1,721,192 research outputs found
Thorough characterization of polyoxyethylene sorbitan monopalmitate plasticized PLA/pectin composites: Insights into material properties and thermomechanical performance
No full text[EN] By using dual-screw extrusion and injection molding process, different polymeric composites based on the combination of polylactic acid and pectin were successfully developed. To enhance the performance of the developed materials, plasticization was carried out by using polyoxyethylene sorbitan monopalmitate. In the composite containing 15¿wt% (weight) of pectin along with the plasticizer in 20 phr (per hundred resin), the elongation at break reached 23.6¿%, accompanied by a limited reduction in tensile strength. The incorporation of the plasticizer played a crucial role in determining the outcome of the composites, as it effectively reduced the glass transition temperature (Tg), thereby promoting improvements in ductile properties at room temperature and also increasing the crystallization ability of the samples. The polymer composites underwent testing through various techniques, including assessments of thermomechanical, chemical, color, and water uptake properties.This research is a part of the grant PID2023 152869OB-C22, and the grant TED2021 131762A-I00, funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU /PRTR. The authors also thank Generalitat Valenciana - GVA, grant number CIGE/2023/46 and CIAICO/2023/253, for supporting this work. L. Quiles-Carrillo would like to thank the Ministry of Science, Innovation and Universities of Spain for the Jos¿e Castillejo grant for the international mobility of early-career researchers, with reference CAS22/
00024. N. Montanes would like to express his gratitude to the Ministry of Science, Innovation and Universities of Spain for the grant awarded under Modality A, Stays for senior teaching and/or research staff in
foreign centers, with reference PRX22/00424. J. Ivorra-Martinez thanks Generalitat Valenciana - GVA for funding a postdoc position through the CIAPOS program co-funded by ESF Investing in your future, grant number CIAPOS/2023/362.Juan Ivorra-Martinez;Quiles-Carrillo, Luis;Montanes, Nestor;Dominici, F.;Puglia, D.;Torre, L. (2025). Thorough characterization of polyoxyethylene sorbitan monopalmitate plasticized PLA/pectin composites: Insights into material properties and thermomechanical performance. Industrial Crops and Products. 226:1-12. https://doi.org/10.1016/j.indcrop.2025.120675S11222
Innovative development and characterization of thermoplastic zein-based biopolymers for food packaging via injection molding
Get PDF[EN] This study focuses on the development of biodegradable polymers using zein (ZEI) plasticized with glycerol (GLY) and urea (UREA), with the goal of replacing conventional plastics in food packaging. The optimized combination of glycerol and urea in zein formulations significantly enhances mechanical properties: ZEI-15GLY-10UREA formulation achieves a maximum tensile strength of 21.3 MPa. Elongation at break is higher in blends with lower urea content, reaching 9.1% in ZEI-20GLY-5UREA. Conversely, formulations with higher urea content exhibit reduced elongation and toughness, evident in the decrease to 1.8 kJ/m2 of impact energy in ZEI-25UREA. Samples show Shore D hardness values up to 82.0. Morphological characterization confirms consistent behavior with mechanical properties, indicating that the glycerol and urea combination promotes a more ductile structure. Incorporation of these plasticizers lowers the glass transition temperature of the compounds from 53.8 °C in ZEI-25GLY to between 48 °C and 49 °C in formulations with 5% and 10% urea. All formulations exhibit biodegradation behaviour, with all of them achieving complete degradation in the final weeks. In all cases, there is a clear trend of mass loss during the first 6 weeks, with all formulations losing more than 80% of their initial mass.This research is a part of the grant PID2023-152869OB-C22, funded by MCIN/AEI/10.13039/501100011033 and the grant TED2021-131762A-I00, funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU /PRTR. Authors also thank Generalitat Valenciana-GVA for funding this research through the grant numbers CIAICO/2023/253 and CIGE/2023/46. Funded with Aid for First Research Projects (PAID-06-22), Vice-rectorate for Research of the Universitat Politecnica de Valencia (UPV). J. G.-C. wants to thank
FPU20/01732 grant funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future.Lluis Plasencia;Marina P. Arrieta;Lázaro-Hernández, C.;Gómez-Caturla, Jaume;Quiles-Carrillo, Luis (2025). Innovative development and characterization of thermoplastic zein-based biopolymers for food packaging via injection molding. Food Hydrocolloids. 163. https://doi.org/10.1016/j.foodhyd.2025.111134S16
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Assessment of Epoxidized Isobutyl Fatty Esters from Soybean Oil Distillates as Biobased Plasticizers
No full text[EN] This study evaluated the production and performance of biobased epoxidized isobutyl esters (EIE) as sustainable plasticizers for polymers, aiming to support circular economy models within the chemical industry. EIE were synthesized through the esterification of isobutyl alcohol with oleic and linoleic acids as well as soybean oil deodorizer distillates (SODD), followed by subsequent epoxidation. The plasticizing effect of epoxidized isobutyl oleate, linoleate, and soyate was assessed by studying their mechanical and thermal properties and performing Dynamic Mechanical Analysis (DMA) on PVC films prepared at a fixed content of 70 phr using the solvent casting method. The chemical structure of the films was identified by Fourier transform infrared (FTIR) spectroscopy while the permanence of the plasticizers was investigated through migration and volatility tests. Finally, barrier properties such as water vapor permeability and migration were evaluated alongside surface characteristics such as contact angle and transparency by UV-visible spectroscopy. Dioctyl phthalate (DOP) and epoxidized soybean oil (ESO) were used as reference commercial plasticizers. Among the different EIE, epoxidized isobutyl soyate (EIS) showed remarkable results such as high elasticity (500%), high thermal stability, tensile strength (11.2 MPa) comparable to the reference plasticizers, and high plasticizing efficiency (106.2%). However, barrier properties, such as water vapor permeability and migration, were affected by the composition of this epoxidized ester. Overall, EIE exhibited moderate migration rates which limit their use as general purpose PVC plasticizers, but they might be effectively used for low temperature applications and as coplasticizers for different polymers.This research is a part of the grant PID2020-116496RB-C22 funded by MCIN/AEI/10.13039/501100011033. Authors also thank Generalitat Valenciana-GVA for funding this research through the grant numbers AICO/2021/025, CIGE/2021/094, and CIGE/2023/46. Funded with Aid for First Research Projects (PAID-06-22), Vice-rectorate for Research of the Universitat Politecnica de Valencia (UPV). This project was also partially funded by grants from the Newton Fund Institutional Links - Project 526061819 according to Minciencias contract 584-2020, by Program ECOSNORD in accordance with Minciencias contract 487-2021, and by Universidad Nacional de Colombia projects HERMES 61109, 53361, and 46517.Nájera, LN.;Orjuela, A.;Narvaez-Rincón, PC.;Sanchez-Nacher, Lourdes;Montanes, Nestor;Quiles-Carrillo, Luis (2024). Assessment of Epoxidized Isobutyl Fatty Esters from Soybean Oil Distillates as Biobased Plasticizers. Industrial & Engineering Chemistry Research. 63(50):22203-22219. https://doi.org/10.1021/acs.iecr.4c03570S2220322219635
Estudio, análisis y propuesta de criterios de selección geométrica y valoración biomecánica de las configuraciones de prótesis inversa de la articulación gleno-humeral de hombro (PIH)
No full text[ES] Análisis bibliográfico del estado del arte de la biomecánica de la articulación gleno-humeral.
Definición y objetivos del estudio biomecánico de las PIH y establecimiento de un modelo matemático de evaluación de las distintas configuraciones.
Estudio de las principales causas de fallo y determinación de las variables de diseño que lo inducen.
Estudio y definición de variables de respuesta biomecánica, que permitan cuantificar el efecto de las variables de diseño sobre las posibles configuraciones de las PIH.
Diseño experimental para conocer las funciones de correlación entre las variables de diseño y variables respuesta.Quiles Carrillo, LJ. (2016). Estudio, análisis y propuesta de criterios de selección geométrica y valoración biomecánica de las configuraciones de prótesis inversa de la articulación gleno-humeral de hombro (PIH). https://riunet.upv.es/handle/10251/73471.TFG
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Desarrollo y optimización de nuevos materiales poliméricos, mezclas y compuestos de alto rendimiento medioambiental a partir de poliésteres y poliamidas procedentes de recursos renovables de interés en el sector envase y embalaje
Get PDFTesis por compendio[ES] El principal objetivo de la presente tesis doctoral se ha centrado en la obtención, desarrollo y caracterización de nuevas formulaciones de alto rendimiento medioambiental a partir de la utilización de poliésteres y poliamidas de origen renovable para el sector del envase y embalaje. A lo largo de todo el proceso de investigación, se han abordado y evaluado diferentes frentes de mejora con el objetivo de mejorar al máximo las propiedades de estos materiales desde un punto de vista altamente eficiente para el medio ambiente. Para este cometido, se han analizado desde diferentes tipos de mezclas binarias y ternarias, hasta la incorporación de cargas y refuerzos naturales, incorporación de aditivos y utilización de plastificantes capaces de solventar problemas de fragilidad y adhesión ligados a ciertos poliésteres como el PLA.
En la primera fase de la tesis se han analizado y estudiado la miscibilidad y propiedades mecánicas, térmicas y morfológicas de mezclas ternarias y binarias basadas en poliéster como el PHBH o el PLA como elementos principales. Se ha utilizado la extrusión reactiva (REX) consiguiendo resultados muy positivos con la incorporación de materiales como el PCL, TPS y PBAT a los poliésteres anteriormente comentados. Se ha mejorado la miscibilidad entre los distintos componentes, a partir de elementos como el ESAO o agentes compatibilizadores como PE-g-MA, PE-co-GMA y DCP, y sobretodo, MLO como compatibilizante natural, para desarrollar plásticos totalmente renovables con ductilidad y tenacidad mejoradas para su aplicación en el sector envase y embalaje. Dentro de las mezclas binarias, la combinación del PLA con un polietileno de origen renovable ha resultado ser una solución prometedora dentro del sector del envase y embalaje.
Por otro lado, para mejorar los problemas de tenacidad y el coste del PLA, se han evaluado y analizado la incorporación de aditivos y cargas naturales. La utilización de aceites naturales derivados de la soja, linaza y cáñamo han mejorado en gran medida la ductilidad del PLA. Además, estos aceites se han combinado con cargas derivadas de la cáscara de almendra y la piel de naranja en proporciones de hasta un 30%, consiguiendo un buen equilibrio de propiedades mecánicas y obteniendo WPCs capaces de ser altamente eficientes y rentables en algunas aplicaciones de envasado.
En la búsqueda de polímeros respetuosos por el medio ambiente, se han evaluado las propiedades de diferentes poliamidas de base biológica, y se ha seleccionado la PA1010 como candidata perfecta, gracias a sus excelentes propiedades y a su origen 100% renovable. En este contexto, se ha estudiado la viabilidad de incorporar fibras naturales como refuerzo, con unos resultados muy prometedores para las fibras de pizarra, consiguiendo mejoras de resistencia máxima de más del doble con elementos totalmente naturales. Hay que resaltar que la combinación de la PA1010 y el PLA con diferentes agentes naturales como el ELO y el MLO para la fabricación de films, han dado como resultado una notable mejora en las propiedades mecánicas, y sobre todo, una mejora en el efecto barrera al oxígeno.
En la última fase de la tesis, se ha optimizado la extracción de elementos antioxidantes como el ácido gálico a partir de residuos agroalimentarios. La incorporación de este elemento en el PLA ha dado como resultado la fabricación de films para envases activos, favoreciendo en gran medida su aplicación en el sector del envasado de alimentos. Además, se ha corroborado el efecto que posee este tipo de antioxidante natural en la preservación de films de bio-HDPE frente a agentes externos como la temperatura y la radiación UV. Por último, se ha conseguido mejorar en gran medida la ventana de procesamiento y las propiedades mecánicas y térmicas de las mezclas de biopolímeros de PA1010 y bio-HDPE.[EN] The main objective of this doctoral thesis has been focused on obtaining, developing and characterizing new formulations with high environmental performance from the use of polyesters and polyamides of renewable origin for the packaging sector. Throughout the research process, different improvement fronts have been addressed and evaluated with the aim of improving the properties of these materials to the maximum from a highly efficient point of view for the environment. For this purpose, different types of binary and ternary mixtures have been analysed, as well as the incorporation of natural fillers and reinforcements, the incorporation of additives and the use of plasticisers capable of solving problems of fragility and adhesion linked to certain polyesters such as PLA.
In the first phase of the thesis, the miscibility and mechanical, thermal and morphological properties of ternary and binary mixtures based on polyester such as PHBH or PLA as main elements have been analysed and studied. Reactive extrusion (REX) has been used, obtaining very positive results with the incorporation of materials such as PCL, TPS and PBAT to the previously mentioned polyesters. Miscibility between the different components has been improved, using elements such as ESAO or compatibilizing agents such as PE-g-MA, PE-co-GMA and DCP, and above all, MLO as a natural compatibilizer, to develop totally renewable plastics with improved ductility and tenacity for application in the packaging sector. Within binary mixtures, the combination of PLA with a polyethylene of renewable origin has proved to be a promising solution within the packaging sector.
On the other hand, to improve the toughness problems and the cost of PLA, the incorporation of additives and natural fillers has been evaluated and analysed. The use of natural oils derived from soya, flax and hemp has greatly improved the ductility of PLA. In addition, these oils have been combined with fillers derived from almond shells and orange peel in proportions of up to 30%, achieving a good balance of mechanical properties and obtaining WPCs capable of being highly efficient and cost-effective in some packaging applications.
In the search for environmentally friendly polymers, the properties of different bio-based polyamides have been evaluated, and PA1010 has been selected as a perfect candidate thanks to its excellent properties and 100% renewable origin. In this context, the viability of incorporating natural fibres as reinforcement has been studied, with very promising results for slate fibres, achieving maximum resistance improvements of more than double with totally natural elements. It should be noted that the combination of PA1010 and PLA with different natural agents such as ELO and MLO for the manufacture of films, have resulted in a significant improvement in mechanical properties, and above all, an improvement in the oxygen barrier effect.
In the last phase of the thesis, the extraction of antioxidant elements such as gallic acid from food waste has been optimized. The incorporation of this element in PLA has resulted in the manufacture of films for active packaging, greatly favoring its application in the food packaging sector. In addition, the effect of this type of natural antioxidant on the preservation of bio-HDPE films against external agents such as temperature and UV radiation has been corroborated. Finally, the processing window and the mechanical and thermal properties of PA1010 and bio-HDPE biopolymer blends have been greatly improved.[CA] El principal objectiu de la present tesi doctoral s'ha centrat en l'obtenció, desenvolupament i caracterització de noves formulacions d'alt rendiment mediambiental a partir de la utilització de polièsters i poliamides d'origen renovable per al sector de l'envàs i embalatge. Al llarg de tot el procés d'investigació, s'han abordat i avaluat diferents fronts de millora amb l'objectiu de millorar al màxim les propietats d'aquests materials des d'un punt de vista altament eficient per al medi ambient. Amb aquest objectiu, s'han analitzat des de diferents tipus de mescles binàries i ternàries, fins a la incorporació de càrregues i reforços naturals, incorporació d'additius i utilització de plastificants capaços de solventar problemes de fragilitat i adhesió lligats a certs polièsters com el PLA. En la primera fase de la tesi s'han analitzat i estudiat la miscibilitat i propietats mecàniques, tèrmiques i morfològiques de mescles ternàries i binàries basades en polièster com el PHBH o el PLA com a elements principals. S'ha utilitzat l'extrusió reactiva (REX) aconseguint resultats molt positius amb la incorporació de materials com el PCL, TPS i PBAT als polièsters anteriorment comentats. Per a la millora de la miscibilitat entre els diferents components, s'han utilitzat elements com el ESAO o agents compatibilitzants com a PE-g-MA., PE-co-GMA i DCP, i sobretot, MLO com compatibilitzant natural, per a desenvolupar plàstics totalment compostables amb ductilitat i tenacitat millorades per a la seua aplicació en el sector envase i embalatge. Dins de les mescles binàries, la combinació del PLA amb un polietilé d'origen renovable ha resultat ser una solució prometedora dins del sector de l'envàs i l'embalatge. D'altra banda, per a millorar els problemes de tenacitat i el cost del PLA, s'han avaluat i analitzat la incorporació d'additius i càrregues naturals. La utilització d'olis naturals derivats de la soja, llinosa i cànem han millorat en gran manera la ductilitat del PLA. A més, aquests olis s'han combinat amb càrregues derivades de la corfa d'ametla i la pell de taronja en proporcions de fins a un 30%, aconseguint un bon equilibri de propietats mecàniques i obtenint WPCs capaços de ser altament eficients i rendibles en algunes aplicacions d'envasament. Dins de la cerca de polímers respectuosos pel medi ambient, s'han avaluat les propietats de diferents poliamides de base biològica, i s'ha seleccionat la PA1010 com a candidata perfecta gràcies a les seues excel¿lents propietats i al seu origen 100% renovable. En aquest context, s'ha estudiat la viabilitat d'incorporar fibres naturals com a reforç, amb uns resultats molt prometedors per a les fibres de pissarra, aconseguint uns resultats de resistència màxima de més del doble amb elements totalment naturals. Hi ha que ressaltar que la combinació de la PA1010 amb el PLA amb diferents agents naturals com el ELO i el MLO per a la fabricació de films atorga una millora notable per a la fabricació de films, gràcies a la seua notable millora en les propietats mecàniques i dúctils, i sobretot, la millora en l'efecte barrera a l'oxigen. En l'última fase de la tesi, s'ha optimitzat l'extracció d'elements antioxidants com l'àcid gàl¿lic a partir de residus agroalimentaris. La incorporació d'aquest element en el PLA ha donat com a resultat la fabricació de films i envasos actius, afavorint en gran manera la seua aplicació en el sector de l'envasament d'aliments. A més, s'ha avaluat l'efecte que posseeix aquest tipus d'antioxidant natural en la preservació de films de bio-HDPE enfront d'agents externs com la temperatura i la radiació UV. Finalment, s'ha aconseguit millorar en gran manera la finestra de processament i les propietats mecàniques i tèrmiques de les mescles de biopolímers com PA1010 i bio-HDPE.Al ministerio de Educación Cultura y Deporte por el apoyo financiero a través
de la ayuda otorgada (FPU15/03812).
A la Conselleria d'Educació, Cultura i Esport de la Generalitat Valenciana por el
apoyo financiero a través de la ayuda otorgada (ACIF/2016/182).
Al ministerio de Ciencia, Innovación y Universidades (MICIU) por el soporte
financiero de este trabajo con el proyecto MAT2017-84909-C2-2-R.Quiles Carrillo, LJ. (2020). Desarrollo y optimización de nuevos materiales poliméricos, mezclas y compuestos de alto rendimiento medioambiental a partir de poliésteres y poliamidas procedentes de recursos renovables de interés en el sector envase y embalaje [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/147479TESISCompendi
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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