EURHEO: the Erasmus Mundus Master in Engineering Rheology

EURHEO (www.eurheo.eu) is a two-year Master course delivered under the prestigious Erasmus Mundus programme. EURHEO aims at offering a pioneer advanced education programme on Rheology and its applications to different Engineering areas. It combines the expertise of six leading European Universities in the field of Rheology (University of Minho (UM - Portugal), the University of Ljubljana (ULJ - Slovenia), the Universidad de Huelva (UHU - Spain), the Kaholieke Universiteit Leuven (KUL - Belgium), the Université catholique de Louvain (UCL - Belgium) and the University of Calabria (UCAL - Italy)) and the syllabus is designed to provide students with the necessary competences to understand the relevance of Rheology in Materials Science and Engineering and apply the knowledge gained in solving real-world Engineering problems both autonomously and included in multidisciplinary research teams. We will present the EURHEO education programme, and the types of grants that Portuguese and Spanish students can apply for. The first scientific EURHEO outputs, namely results from selected Master theses, will be presented in 2 posters which report the research carried out by 2 students at UM.European Union and EACEA for granting project 2008-0099-EURHEO: The Erasmus Mundus Master in Engineering Rheology

In-line rheo-optical investigation of the dispersion of organoclay in a polymer matrix during twin-screw compounding

The dispersion mechanisms in a clay-based polymer nanocomposite (CPNC) during twin-screw extrusion are studied by in-situ rheo-optical techniques, which relate the CPNC morphology with its viscosity. This methodology avoids the problems associated with post extrusion structural rearrangement. The polydimethylsiloxane (PDMS) matrix, which can be processed at ambient and low temperatures, is used to bypass any issues associated with thermal degradation. Local heating in the first part of the extruder allows testing of the usefulness of low matrix viscosity to enhance polymer intercalation before applying larger stresses for clay dispersion. The comparison of clay particle sizes measured in line with models for the kinetics of particle dispersion indicates that larger screw speeds promote the break-up of clay particles, whereas smaller screw speeds favor the erosion of the clay tactoids. Thus, different levels of clay dispersion are generated, which do not simply relate to a progressively better PDMS intercalation and higher clay exfoliation as screw speed is increased. Reducing the PDMS viscosity in the first mixing zone of the screw facilitates dispersion at lower screw speeds, but a complex interplay between stresses and residence times at larger screw speeds is observed. More importantly, the results underline that the use of larger stresses is inefficient per se in dispersing clay if sufficient time is not given for PDMS to intercalate the clay galleries and thus facilitate tactoid disruption or erosion.The authors thank the FCT (Fundação para a Ciência e Tecnologia) for financial support under the framework of Strategic Funding grant UID/CTM/50025/2020. L.H. acknowledges funding from the FCT Investigator Programme through grant IF/00606/2014

Dispersion of graphite nanoplates during melt mixing

Artigo publicado a convite da Society for Polymer EngineersThe behavior of pristine and functionalized particles within polypropylene was investigated with the use of a prototype small-scale mixer.Matepro (NORTE-07-0124-FEDER-000037); Foundation for Science and Technology (project PEst-C/CTM/LA0025/2011); PhD grant FRH/BD/87214/201

Influence of the concentration of locust bean gum on the gelling ability of whey peptic hydrolysates

The gelling ability of whey proteins can be changed by limited hydrolysis and by the presence of other components such as polysaccharides; depending on the environmental conditions it can either be improved or impaired. In this work the effect of LBG on the heat-set gelation of aqueous whey protein hydrolysates (10 % w/w) from pepsin was assessed at pH 7.0 by small deformation rheology. Whey protein concentrate (WPC) and hydrolysates with a degree of hydrolysis (DH) of 1.5, 2.5 and 4.9 % were used. Different LBG concentrations were tested: 0, 0.1, 0.3 and 0.55 % (w/w). The behaviour of gels from whey proteins or whey protein hydrolysates towards the presence of LBG was very similar. The evolution of the viscous and storage moduli followed the general behaviour reported for many biopolymer heat-set gelation processes including whey proteins gelation. The increase in the LBG concentration generally led to a decrease in the gel strength. However, for whey proteins a small amount of LBG (0.1 %) leads to a big enhancement in the gel strength probably due to an increase in the protein concentration of the protein enriched phase. Further increases in the LBG concentration led to a decrease in the gel strength. The gelation process is very sensible to environmental conditions and to processing and often leads to rather coarse data. The factorial planning used allowed validating conclusions using fewer experiments than those needed if no planning had been used, while still getting statistical significance out of the results. However, as many factors are involved, the modelling of the process was not straightforward

From seaweeds to hydrogels: Recent progress in kappa-2 carrageenans

Hybrid carrageenans, also called kappa-2 (K2) or weak kappa, are a class of sulfated polysaccharides with thermo-reversible gelling properties in water and are extracted from a specific family of red seaweeds. K2 are known in the industry for their texturizing properties which are intermediate between those of kappa-carrageenans (K) and iota-carrageenans (I). As such, K2 are gaining industrial interest, as they can replace blends of K and I (K + I) in some niche applications. Over the last decade or so, some progress has been made in unravelling K2's chemical structure. The understanding of K2 gel's structure-rheological properties' relationships has also improved. Such recent progress is reported here, reviewing the literature on gelling K2 published since the last review on the topic. The focus is on the seaweeds used for extracting K2, their block copolymer chemical structures, and how these impact on the gel's formation and rheological properties. The outcome of this review is that additional rheological and structural studies of K2 hydrogels are needed, in particular to understand their viscoelastic behavior under large deformation and to unravel the differences between the texturizing properties of K2 and K + I.This work was supported by the Fundação para a Ciência e Tecnologia (FCT), through the E2B2-PHACAR project, grant number: PTDC/BII-BIO/5626/2020. Additional financial support by the FCT under the framework of Strategic Funding grant: UID/CTM/50025/2020 and grant: CEECINST/00156/2018 are also acknowledged

Film blowing of PHB-based systems for home compostable food packaging

One of the routes to minimize the environmental impact of plastics waste is the use of bio-sourced and biodegradable alternatives, particularly for packaging applications. Although Polyhydroxyalkanoates (PHA) are attractive candidates for food packaging, they have poor processability, particularly for extrusion film blowing. Thus, one relatively successful alternative has been blending PHA with a biodegradable polymer. This work proposes film blowing of a co-extruded Poly (hydroxybutyrate) (PHB) layer with a poly butylene adipate-co-terephtalate (PBAT) layer to enhance bubble stability, mechanical and barrier properties. Co-extrusion is detailed, together with the different strategies followed to improve adhesion between film layers and the PHB content in the films. Films with thicknesses below 50 micron and elongation at break beyond 500 % were consistently produced.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 774088. LH also acknowledges funding from the Portuguese Foundation for Science and Technology Investigator Programme through grant IF/00606/2014

Rheological and structural characterization of gels from whey protein hydrolysates/locust bean gum mixed systems

The gelling ability of whey proteins can be changed by limited hydrolysis and by the addition of other components such as polysaccharides. In this work the effect of the concentration of locust bean gum (LBG) on the heat-set gelation of aqueous whey protein hydrolysates (10% w/w) from pepsin and trypsin was assessed at pH 7.0. Whey protein concentrate (WPC) mild hydrolysis (up to 2.5% in the case of pepsin and 1.0% in the case of trypsin) ameliorates the gelling ability. The WPC synergism with LBG is affected by the protein hydrolysis. For a WPC concentration of 10% (w/w), no maximum value was found in the G′ dependence on LBG content in the case of the hydrolysates, unlike the intact WPC. However, for higher protein concentrations, the behaviour of gels from whey proteins or whey protein hydrolysates towards the presence of LBG becomes very similar. In this case, a small amount of LBG in the presence of salt leads to a big enhancement in the gel strength. Further increases in the LBG concentration led to a decrease in the gel strength

Nanocomposite-forming solutions based on cassava starch and laponite: viscoelastic and rheological characterization

Nanocomposites-forming solutions (NFS) based on cassava starch and laponite were prepared and next characterized by means of dynamic oscillatory and steady shear rheological tests to evaluate their ability to be processed by knife coating. The effects of speed (rpm) and homogenization time on the laponite dispersion characteristics were first analyzed. Laponite dispersions were affected by both process parameters. High speed (rpm), i.e. 20,000 or 23,000 rpm for 30 min or prolonged homogenization time (10,000 rpm 6 speed agitation 6 23,000 rpm, for 60 min) led to high f-potential values, with laponite particles size <80 nm. With addition of laponite nanoparticles to cassava starch dispersion, an evident transition in NFS from liquid-like viscous to solid-like elastic behavior was observed. Rheological results indicated that laponite nanoparticles induced new interactions with starch chains allowing to obtain a network structure typical of a semi-rigid gel which shows some spread ability.São Paulo Research Foundation (FAPESP), the grant (2013/07914-8)

Plastic waste use as aggregate and binder modifier in open-graded asphalts

Road pavements are very important infrastructures for the Society, but they can cause serious environmental impacts during construction, operation and rehabilitation phases. Thus, it is essential to develop surface paving solutions that promote not only the durability but also a comfortable and safe use. In fact, this work aims to study the properties of new opengraded mixtures for surface layers produced with plastic wastes. First, HDPE and EVA wastes were used as bitumen modifiers, and then another plastic waste (PEX) replaced part of the aggregates. After studying the modified binders, the open-graded mixtures were designed, and then they were tested concerning their particle loss, rutting resistance, surface texture and damping effect. It was concluded that both ways of using the plastic wastes can improve the mechanical and functional properties of the open-graded mixtures related to the pavement performance.ERDF funds through the Operational Competitiveness Program – COMPETE and the National funds by FCT – Portuguese Foundation for Science and Technology in the scope of PLASTIROADS Project FCOMP-01-0124-FEDER-020335 (PTDC/ECM/119179/2010)

Impact of composition and morphology on the optical properties of Si-NC/P3HT thin films processed from solution

Blends of Si nanocrystals (Si-NCs) and organic semiconductors are promising materials for new optical and electronic devices processed from solutions. Here, we study how the optical properties of composite films containing Si-NCs and the organic semiconductor poly(3-hexylthiophene) (P3HT) are influenced by the composition and morphology resulting from different solution-processing parameters and different solvents used dichlorobenzene vs. chloroform). The optical spectra of the hybrid films are described using a simple phenomenological model, with which we can discern the contribution of each material in the films to the optical properties. From this analysis, we obtain quantitative information about the composition and morphology of the hybrid nanostructured films, which otherwise would be obtained from more demanding microscopy and spectroscopy techniques. For the case of the Si-NC/P3HT blend, we find that in films deposited from dichlorobenzene solutions the Si-NCs contribute sizably to light absorption.This work was funded by FCT/I3N via the HybridSolar project, by the DFG via Teilprojekt B2 and by the European Union and the Ministry of Innovation, Science and Research of the German State of North Rhine-Westphalia in the framework of an Objective 2 Programme (European Regional Development Fund, ERDF). Funding is also acknowledged from the Portuguese Foundation for Science and Technology (FCT) through the Projects Nos. PTDC/FIS/112885/2009 and PEst-C/CTM/LA0025/2011 and via the Strategic Project LA 25:2011-2012