Search

Stable polyethylene glycol-in-silicone oil phase change emulsions were successfully prepared with a selected silicone surfactant. These oil-in-oil (o/o) emulsions have been scarcely examined up, despite the highly remarkable properties of both phases for energy recovery applications and cosmetic/pharmaceutical compositions. The objective of the present work was to study the effect of composition (surfactant and disperse phase concentrations) and the post-processing conditions (further agitation at the processing temperature for 24 h) on the final features of the emulsion. For this purpose, optical morphology, thermo-physical and the rheological behaviour of the emulsions and binary blends of their compounds were measured and analysed. Special attention has been paid to structural changes and crystallinity modifications of the emulsion disperse phase. The observed miscibility of the silicone surfactant and silicone chains with the disperse phase reduces its crystallinity degree and modifies in the crystallization mechanism of the polyethylene glycol, from heterogeneous to homogeneous nucleation. Interestingly, the change in the disperse phase crystallinity remarkably modifies final thermal and rheological properties of the emulsion.

14 Pág. Centro de Investigación Forestal (CIFOR), Oil-in-water bitumen emulsions stabilized by biobased surfactants such as lignin are in line with the current sustainable approaches of the asphalt industry involving bitumen emulsions for reduced temperature asphalt technologies. With this aim, three lignins, derived from the kraft pulping and bioethanol industries, were chemically modified via the Mannich reaction to be used as cationic emulsifiers. A comprehensive chemical characterization was conducted on raw lignin-rich products, showing that the kraft sample presents a higher lignin concentration and lower molecular weight. Instead, bioethanol-derived samples, with characteristics of non-woody lignins, present a high concentration of carbohydrate residues and ashes. Lignin amination was performed at pH = 10 and 13, using tetraethylene pentamine and formaldehyde as reagents at three different stoichiometric molar ratios. The emulsification ability of such cationic surfactants was firstly studied on prototype silicone oil-in-water emulsions, attending to their droplet size distribution and viscous behavior. Among the synthetized surfactants, cationic kraft lignin has shown the best emulsification performance, being used for the development of bitumen emulsions. In this regard, cationic kraft lignin has successfully stabilized oil-in-water emulsions containing 60% bitumen using small surfactant concentrations, between 0.25 and 0.75%, which was obtained at pH = 13 and reagent molar ratios between 1/7/7 and 1/28/28 (lignin/tetraethylene pentamine/formaldehyde)., This research is part of SUP&R ITN (FP7-PEOPLE-2013-ITN, Grant agreement 607524) and GreenAsphalt project (ref. 802C1800001) co-funded 80% by FEDER European Programme and 20% by Junta de Andalucía (Consejería de Economía, Conocimiento, Empresas y Unversidades/Agencia IDEA). The authors also wish to thank Comunidad de Madrid and MCIU/AEI/FEDER, UE via grant number SUSTEC-CM S2018/EMT-4348 and RTI2018-096080-B-C22, respectively. The contribution of COST Action LignoCOST (CA17128), supported by COST (European Cooperation in Science and Technology), in promoting the interaction, exchange of knowledge and collaborations in the field of lignin valorization is gratefully acknowledged.

This work assesses the applicability of low density polyethylene (LDPE), recycled from greenhouses used in agriculture, as a modifier of asphalt mixes manufactured by a dry process. To that end, a ...

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 offered, This research was funded by Basque Government, IT1309-19. LS acknowledges the postdoctoral grant from Basque Government

Oil-in-oil phase change emulsions, composed of phase change materials (PCMs) dispersed in a continuous oily medium, have never been reported in the literature. The current study involves the formulation, stabilisation and characterisation of novel anhydrous emulsions of polyethylene glycol (PEG4000) as PCM in silicone oil. Emulsions with different dispersed phase concentrations were evaluated by analysing the viscous flow properties, optical microscopy and modulated differential scanning calorimetry. The results evidence that the emulsions can be pre-stabilised at 80 °C, under high shear conditions, by selecting an adequate silicone surfactant but undergo a severe destabilisation after a cooling and heating cycle. Nevertheless, a post-processing protocol (low shear agitation at 80 °C for 24 h) leads to thermal cycle resistant and storage stable nonaqueous dispersions. This process gives rise to a reduction of the shear-thinning character of the emulsion, shifts the melting and crystallization temperature of the PEG4000 to lower values and reduce its crystallinity. This is attributed to partial compatibility of the crystalline fraction of PEG4000 with other compounds of the emulsion., This work has received funding from MINECO (Economy and compe titiveness Ministry of Spain) and from Junta de Andalucía (Spain) through the projects CTQ2017-89792-R (AEI/FEDER, UE) and P18-RT-4684., This work has received funding from MINECO (Economy and compe titiveness Ministry of Spain) and from Junta de Andalucía (Spain) through the projects TQ2017-89792-R (AEI/FEDER, UE) and P18-RT-4684.

Lignin is an abundant biopolymer with potential value-added applications that depend on biomass source and fractioning method. This work explores the use as emulsifiers of three native lignin-rich product coming from industrial bioethanol production and alkali or Kraft pulping. In addition to their distinctive characteristics, the different molecular organization induced by emulsification pH is expected to interact in various ways at the water-oil interface of the emulsion droplets. Initially, model oil-in-water (O/W) emulsions of a silicone oil will be studied as a function of lignin source, disperse phase concentration and emulsification pH. Once stablished the effect of such variables, emulsion formulations of three potential bitumen rejuvenators (waste vegetable cooking oil, recycled lubricating oil and a 160/220 penetration range soft bitumen). Droplet size distribution, Z-potential and viscous tests conducted on model emulsions have shown that emulsification pH strongly affects stabilization ability of the lignins tested. Regarding bitumen rejuvenators, lignin emulsification capability will be affected by surfactant source, pH and, additionally, by the dispersed phase characteristics. Lower Z-potential values shown by KL at pH 9 and 11 seem to facilitate emulsification of the less polar disperse phases formed by RLUB and bitumen. In any case, lower particle size and higher yield stress values were found for both bioethanol-derived lignins emulsifying RVO and RLUB at pH 13, which are expected to exhibit a longer stability

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 environment.

Aiming to gain knowledge in the epoxy-bitumen modification mechanisms, this work explores the e ects that epoxy concentration and ambient curing exert on the physico-chemistry and thermo-rheological properties of epoxy-modified binders. Process rheokinetics of epoxy-bitumen blends indicates that binder short-term modification (i.e., during processing) is accelerated by epoxy concentration. Furthermore, a synergistic e ect of epoxy concentration and ambient curing is found during long-term modification (i.e., during curing at ambient conditions). As a result, viscous and viscoelastic rheological properties of binders are enhanced at medium/high in-service temperatures, at least, after one month of curing. FTIR (Fourier Transform Infrared spectroscopy) tests and SARAs (Saturates, Aromatics, Resins and Asphaltenes) analysis confirm the existence of esterification/etherification reactions between epoxy oxirane groups and the carbonyl groups available in aromatic and resin molecules. Thus, the new high molecular weight compounds increase the asphaltenic fraction of modified bitumen. Likewise, nonreversing heat flow curves obtained by modulated calorimetry corroborate the formation of such highly structured domains responsible for the final binder performance.

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 environment.

Crumb Tire Rubber (CTR) modification of bitumen has been extensively proven that exerts a notable improvement the in-service properties. However, the problem of its inherent storage instability is a major concern that limits the industrial application. With this aim, here, Hybrid Systems were formulated by the addition of selected polymers (SBS, EBA, EBA and EPDMs) to a model rubberised bitumen (10 wt% CTR) and cured with sulphur. The resulting binders were characterised by rheological techniques, technological tests, Modulated Scanning Calorimetry and fluorescence microscopy. The results obtained pointed out that both, in-service properties and storage stability were notably enhanced by the development of a complex multiphasic structure of: polymer-rich and asphaltene-rich phases, non-degraded rubber particles and digested rubber chains. The capability of modification of the polymeric additives were established as follows: SBS > EBA > EVA > EPDMs. The Hybrid System containing SBS (HS-SBS) presented, by far, the best overall performance due to the development a continuous SBS-rich network structure as a consequence of sulphur crosslinking reactions.

Bitumen modification with ethylene-vinyl acetate (EVA), in a wide range temperatures (between − 30 and 100 °C), has been studied as a function of polymer concentration and EVA characteristics (vinyl acetate (VA) content and melt flow index (MFI)). Viscous flow, dynamic shear (DSR) temperature sweep, and technological tests were conducted to assess binder performance at medium-to-high in-service temperatures. Evaluation of binder low-temperature viscoelastic behavior has been performed using a solid rectangular fixture (SRF) in torsional mode, either in the linear viscoelastic region or under non-linear conditions (by strain breakage tests between − 30 and 0 °C). Further microstructural analysis based on modulated differential scanning calorimetry (MDSC) and optical microscopy was conducted to support rheological and technological results. Hence, total crystalline fraction (related to the VA content and polymer concentration) turned out to be a key parameter to achieve a suitable binder modification at medium-high temperatures. In addition, MFI appears to be an important EVA parameter at low temperatures, as it was found that lower MFI values enhanced resistance to low-temperature cracking.

A lignocellulosic material, like ethylcellulose (EC), is assessed for bitumen modification, as a more sustainable alternative to polymers derived from non-renewable sources. However, ethylcellulose alone hardly enhances bitumen performance. This work studies novel bituminous binders prepared with ethylcellulose powder and polyphosphoric acid (PPA) as bitumen modifiers for paving applications. Rheological tests demonstrated that the addition of 0.5 wt% PPA to a binder containing 5 wt% EC, along with a thermal curing, leads to binders with improved rutting resistance at high in-service temperatures, compared to binders prepared solely with EC or PPA. TLC–FID chromatography, FTIR spectroscopy and modulated DSC were conducted on binders to shed some light on modification route. From them, it is possible to state that the rheological enhancement is related to a change in SARAs fractions (i.e., binder colloidal index), derived from the asphaltenes disaggregation and formation of new phosphorylated adducts. Therefore, the use of ethylcellulose as lignocellulosic raw material seems to be a promising alternative to design bituminous binders for paving applications with enhanced rheological properties at high in-service temperatures.

Sustainable asphalt technologies involving materials recycling and energy-saving approaches are growing demands. Among waste polymers, recycled low density polyethylene (LDPE R ) is a promising bitumen modifier. Technological and viscous flow tests showed enhanced performance in LDPE R -modified bitumens (PMBs) above 4 wt% polymer. However, 4 wt% LDPE R underwent phase separation within 1 h when PMB was stored at high temperature, affecting product industrial implementation. Aiming at preventing polymer separation and promoting energy-saving technologies, bituminous binders (containing 2–5 wt% LDPE R ) were successfully dispersed as oil-in-water emulsions (O/W) by an inline emulsification procedure at controlled temperature and pressure. Emulsions with up to 63 wt% bitumen phase exhibited broad droplet size distributions and non-Newtonian flow behaviors strongly affected by the emulsion and PMB formulations. Optical and calorimetric techniques conducted on emulsion bituminous residues showed that shear conditions during emulsification increased dispersion of the swollen polymer phase, which led to better properties than the parent PMBs at high in-service temperature.

This article compares bituminous mastics modified by either the tri-block copolymer styrene-butadiene-styrene (SBS) or low density polyethylene (LDPE). Linear and non-linear oscillatory measurements were conducted at 25 and 55 °C, taken as representative of the medium and high in-service temperatures, respectively. For 3 wt.% polymer, distinct rheological responses were found. The LDPE-mastic showed enhanced linear complex shear modulus and elasticity at 55 °C. Conversely, if subjected to deformations beyond the linear viscoelasticity (LVE) limit, the SBS-mastic presented an improved capacity of complex modulus recovery, at 25 °C, when it returned to the LVE regime.

This work studies the microstructure and stability against aggregation of non-aqueous polymer dispersions. Styrene-co-acrylonitrile particles were sterically stabilized by block copolymer dispersants composed of one block adsorbed on the particle surface and the counter-part soluble in the continuous medium (a liquid polyether). A comprehensive rheological characterization (by steady and transient flow tests and linear viscoelastic measurements) and a microstructural study (by SEM microscopy, particle size distribution, etc.) were conducted on systems with different particle volume fraction, dispersant concentration and styrene to acrylonitrile ratio. A trend to particle aggregation, related to either low particle surface dispersant coverage or weakly dispersant adsorption onto the particle surface, has been identified through viscous flow tests, mainly assessing shear-thickening phenomena related to flow-induced particle aggregation, and by linear viscoelastic frequency sweep measurements. This work shows the use of rheological techniques as a powerful tool for stability testing and dispersant design of these sterically stabilized dispersions.

Efficient dispersion of nanoclays in biopolymer matrices is a key problem in nanobiocomposite development. A particular challenge is the homogeneous dispersion of layered silicates, termed exfoliation in biopolymer matrices as opposed to agglomeration and intercalation of such filler materials, since inhomogeneous nanobiocomposites often have unsatisfying properties. This work reports the successful elaboration of egg white protein/montmorillonite clay nanobiocomposites obtained by thermomechanical processing. A synergistic effect of combined natural (MMT-Na) and organomodified (OMMT) nanoparticles has been observed to elaborate exfoliated egg-white protein-based nanobiocomposites. Tensile tests performed on the obtained nanobiocomposites showed that exfoliated nanobiocomposites display enhanced mechanical properties compared to those of the intercalated nanobiocomposites and neat matrix. These results clearly highlight the great interest in using combined nanoclays to obtain protein-based nanobiocomposites with improved properties.

Hybrid modification is a relatively new concept of incorporating two or more polymeric modifiers of different nature to a bitumen, in order to take advantage of their complementary features. Aiming to this, in this paper, the so-called Hybrid Systems (HSs) were prepared by the addition of an ethylene-based copolymer (reactive or non-reactive) to a model rubberised binder (Crumb Tyre Rubber Modified Bitumen). The resulting binders (referred to as reactive and non-reactivate HSs, depending on copolymer used) were evaluated by means of thermorheological analysis, technological characterisation, fluorescence microscopy and modulated differential scanning calorimetry. From the experimental results, it may be deduced a positive synergistic effect of non-dissolved Crumb Tyre Rubber (CTR) particles and a second polymeric phase that not only improves the in-service performance but also the high-temperature storage stability. This enhancement is attributed to the development of a multiphasic system composed of non-dissolved CTR particles, a polymer-rich phase and an asphaltene-rich phase. In the case of non-reactive HSs, droplets of swollen ethylene copolymer form a well-defined dispersed phase. By contrast, reactive HSs display a different morphology, almost invisible by optical microscopy, related to the development of a chemical network that yields, by far, the highest degree of modification.

High energy consumption and environmental risks are both associated to the use of hot asphalt mixes. In response to the need of more sustainable pavements, the modification of bitumen with low melting point EVA copolymers is investigated. Firstly, different modified binders containing EVA with varying VA contents (and so different crystalline fractions and melting temperatures) and Melt Flow Index (MFI) values were investigated. In the second stage, emulsification was implemented, in which the above EVA modified bitumen was suspended in the form of micro-size droplets in aqueous phase, in the presence of a surfactant. The results suggest that an optimum balance between VA content and MFI value will improve the binder rheological performance at medium-high in-service temperatures as well as its workability, and will facilitate its emulsification. Additionally, the binder viscosity is tremendously reduced after its emulsification, which allows mixing to be performed at much lower temperature, so reducing both energy consumption and environmental risks.

Background The incorporation of natural biocide agents into protein-based bioplastics, a source of biodegradable polymeric materials, manufactured by a thermo-mechanical method is a way to contribute to a sustainable food packaging industry. This study assesses the antimicrobial activity of 10 different biocides incorporated into wheat gluten-based bioplastics. The effect that formulation, processing, and further thermal treatments exert on the thermo-mechanical properties, water absorption characteristics and rheological behaviour of these materials is also studied. Results Bioplastics containing six of the 10 examined bioactive agents have demonstrated suitable antimicrobial activity at 37 °C after their incorporation into the bioplastic. Moreover, the essential oils are able to create an antimicrobial atmosphere within a Petri dish. Conclusion Depending on the selected biocide, its addition may alter the bioplastics protein network in a different extent, which leads to materials exhibiting less water uptake and different rheological and thermo-mechanical behaviours. © 2015 Society of Chemical Industry.

This work aims to develop asphalt mixes with 100% reclaimed asphalt pavements (RAP) as source of aggregates and bitumen emulsions stabilized by amine-functionalized lignin. To that end, reduced-temperature asphalt technologies between 80 and 130 °C were assessed. Previously, processing parameters of emulsions were evaluated by droplet size distribution and rheology measurements. Furthermore, a study combining Pendant drop and Sessile drop (on a prototype polyethylene surface) tests showed that emulsion aqueous phase containing modified lignin would be able to wet the hydrophobic surface of RAP. Manufactured asphalt mixes were characterized according to French design method for hot mixes, including gyratory compaction, rutting resistance, complex modulus and fatigue resistance tests. The results obtained showed that reduced-temperature asphalt mixes could be successfully prepared to meet French design requirements, which would further minimize impact to environment. However, mix design has required a semi-quantitative approach for estimating ‘active’ RAP binder content, by balancing the manufacturing temperature and the fresh bitumen required.

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)

The influence of adding different polysaccharides (locust bean gum, LBG; methyl cellulose, MC; and carboxymethyl cellulose, CMC) to gluten-based biodegradable polymeric materials was assessed in this work. Gluten/polysaccharide/plasticiser bioplastics were prepared at different polysaccharide concentrations (0–4.5%) and pH values by mixing in a two-blade counter-rotating batch mixer (at 25 °C under adiabatic conditions) and thermomoulding at 9 MPa and 130 °C. Bioplastic probes were evaluated through dynamic mechanical thermal analysis, tensile strength and water absorption capacity tests. Results pointed out that a moderate enhancement of the network structure may be achieved by adding polysaccharide at a pH close to the protein isoelectric point (pH 6), which also conferred a further thermosetting capacity to the system. Moreover, the addition of MC and CMC was found to significantly enhance material elongation properties. However, the presence of charges induced by pH leaded to a higher incompatibility between the polysaccharide and protein domains forming the composite. The pH value played a relevant role in the material water absorption, which significantly increased under acidic or basic conditions (particularly at pH 3).

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 °C, 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.

Recently, bioplastic have generated an increasing interest as an alternative to conventional plastics. For this reason, their manufacture using the traditional techniques used for the production of plastics, such as extrusion, would help transferring bioplastics production to an industrial scale. In this way, the preparation of wheat gluten bioplastics by extrusion was the main objective of this research, modifying their structure by varying the pH value or by incorporating additives (glyoxal or xanthan gum). These bioplastics were characterized by the measurement of their mechanical properties and their water uptake capacity, proving that the modification of bioplastics cause variations in their properties. Thus, extrusion resulted in a greater gluten-plasticizer compatibility compared to compression, as denoted the temperature ramp tests, especially in the presence of additives (ie. Xanthan gum, glyoxal). Moreover, tensile strength was enhanced at pH 9, probably due to bonding promotion at alkaline conditions. These results demonstrate the great potential of these materials for the replacement of conventional plastics.

Protein–protein crosslinks play an important role in the design of biodegradable polymeric materials requiring suitable rheological and mechanical properties. The addition of aldehydes to the bioplastic formulation may result in their involvement in some form of protein cross-linking. The objective of this contribution is to evaluate the effect of adding some aldehydes (formaldehyde, glutaraldehyde and glyoxal) on the thermomechanical properties of gluten-based biodegradable polymeric materials processed by a mixing stage followed by compression moulding at 9 MPa and 130 °C. Different bioplastic probes were evaluated by means of DMA measurements, recording the elastic and loss moduli as a function of temperature and uniaxial tensile strength tests. Water absorption capacity and solubility under different extraction media of bioplastic specimens, were also evaluated. Solubility measurements were carried out in order to analyse the effect of the aldehyde on the nature of the interactions taking place in the system, being compared to those performed on blends previous to the moulding process. Glyoxal is the aldehyde that seems to produce bioplastics with best thermal and mechanical properties. This study would contribute to evaluate the potentials of adding aldehyde to gluten/plasticiser systems to control the microstructure and properties of the final bioplastics.

This study focuses on the development of new bio-active protein-based bioplastics through a thermo-mechanical processing, which involves a first compounding step followed by compression-moulding of the resulting material into the desired shape. Two types of proteins, wheat gluten and egg-white albumen, and two different bioactive agents, formic acid and oregano essential oil, were selected. The effect of biocide addition on the material rheological response, its antimicrobial activity and biocide release behaviour have been assessed. Rheological tests demonstrated that formulation and processing may exert a notable effect on the material linear viscoelasticity. Kirby–Bauer tests carried out on four selected types of microorganisms revealed that oregano essential oil into a wheat gluten-based matrix may be suitable for applications where the active agent must be progressively delivered (for up to 7 days). Moreover, this biocide can inhibit microorganisms’ growth even if the bioplastic is not in direct contact with the substrate.

The use of biomaterials from renewable sources in the synthesis of polyurethane-derived polymers is lately receiving great attention from social, environmental and economic standpoints. In this work, prepolymers having different -NCO/-OH ratio were synthesized, by reaction of 4,4´-diphenylmethane diisocyanate (MDI) with castor oil (CO), to be used as modifying agent of asphaltic bitumen. Reactions between MDI and CO, performed with -NCO/-OH molar ratios of 8:1 and 4:1, have led to suitable bitumen modifiers. Modification has been related to chemical reactions between -NCO groups, some bitumen compounds and air moisture (or added water), which gave rise to binders with enhanced resistance to permanent deformation. The results showed that a 2 wt.% of MDI-CO prepolymer leads to binders with higher viscosity than that corresponding to a 3 wt.% Styrene-Butadiene-Styrene (SBS) block copolymer, a polymer and concentration widely used in the paving industry. Furthermore, the resulting prepolymers are liquids that can be easily mixed with bitumen at 90 ºC, which significantly lowers the typical temperature used for commercial SBS-modified bitumen (about 180 ºC). This fact may represent energy savings, reduce bitumen oxidation and result in improvements of health and safety conditions during the product manufacture. However, if high processing temperatures are required, MDI-CO based modifiers have demonstrated much higher thermal stability than prepolymers derived from crude oil (e.g. based on polyethylene glycol). As a result, NCO-terminated prepolymers obtained from biomass-derived polyols (castor oil in this article) may become a promising alternative to the use of other petrochemicals in the paving industry., This work is part of a research project sponsored by Junta de Andalucia-CEIC (TEP6689) and also by “Ministerio de Educacion” through its Research Mobility Programme (Ref. PR2010-0593) and through the Cuadri’s F.P.U. research grant (AP2008-01419). Authors gratefully acknowledge their financial support.

Bioplastics made from renewable and biodegradable polymers are considered as promising materials for relevant industrial applications in agriculture, packaging, pharmacy, etc. Their added value would arise from their hydrophilic character and ability controlling the release of “active agents”. On these grounds, this work deals with the development of protein-based bioplastics to be used as water resources (with improved water uptake) and able to control the release of an agricultural nutrient (KCl), both of them required for the suitable plant growth. Their thermo-mechanical and physico-chemical properties were determined through dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), water absorption and diffusion tests. The use of less hygroscopic plasticizers, in the new formulations proposed, has modified bioplastic release/swelling properties. Among the modifiers studied, citric acid achieved the most suitable balance between an enhanced protein/salt affinity and the material mechanical properties, yielding slow release patterns, higher KCl leaching capacity and suitable water uptake.

Straight-run bitumens are no longer suitable in new asphalt mixtures. Consequently, the use of modified bitumens has become more important. In order to both improve binders mechanical properties and prevent it from phase separation whilst stored at high temperature, the paving industry is currently developing new modification routes based on reactive agents. This work studies the use of thiourea, which has proven to efficiently broaden the temperature interval over which the binder demonstrates an adequate performance. On the one hand, viscous flow and dynamic shear tests indicate an enhancement in the high in-service temperature strength, along with a reduced thermal susceptibility. On the other hand, results of dynamic flexural tests reveal a significant decrease in the binder glass transition temperature. Finally, the use of master curves and a further frequency/temperature conversion are proposed, in order to attain a suitable viscoelastic characterisation of bituminous binders at low temperatures., This work is part of a research project sponsored by Junta de Andalucia-CEIC (TEP6689) and also by "Ministerio de Educacion" through its Research Mobility Programme (Partal's grant Ref. PR2010-0593) and through the Cuadri's F.P.U. research grant (AP2008-01419). Authors gratefully acknowledge their finncial support.This work is part of a research project sponsored by Junta de Andalucia-CEIC (TEP6689) and also by “Ministerio de Educacion” through its Research Mobility Programme (Partal’s grant Ref. PR2010-0593) and through the Cuadri’s F.P.U. research grant (AP2008-01419). Authors gratefully acknowledge their financial support.

This work deals with the manufacture of oil-in-water food emulsions stabilised by tuna proteins. The influence of protein and oil concentrations on the linear viscoelastic properties and microstructure of these emulsions was analysed. Stable emulsions with suitable linear viscoelastic response and microstructural characteristics were formulated with 70 wt.% oil and, at least, 0.25 wt.% tuna protein. Similarly, emulsions with oil concentrations between 45 and 70 wt.% were prepared using 0.50 wt.% protein. All these emulsions showed a predominantly elastic response in the linear viscoelastic region and a well-developed plateau region in its mechanical spectrum. Rheological and droplet size distribution results pointed out an extensive droplet flocculation, due to interactions among emulsifier molecules located at the oil–water interface of adjacent droplets. As a result, the linear viscoelastic behaviour was controlled by protein–protein interactions, allowing the use of the plateau modulus to successfully normalise both the storage and loss moduli as a function of frequency onto a master curve, irrespective of the selected emulsion formulation.

No-agitation Tyre Rubber Modified Bitumens (TR-MBs), also known as “terminal blends” or “field-blends”, are quite new technologies leading to bituminous binders similar to polymer modified bitumens in terms of both rheology and needed efforts during paving operations. Their manufacturing, as well as other TR-MBs, is strongly dependent on the selected processing variables as well as on the chosen materials. This study presents a literature review to provide an overview of the TR-MB technologies which focuses on the influence of processing conditions on the modification process, storage stability and overall properties of the final bitumen - tyre rubber blends.

This work deals with the effect that processing temperature exerts on the modification of bitumen by thiourea dioxide (ThD). In that sense, shear and bending rheological tests, (thermal analysis thermogravimetric analysis/derivative thermogravimetric analysis/differential thermal analysis (TG/DTG/DTA) and modulated differential scanning calorimetry (MDSC)), and chemical characterization by thin layer chromatography coupled with a flame ionization detector (TLC-FID) were carried out on neat bitumen with a penetration grade (pen.) of 40/50 and corresponding 9 wt % ThD modified samples, prepared at 90, 130, and 180 °C. Tests carried out on those binders revealed the existence of a different modification mechanism at every temperature. In any case, viscosity was always seen to increase after ThD addition. Also, modification enhanced elastic properties and thermal susceptibility at high in-service temperatures and yielded improved binder resistance to thermal cracking by a decrease in its glass transition temp...

Synthetic binders are special paving materials manufactured by mixing polymers, resins, and oils. These materials may have improved mechanical properties as compared with the traditional modified bitumen. This work is part of a comprehensive study on the design of synthetic binders with selected mechanical properties. In this sense, upgraded mechanical properties of the final synthetic binder can be attained by understanding and correlating the mechanical properties of its individual constituents as a function of composition and temperature. With this aim, this work deals with the thermomechanical properties of recycled polymer/resin blends, over a wide range of temperature and composition. Recycled polymer/resin blends are thermorheologically complex materials, due to the development of multiphase domains depending on polymer concentration. Thus, these blends show a predominantly gel-like behavior at high polymer concentrations and a predominantly viscous behavior, with high thermal susceptibility, for low polymer concentrations. The dynamic viscosities of the blends, as a function of polymer concentration and temperature, can be predicted using a logarithmic mixing rule. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Dysphagia, or abnormal swallowing of foods and/or liquids, may result as a consequence of different common diseases. Management of dysphagia is commonly done by the prescription of texture-controlled diets. The aim of the present study was to characterize the rheological behaviour, as a function of ageing, of a new ready-to-serve dysphagia diet food with spoon-like consistency (pudding). Linear (small amplitude oscillatory shear) and non-linear (steady-state flow and relaxation) material functions were measured as a function of product shelf-life at different storage temperatures. From the experimental results obtained, it may be concluded that both linear viscoelasticity moduli and viscosities of the commercial pudding studied always increase with ageing, showing maximum values for samples stored at 40 °C. A power-law model describes the frequency dependence of pudding elastic modulus. The power-law index shows minimum values for the sample stored at 40 °C, and does not depend on ageing. Linear viscoelasticity functions versus frequency curves, as a function of ageing, can be superposed into a master one. The non-linear relaxation modulus is factorable into time and strain dependent components. Commercial pudding Sauter’s diameter increases with ageing and storage temperature. However, the differences are not large enough to explain the significant increase in the rheological functions found during storage at high temperature. Protein aggregation enhancement in the continuous phase, during storage at high temperature, may explain the experimental results obtained.

The development of biodegradable materials to be used by the plastic industry has been receiving increasing interest over the last few years. In this work, different blends of albumen protein and starch (potato and corn) have been used as raw materials for bioplastics exhibiting high transparency and a suitable mechanical behaviour. In order to study the effect of processing on the mechanical and optical properties of albumen/starch-based bioplastics, three different procedures were followed: (i) compression-moulding-based manufacture, (ii) extrusion, and (iii) combination of both. Dynamic bending (DMTA) and tensile tests, together with %-transmittance measurements demonstrated that the resulting material properties strongly depend upon the selected procedure and its processing conditions. Thus, compression-moulding after blending the ingredients by kneading was seen to produce much more promising results, concerning material transparency and strength, if compared to extrusion. However, results can further be improved by extruding starch and glycerol before blending with the protein.

BACKGROUND: Gluten has been investigated as a source for biodegradable polymeric materials because it is a renewable, available and low-cost raw material. The aim of this study was to evaluate the influence of some variables involved in the two stages of protein/plasticiser thermo-mechanical processing, where a mixture of glycerol and water was used as the plasticiser. RESULTS: Gluten/glycerol/water blends mixed under different thermal conditions (adiabatic starting at 25 ◦ C and isothermal at 60 and 90 ◦ C) exhibited shear thinning capillary flow behaviour, where a marked increase in flow properties was obtained at the highest temperature. Two thermal events, glass transitions related to the plasticiser blend and gluten, were detected by Modulated Differential Scanning Calorimetry (MDSC) and Dynamic Mechanical Analysis (DMA) tests. Moderate moulding temperature led to less resistant materials showing higher ductility, whereas higher mixing and moulding temperatures led to bioplastics with higher mechanical properties. CONCLUSION: A moulding temperature of 130 ◦ C (close to the denaturation temperature) was found to be suitable for the thermomoulding process. In addition, the use of moderate mixing temperature seems to be convenient for those applications that required materials exhibiting high water absorption behaviour and suitable mechanical properties. Protein extractability results reflect the benefits of combining high shear and high temperature during processing to improve cross-linking reactions. c � 2010 Society of Chemical Industry

In this work, bitumen modification, by “in situ” formation of poly-urethane/urea-based polymers in the bituminous matrix, has been studied. This procedure consisted of a first modification by the addition of MDI-PPG reactive prepolymer (polypropylene-glycol, PPG, functionalized by polymeric MDI, 4,4′-diphenylmethane diisocyanate), in a first stage, and a further modification of the new bitumen-MDI-PPG molecules as water was added, in a second stage. Thin layer chromatography, TLC–FID, and infrared spectroscopy, FTIR, techniques have been used to follow the reactions occurring in four different types of bitumen. Rheological measurements have demonstrated that the resulting bitumen modification strongly depends on the processing conditions selected during the first stage. Thus, bitumen modification degree after water addition increases as processing time does. Furthermore, water addition has been found to promote bitumen foaming at low processing temperatures, which could be used in novel applications where a foamed binder is required. As a result, a reactive bitumen modification mechanism, involving a set of three chemical reactions, has been proposed.

As an alternative to traditional hot-mix asphalt paving, bitumen foaming technologies have been extensively used in road recycling over the last decades. However, much more work on the use of foam-enhancing chemical agents is needed. This research deals with the influence that temperature and processing protocol exert on the bitumen foaming process promoted by a poly(propylene glycol) functionalized with a polymeric 4,4′-diphenylmethane diisocyanate. Likewise, rheological and microstructural characterizations have been carried out on the modified bituminous residues obtained after foaming. From the experimental results obtained, it may be concluded that reactive isocyanate-based polymers can be used to obtain foamed binders with different foamability and stability characteristics. On the other hand, both foaming and bitumen modification are seen to occur simultaneously, as a result of bitumen/polymer reactions involving water. Finally, dynamic shear tests and atomic force microscopy observations reveal ve...

This paper summarises the effect of recycled polymers, such as ground tire rubber (GTR) and recycled polyethylene (RPE), on the thermal and rheological properties of modified bitumen blends. From the experimental results obtained, it can be deduced that GTR or RPE may enhance bitumen thermo-rheological behaviour. However, much more enhanced mechanical properties can be obtained using a combination of both recycled polymers. In that sense, GTR would mainly improve material behaviour at low in-service temperatures, since the glassy region is significantly shifted to much lower temperatures. Complementarily, RPE would mainly improve the high in-service temperature properties by largely increasing material elastic and viscous properties in this temperature region. As a result, and from an environmental point of view, the use of both GTR and RPE may contribute to solve a waste disposal problem, and to improve the quality of the resulting blends for roofing and waterproofing applications.

Reactive 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 effect of both bitumen type and processing method, isocyanate-based reactive modification was carried out with four types of bitumen from different sources, by following two different procedures (“water-free” and “water-involved” processing). The polymer used (MDI–PPG) was synthesized from the reaction of 4,4′-diphenylmethane diisocyanate with a low molecular weight polypropylene glycol. The results obtained demonstrate that the addition of small quantities of this reactive polymer to bitumen endows the resulting modified binder with an improved performance at high in-service temperatures. Interestingly, two different modification pathways have been identified: the first one, which occurs during mixing, is the result of chemical reactions between -NCO groups of the reactive polymer with functional groups containing active hydrogen atoms (mainly, –OH), such as those typically present in the most polar bitumen fractions; the second one has been proved to be a consequence of series reactions involving water. Both pathways, but mainly the latter, lead to bituminous paving materials showing a more complex microstructure, with the consequent change in their rheological response. Finally, very different degrees of modification, depending on the colloidal features of the as-received bitumen, were observed.

This work deals with the influence that bitumen colloidal nature exerts on the rheological properties of bitumen samples modified by isocyanate-based reactive polymers. Shear rheology tests, modulated differential scanning calorimetry (MDSC), chemical characterization by TLC-FID, and AFM microstructural analysis were carried out on four different 150/200 penetration neat bitumen samples and the corresponding MDI-PPG (a low molecular weight polypropylene glycol functionalized with a polymeric 4,4′-diphenylmethane diisocyanate) modified binders. The results obtained demonstrate that the bitumen modification degree depends on bitumen reactivity and microstructure. Thus, the highest modification capability is obtained with neat bitumen samples that exhibit both a well-developed three-dimensional network and a high chemical reactivity with the isocyanate groups. The results obtained may be used to improve the performance of these materials, according to their final application.

The main goal of this research was to compare the modification capability of two different types of bitumen modifiers: non-reactive plastomers and elastomers, and reactive polymers. The group of non-reactive polymers included a block copolymer (SBS), recycled thermoplastic polymers (EVA/LDPE blends), and crumb tire rubber, which were mixed at a processing temperature of 180 °C. In the second group, a reactive MDI–PEG prepolymer, a low processing temperature modifier (90 °C), was considered. The study was mainly focused on the characterization of the thermorheological behaviour of selected modified bitumen samples. In addition, the thermal behaviour (by modulated DSC), and morphology (by optical microscopy) of these modified bitumen samples were also evaluated. All of these bitumen modifiers significantly improve the thermomechanical properties of the resulting binder, especially at high in-service temperatures. However, whereas bitumen modified by non-reactive polymers undergo marked oxidation events due to the high processing temperature used (180 °C), MDI–PEG modified bitumen does not experience this phenomenon because of the lower processing temperature involved (90 °C). In general, non-reactive polymers should be added in much larger concentrations than the reactive polymer to obtain similar results, although the latter requires a further period of curing, at room temperature, to induce suitable modification. Finally, only MDI–PEG modified bitumen is stable when stored at high temperature (163 °C), whereas all the non-reactive polymer-modified bitumen studied undergo either phase separation or particle precipitation.

Reactive polymers are lately gaining acceptance to give added value to a residue of the crude oil refining process such as bitumen. The resulting material should display enhanced mechanical properties to be considered for advanced applications in construction. In the present paper, we report the effect of processing temperature on the reaction between bitumen compounds and an isocyanate-based reactive polymer, synthesized by reaction of polymeric MDI (4,4′-diphenylmethane diisocyanate) with a low molecular weight polyethylene-glycol (PEG). Rheokinetics experiments, viscosity measurements at 60 °C, atomic force microscopy (AFM) characterization, thin layer chromatography (TLC-FID) analysis and thermogravimetric studies (TGA) were performed on the reactive polymer and on samples of MDI-PEG modified bitumen containing 2 wt.% of the polymer. Results showed the existence of an optimum processing temperature arisen as a consequence of opposite effects: microstructural availability for the formation of a polymer–bitumen network, reaction ability and polymer thermal degradation. Consequently, this study aims to serve as a guideline for the refining and asphalt industries facing the stage of selecting the optimum processing parameters.

Bioplastics based on glycerol, water and wheat gluten have been manufactured in order to determine the effect that mechanical processing and further thermal treatments exert on different thermo-mechanical properties of the biomaterials obtained. An "active agent", KCl was incorporated in these matrices to develop controlled-release formulations. Oscillatory shear, dynamic mechanical thermal analysis (DMTA), diffusion and water absorption tests were carried out in order to study the influence of the above-mentioned treatments on the physico-chemical characteristics and rheological behaviour of these bioplastic samples. Wheat gluten protein-based bioplastics studied in this work present a high ability for thermosetting modification, due to protein denaturation, which may favour the development of a wide variety of biomaterials. Bioplastic hygroscopic properties depend on plasticizer nature and processing procedure, and may be a key factor for industrial applications where water absorption is required. On the other hand, high water absorption and slow KCl release from bioplastic samples (both of them suitable properties in agricultural applications) may be obtained by adding citric acid to a given formulation, at selected processing conditions.

This paper deals with the influence that polymer concentration exerts on the rheological and thermal properties and microstructure of recycled polyethylene modified bitumen. With this aim, a recycled polyethylene was used as modifying agent to improve the mechanical characteristics of a 150/200 penetration grade bitumen. The evolution of microstructure and thermal and rheological behaviour of the blends has been followed by optical microscopy, MDSC measurements, steady and oscillatory shear tests and dynamic mechanical thermal analysis (DMTA), respectively. Recycled polymer concentrations up to 15 wt. % lead to enhanced rheological properties of the modified bitumen, useful for paving applications. Larger recycled polymer concentrations yield modified binders suitable for roofing membranes.