Rheology of Polymer Processing in Spain (1995–2020)

The contribution of Spanish scientists to the rheology involved in polymer processing during the last 25 years is investigated. It is shown that the performed research covers, at different levels, all industrial polymeric materials: thermoplastics, thermosets, adhesives, biopolymers, composites and nanocomposites, and polymer modified bitumen. Therefore, the rheological behaviour of these materials in processing methods such as extrusion, injection moulding, additive manufacturing, and others is discussed, based on the literature results. A detailed view of the most outstanding achievements, based on the rheological criteria of the authors, is offeredThis research was funded by Basque Government, IT1309-19. LS acknowledges the postdoctoral grant from Basque Governmen

Effect of pH and nanoclay content on the morphology and physicochemicalproperties of soy protein/montmorillonite nanocomposite obtained byextrusion

The present work attempts to clarify the influence of montmorillonite nanoclay content and pH on the me-chanical properties of extruded soy protein nanocomposites. The mechanical behaviour is dominated by theformation of positive synergies between protein and nanoclay above a nanoclay concentration threshold.Moreover, the presence of nanoclay can improve water uptake. The pH also exerts a strong influence on me-chanical and water absorption properties, although montmorillonite tend to reduce this effect.Eventually, this study put forward the feasibility of using a combination of soy protein and montmorillonite toobtain potentially attractive biodegradable nanocomposite materials, processed by means of a simple and easilyscalable twin-screw extruder.Junta de Andalucía (project TEP-6134)Ministerio de Economía y Competitividad (CTQ2015-71164-P

Oil-in-Oil emulsions of stearic acid dispersed in silicone oil with enhanced energy storage capability for heat transfer fluids

Non-aqueous phase change emulsions are very unknown and promising multifunctional fluids consisting of phase change materials dispersed in carrier fluids, both being oily phases. The oil-in-oil phase change emulsions allow the possibility of using the same medium for latent heat storage and transport under more extreme pressure and temperature conditions. In this paper, stable emulsions composed of stearic acid with a melting point of 68–71 °C dispersed in silicone oil have been developed. Stearic acid-in-silicone oil emulsion samples with different phase concentrations were evaluated by analysing their thermophysical properties, viscous and viscoelastic behaviour and microstructure. Emulsion properties below the melting point of the phase change material were greatly influenced by the concentration of the disperse phase. Thus, as the temperature lowered, a well-developed three-dimensional network of stearic acid crystalline structures interconnected with each other was formed. Furthermore, emulsion physicochemical and thermal stabilities were examined and proved under several mechanical–thermal cycles, withstanding more than 100 cycles in the calorimeter. The results indicate that stearic acid-in-silicone oil emulsions are an attractive candidate for energy storage applications with a phase change enthalpy in emulsions with the 10 wt% of phase change material of 22.32 J/g.Non-aqueous phase change emulsions are very unknown and promising multifunctional fluids consisting of phase change materials dispersed in carrier fluids, both being oily phases. The oil-in-oil phase change emulsions allow the possibility of using the same medium for latent heat storage and transport under more extreme pressure and temperature conditions. In this paper, stable emulsions composed of stearic acid with a melting point of 68–71 C dispersed in silicone oil have been developed. Stearic acid-in-silicone oil emulsion samples with different phase concentrations were evaluated by analysing their thermophysical properties, viscous and viscoelastic behaviour and microstructure. Emulsion properties below the melting point of the phase change material were greatly influenced by the concentration of the disperse phase. Thus, as the temperature lowered, a well-developed three- dimensional network of stearic acid crystalline structures interconnected with each other was formed. Furthermore, emulsion physicochemical and thermal stabilities were examined and proved under several mechanical–thermal cycles, withstanding more than 100 cycles in the calorimeter. The results indicate that stearic acid-in-silicone oil emulsions are an attractive candidate for energy storage applications with a phase change enthalpy in emulsions with the 10 wt% of phase change material of 22.32 J/g

Bitumen chemical modification by thiourea dioxide

This work evaluates a novel bitumen modification through the use of a chemical agent, thiourea dioxide, substance which has been traditionally used as a reducing agent. Thermogravimetric analysis demonstrated the formation of new chemical compounds, most probably originated through reactions between products from thiourea dioxide thermal decomposition and some highly polar bitumen molecules. As a result of these reactions, which continues even after 60 days, bitumen permanent deformation resistance at high temperature is enhanced, as indicated by a significant increase in its viscosity and elastic features. On the other hand, thiourea dioxide addition produces changes in the bitumen colloidal nature, which improve its flexibility at low in-service temperatures, and consequently its resistance to thermal cracking under loading. In fact, dynamic bending tests indicated a remarkable decrease in the value of binder glass transition temperature, which was further corroborated by differential scanning calorimetry. As a conclusion, thiourea dioxide can be seen as a promising modifiying agent, which can extend the in-service temperature range at which bitumen would present a satisfactory performance.This work is part of a research project sponsored by a MEC-FEDER Programme (Research Project MAT2007-61460) and by a Junta de Andalucía Programme (TEP6689). The authors gratefully acknowledge its financial support. A.A.Cuadri also acknowledges the concession of MEC FPU research fellowship (AP2008-01419).This work is part of a research project sponsored by a MEC - FEDER P rogramme (Research Project MAT2 007 - 61460) and by a Junta de Andaluc í a Programme (TEP6689). The authors gratefully acknowledge its financial support. A.A.Cuadri also acknowledges the concession of MEC FPU research fellowship (AP2008 - 01419).This work is part of a research project sponsored by a MEC-FEDER Programme (Research Project MAT2007-61460) and by a Junta de Andalucia Programme (TEP6689). The authors gratefully acknowledge its financial support. A.A. Cuadri also acknowledges the concession of MEC FPU research fellowship (AP2008-01419)

Rheological and phase behaviour of paraffin wax/bitumen blends with thermal storage characteristics

This paper analyses the thermomechanical properties, heat storage characteristics and compatibility of bitumen blends with a paraffin wax, having a melting point around 60 ◦C, as phase change material. To that end, temperature sweeps in the linear viscoelastic range, technological properties, Modulated Differential Scanning Calorimetry (MDSC), and cross-polarised optical microscopy observations were carried out on blends and pure compounds. The obtained results reveal a partial compatibility between the compounds and the development of a multiphasic microstructure, where the paraffin-rich or bitumen-rich domains form the continuous phase depending on the concentration, with the phase inversion around 20 wt% wax. Below this threshold concentration, the disperse paraffin-rich phase acts as filler that reinforces the continuous bitumen matrix until it reaches the melting transition. Above the critical concentration for the phase inversion, the continuous paraffin- rich phase controls the rheological response. However, both phases retain their own identity and show their individual transitions and relaxations. Despite the partial compatibility, a high degree of crystallinity is found, especially for high paraffin contents, which would result in a significant capacity to store thermal energy, for applications such as solar thermal collection or thermoregulation materials for buildings, etc.This work is part of the projects TED2021-131284B-I00 and PID2020-116905RB-I00 funded by MCIN/AEI/10.13039/ 501100011033 (Spanish Ministry of Science and Innovation) and European Union “NextGenerationEU” and the Cátedra Fundación CEPSA edition 2022. Adrián Tenorio also acknowledges financial support from Junta de Andalucía through the post-doctoral Grant POSTDOC_21_00644, co-funded by the EU Fondo Social Europeo (FSE)

Non-bituminous binders formulated with bio-based and recycled materials for energy-efficient roofing applications

Non-bituminous binders have been designed as potential roofing materials with sustainable characteristics. To that end, three bio-based rosin esters (R), a waste cooking oil (O) and a recycled polyethylene from greenhouse agriculture (LDPEr) have been used in their formulations. A comprehensive rheological, microstructural, calorimetric, and technological characterization have been performed on binary (polymer/oil or rosin/oil) and ternary (polymer/rosin/oil) blends, allowing the compatibility among binder compounds to be studied. Additionally, thermal conductivity and solar radiation tests have been conducted on a selected non-bituminous binder and compared with a reference polymer modified bitumen. The formulation composed of 61.0% phenolic-modified rosin, 30.5% oil and 8.5% LDPEr has shown suitable mechanical properties for roofing materials, and has exhibited enhanced energy efficiency derived from its light yellowish to brownish color. Under the experimental radiant flux conditions, surface temperature of the non-bituminous binder was 8 °C lower than that of the black bitumen. Moreover, conduction heat transfer through this roofing material was about 14% lower than that conducted through a bitumen-based membrane with the same thickness. Accordingly, developed binders are expected to behave as reflective building materials aiming to reduce the heat island effects and save energy.This work is part of GreenAsphalt project (ref. 802C1800001), cofunded by FEDER European Programme (80%) and Junta de Andalucía (Consejería de Economía, Conocimiento, Empresas y Unversidades/ Agencia-IDEA), and has been also co-funded by FEDER/Junta de Andalucía-Consejería de Economía y Conocimiento/Project UHU- 1256916. Clara Delgado-S´anchez also acknowledges financial support from Junta de Andalucía through post-doctoral Grant No. DC 01228 (PAIDI 2020), co-funded by the EU Fondo Social Europeo (FSE). Funding for open access charge: Universidad de Huelva / CBUA

Thermal, rheological and microstructural characterisation of commercial biodegradable polyesters

Growing environmental concerns along with new regulations are forcing the industries to seek renewable raw materials for their products. In this sense, this work studies the thermo-rheological properties of commercial biodegradable polyesters: two polylactic acids (PLAs), a polycaprolactone (PCL) and a PLA/PCL blend. A comprehensive material characterization by means of thermogravimetry/differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), frequency sweep tests and polarized light microscopy was carried out. The results have shown that the material thermal/thermo-rheological properties and, therefore, its microstructure, are strongly dependent on its thermal history. This fact arises from the slow recrystallization kinetics shown by PLA. Interestingly, PCL may play the role of nucleating agent for the PLA crystallization, making it faster. This issue must be carefully considered so that a reliable material characterization is achieved.This work is part of a research project sponsored by the “Ministerio de Economía y Competitividad” (ref. MAT2011-29275-C02-01). The authors gratefully acknowledge its financial support. A.A. Cuadri also thanks “Ministerio de Educación” for the concession of a F.P.U. research grant (AP2008-01419).This work is part of a research project sponsored by the "Ministerio de Economia y Competitividad" (ref. MAT2011-29275-C02-01). The authors gratefully acknowledge its financial support. A.A. Cuadri also thanks "Ministerio de Educacion" for the concession of a F.P.U. research grant (AP2008-01419)

Influence of the prepolymer molecular weight and free isocyanate content on the rheology of polyurethane modified bitumens

Isocyanate-based modification is lately gaining acceptance as a successful way to give added value to bitumen, a crude oil refining by-product. In order to study the influence of prepolymer type on the rheological properties of the resulting binders, six prepolymers synthesized from polypropylene-glycols (PPG) with varying molecular weight (between 440 and 2425) and different molar excess of a polymeric MDI (4,4’-diphenylmethane diisocyanate) were used. Two modification procedures, either involving or not water addition were followed. The modification achieved depends on both the selected polyol molecular weight and the excess in MDI (i.e., free isocyanate content), although not in a similar extent. Viscous flow and dynamic oscillatory shear tests, at 60 ºC, demonstrated a much higher level of bitumen modification by using the prepolymer prepared with the polyol having a molecular weight of 940 and with a free isocyanate content of 17.4 wt.%, mainly after addition of water. On the other hand, bitumen nature greatly affects the final rheological properties of these bituminous products. In that sense, modification results much more effective when conducted on bitumen with a well-developed colloidal microstructure.This work is part of two research projects sponsored by a MEC-FEDER Programme (Research Project MAT2007-61460) and by a Junta de Andalucia Programme (TEP6689). The authors gratefully acknowledge their financial support. A.A. Cuadri also thanks “Ministerio de Educación” for the concession of a F.P.U. research grant (AP2008-01419)

Education of chemical engineering in Spain: A global picture

The general framework of the Chemical Engineering studies in Spain includes the Bachelor's Degree (4 years), Master's Degree (the most common duration is 1.5 years) and Doctorate (3-4 years). In 2008, the Conference of Directors and Deans of Chemical Engineering (CODDIQ) was constituted with the main objective of promoting and improving the quality of Chemical Engineering studies in Spain. Currently, Faculties and Schools of 29 Spanish universities are members of CODDIQ. An analysis of the most characteristic indicators provides a representative radiography of the Chemical Engineering Studies in Spain, whose most outstanding data are: (i) 7,396 undergraduate students, 1,014 Master students and 556 PhD students, (ii) according to the gender profile of undergraduates and graduates, the percentage of women is similar to that of men, while for faculty staff, the percentage of women is 43% and 46% for Associate and Assistant Professor (respectively) and 23% for the category of Full Professor category; (iii) after completing the Bachelor studies, most of them continue their training in the MSc in Chemical Engineering, (iv) the employability after obtaining the Master's degree is very high (>75%), which in the case of PhDs is close to 100%. The studies of Chemical Engineering in Spain have a very direct relationship with society, especially in the chemical, environmental, biotechnological and energy fields. The companies that collaborate in the training of future professionals are distributed throughout the national territory, which allows a strong connection with the socioeconomic environmen