NR) is a promising elastocaloric (eC) polymer as it requires low external stress to induce a wide temperature span, ¿T. Nonetheless, solutions are needed to further improve DT, especially when targeting cooling applications. To this aim, we designed NR-based materials and optimized the specimen thickness, the density of their chemical crosslinks, and the quantity of ground tire rubber (GTR) used as reinforcing fillers. The eC properties under a single and cyclic loading conditions of the resulting vulcanized rubber composites were investigated via the measure of the heat exchange at the specimen surface using infrared thermography. The highest eC performance was found with the specimen geometry with the lowest thickness (0.6 mm) and a GTR content of 30 wt.%. The maximum temperature span under single interrupted cycle and multiple continuous cycles were equal to 12 °C and 4 °C, respectively. These results were assumed to be related to more homogeneous curing in these materials and to a higher crosslink density and GTR content which both act as nucleating elements for the strain-induced crystallization at the origin of the eC effect. This investigation would be of interest for the design of eC rubber-based composites in eco-friendly heating/cooling devices., Peer Reviewed, Postprint (published version)

As a consequence of massive production and consumption of rubbers, rubber blends, and rubber composites for myriad applications, elastomeric products have enormously accumulated and become an environmental threat. The disposal and burning of rubber wastes have been banned because of environmental and economic reasons. By contrast, a great deal of attention has been directed toward strategies enabling recycling and reuse of rubbers. Basically, conventional recycling methods suffer from several drawbacks such as the formation of dust, fumes, and toxic gases in the air, as well as contamination of underground water resources. Thus, green and sustainable formulations and processing methods nowadays are of priority and importance. Taking advantage of sustainable development horizons, scientific and technological aspects of waste rubber management such as processing techniques, properties of the resulting products, industrial applications, and compatibilization with other materials such as thermoplastics, thermosets, and rubbers are herein reviewed and discussed. A particular emphasis is placed on reactive extrusion as a highly flexible in situ compounding method enabling innovations and taking care of sustainability concerns. Finally, the current status of green rubber recycling and future opening doors ahead of this technology are highlighted, M.R. Saeb acknowledges the financial support provided by the Gdańsk University of Technology, the DEC-1/2021/IDUB/I.1Pt grant under the Platinum Establishing Top-Class Research Teams—Excellence Initiative—Research University’ program. X. Colom thanks the financial support from Ministerio de Ciencia e Innovación, project reference PID2021-126165OB-I00, corresponding to the 2021 call for Knowledge Generation Projects 2021., Postprint (author's final draft)

Medical gloves, along with masks and gowns, serve as the initial line of defense against potentially infectious microorganisms and hazardous substances in the health sector. During the COVID-19 pandemic, medical gloves played a significant role, as they were widely utilized throughout society in daily activities as a preventive measure. These products demonstrated their value as important personal protection equipment (PPE) and reaffirmed their relevance as infection prevention tools. This review describes the evolution of medical gloves since the discovery of vulcanization by Charles Goodyear in 1839, which fostered the development of this industry. Regarding the current market, a comparison of the main properties, benefits, and drawbacks of the most widespread types of sanitary gloves is presented. The most common gloves are produced from natural rubber (NR), polyisoprene (IR), acrylonitrile butadiene rubber (NBR), polychloroprene (CR), polyethylene (PE), and poly(vinyl chloride) (PVC). Furthermore, the environmental impacts of the conventional natural rubber glove manufacturing process and mitigation strategies, such as bioremediation and rubber recycling, are addressed. In order to create new medical gloves with improved properties, several biopolymers (e.g., poly(vinyl alcohol) and starch) and additives such as biodegradable fillers (e.g., cellulose and chitin), reinforcing fillers (e.g., silica and cellulose nanocrystals), and antimicrobial agents (e.g., biguanides and quaternary ammonium salts) have been evaluated. This paper covers these performance-enhancing materials and describes different innovative prototypes of gloves and coatings designed with them., Peer Reviewed, Objectius de Desenvolupament Sostenible::3 - Salut i Benestar, Postprint (published version)

En el panorama actual, gran part de la inversió mundial es destina al desenvolupament de materials respectuosos amb el medi ambient com a font d'energia alternativa sostenible i a la gestió de residus de cautxú i plàstic. Aquesta tesi té com a objectiu processar mescles de cautxú utilitzant partícules de deixalla, per a caracteritzar les seves propietats elastocalòriques (eC) i la seva capacitat de Cristal·lització Induïda per Deformació (SIC). S'ha incorporat cautxú de pneumàtic triturat (GTR) en una matriu de cautxú natural (NR) amb un contingut de 0, 20 i 30% en pes en un procediment de dos passos: barrejat intern per a mesclar els materials i premsatge en calent per a vulcanitzar-los. Es va utilitzar peròxid de Dicumyl (DCP) com a agent vulcanitzant. Ens hem centrat en l'efecte del temps de vulcanització dissenyant materials curats amb tres temps diferents (10%, 50% i 90%). Les propietats elàstiques dels materials processats es van analitzar mitjançant inflament, duresa shore A i mòdul elàstic, i les propietats de gran velocitat de deformació (hiperelàstiques) es van caracteritzar mitjançant càrrega única de tracció d'alta velocitat de deformació fins a la fallada i mitjançant cicles d'alta velocitat de deformació. Els resultats mostren que com més gran és el temps de vulcanització, majors són les propietats elàstiques com la duresa, el mòdul elàstic i la densitat de reticulació, independentment de la presència de les partícules GTR. Això es deu a la creació d'entrecreuaments (enllaços químics i físics atrapats) que participen en una xarxa elàsticament resistent. A altes deformacions, l'augment concomitant del reforç mecànic i de la resposta elastocalòrica amb l'augment del temps de curat, s'atribueix en part a l'aparició del SIC. En efecte, a major densitat de cadenes de cautxú, més enllaços creuats (químics o físics) actuen com a punts d'ancoratge per a l'orientació de les cadenes al llarg de l'eix de tracció i, per tant, perquè es produeixi el SIC., En el panorama actual, gran parte de la inversión mundial se destina al desarrollo de materiales respetuosos con el medio ambiente como fuente de energía alternativa sostenible y a la gestión de residuos de caucho y plástico. Esta tesis tiene como objetivo procesar mezclas de caucho utilizando partículas de desecho, para caracterizar sus propiedades elastocalóricas (eC) y su capacidad de Cristalización Inducida por Deformación (SIC). Se ha incorporado caucho de neumático triturado (GTR) en una matriz de caucho natural (NR) con un contenido de 0, 20 y 30 % en peso en un procedimiento de dos pasos: mezclado interno para mezclar los materiales y prensado en caliente para vulcanizarlos. Se utilizó peróxido de Dicumyl (DCP) como agente vulcanizante. Nos hemos centrado en el efecto del tiempo de vulcanización diseñando materiales curados con tres tiempos diferentes (10%, 50% y 90%). Las propiedades elásticas de los materiales procesados se analizaron mediante hinchamiento, dureza shore A y módulo elástico, y las propiedades de gran velocidad de deformación (hiperelásticas) se caracterizaron mediante carga única de tracción de alta velocidad de deformación hasta el fallo y mediante ciclos de alta velocidad de deformación. Los resultados muestran que cuanto mayor es el tiempo de vulcanización, mayores son las propiedades elásticas como la dureza, el módulo elástico y la densidad de reticulación, independientemente de la presencia de las partículas GTR. Esto se debe a la creación de entrecruzamientos (enlaces químicos y físicos atrapados) que participan en una red elásticamente resistente. A altas deformaciones, el aumento concomitante del refuerzo mecánico y de la respuesta elastocalórica con el aumento del tiempo de curado, se atribuye en parte a la aparición del SIC. En efecto, a mayor densidad de cadenas de caucho, más entrecruzamientos que actúan como puntos de anclaje (orientación de las cadenas a lo largo del eje de tracción) para que se produzca el SIC., In the current scenario, much of the global investment is devoted to the development of environmentally friendly materials as a sustainable alternative energy source and to the management of rubber and plastic waste. This thesis aims to process rubber blends using waste particles, to characterize their elastocaloric (eC) properties and their Strain Induced Crystallization (SIC) ability. Ground Tire Rubber (GTR) have been incorporated in a Natural rubber (NR) matrix with content of 0, 20 and 30 wt.% in a two-step procedure: internal mixing to blend the materials and hot press to vulcanize them. Dicumyl Peroxide (DCP) was used as the vulcanizing agent. We have focused on the effect of the time of vulcanization by designing materials cured with three different times (10%, 50% and 90%). The elastic properties of the processed materials were analyzed through to swelling, shore A hardness, and Elastic modulus, and the large strain rate (hyperelastic) properties were characterized by high strain rate tensile single loading up to fail and by and high strain rate cycles. The results show that the higher the vulcanization time, the higher the elastic properties such as hardness, elastic modulus, and crosslink density, independently on the presence of the GTR particles. This is due to the creation of crosslinks (chemical and trapped physical bonds) that participate in an elastically resistant network. At high strains, the concomitant rise in mechanical reinforcement and elastocaloric response with increased curing time, is partly attributed to occurrence of SIC. Indeed, at higher density of rubber chains, more crosslinks (chemical or physical) act as anchoring points for chains orientation along tensile axis and hence for SIC to occur.

PLA/natural rubber (NR)/wastes tire rubber (GTR) were dynamically vulcanizing using dicumyl peroxide (DCP). Swelling, dissolution, and electron microscopy revealed that the unvulcanized and weekly vulcanized blends (DCP¿<¿3 wt%) show a continuous rubber phase while the highly vulcanized blends (DCP¿>¿3 wt%) show co-continuous rubber/PLA phase. In the latter blends, the tensile toughness (1.3 MJ¿m-3) and the tensile-impact strength of the neat PLA (58¿kJ¿m-2) were increased of a factor 12.5 and 8.3 respectively. Moreover, the appropriate crosslinking agent content (3–3.75¿wt%) in the ternary blends allowed to reach same tensile toughness, impact strength, shape recovery and shape fixity as compared to their equivalent binary PLA/NR blends., Peer Reviewed, Postprint (author's final draft)

Vulcanized natural rubber (NR)/cellulose nanocrystals (CNC) composites with a CNC content of up to 5 wt% using physical blending and dicumyl peroxide crosslinking were prepared. The tensile properties were investigated at slow and high strain rates. The slow strain rate tests revealed an increase of the elastic modulus concomitant with a decrease of strain at the crystallization onset while increasing the CNC fraction. The high strain rate tests performed near adiabatic conditions demonstrated the ability of the CNC to improve the elastocaloric properties of the NR matrix, with an increase of 30% and 15% of heating and cooling capacities, respectively, in the presence of 3 wt% CNC. Such results were ascribed to (i) a higher thermoelastic effect, due to strain amplification in the NR matrix in the presence of CNC and (ii) a nucleating effect of the CNC on strain induced crystallization. This series of materials can be proposed as a promising eco-friendly alternative to conventional carbon black filled rubber as potential green elastocaloric materials (heating pump, cooling machines)., Peer Reviewed, Postprint (author's final draft)

The reduction in the production of conventional polymers based on crude oil by using bio-based plastics and by valorizing rubber wastes is an essential route to reverse the negative impact of the polymer industry on the environment. To contribute to this challenge, we prepared polylactic acid (PLA)/natural rubber (NR)/ground tyre rubber (GTR) blends via dynamic vulcanization. The PLA/NR/GTR blends with a rubber content and above 30 wt% show a continuous rubber phase (NR/GTR) where the GTR particles are encapsulated into the NR matrix as shown by dissolution experiment in dichloromethane and microscopy images on etched samples. PLA/NR/GTR blends with 30 wt% of rubber show a tensile modulus of 1.3 GPa, a tensile toughness of 8.3 MJ m-3 and an impact strength of 260 kJ m-2 higher than 1.1 GPa, 4.2 MJ m-3 and 160 kJ m-2, respectively, for the binary PLA/NR blend. The presence of reinforcing carbon black particles in the GTR as well as their partially vulcanized state of the GTR before dynamic vulcanization may result in a higher cross-linking level of the rubber phase in the ternary blends as compared to binary blends that likely contribute to concomitantly improve tensile modulus, toughness and impact tensile strength., Peer Reviewed, Postprint (author's final draft)

El presente estudio ha consistido en el análisis de comportamiento de una cubierta verde extensiva hidropónica con sustrato de lana de roca, donde se ha reemplazado la capa drenante por caucho triturado de distintas granulometrías (2 – 4 mm, 5 – 7 mm y 2 – 7 mm), en comparación con soluciones de cubiertas constructivas existentes, donde la capa drenante es greda volcánica o lámina nodular de polietileno de alta densidad. Se ha llevado a cabo un extenso estudio para definir el estado del arte existente como punto de partida y posibles hipótesis de resultados, de modo que esta información ha servido para definir y construir las probetas, y para proponer ensayos que permitan evaluar el comportamiento de las diferentes soluciones constructivas. Los ensayos propuestos se han centrado en tres parámetros principales: lixiviación del material, capacidad drenante y comportamiento térmico medido durante 14 ciclos diarios para el clima mediterráneo seco. Los resultados de lixiviación evidencian que no existen valores que en circunstancias normales puedan representar un peligro medioambiental o para la infraestructura de aguas residuales de la ciudad, coincidiendo con estudios previamente realizados. Los resultados de capacidad drenante muestran que, en la solución constructiva completa, la lana de roca es más que suficiente para absorber el agua del peor escenario y que la función de la capa drenante queda reducida a sólo el drenaje de cualquier exceso, en donde el resultado obtenido es que el caucho tiene mejores capacidades drenantes que las soluciones comparadas. En cuanto al comportamiento térmico, se evidencia que el caucho triturado tiene un aporte mayor en cuanto a mejora de la transmitancia e inercia térmicas, en todas sus granulometrías, no obstante, los mejores resultados los muestra el caucho de granulometría 5 – 7 mm y 2 – 7 mm, presentado una ventaja en todos los casos en comparación con las soluciones de greda volcánica o lámina nodular de polietileno de alta den

El cautxú d'etilè propilè diè (EPDM) és un elastòmer àmpliament utilitzat a nivell industrial per aplicacions molt diverses. En aquest estudi, es van tractar restes granulars d'EPDM mitjançant processos de desvulcanització termomecànica incloent l’acció d’un activador com és el peròxid de benzoïl (BPO). Tot seguit, es van barrejar diferents percentatges d’aquest EPDM desvulcanitzat amb pèl·lets d’EPDM verge prevulcanitzats obtenint un material que, un cop vulcanitzat, pogués ser emprat en la construcció de superfícies esportives. El vulcanitzat es va dur a terme mitjançant dues vies: premsa a 165ºC i reòmetre a la mateixa temperatura. El compost obtingut es va caracteritzar d’una banda, a partir d’assajos de tracció per determinar les propietats físiques i, de l’altra, a partir dels assajos reomètrics es van extreure les característiques de la vulcanització. Els resultats obtinguts mostren que la desvulcanització a través d’un únic mètode termomecànic autònom resulta insuficient per obtenir rendiments elevats, tot i que la presència del BPO resulta eficient en la desvulcanització dels grànuls d’EPDM residuals. Finalment, un cop estudiades i analitzades les corbes reomètriques obtingudes que denotaven una bona densitat d’entrecreuament de les cadenes polimèriques del compost final, es va determinar l’enorme influència de l’EPDM residual en la pèrdua de les propietats físiques del material., El caucho de etileno propileno dieno (EPDM) es un elastómero ampliamente utilizado a nivel industrial para aplicaciones muy diversas. En este estudio, se trataron restos granulares de EPDM mediante procesos de desvulcanización termomecánica incluyendo la acción de un activador como es el peróxido de benzoilo (BPO). A continuación, se mezclaron diferentes porcentajes de este EPDM desvulcanizado con pellets de EPDM virgen prevulcanizados obteniendo un material que, una vez vulcanizado, pudiera utilizarse en la construcción de superficies deportivas. El vulcanizado se realizó mediante dos vías: prensa a 165ºC y reómetro a la misma temperatura. El compuesto obtenido se caracterizó por un lado, a partir de ensayos de tracción para determinar las propiedades físicas y, por otro, a partir de los ensayos reométricos se extrajeron las características de la vulcanización. Los resultados obtenidos muestran que la desvulcanización a través de un único método termomecánico autónomo resulta insuficiente para obtener elevados rendimientos, aunque la presencia del BPO resulta eficiente en la desvulcanización de los gránulos de EPDM residuales. Finalmente, una vez estudiadas y analizadas las curvas reométricas obtenidas que denotaban una buena densidad de cruce de las cadenas poliméricas del compuesto final, se determinó la enorme influencia del EPDM residual en la pérdida de las propiedades físicas del material., Ethylene propylene diene rubber (EPDM) is an elastomer widely used in industry for very different applications. In this study, granular residues of EPDM were treated by thermomechanical devulcanization processes including the action of an activator such as benzoyl peroxide (BPO). Different percentages of this vulcanized EPDM were mixed with pre-vulcanized virgin EPDM pellets to obtain a material that, once vulcanized, could be used in the construction of sports grounds. The vulcanization was carried out by two routes: press at 165°C and rheometer at the same temperature. The obtained compound was characterized, on the one hand, by tensile tests to determine the physical properties and, on the other hand, the vulcanization parameters were extracted from the rheometric tests. The results obtained show that devulcanization through a single thermomechanical method is insufficient to obtain high yields, although the presence of BPO is efficient in devulcanization of residual EPDM granules. Finally, after studying and analysing the obtained rheometric curves that denoted a good crosslinking density of the polymer chains which make up the final compound, the influence of the residual EPDM on the insufficient physical properties of the material obtained was determined.

In this work, GTR/thermoplastics blends (in ratio 50/50 and 75/25 wt.%) were prepared by melt-compounding in an internal mixer. During research, trans-polyoctenamer rubber (TOR), ethylene-vinyl acetate copolymer (EVA), ethylene-octene copolymer (EOC), and linear low-density polyethylene (LLDPE), were used in their thermoplastic phase. Microstructure and processingperformance property interrelationships of the studied materials were investigated by: atomic force microscopy (AFM), scanning electron microscopy (SEM), rubber process analyzer (RPA), Mooney viscometer, plastometer, gas chromatography with mass spectrometry, differential scanning calorimetry (DSC), tensile tests and swelling behavior. In blends of thermoplastics with a high content of GTR (50 and 75 wt.%), the thermoplastic modifier type had a significant impact on the processing behavior and microstructure of blends. In terms of the physico-mechanical properties, the GTR/thermoplastics ratio affected elongation at break, hardness, and density, while its effect on tensile strength was negligible. DSC analysis showed that thermoplastics, as modifiers of GTR, should be considered as binders and not plasticizers, as reflected in the almost constant glass-transition temperature of the blends. RPA measurements indicated higher values of G* and ¿* for GTR-rich blends. SEM showed a rubber-like interfacial break, while AFM confirmed interfacial contact between GTR and thermoplastics, Postprint (published version)

Strain induced crystallization (SIC) of peroxide vulcanized natural rubber (NR)/ground tire rubber (GTR) composites is studied by combining mechanical and microstructural characterization techniques. It is found that the incorporation of GTR into the NR matrix leads to more effective reinforcement at large strains at room temperature in the NR/GTR composites as compared to the neat NR. It is attributed to (i) the presence of the GTR particles acting as reinforcing fillers owing their high carbon black content, and (ii) the nucleating effect of the GTR for SIC in the NR matrix inducing further reinforcement through the generation of an increasing number of oriented crystallites that behave as supplementary reinforcing fillers., Peer Reviewed, Postprint (published version)

El reciclatge dels elastòmers ha esdevingut una peça més a tenir en compte davant el marc climàtic actual. Els cautxús d’etilè propilè diè (EPDM) són un material utilitzat àmpliament en el món industrial i el seu desvulcanitzat que permet el reciclatge juga un paper molt important per a fer una passa més cap a un món més sostenible. En aquest treball s’ha estudiat la capacitat de reutilitzar residus d’EPDM industrials desvulcanitzats amb una tècnica combinada termomecànica i microones per incorporació a una matriu de natural rubber (NR), l’elastòmer d’origen natural. Els materials obtinguts s’han caracteritzat mesurant la resistència màxima a tracció, la deformació, la duresa i el comportament acústic. S’ha estudiat la degradació a una temperatura que simula la radiació solar. Les mostres s’han analitzat també amb TGA i SEM. S’ha vist que una matriu d’NR pot incloure fins a un 40-50% d’EPDM desvulcanitzat conservant unes bones propietats mecàniques. La incorporació d’òxid de silici suposa una millora de les propietats i la duresa, així com de la temperatura de degradació. No obstant, s’ha observat que totes millores presentades es perden davant la degradació tèrmica de les mostres., The recycling of elastomers has become another piece to consider in the face of the current climate framework. Ethylene propylene diene (EPDM) rubbers are a widely used material in the industrial world and their devulcanization, which allows recycling, plays a very important role in taking a step towards a more sustainable world. This work has studied the ability to reuse industrialized EPDM waste devulcanized with a combined thermomechanical and microwave technique by incorporation into a matrix of natural rubber (NR), the elastomer of natural origin. The materials obtained have been characterized by measuring the maximum tensile stress, deformation, hardness and acoustic behaviour. Degradation has been studied at a temperature that simulates solar radiation. Samples were also analysed with TGA and SEM. It has been shown that an NR matrix can include up to 40-50% of vulcanized EPDM while retaining good mechanical properties. The incorporation of silicon oxide improves the properties and hardness, as well as the degradation temperature. However, it has been observed that all the improvements presented are lost due to the thermal degradation of the samples.

Waste from pneumatic wheels is one of the major environmental problems, and the scientific community is looking for methods to recycle this type of waste. In this paper, ground tire rubber particles (GTR) from disused tires have been mixed with samples of low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and morphological tests have been performed using scanning electron microscopy (SEM), as well as the dynamic electric analysis (DEA) dielectric characterization technique using impedance spectroscopy. From this experience, how GTR reinforcement influences polyethylene and what influence GTR particles have on the branched polyethylene has been detected. For pure LDPE samples, a Debye-type dielectric behavior is observed with an imperfect semicircle, which depends on the temperature, as it shows differences for the samples at 30 ¿C and 120 ¿C, unlike the HDPE samples, which do not show such a trend. The behavior in samples with Debye behavior is like an almost perfect dipole and is due to the crystalline behavior of polyethylene at high temperature and without any reinforcement. These have been obtained evidence that for branched PE (LPDE) the Maxwell Wagner Sillars (MWS) effect is highly remarkable and that this happens due to the intrachain polarization effect combined with MWS. This means that the permittivity and conductivity at LDPE/50%GTR are high than LDPE/70%GTR. However, it does not always occur that way with HDPE composites in which HDPE/70%GTR has the highest values of permittivity and conductivity, due to the presence of conductive fraction (Carbon Black-30%) in the GTR particles and their dielectric behavior, Postprint (published version)

Per tal de fer front al problema dels residus de plàstic i participar al desenvolupament d'una economia circular en la indústria del cautxú, s’ha proposat la creació de materials amb residus de pneumàtics, anomenats “ground tyre rubber” (GTR), per reforçar el polímer àcid polilàctic (PLA) , un termoplàstic fràgil i de base biològica. La compatibilitat entre aquests dos polímers s’ha optimitzat amb l'ús de cautxú natural (NR) com a tercer component, amb l'objectiu d'encapsular les partícules de GTR. Les mescles han sigut vulcanitzades dinàmicament amb “dicumyl peroxide” (DCP). S’han investigat els efectes dels paràmetres de procés (temps de residència, temperatura de procés) així com els efectes dels paràmetres dels materials (mida de les partícules de GTR, proporció i origen de l'PLA i de el cautxú) sobre les propietats mecàniques de les mescles. Les millors propietats mecàniques s’han obtingut amb l'ús d'una mida de partícules més fines (diàmetre <63 micres) per a cada tipus de mescla amb una base de PLA-GTR, amb o sense NR. A més, el fet de reemplaçar 1/3 de NR per GTR en les mescles ternàries PLA / NR / GTR ha permès augmentar el mòdul elàstic, el límit elàstic, la tenacitat i la resistència a l'impacte fins a una incorporació de 15 wt.% de cautxú reciclat. Els resultats han sigut atribuïts a (i) una encapsulació eficaç que permet una distribució homogènia de les partícules de GTR, (ii) una bona compatibilitat entre el NR i ambdós PLA i GTR (iii) un reforç mecànic a causa del fenomen de cristal·lització induït per deformació de l’NR., Para hacer frente al problema de los residuos de plástico y participar en el desarrollo de una economía circular en la industria de caucho, la creación de materiales que contienen residuos de neumáticos, llamados ground tire rubber (GTR), para reforzar el ácido poliláctico (PLA), un termoplástico frágil y de base biológica, fue propuesta. La compatibilidad entre estos dos polímeros fue optimizada con el uso de caucho natural (NR) como tercer componente, con el objetivo de encapsular las partículas de GTR. Las mezclas fueron vulcanizadas dinámicamente con dicumyl peroxide (DCP) durante el proceso de mezcla por fundición. Los efectos de los parámetros de proceso (tiempo de residencia, temperatura de proceso) así como los parámetros de los materiales (tamaño de las partículas de GTR, proporción y origen del PLA y del caucho) sobre las propiedades mecánicas de las mezclas fueron investigados. El uso de un tamaño de partículas más fino (diámetro <63 µm) dio las mejores propiedades de tensión para cada tipo de mezcla con una basa de PLA-GTR, con o sin NR. Además, remplazar 1/3 del NR por GTR en las mezclas ternarias PLA/NR/GTR permitió aumentar el módulo elástico, el límite elástico, la tenacidad y la resistencia al impacto hasta una incorporación de 15 wt.% de caucho reciclado. Los resultados fueron atribuidos a (i) una encapsulación eficaz que permite una distribución homogénea de las partículas de GTR, (ii) una buena compatibilidad entre el NR y ambos PLA y GTR (iii) un refuerzo mecánico debido al fenómeno de cristalización inducida por deformación del NR., To face the problem of plastic wastes generation and to participate in the development of a circular economy of the rubber industry, the design of materials incorporating waste ground tire rubber (GTR) to toughen the Polylactic Acid (PLA), a brittle biobased thermoplastic, has been proposed. The compatibility between these two polymers was optimized by using natural rubber (NR) as a third component, aiming to encapsulate the GTR particles. The blends were dynamically vulcanized with dicumyl peroxide (DCP) during melt-blending. The effects of the processing parameters (residence time, processing temperature) as well as the material parameters (GTR particles size, PLA and rubber content and origin) on the mechanical properties of the blends were investigated. The finest GTR particles size (diameter <63 µm) was found to render the best tensile properties for all type of PLA-GTR based blend, with or without NR. In addition, the replacement of 1/3 of the NR by GTR in ternary PLA/NR/GTR blends resulted in the improvement of the elastic modulus, the yield strength, the toughness and the impact strength using up to 15 wt.% of wastes rubber. The results were ascribed to (i) an efficient encapsulation allowing a homogeneous distribution of the GTR particles, (ii) a good compatibility of NR with both PLA and GTR and (iii) a mechanical reinforcement due to strain induced crystallization of the NR., Incoming, Objectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables

The constant growth of the rubber market and the increasing concern for the environment have pushed industry and researchers to develop new ways of recycling. In this thesis Ethylene Propylene Diene Monomer rubber (EPDM) scraps were devulcanized by microwaves and mixed with fresh EPDM. The final compound was characterized. The effect of including 25phr of Silica and the thermal degradation were also studied. The characterization of the obtained materials included swelling, crosslinking degree, mechanical tests, acoustic properties, hardness, TGA and SEM. The obtained results show that adding devulcanized EPDM to the compound generally decreases the mechanical properties while increases the thermal stability. The addition of Silica produces a decrease of the tensile strength and the elongation while increasing the Young’s modulus and the hardness. The differences in properties between the samples with and without Silica are diminished by thermal degradation

La masiva fabricación de neumáticos y su dificultad para su posterior reciclaje, representa hoy por hoy, un grave problema medio ambiental. Existen varios métodos para intentar reciclar los neumáticos usados, uno de ellos consiste en su separación mecánica, en el cual el caucho vulcanizado se separa del acero y de las fibras, lo que da como resultado un caucho que puede presentarse molido en pequeñas partículas (Ground Tire Rubber, o GTR). Este caucho puede utilizarse en diversas aplicaciones, como la que presenta esta investigación, en la cual una vez mezclado con polimeros de uso habitual, ha de servir para la fabricación de los aislamientos para calzado industrial de trabajo. Por tanto, el objetivo de este estudio, pasa por evaluar los resultados de mezclar estas partículas de GTR con varias matrices poliméricas de uso habitual (polimero+GTR), comprobando que tanto sus propiedades mecánicas como dieléctricas cumplen con las normas establecias para la fabricación de los aislamientos para zapatos de uso industrial. El análisis se llevará a cabo utilizando siete matrices poliméricas mezcladas con diferentes concentraciones de GTR., Esta investigación fue financiada por el MINISTERIO DE ECONOMIA Y COMPETITIVIDAD, Gobierno de España ENE2015-64117-C5-3-R (MINECO/FEDER)., Peer Reviewed, Postprint (author's final draft)

Ethylene-propylene-diene rubber (EPDM) is a elastomer widely used in common industrial applications. EPDM can be shaped into sheets and employed as isolating material for roofing systems. In this study, scraps of EPDM from commercial, industrial and residential roofing systems were treated by combined thermo-mechanical and microwave devulcanization processes including peroxide of benzoyl (BPO). The devulcanized EPDM (Dev-EPDM) was characterized by cross-link density, Horikx plot, sol fraction content, SEM and TGA analysis. In order to assess the effect of the different factors implied (type of devulcanization process, temperature and amount of BPO), the Fractional Factorial Design (FFD) method has been applied. The obtained results show that, when thermo-mechanical and microwave methods are combined, produce an intense devulcanization effect. It was also found that the presence of BPO has significative influence in the devulcanization and that the effect of the temperature is related to the amount of BPO, Postprint (author's final draft)

El present Treball de Fi de Màster (TFM) és una revisió d'articles científics, material bibliogràfic i antecedents històrics sobre els guants mèdics d’un sol ús. En aquesta revisió, s'han estudiat dades des de l'origen d'aquests guants fins a les últimes innovacions i millores que s'estan realitzant en aquests productes amb creixent demanda mundial. A més, s'ha analitzat l'ús del cautxú natural, la seva extracció com a làtex de l'arbre Hevea brasiliensis, la seva composició i les alternatives de cautxús sintètics amb els seus respectives avantatges i inconvenients. Addicionalment, s'han avaluat els additius que s'han emprat tradicionalment en les formulacions de guants i les alternatives més recents entre els quals es destaquen els reticulants biobasats, els farcits biodegradables, així com els agents amb propietats antimicrobianes. Aquests últims en la seva aplicació com revestiments, trícapas o nanofils que s'incorporen a l'estructura del guant. D'altra banda, es van comparar els tipus de producció per lots i en continu, s’ha explicat un procés genèric de fabricació de guants amb les diferents condicions usuals de procés i s’han analitzat les diferents opcions de tractaments superficials per obtenir guants amb i sense pols. A continuació, s'ha revisat la normativa que regula els requisits que han de complir els diferents tipus de guants metges i els assajos que s'han de fer per verificar-ne el seu compliment d'aquests requisits. Posteriorment, es van identificar els aspectes dels guants d'un sol ús que afecten el medi ambient i les opcions de reduir l'impacte com la bioremediació i el reciclatge de cautxú. Finalment, s'han suggerit les rutes que han de prendre les investigacions futures en aquest camp., El presente Trabajo de Fin de Máster (TFM) es una revisión de artículos científicos, material bibliográfico y antecedentes históricos sobre los guantes médicos desechables. En esta revisión, se han estudiado datos desde el origen de estos guantes hasta las últimas innovaciones y mejoras que se están realizando en estos productos con creciente demanda mundial. Además, se ha analizado el empleo del caucho natural, su extracción como látex del árbol Hevea brasiliensis, su composición y las alternativas de cauchos sintéticos con sus respectivas ventajas e inconvenientes. Adicionalmente, se han evaluado los aditivos que se han empleado tradicionalmente en las formulaciones de guantes y las alternativas más recientes entre los que se destacan los reticulantes biobasados, los rellenos biodegradables, así como los agentes con propiedades antimicrobianas. Estos últimos en su aplicación como revestimientos, trícapas o nanohilos que se incorporan a la estructura del guante. Por otro lado, se compararon los tipos de producción por lotes y en continuo, se explicó un proceso genérico de fabricación de guantes con las distintas condiciones usuales de proceso y se analizaron las distintas opciones de tratamientos superficiales para obtener guantes con y sin polvo. A continuación, se ha revisado la normativa que regula los requisitos que deben cumplir los distintos tipos de guantes médicos y los ensayos que deben realizarse para verificar el cumplimiento de dichos requisitos. Posteriormente, se identificaron los aspectos de los guantes desechables que afectan al medio ambiente y las opciones de reducir el impacto como la biorremediación y el reciclaje de caucho. Finalmente, se han sugerido las rutas que deben tomar las investigaciones futuras en este campo., The present Final Master's Work is a review of scientific articles, bibliographic material and historical background on disposable medical gloves. In this review, data has been studied from the origin of these gloves to the latest innovations and improvements being made in these products with increasing global demand. The use of natural rubber, its extraction as latex from the Hevea brasiliensis tree, its composition and synthetic rubber alternatives with their respective advantages and disadvantages have also been analyzed. In addition, the additives that have traditionally been used in glove formulations and the most recent alternatives have been evaluated, among which are biobased crosslinkers, biodegradable fillers, as well as agents with antimicrobial properties. The latter in their application as coatings, trilayers or nanowires that are incorporated into the glove structure. On the other hand, the types of batch and continuous production were compared, a generic glove manufacturing process was explained with the different usual process conditions and the different surface treatment options to obtain gloves with and without powder were analyzed. Subsequently, the regulations governing the requirements that the different types of medical gloves must meet and the tests that must be carried out to verify compliance with those requirements have been reviewed. Afterwards, aspects of disposable gloves that affect the environment and options to reduce impact such as bioremediation and rubber recycling were identified. Finally, the routes that future research should take in this field have been suggested.

The application of wastes as a filler/reinforcement phase in polymers is a new strategy to modify the performance properties and reduce the price of biocomposites. The use of these fillers, coming from agricultural waste (cellulose/lignocellulose-based fillers) and waste rubbers, constitutes a method for the management of post-consumer waste. In this paper, highly-filled biocomposites based on natural rubber (NR) and ground tire rubber (GTR)/brewers’ spent grain (BSG) hybrid reinforcements, were prepared using two different curing systems: (i) sulfur-based and (ii) dicumyl peroxide (DCP). The influence of the amount of fillers (in 100/0, 50/50, and 0/100 ratios in parts per hundred of rubber) and type of curing system on the final properties of biocomposites was evaluated by the oscillating disc rheometer, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, swelling behavior, tensile testing, and impedance tube measurements. The results show, that the scorch time and the optimum curing time values of sulfur cured biocomposites are affected by the change of the hybrid filler ratio while using the DCP curing system, and the obtained values do not show significant variations. The results conclude that the biocomposites cured with sulfur have better physico-mechanical and acoustic absorption, and that the type of curing system does not influence their thermal stability. The overall analysis indicates that the difference in final properties of highly filled biocomposites cured with two different systems is mainly affected by the: (i) cross-linking efficiency, (ii) partial absorption and reactions between fillers and used additives, and (iii) affinity of additives to applied fillers, Postprint (published version)

Base (seismic) isolation is a promising technology for seismic protection of buildings and other constructions. Nowadays, it is accepted that such a technique is efficient and reliable; however, it has two major limitations: soft foundation soil, and tall buildings. The first issue restrains the seismic isolation spreading, given that soft soil is frequent in densely populated areas, and usually such a soil type concentrates the highest seismicity levels. This paper aims to contribute to demonstrating that base isolation, if properly implemented, can be suitable for soft soil. A representative case study is analyzed: a 6-story reinforced concrete (RC) building with base isolation that has recently been built in Shanghai. Since the building is founded on soft soil, concern regarding base isolation suitability arose; even the Chinese design code does not recommend this solution for soft soil. To clarify this issue, non-linear time-history analyses are carried out for a number of natural and artificial seismic inputs that represent the site seismicity; the superstructure behavior is linear, while nonlinearities are concentrated in the isolation layer. The adequacy of base isolation is assessed in the superstructure (in terms of reduction of interstory drift, absolute acceleration and shear force) and in the isolation layer (in terms of axial force, torsion angle and shear strain). The relevance of soil–structure interaction is discussed. The behavior when the mechanical parameters of the isolation units have experienced important changes is also analyzed. The major conclusion is that base isolation of ordinary mid-height RC buildings founded on soft soil can perform satisfactorily in medium seismicity regions., Peer Reviewed, Postprint (published version)

La generació de residus de cautxú de neumàtics representa un pèrdua econòmica per la industria automòbil i un enorme risc ecològic, fet pel qual la seva revaloritzacio ha esdevingut imprescindible. Per abordar aquest problema, el cautxú “ground tire rubber” (GTR) va ser reciclat barrejant-lo amb àcid polilàctic (PLA), un termoplàstic biobasat fràgil, per augmentar l’energia de ruptura del PLA, a fi de fer-lo adequat per aplicacions industrials. Les mescles de PLA/GTR es van preparar mitjançant vulcanització dinàmica. Les condicions de processament (temps de residencia, temps de premsa), i els paràmetres dels materials (tipus de GTR, mida de partícules, rati PLA/GTR, agent de vulcanització) es van variar amb l’objectiu d’optimitzar les propietats de tracció de les mescles preparades. Una incorporació de menys del 10% de GTR triturat a temperatura ambient i tamisat (<125 µm) en mescles de PLA/GTR va produir un increment del doble de la deformació de ruptura i un augment del 70% de l’energia de ruptura. Una major quantitat de GTR (15%) en presència d’un agent de vulcanització va mostrar propietats similars. Els resultats obtinguts es van atribuir a (i) una baixa densitat d’entrecreuament del GTR, (ii) una bona distribució de les partícules de GTR tamisades en la matriu de PLA, (iii) una re-vulcanització dinàmica, millorada amb la presència d’un agent de reticulació., La generación de residuos de caucho de neumáticos representa una pérdida económica para la industria automóvil y un enorme riesgo ecológico, por lo que su revalorización es imprescindible. Para abordar este problema, el caucho “ground tire rubber” (GTR) fue reciclado mezclándolo con ácido poliláctico (PLA), un termoplástico bio-basado frágil, para aumentar la energía de rotura del PLA con el fin de hacerlo adecuado para aplicaciones industriales. Las mezclas de PLA/GTR se prepararon mediante vulcanización dinámica. Las condiciones de procesamiento (tiempo de residencia, tiempo de prensa) y los parámetros de los materiales (tipo de GTR, tamaño de partículas, ratio PLA/GTR, agente de reticulación) se variaron con el objetivo de optimizar las propiedades de tracción de las mezclas preparadas. Una incorporación de menos de 10 % de GTR triturado a temperatura ambiente y tamizado (< 125 µm) en mezclas de PLA/GTR produjo un incremento del doble de la deformación de rotura y un aumento del 70 % de la energía de rotura. Una mayor cantidad de GTR (15 %) en presencia de un agente de vulcanización mostró propiedades similares. Los resultados obtenidos se atribuyeron a (i) una baja densidad de entrecruzamiento del GTR, (ii) una buena distribución de las partículas de GTR tamizado en la matriz de PLA, y (iii) una re-vulcanización dinámica, mejorada en presencia de un agente de reticulación., The generation of waste rubber from pneumatic tires represents an economic loss for the automotive industry and a huge ecological risk, making its revalorization inevitable. To tackle this issue, waste ground tire rubber (GTR) was recycled by blending it with Polylactic acid (PLA), a brittle bio-based thermoplastic, to toughen PLA and make it suitable for non-tire automotive applications. PLA/GTR blends were prepared by melt-blending via dynamic vulcanization. Processing conditions (residence time, moulding time) and materials’ parameters (GTR type, particle size, PLA/GTR ratio, vulcanizing agent) were varied to improve the tensile properties of the prepared blends. It was found that the incorporation of less than 10 % of ambient grinded GTR crumbs (sieved: diameter < 125 µm) into PLA/GTR blends yielded in a two-fold increase in strain at break and an increase of 70 % of the tensile energy at break. A higher quantity of GTR (15 wt. %) in presence of a crosslinking agent showed similarly improved properties. Results were ascribed to (i) a low network chains density of the GTR crumbs obtained by grinding, (ii) a good stress distribution of the selected GTR particles over the PLA matrix, and (iii) dynamic re-vulcanization, enhanced in presence of the crosslinking agent., Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.4 - Per a 2030, modernitzar les infraestructures i reconvertir les indústries perquè siguin sostenibles, usant els recursos amb més eficàcia i promovent l’adopció de tecnologies i processos industrials nets i racionals ambiental­ment, i aconseguint que tots els països adoptin mesures d’acord amb les capacitats respectives

The proposed method of ground tire rubber (GTR) utilization involves the application of trans-polyoctenamer rubber (TOR), a commercially available waste rubber modifier. The idea was to investigate the influence of various curing additives (sulfur, N-cyclohexyl-2-benzothiazole sulfenamide (CBS), dibenzothiazole disulfide (MBTS) and di-(2-ethyl)hexylphosphorylpolysulfide (SDT)) on curing characteristics, physico-mechanical, thermal, acoustic properties as well as the morphology of modified GTR, in order to evaluate the possibility of reclaiming GTR and the co-cross-linking between applied components. The results showed that the presence of the modifier without the addition of curing additives hinders the physico-mechanical properties of revulcanized GTR. The addition of SDT, CBS, MBTS and sulfur change the melting kinetics of TOR, indicating partial degradation and/or co-cross-linking between components. In the studied conditions, the best mechanical properties were obtained by the samples cured with sulfur. The morphology analysis, combined with the physico-mechanical results, indicated that when the surface of the GTR is more developed, obtained by the addition of TOR, the properties of the GTR improve, Postprint (published version)

Currently, the huge use of tires generates large quantities of waste material which represents a severe environmental problem. The common technique used for processing waste tires is crushing using mechanical methods and separating tire components like fibers, metals, and rubber from the used tire. The aim of this research is the recycling of this rubber from crushed tires, called ground tire rubber (GTR). With this aim, the manuscript analyses key mechanical properties of the thermoplastic composites produced by blending of crushed and micronized small particles of waste rubber tires with several industrial thermoplastic polymers. These types of composites are defined based on the total amount GTR in percent by weight, in the composite, and also, the particle sizes used in each case, so these aforementioned two variables (microparticle size and amounts) along with seven common industrial polymers define a series of composites for which the mechanical properties were tested, studied, analyzed and finally presented. Finally, the results obtained show that this proposed recycling method could be a way to enhance some specific polymer properties and could contribute to reducing the total of end of life used tire stocks environmental problem, Postprint (published version)

In the present research, we investigated the conceivable outcomes of using ground tire rubber (GTR) particle polymeric blends. Special methods of restoring tires that are no longer in use include GTR retreading, GTR blending destined for recycling to attain raw substances utilized in other industrial application production processes, and the valorization of GTR for power/energy generation. The recycling of end-of-life tires enables the recovery of rubber, steel, and fibers, all of which are valid on the market as raw materials to be used for other processes. There are methods to recycle GTRs in a clean and environmentally friendly way. In the present research, several industrial applications of GTR polymer blends were developed and compared with standard values from the Spanish Association for Standardization (UNE) and the International Electrotechnical Commission (IEC). In order to analyze the viability in many of the industrial applications selected, certain compounds obtained from the GTR polymer blends were analyzed regarding their use in nine low requirement insulator applications. The research and analysis developed in this manuscript used standard values from the UNE and IEC, and these standard values were compared with the test values. The obtained results were used to provide an application list that could be helpful for industrial applications. In this research, the pre-owned polymers were as follows: polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), acrylonitrile butadiene-styrene (ABS), ethylene vinyl acetate (EVA), polyvinyl chloride (PVC), and polyamide (PA). The filler used was GTR with particle sizes lower than 200 microns. The amounts of GTR particles in the compound materials were 0% (raw polymer), 5%, 10%, 20%, 40%, 50%, and 70% (the latter being found in polymeric blends). We discovered six plausible modern applications of GTR polymer blends as indicated by the UNE and IEC standards., Peer Reviewed, Postprint (published version)

The amount of elastomeric waste, especially from tires is constantly increasing on a globalscale. The recycling of these residua should be considered a priority. Compounding the waste rubberswith other polymers can be an excellent alternative to reuse waste materials. This procedure requiressolving 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 theirenvironmental impact. In this work, reclaimed rubber/poly(e-caprolactone) (RR/PCL) blends areproposed to enhance the recycling and upcycling possibilities of waste rubbers. The results showthat 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. Structureand properties of the proposed RR/PCL have been studied by means of static and dynamic mechanicaltesting, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC),and thermogravimetric analysis (TGA)-FTIR analysis, Postprint (published version)

The waste rubber vulcanizate, on account of its stable, cross-linked and three-dimensional structural arrangement, is difficult to biodegrade. Thus, the ever-increasing bulk of worn-out tires is a serious environmental issue and its safe disposal is still a challenging task reported widely by the scientific community. The rubber materials, once they end their useful life, may present difficulties to be reused or recycled. At present, only one tire recycling method is used, which involves grinding and separating steel and fibers from vulcanized rubber, and then using rubber for industrial applications, such as flooring, insulation, footwear. In this paper, a new compound material is presented from a base of reused tire powder (Ground Tire Rubber: GTR) as a mixer and linear low-density polyethylene (LLDPE) as a matrix. The reused tire powder, resulting from grinding industrial processes, is separated by sieving into just one category of particle size (<200 µm) and mixed with the LLDPE in different amounts (0%, 5%, 10%, 20%, 40%, 50% and 70% GTR). Due to the good electrical properties of the LLDPE, this study’s focus is settled on the electrical behavior of the obtained composites. The test of the dielectric behavior is carried out by means of DEA test (Dynamic Electric Analysis), undertaken at a range of temperatures varying from 30 to 120 °C, and with a range of frequencies from 1 to 102, to 3·106 Hz, from which permittivity, conductivity, dielectric constant and electric modulus have been obtained. From these experimental results and their analysis, it can be drawn that the additions of different quantities of GTR to LLDPE could be used as industrial applications, such as universal electrical cable joint, filler for electrical applications or cable tray systems and cable ladder system., Peer Reviewed, Postprint (published version)