Study on Miscibility, Thermomechanical Behavior, and Thermoregulation Performance of Paraffin Wax/Bituminous Blends for Solar Thermal Energy Storage Applications.

The goal of this work was to study the miscibility, thermal stability, thermomechanical properties, and temperature regulation performance of paraffin wax/bitumen blends for their potential use in solar thermal energy storage applications. Results indicated that these blends present a suitable thermal stability, and their thermomechanical properties are strongly dependent on composition, developed microstructure, and temperature. Among all paraffin wax concentrations studied, the blend containing 40 wt % paraffin wax displays enhanced binder elastic properties together with lower thermal susceptibility compared to base bitumen. In addition, this binder also presents improved thermal properties (thermal conductivity and specific heat capacity) and still maintains a high crystallinity, thereby retaining a large enough latent heat to be used for thermal energy storage. Thus, results from the temperature regulation test, which was conducted by subjecting the sample to simulated solar irradiation at a constant radiant flux density, provide a higher latent heat thermoregulation index value than other microencapsulated phase change materials systems. Therefore, it can be stated that paraffin wax/bitumen blends are promising base materials to formulate form-stable products for thermal energy storage applications for thermoregulation purposes.

Emulsion Stabilization by Cationic Lignin Surfactants Derived from Bioethanol Production and Kraft Pulping Processes.

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).

Ageing Effects on a Softened Bitumen by the Addition of DSA (Dodecenyl Succinic Anhydride).

The softening of aged bitumen is necessary for a successful asphalt rejuvenation in road recycling operations. Thus, this study proposes a novel and successful approach by using Dodecenyl Succinic Anhydride (DSA), a reactive surfactant with a polar head capable of reacting with some polar compounds of bitumen. On this basis, this paper analyses the softening potential and ageing inhibition capability of the addition of 3 wt.% DSA before and after the application of standard laboratory ageing methods (rolling thin film oven, RTFOT and pressure aging vessel (PAV) tests). To that end, different modified bitumens were evaluated by analysing the linear viscoelastic behaviour, viscous flow properties, thin layer chromatography, Fourier transform infrared spectroscopy (FTIR), contact angle measurements and compactibility tests. The results obtained for DSA show its greater potential to soften a model bitumen, when compared to a diluent oil, through physico-chemical processes that bring about a lowering in the polarity along with the alteration of its colloidal stability. Even though ageing processes in bitumen negatively affect its softening capacity, the developed structures still retain the ability to partially compensate for the adverse hardening effects. Furthermore, DSA addition greatly enhances the binder's wettability on a siliceous-type aggregate and favours asphalt compaction.

Bioethanol Production and Alkali Pulp Processes as Sources of Anionic Lignin Surfactants.

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.

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 offered.

Short- and Long-Term Epoxy Modification of Bitumen: Modification Kinetics, Rheological Properties, and Microstructure.

Aiming to gain knowledge in the epoxy-bitumen modification mechanisms, this work explores the effects 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 effect 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.

Hybrid Rubberised Bitumen from Reactive and Non-Reactive Ethylene Copolymers.

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.

Development of antimicrobial active packaging materials based on gluten proteins.

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.

Droplet-size distribution and stability of commercial injectable lipid emulsions containing fish oil.

PURPOSE: The droplet size of commercial fish oil-containing injectable lipid emulsions, including conformance to United States Pharmacopeia (USP) standards on fat-globule size, was investigated. METHODS: A total of 18 batches of three multichamber parenteral products containing the emulsion SMOFlipid as a component were analyzed. Samples from multiple lots of the products were evaluated to determine compliance with standards on the volume-weighted percentage of fat exceeding 0.05% (PFAT(5)) specified in USP chapter 729 to ensure the physical stability of i.v. lipid emulsions. The products were also analyzed to determine the effects of various storage times (3, 6, 9, and 12 months) and storage temperatures (25, 30, and 40 °C) on product stability. Larger-size lipid particles were quantified via single-particle optical sensing (SPOS). The emulsion's droplet-size distribution was determined via laser light scattering. RESULTS: SPOS and light-scattering analysis demonstrated mean PFAT(5) values well below USP-specified globule-size limits for all the tested products under all study conditions. In addition, emulsion aging at any storage temperature in the range studied did not result in a significant increase of PFAT(5) values, and mean droplet-size values did not change significantly during storage of up to 12 months at temperatures of 25-40 °C. CONCLUSION: PFAT(5) values were below the USP upper limits in SMOFlipid samples from multiple lots of three multichamber products after up to 12 months of storage at 25 or 30 °C or 6 months of storage at 40 °C.

Wheat gluten-based materials plasticised with glycerol and water by thermoplastic mixing and thermomoulding.

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.

Droplet-size distribution and stability of lipid injectable emulsions.

PURPOSE: The droplet-size distribution (DSD) and stability of multiple lots of lipid injectable emulsions were studied. METHODS: A total of 234 commercial batches of Intralipid (Fresenius Kabi, Uppsala, Sweden) were characterized, and the influence of the emulsions' oil content on samples packaged in single- and three-chamber bags was tested. Larger-sized lipid particles were quantified using a single-particle optical sensing device. For this test, a 1-mL sample of each product was analyzed using a dilution factor of 90-400, depending on oil concentration. Analyses were performed in triplicate. Measurements were also performed in single-bag products after up to six months of storage at 23-27 degrees C and 40 degrees C. DSD measurements were determined by laser light scattering. Droplet sizes were determined using laser diffraction, with aliquots of emulsions carefully dispersed step by step applying gentle agitation. Standard deviation analyses were performed using analysis of variance. RESULTS: The volume-weighted percentage of fat droplets greater than 5 mum (PFAT(5)) values of all samples were below the large-globule size limit (0.05%) established by the United States Pharmacopeia for lipid injectable emulsions. Container volume did not significantly influence globule size, though a slight tendency for larger bag volumes to have larger PFAT(5) values was apparent. PFAT(5) and mean volume diameter values increased with oil concentration in the emulsion. Storage time and temperature had no significant effect on PFAT(5) and mean droplet-size values. CONCLUSION: Multiple lots of a lipid emulsion were found to have acceptable PFAT(5) and mean droplet-size values, regardless of oil content, container size, or storage time and tempearture.