Molecular mobility. Structure-property relationship of polymeric materials

Tesis por compendio[EN] The present work examines the influence of the chemical structure of polymers on thermal, mechanical and dielectric behavior. The experimental techniques used for the purpose are differential scanning calorimetry, dynamo-mechanical analysis and dielectric spectroscopy. Additionally, in order to confirm the results obtained using the above methods, other techniques such as ray diffraction have also been employed. Chapters 1 and 2 contain the introduction and the objectives, respectively. Chapter 3 briefly describes the experimental techniques used. Chapter 4 contains the findings of the comparative analysis of the response to electrical noise fields for three poly(benzyl methacrylates) with different structures. The analysis was carried out under a wide range of frequencies and temperatures on three poly(benzyl methacrylates) containing two dimethoxy groups in positions 2,5-, 2,3- and 3,4-. The results show that the position of the dimethoxy groups on the aromatic ring has a significant effect on the molecular dynamics of poly(benzyl methacrylate). The spectra obtained were of high complexity and therefore, in order to perform a better analysis, numerical methods for time-frequency transformation including the use of parametric regularization techniques were used. We studied the effect of this structural change on the secondary relaxation processes and relaxation process , relating to the glass transition. We also analyzed the effect of the dimethoxy group position on the formation of nanodomains, in which the side chains are predominant, and on the conduction processes of the materials tested. In Chapter 5, the conductivity of rubbery liquids was studied by analyzing poly(2,3-dimethoxybenzyl methacrylate), which exhibits its own particular behavior. The chapter analyzes the principle of time-temperature superposition, employing different interrelated variables. Chapter 6 focuses on how the presence of crosslinking affects the molecular mobility of polymethacrylates containing aliphatic alcohol ether residues. In this case, the effect of crosslinking on the secondary and primary relaxation processes was analyzed. The creation of nanodomains in the side chains as a result of the presence of crosslinking was also studied.[ES] En este trabajo se presenta un estudio de la influencia de la estructura química de los polímeros en su comportamiento térmico, mecánico y dieléctrico. Las técnicas experimentales empleadas para ello han sido la calorimetría diferencial de barrido, el análisis dinamo-mecánico y la espectroscopia dieléctrica. Adicionalmente, se han empleado otras técnicas como la difracción de rayos, con objeto de corroborar los resultados obtenidos por las primeras. En los Capítulos 1 y 2 se recoge la introducción y los objetivos, respectivamente. El Capítulo 3 presenta una breve descripción de las técnicas experimentales empleadas. En el Capítulo 4 se recogen los resultados obtenidos en el análisis comparativo de la respuesta a campos de perturbación eléctrica en un amplio rango de frecuencias y temperaturas para tres polimetacrilatos de bencilo con dos grupos dimetoxi en posiciones 2,5-, 2,3- y 3,4-. Los resultados obtenidos señalan el importante efecto de la posición de los grupos dimetoxi en el anillo aromático, sobre la dinámica molecular del polimetacrilato de bencilo. Los espectros obtenidos fueron muy complejos, por ello en orden a llevar a cabo un mejor análisis se emplearon métodos numéricos para la transformación tiempo-frecuencia que incluyeron el uso de técnicas de regularización paramétrica. Se ha estudiado el efecto que dicho cambio estructural ejerce tanto sobre los procesos de relajación secundaria como sobre el proceso de relajación α, relacionado con la transición vítrea. Así mismo, se ha analizado el efecto de la posición de los grupos dimetoxi en la formación de iii nanodominios en los que predominan las cadenas laterales, y su efecto en los procesos de conducción de los materiales analizados. En el Capítulo 5 se recoge el estudio de la conductividad de líquidos gomosos tomando como modelo el poli (metacrilato de 2,3-dimetoxibencilo), por su peculiar comportamiento. En este capítulo se ha realizado un análisis del principio de superposición tiempo-temperatura, empleando para ello diferentes variables relacionadas entre sí. En el Capítulo 6 se recoge el efecto de la presencia de entrecruzante en la movilidad molecular de polimetacrilatos que contienen residuos de éteres de alcoholes alifáticos. En este caso, se ha analizado el efecto de la presencia de entrecruzante tanto en los procesos de relajación secundarios, como en el proceso de relajación principal. También se llevó a cabo un análisis del efecto que la presencia de entrecruzante tiene sobre la creación de nanodominios gobernados por las cadenas laterales.[CA] En aquest treball es presenta un estudi de la influència de l'estructura química dels polímers en el seu comportament tèrmic, mecànic i dielèctric. Les tècniques experimentals utilitzades han sigut la calorimetria diferencial de rastreig, l'anàlisi dinamo-mecànic i l'espectroscòpia dielèctrica. Addicionalment, s'han empleat altres tècniques com la difracció de rajos X a fi de corroborar els resultats obtinguts per les primeres. En els Capítols 1 i 2 s'arreplega la introducció i els objectius, respectivament. Al Capítol 3 es presenta una breu descripció de les tècniques experimentals emprades. En el Capítol 4 es recull els resultats obtinguts en l'anàlisi comparativa de la resposta a camps de pertorbació elèctrica en un ampli rang de freqüències i temperatures de tres polimetacrilats de benzil amb dos grups metoxi en posicions 2,5-, 2,3- i 3,4-. Els resultats obtinguts assenyalen l'important efecte de la posició dels grups metoxi en l'anell aromàtic, sobre la dinàmica molecular del polimetacrilat de benzil. Els espectres obtinguts van ser molt complexos, per aquesta raó per a dur a terme un millor anàlisi es van emprar mètodes numèrics per a la transformació temps-freqüència que van incloure l'ús de tècniques de regularització paramètrica. S'ha estudiat l'efecte que el dit canvi estructural exerceix tant sobre els processos de relaxació secundària com sobre el procés de relaxació , relacionat amb la transició vítria. Així mateix, s'ha analitzat l'efecte de la posició dels grups metoxi en la formació de nanodominis en els que predominen les cadenes laterals, i el seu efecte en els processos de conducció dels materials analitzats. En el Capítol 5 s'arreplega l'estudi de la conductivitat de líquids gomosos prenent com a model el poli-(metacrilat de 2,3-dimetoxibencilo), pel seu peculiar comportament. En aquest capítol s'ha realitzat un anàlisi del principi de superposició temps-temperatura, emprant per a això diferents variables relacionades entre sí. En el Capítol 6 s'arreplega l'efecte de la presència d'entrecreuat en la mobilitat molecular de polimetacrilats que contenen residus d'èters d'alcohols alifàtics. En aquest cas, s'ha analitzat l'efecte de la presència d'entrecreuat tant en els processos de relaxació secundaris, com en el procés de relaxació principal. També es va dur a terme un anàlisi de l'efecte que la presència d'entrecreuat químic té sobre la creació de nanodominis governats per les cadenes laterals.Carsí Rosique, M. (2015). Molecular mobility. Structure-property relationship of polymeric materials [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/59460TESISPremios Extraordinarios de tesis doctoralesCompendi

Thermal and Dielectric Characterization of Multi-Walled Carbon NanotubesThermoplastic Polyurethanes Composites

[EN] Multi-walled carbon nanotubes-thermoplastic polyurethanes composites were characterized by means of differential scanning calorimetry and dielectric relaxation spectroscopy. The composite is characterized by two glass transition temperatures T (g) . The T (g) associated with the soft segment decreases by increasing of carbon nanotubes content, while carbon nanotubes content has practically no effect on the value of the T-g associated with the hard segments. It was observed that rising the temperature and carbon nanotubes content resulted in the increased of both the dielectric permittivity and the loss factor. The presence of carbon nanotubes produces an enhancement of charge carriers trapping, increasing the electrical conductivity. The electrical conductivity of the composite was found to exhibit an insulator to conductor transition at a carbon nanotubes critical content, i.e., the percolation threshold, near 6 wt %.MJS and MC acknowledge the financial support of the DGCYT through Grant MAT2015-63955-R.Sanchis Sánchez, MJ.; Carsí Rosique, M.; Gracia-Fernandez, C. (2017). Thermal and Dielectric Characterization of Multi-Walled Carbon NanotubesThermoplastic Polyurethanes Composites. Polymer Science Series A. 59(4):543-553. https://doi.org/10.1134/S0965545X17040083S543553594D. W. Schaefer and R. S. Justice, Macromolecules 40 (24), 8501 (2007).D. R. Raul and L. M. Robeson, Polymer 49 (15), 3187 (2008).P. J. Brigandi, J. M. Cogen, and R. A. Pearson, Polym. Eng. Sci. 54 (1), 1 (2014).H. Deng, L. Lin, M. Ji, S. Zhang, M. Yang, and Q. Fu, Prog. Polym. Sci. 39 (4), 627 (2014).Polymer-Matrix Composites. Types, Applications and Performance, Ed. by R. Kumar (Nova Sci. Publ., New York, 2014).Z. Wenying and Y. Demei, J. Appl. Polym. Sci. 118 (6), 3156 (2010).Y. P. Mamunya, V. V. Davydenko, P. Pissis, and E. V. Lebedev, Eur. Polym. J. 38 (9), 1887 (2002)B. Redondo-Foj, P. Ortiz-Serna, M. Carsí, M. J. Sanchis, M. Culebras, C. M. Gomez, and A. Cantarero, Polym. Int. 64, 284 (2015).S. Deng, Y. Zhu, X. Qi, W. Yu, F. Chen, and Q. Fu, RSC Adv. 6 (51), 45578 (2016).M. Khissi, M. El Hasnaoui, J. Belattar, M. P. F. Graca, M. E. Achour, and L. C. Costa, J. Mater. Environ. Sci. 2 (3), 281 (2011).M. Hindermann-Bischoff and F. Ehrburger-Dolle, Carbon 39 (3), 375 (2001).I. Balberg, Carbon 40 (2), 139 (2002).M. Moniruzzaman and K. I. Winey, Macromolecules 39, 5194 (2006).A. Bharati, R. Cardinaels, J. W. Seo, M. Wubbenhorst, and P. Moldenaers, Polymer 79 (19), 271 (2015)Szycher's Handbook of Polyurethanes, Ed. by M. Szycher (CRC Press, Washington, DC, 1999).C. Prisacariu, Polyurethane Elastomers. From Morphology to Mechanical Aspects (Springer, New York, 2011).P. Król, Prog. Mater. Sci. 52 (6), 915 (2007).P. R. de C. Coelho Filho, M. S. Marchesin, A. R. Morales, and J. R. Bartoli, Mater. Res. 17 (1), 127 (2014).R. H. Baughman, A. A. Zakhidov, and W. A. de Heer, Science 297 (5582), 787 (2002).J. Kim and Y. Son, Polymer 88, 29 (2016)M. A. Nikje Mir and A. Yaghoubi, Polimery 59(11–12), 776 (2014).C. Kingston, R. Zepp, A. Andrady, D. Boverho, R. Fehir, D. Hawkins, J. Roberts, P. Sayre, B. Shelton, Y. Sultan, V. Vejins, and W. Wohlleben, Carbon 68, 33 (2014).Anelastic and Dielectric Effects in Polymeric Solids, Ed. by N. G. McCrum, B. E. Read, and G. Williams (Wiley, London, 1967).In Broadband Dielectric Spectroscopy, Ed. by F. Kremer, and A. Schonhals (Springer, Berlin, 2003).E. Riande and R. Diaz-Calleja, Electrical Properties of Polymers (Marcel Dekker, New York, 2004).I. M. Hodge, K. L. Ngai, and C. T. Moynihan, J. Non-Cryst. Solids 351 (2), 104 (2005).A. Eceiza, M.D. Martin, K. de la Caba, G. Kortaberria, N. Gabilondo, M. A. Corcuera, and I. Mondragon, Polym. Eng. Sci. 48 (2), 297 (2008)A. K. Jonscher, Universal Relaxation Law: A Sequel to Dielectric Relaxation in Solids (Chelsea Dielectrics Press, London, 1996), Chap. 5.A. K. Jonscher, Nature 267, 673 (1977).G. Li, L. Feng, P. Tong, and Z. Zhai, Prog. Org. Coat. 90, 284 (2016)K. Petrie, M. Kontopoulou, and A. Docoslis, Polym. Compos. 37 (9), 2794 (2016)N. Aranburu and J. I. Eguiazabal, Polym. Compos. 35 (3), 587 (2014)Impedance Spectroscopy. Theory, Experiment, and Applications, Ed. by E. Barsoukov and J. R. Macdonals (Wiley Intersci., New York, 2005).S. Havriliak and S. J. Havriliak, Dielectric and Mechanical Relaxation in Materials (Hanser, Munich, 1997), p. 57.S. Havriliak and S. Negami, Polymer 8 (4), 161 (1967)

Effect of Chitin Whiskers on the Molecular Dynamics of Carrageenan-Based Nanocomposites

[EN] Films of carrageenan (KC) and glycerol (g) with different contents of chitin nanowhiskers (CHW) were prepared by a solution casting process. The molecular dynamics of pure carrageenan (KC), carrageenan/glycerol (KCg) and KCg with different quantities of CHWs as a filler was studied using dielectric relaxation spectroscopy. The analysis of the CHW effect on the molecular mobility at the glass transition, T-g, indicates that non-attractive intermolecular interactions between KCg and CHW occur. The fragility index increased upon CHW incorporation, due to a reduction in the polymer chains mobility produced by the CHW confinement of the KCg network. The apparent activation energy associated with the relaxation dynamics of the chains at T-g slightly increased with the CHW content. The filler nature effect, CHW or montmorillonite (MMT), on the dynamic mobility of the composites was analyzed by comparing the dynamic behavior of both carrageenan-based composites (KCg/xCHW, KCg/xMMT).This research was funded by the DGCYT grant number [MAT2015-63955-R] and the Vice-Rectorate for Research of the Pontificia Universidad Catolica del Peru and the the Peruvian Science and Technology Program (INNOVATE-PERU) And The APC was funded by MDPI.Carsí Rosique, M.; Sanchis Sánchez, MJ.; Gómez, CM.; Rodriguez, S.; García-Torres, F. (2019). Effect of Chitin Whiskers on the Molecular Dynamics of Carrageenan-Based Nanocomposites. Polymers. 11(6):1-16. https://doi.org/10.3390/polym11061083116116Zheng, Y., Monty, J., & Linhardt, R. J. (2015). Polysaccharide-based nanocomposites and their applications. Carbohydrate Research, 405, 23-32. doi:10.1016/j.carres.2014.07.016Jamróz, E., Kulawik, P., & Kopel, P. (2019). 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Monitoring molecular dynamics of bacterial cellulose composites reinforced with graphene oxide by carboxymethyl cellulose addition

[EN] Broadband Dielectric Relaxation Spectroscopy was performed to study the molecular dynamics of dried Bacterial Cellulose/Carboxymethyl Cellulose-Graphene Oxide (BC/CMC-GO) composites as a function of the concentration of CMC in the culture media. At low temperature the dielectric spectra are dominated by a dipolar process labelled as a beta -relaxation, whereas electrode polarization and the contribution of dc-conductivity dominate the spectra at high temperatures and low frequency. The CMC concentration affects the morphological structure of cellulose and subsequently alters its physical properties. X-ray diffractometry measurements show that increasing the concentration of CMC promotes a decrease of the Ia/Ib ratio. This structural change in BC, that involves a variation in inter- and intramolecular interactions (hydrogen-bonding interactions), affects steeply their molecular dynamics. So, an increase of CMC concentration produces a significantly decrease of the -relaxation strength and an increase of the dc-conductivity.This work was supported by the DGCYT [MAT2015-63955-R]; the Vice-Rectorate for Research of the Pontificia Universidad Catolica del Peril and the National Council of Science, Technology and Technological Innovation of Peru (CONCYTEC/FONDECYT).Sanchis Sánchez, MJ.; Carsí Rosique, M.; Gomez, CM.; Culebras, M.; Gonzales, K.; Gisbert Torres, F. (2017). Monitoring molecular dynamics of bacterial cellulose composites reinforced with graphene oxide by carboxymethyl cellulose addition. Carbohydrate Polymers. 157:353-360. https://doi.org/10.1016/j.carbpol.2016.10.00135336015

Renewable polyol obtained by microwave-assisted alcoholysis of epoxidized soybean oil: Preparation, thermal properties and relaxation process

[EN] The soybean oil polyol (SOP) use as feedstock in the polyurethane industry has been recently emphasized due to its excellent resistance to hydrolysis, which is also applicable in coatings and thermal insulation. In this article, the SOP was obtained by a very fast microwave-assisted alcoholysis of epoxidized soybean oil (ESO). The preparation method, thermal properties, and relaxation process were evaluated. High yields as opening and consumption epoxy group and selectivity of 99.8 mol%, 985 mol%, and 71.2 mol% were obtained. Through titrations, nuclear magnetic resonance and gel permeation chromatography were identified parameters as 0.32 mg KOH.g(-1) acid number, 190 mg KOH.g(-1) hydroxyl number, 150 mg KOH.g(-1) saponification index, 0.17 wt% water content, 1463 g.mol(-1) molecular weight, 4.98 average functionality, 2.4 x 10(-5) mPa.s(-1) viscosity at 333 K and 1.00 g.cm(-3) density. The dielectric relaxation spectroscopy allowed identifying the alpha-relaxation process with a 193.5 K glass transition (T-g), 63.2 fragility index and 234.1 kJ mol(-1) activation energy associated with T-g from the dynamic fragility index. The ionic conductivity temperature dependence on SOP obeys Arrhenius behavior. In summary, the SOP structure and thermal relaxation parameters determination are fundamental for the understanding of the structure-properties relationship of renewable polyurethanes. (C) 2019 Published by Elsevier B.V.The authors thank the financial support from the Brazilian Agency Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) and Sindicato das Industrias de Material Plastic do Nordeste Gaucho (SIMPLAS) for the gratification received at Jovens Pesquisadores 2017, da University of Caxias do Sul (UCS). CAF and OB are National Council for Scientific and Technological Development (CNPq) fellows. CMG and MJS thank the Spanish Ministerio de Economia y Competitividad (MAT2015-63955-R) for partial financial help. The authors also thank Dr. Cesar H. Wanke for the suggestions. This work was supported by CNPq-Brazil (06086/2018-2).Favero, D.; Marcon, VR.; Barcellos, T.; Gomez-Clari, CM.; Sanchis Sánchez, MJ.; Carsí Rosique, M.; Figueroa, CA.... (2019). Renewable polyol obtained by microwave-assisted alcoholysis of epoxidized soybean oil: Preparation, thermal properties and relaxation process. Journal of Molecular Liquids. 285:136-145. https://doi.org/10.1016/j.molliq.2019.04.078S13614528

The effect of cross-linking on the molecular dynamics of the segmental and β Johari–Goldstein processes in polyvinylpyrrolidone-based copolymers

The effect of the cross-link density on the molecular dynamics of copolymers composed of vinylpyrrolidone (VP) and butyl acrylate (BA) was studied using differential scanning calorimetry (DSC) and dielectric relaxation spectroscopy (DRS). A single glass transition was detected by DSC measurements. The dielectric spectra exhibit conductive processes and three dipolar relaxations labeled as a, b and g in the decreasing order of temperatures. The cross-linker content affects both a and b processes, but the fastest g process is relatively unaffected. An increase of cross-linking produces a typical effect on the a process dynamics: (i) the glass transition temperature is increased, (ii) the dispersion is broadened, (iii) its strength is decreased and (iv) the relaxation times are increased. However, the b process, which possesses typical features of a pure Johari Goldstein relaxation, unexpectedly loses the intermolecular character for the highest cross-linker content.B.R.F., M.J.S., P.O.S. and M.C. gratefully acknowledge CICYT for grant MAT2012-33483. F.G. and J.M.G. acknowledge the Spanish Ministerio de Economia y Competitividad-FEDER (MAT2014-54137-R) and the Junta de Castilla y Leon (BU232U13).Redondo Foj, MB.; Sanchis Sánchez, MJ.; Ortiz Serna, MP.; Carsí Rosique, M.; García, JM.; García, FC. (2015). The effect of cross-linking on the molecular dynamics of the segmental and β Johari–Goldstein processes in polyvinylpyrrolidone-based copolymers. Soft Matter. 11:7171-7180. https://doi.org/10.1039/c5sm00714cS7171718011V. Bühler , Polyvinylpyrrolidone Excipients for Pharmaceuticals: Povidone, Crospovidone and Copovidone , Springer , Berlin , 2005Haaf, F., Sanner, A., & Straub, F. (1985). Polymers of N-Vinylpyrrolidone: Synthesis, Characterization and Uses. 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Uso de las TIC como tecnologías facilitadoras del aprendizaje. Ayudas gráficas para facilitar la visión espacial de superficies pvT en la asignatura Termodinámica.

[EN] This paper proposes the use of graphical helps to facilitate the spatial vision of the threedimensional pvT diagrams used in thermodynamics for the analysis of thermodynamic processes experienced by a simple substance. Specifically, we propose the use of 3D models built by 3D printing and the development of Augmented Reality (AR) applications to visualize thermodynamic projections autonomously by students both inside and outside the classroom. Both tools have constituted a significant advance in the students' understanding of the thermodynamic problem indicated, as reflected in the results obtained.[ES] En esta comunicación se propone el uso de ayudas gráficas para facilitar la visión espacial de los diagramas tridimensionales pvT empleados en Termodinámica para el análisis de los procesos termodinámicos experimentandos por una sustancia simple. Concretamente se propone el uso de modelos 3D construidos mediante impresión 3D y el desarrollo de aplicaciones de Realidad Aumentada (RA) para visualizar las proyecciones termodinámicas de manera autonóma por parte del alumnado tanto dentro como fuera del aula. Ambas herramientas han constituido un avance significativo en la comprensión por parte del alumnado del problema termodinámico indicado, tal como se refleja en los resultados obtenidos.Carsí Rosique, M.; Juan Lizandra, MC.; Sanchis Sánchez, MJ. (2023). Uso de las TIC como tecnologías facilitadoras del aprendizaje. Ayudas gráficas para facilitar la visión espacial de superficies pvT en la asignatura Termodinámica. Editorial Universitat Politècnica de València. 1194-1206. https://doi.org/10.4995/INRED2023.2023.166981194120

Molecular Dynamics of Functional Azide-Containing Acrylic Films

A report on the syntheses, thermal, mechanical and dielectric characterizations of two novel polymeric acrylic materials with azide groups in their pendant structures is presented. Having the same general structure, these polymers differ in length of oxyethylene units in the pendant chain [-CONH-CH2CH2-(O-CH2CH2)nN3], where n is 1 (poly(N-(2-(2-azidoethoxy)ethyl)methacrylamide), PAzMa1) or 2 (poly(N-2-(2-(2-azidoethoxy)ethoxy)ethyl)methacrylamide), PAzMa2), leading with changes in their dynamics. As the thermal decomposition of the azide group is observed above 100 °C, dielectric analysis was carried out in the temperature range of −120 °C to 100 °C. Dielectric spectra of both polymers exhibit in the glassy state two relaxations labelled in increasing order of temperature as γ- and β-processes, respectively. At high temperatures and low frequencies, the spectra are dominated by ohmic conductivity and interfacial polarization effects. Both, dipolar and conductive processes were characterized by using different models. Comparison of the dielectric activity obtained for PAzMa1 and PAzMa2 with those reported for crosslinked poly(2-ethoxyethylmethacrylate) (CEOEMA) was performed. The analysis of the length of oxyethylene pendant chain and the effect of the methacrylate or methacrylamide nature on the dynamic mobility was analysed

Effect of chain extenders on the hydrolytic degradation of soybean polyurethane

[EN] This publication highlights the effect that different chain extenders (CEs) have on the structure-property relationships of soy-based polyurethanes that have been exposed to hydrolytic degradation for 480 and 960 h at 80 degrees C. Gel content, crosslinking densities, surface energy, atomic force microscopy, dielectric, and dynamic mechanics were used for monitored structural changes. Polyurethanes (PU) is composed of a structure with minor phase separation when a chain extender is not used, maintaining all properties over time. However, when a chain extender, butane-1.4-diol (BDO), ethane-1.2-diol (MEG) our (2-hydroxypropoxy)-propane-2-ol are added, it is noted that there is a more significant degradation in the flexible domains, modifying the fraction between the initial rigid (HS)/soft (SS) segment that makes the polymer stiff and brittle. The hydrolysis degradation generates new Fourier transform infrared bands relative to urea (1640 cm(-1)) and amide (1800 cm(-1)). The reduction in band intensity of the C=O-free at 1730 cm(-1), while increasing the intensity of C=O-bonded at 1710 cm(-1) indicated a higher phase separation degree. After 960 h the T-gS decreased, while the T-gH was practically unchanged. The higher polarization observed in the PUs with BDO and MEG samples indicates the increased phase separation resulting in hydrolytic degradation.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Grant/Award Numbers: 308567/2018-8, 305814/2021-4; Ministerio de Economia y Competitividad, Grant/Award Number: RTI2018-093711-B-100; National Council for Scientific and Technological Development; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior.Favero, D.; Marcon, V.; Agnol, LD.; Gómez, CM.; Cros, A.; Garro, N.; Sanchis Sánchez, MJ.... (2022). Effect of chain extenders on the hydrolytic degradation of soybean polyurethane. Journal of Applied Polymer Science. 139(28):1-13. https://doi.org/10.1002/app.526231131392

Electrical conductivity of natural rubber cellulose II nanocomposites

[EN] Nanocomposite materials obtained from natural rubber (NR) reinforced with different amounts of cellulose II (cell) nanoparticles (in the range of 0 to 30 phr) are studied by dielectric spectroscopy (DS) in a broad temperature range (¿150 to 150 °C). For comparative purposes, the pure materials, NR and cell, are also investigated. An analysis of the cell content effect on the conductive properties of the nanocomposites was carried out. The dielectric spectra exhibit conductivity phenomena at low frequencies and high temperatures: Maxwell¿Wagner¿ Sillars (MWS) and electrode polarization (EP) conductive processes were observed in the nanocomposite samples.We thank Professor Regina Nunes of the Instituto de Macromoleculas Eloisa Mano (Universidade Federal do Rio de Janeiro) for providing us the NR and NR-cell samples. This work was financially supported by DGCYT through grant MAT2012-33483.Ortiz Serna, MP.; Carsí Rosique, M.; Redondo Foj, MB.; Sanchis Sánchez, MJ. (2014). Electrical conductivity of natural rubber cellulose II nanocomposites. Journal of Non-Crystalline Solids. 405:180-187. doi:10.1016/j.jnoncrysol.2014.09.026S18018740