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An o-nitrobenzyl-protected precursor was used as a phototrigger for the release of the diamine cadaverine in polyurethane adhesives based on castor oil as a renewable source of polyol and organic diisocyanates. This resulted in formulations with suitably controlled curing by photoactivation. This material shows faster curing when UV light is applied as compared to curing in the absence of irradiation, which was in situ monitored by rheological measurements. In addition, the adhesion performance is superior, reaching lap shear strength values of up to 4600 kPa, which is unprecedented for bio-based adhesives. On one hand, the in-depth chemical characterization with FTIR spectroscopy revealed that the slow release of cadaverine yields a well-balanced urethane/urea composition with direct impact on adhesion properties. The photocured bioadhesive was shown to bond a variety of surfaces, such as polyethylene or even wood. On the other hand, the direct one-time addition of cadaverine yields a material with approximately the same viscoelastic properties, which were achieved almost immediately as a consequence of the favored fast formation of urea bonds in detriment of urethanes, however, lacking adhesion properties., We are grateful for financial support through the project UHU-1252599, financed by the University of Huelva, in the frame of the European Regional Development Fund (ERDF)-Junta de Andalucía 2014−2020 Operational Programme. A.M.B.-L. acknowledges the Spanish Ministerio de Educación, Cultura y Deporte for the award of a doctoral fellowship (FPU16/03697)., Funding for open access charge: Universidad de Huelva / CBUAUniversity of Huelva, in the frame of the European Regional Development Fund (ERDF)-Junta de Andalucía 2014−2020 Operational Programme. Ministerio de Educación, Cultura y Deporte (FPU16/ 03697) Funding for open acess charge: Universidad de Huelva/CBUA

Nowadays, there is a marked tendency in order to develop new composite fibers based on proteins and polysaccharides due to these materials can exhibit a wide range of tailored functional properties. In this framework, this study has been focused on the development of novel potato protein (PP)-based composite fibers by electrospinning technique using formic acid as solvent media. At the selected electrospinning conditions, PP pure solutions (3–8 wt.%) showed inadequate spinnability. Interestingly, the addition of polyethylene oxide (PEO) as co-blending polymer improved the solutions viscoelasticity and hence, the solutions spinnability. Composite fibers with enhanced properties were obtained at higher PEO concentrations while systems with higher PP protein contents led to electrosprayed separate aggregates of particles. Fourier-transformed infrared spectroscopy and thermogravimetric analysis results showed that the obtained composite fibers were composed of both PP and PEO materials. DSC results show that PP influences on PEO polymer thermal behaviour lowering its melting point, and an increase of the PEO amount produces a decrease of the α-helix denaturation temperature. Due to the properties of PP and PEO, these novel composite fibers could find importance in a diverse range of applications as advanced functional materials in fields like food science and biomedical applications.

To obtain multiple emulsions containing Agnique™ AE 3-2H as oil phase and Atlas™ G-5000 as emulsifier, two formulation variables were studied: the effect of the Atlas™ G-5000 concentration in emulsions containing 15 wt% Agnique™ AE 3-2H and the study of the influence of the solvent concentration maintaining the Agnique™ AE 3-2H/Atlas™ G-5000 ratio equal to 10. To assess microstructure and physical stability of these emulsions different techniques were employed, namely laser diffraction, transmitted light optical microscopy, steady-state measurements, and multiple light scattering. An increase in copolymer concentration and solvent concentration provoked a decrease in Sauter diameter but an increase in volume mean diameter and polydispersion due to droplet coalescence. Regardless of polymer concentration, all emulsions showed Newtonian behavior which led to shear thinning with increasing oil concentration. The main destabilization processes are creaming, when the concentration of polymer or solvent is low, and coalescence, when both concentrations are high.

The overall objective of this work was to study the combined effect of hydrogen peroxide (H2O2) and light emitting diodes (LED) process assisted by titanium dioxide (TiO2) on the photo-oxidation behaviour of polylactic acid (PLA). The photochemical behaviour of PLA in a TiO2 suspensions was studied by irradiation under photo-oxidative conditions (λ > 454 nm, ambient temperature and with or without the presence of H2O2). The chemical and thermal properties induced by LED irradiation process were analyzed using fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the presence of photoactive TiO2 particles, combined with H2O2 leads to strong impact on the physicochemical properties of the samples during photochemical ageing. A new comprehensive mechanism for the photo-oxidation of PLA for these conditions was discussed.

This work explores the electrospinnability of low-sulfonate Kraft lignin (LSL)/polyvinylpyrrolidone (PVP) solutions in N,N-dimethylformamide (DMF) and the ability of the different micro- and nano-architectures generated to structure castor oil. LSL/PVP solutionswere prepared at different concentrations (8–15wt%) and LSL:PVP ratios (90:10–0:100) and physico-chemically and rheologically characterized. The morphology of electrospun nanostructures mainly depends on the rheological properties of the solution. Electrosprayed nanoparticles or micro-sized particles connected by thin filamentswere obtained fromsolutionswith lowLSL/PVP concentrations and/or high LSL:PVP ratios,whereas beaded or bead-free nanofibers were produced by increasing concentration and/or decreasing LSL:PVP ratio, due to enhanced extensional viscoelastic properties and non-Newtonian characteristics. Electrospun LSL/PVP nanofibers are able to form oleogels by simply dispersing them into castor oil at concentrations between 10 and 30 wt%. The rheological properties of the oleogels may be tailored bymodifying the LSL:PVP ratio and nanofibers content. The potential application of these oleogels as bio-based lubricants was also explored in a tribological cell. Satisfactory friction and wear results are achieved when using oleogels structured by nanofibers mats with enhanced gel-like properties as lubricants. Overall, electrospinning of lignin/ PVP solutions can be proposed as a simple and effective method to produce nanofibers for oil structuring, Funding for open access charge: Universidad de Huelva / CBUAThis work is part of a research project (RTI2018-096080-B-C21) sponsored by the MICINN-FEDER I+D+i Spanish Programme

Summary The interplay between the phytohormone abscisic acid (ABA) and the gasotransmitter nitric oxide (NO) regulates seed germination and post-germinative seedling growth. We show that GAP1 (germination in ABA and cPTIO 1) encodes the transcription factor ANAC089 with a critical membrane-bound domain and extranuclear localization. ANAC089 mutants lacking the membrane-tethered domain display insensitivity to ABA, salt, and osmotic and cold stresses, revealing a repressor function. Whole-genome transcriptional profiling and DNA-binding specificity reveals that ANAC089 regulates ABA- and redox-related genes. ANAC089 truncated mutants exhibit higher NO and lower ROS and ABA endogenous levels, alongside an altered thiol and disulfide homeostasis. Consistently, translocation of ANAC089 to the nucleus is directed by changes in cellular redox status after treatments with NO scavengers and redox-related compounds. Our results reveal ANAC089 to be a master regulator modulating redox homeostasis and NO levels, able to repress ABA synthesis and signaling during Arabidopsis seed germination and abiotic stress., Graphical abstract, Highlights • GAP1 encodes transcription factor ANAC089, expressed in seeds and stress • Changes in cellular redox status induce translocation of ANAC089 to the nucleus • ANAC089 binds specifically to genes controlling seed germination and abiotic stress • ANAC089 regulates NO levels and cell redox and represses ABA synthesis and signaling, Albertos et al. report the cleavage of ANAC089 transcription factor from the membrane-anchoring domain in the endoplasmic reticulum, controlled by cell redox alterations. Once in the nucleus, ANAC089 induces redox homeostasis-related genes and represses ABA-responsive genes to increase NO levels and ABA insensitivity during seed germination and abiotic stress.

This work presents a comprehensive study on the influence of processing variables (temperature, agitation speed) and type of diisocyanate crosslinker on the rheological properties of liquid and gel-like polyurethane formulations based on lignin and castor oil. With this aim, a green and facile one-step preparation protocol which avoids the use of any harmful catalyst or solvent was proposed. Different processing temperatures (25, 45, 70 °C), stirring speeds (23, 70, 140 rpm) and kinds of diisocyanates (hexamethylene diisocyanate, and toluene diisocyanate) were selected to process the different bio-sourced polyurethane samples. These processing variables have proven to be crucial to modulate and control the rheological (viscous and viscoelastic) properties, and curing kinetics after processing, due to the different chemical structures achieved that were elucidated by means of Fourier-transform infrared spectroscopy and differential scanning calorimetry. In general, a low processing temperature and low stirring speed favour the achievement of gel-like characteristics and/or the formation of highly viscous polyurethanes, as a consequence of a higher number of total hydrogen-bonded carbonyl groups, urethane/urea ratio and ratio of hydrogen-bonded/non-bonded urethane and urea linkages. Besides, the selected one-step process, in comparison with the reported two-step process, provides polyurethanes with similar rheological characteristics by significantly reducing the isocyanate content. Finally, lignin was demonstrated to act as an effective filler agent increasing the values of the viscoelastic moduli.

The replacement of mineral oils and non-renewable gelling agents is an imperative requirement for the lubricant industry in the near future. In this framework, cellulose pulp and castor oil are proposed as sustainable substitutes for these components. Biological treatment has been explored and evaluated to enhance the dispersing and thickening properties of cellulose pulp in oil media. Streptomyces sp. MDG147 and MDG301 strains were employed to modify agricultural wheat and barley straw residues from which cellulose pulp was obtained afterwards. In addition, an environmentally friendly process for the production of cellulose-pulp-/castor-oil-based polyurethanes was applied, in which neither catalysts nor harmful solvents were used, resulting in chemical oleogels. These oleogels were rheologically and tribologically characterized to evaluate their performance as lubricating greases. The enzymatic activity pattern developed was dependent on the raw material, the strain type, and the temperature, influencing the cellulose pulp&rsquo, s composition, polymerization degree, and crystallinity. These modified characteristics tuned the rheological behavior of the different oleogels, providing a beneficial range of viscoelastic responses and viscosity values that were generally favored by the Streptomyces action. Furthermore, the friction coefficient and dimensions of wear scars measured in a tribological contact were comparable to, or even lower than, those found with commercial and other bio-based lubricating greases that have previously been studied.

This study explores the suitability of residual lignin-containing fractions generated as side-streams in different conversion processes of eucalypt and pine woods as thickening agents in bio-lubricant formulations. These conversion processes included fermentable sugars extraction by autohydrolysis or steam explosion and kraft pulping. Structural properties of lignin fractions were characterized by FTIR, 1H and 13C NMR, two-dimensional NMR, TGA and SEC, whereas their compositions were analysed by standard analytical methods. On the other hand, chemical oleogels were prepared with NCO-functionalized residual lignin fractions, and characterized by means of rheological, tribological and AFM techniques. Hydrolysis lignin fractions exhibited a great content of carbohydrates, especially glucose (46.0-48.5%), xylose (4.3-15.6%) and lignin (32.5-39.9%) with a well-maintained structure, displaying the main inter-unit linkages and low phenolic content. By contrast, kraft lignin fractions presented a lower carbohydrate content, mainly xylose (3.4-4.3%), and higher content (44.9-67%) of severely degraded lignin, showing a dramatic reduction of inter-unit linkages, and thereby high phenolic content. The rheological response of NCO-functionalized lignin fractions-based oleogels is highly influenced by the composition and chemical structure of residual lignin fractions. Moreover, these oleogels presented suitable tribological properties with values of the friction coefficient lower than those typically exhibited by standard lubricating greases.

There is a growing concern about chronic diseases such as obesity, diabetes, hypertension, hypercholesterolemia, cancer and cardiovascular diseases resulting from profound changes in the western lifestyle. Aquaculture by-products are generated in large quantities and they can be profitably recycled through their bioactive compounds used for health or food supplements. Improving waste utilization in the field of aquaculture is essential for a sustainable industry to prevent or minimize the environmental impact. In this sense fish by-products are a great source of protein and omega-3 polyunsaturated fatty acids which are particularly studied on Atlantic salmon or rainbow trout. Fish protein hydrolysate (FPH) obtained from chemical, enzymatical and microbial hydrolysis of processing by-products are being used as a source of amino acids and peptides with high digestibility, fast absorption and important biological activities. Omega-3 polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) from fish discards have been reported to decrease postprandial triacylglycerol levels, reduction of blood pressure, platelet aggregation and the inflammatory response. Crustacean by-products can also be used to produce chitosan with antioxidant and antimicrobial activity for food and pharmaceutical industries and carotenoids with important biological activity. Seaweeds are rich in bioactive compounds such as alginate, carrageenan, agar, carotenoids and polyphenols with different biological activities such as antioxidant, anticancer, antidiabetic, antimicrobial or anti-inflammatory activity. Finally, regarding harvest microalgae, during the past decades, they were mainly used in the healthy food market, with > 75% of the annual microalgal biomass production, used for the manufacture of powders, tablets, capsules or pills. We will report and discuss the present and future role of aquaculture by-products as sources of biomolecules for the design and development of functional foods/beverages. This chapter will focus on the main bioactive compounds from aquaculture by-products as functional compounds in food and their applications in biomedicine for the prevention and treatment of diseases.

A method to prepare solvent free castor oil (CO) based polyurethane (PU) adhesives with different ratios of CO and hexamethylene diisocyanate (HMDI) has been developed and the relationships between the microstructure and mechanical properties investigated. Solvent free castor oil-based PU adhesives were synthesized by promoting the reaction between castor oil and HMDI, at room conditions, and by varying the CO/HMDI weight ratio in the range 1:0.032–1:0.32 wt%. The curing of these adhesives did not require any external stimuli such as heat or irradiation treatment and once cured at room temperature they were stable up to 140 °C and water-resistant. A multi-technique approach was used to characterize so-obtained adhesives. The adhesion energy in metal–metal contact was evaluated as a function of the debonding velocity (Vd) through tack experiments. The mechanical properties were influenced by the NCO/ OH ratio, which varies the crosslinking density in the adhesives. Moreover, the structure–mechanical property relationship was explored and the inter-correlation between the storage modulus (G’), adhesion energy (Ead) and correlation length (ξ) detailed, with both G’, Ead increasing while ξ decreased. These solvent-free bio-based adhesives showed capability to adhere different substrates such as wood, paper, textile, and metal, which makes them promising candidates in different industrial and commercial applications.

The main aim of this study was to elucidate the influence of an alkali treatment on the rheological and tribological properties, and microstructure, of cellulose pulp-based gel-like dispersions potentially usable as biodegradable lubricating greases. For this purpose, cellulose pulp was treated with sodium hydroxide under different conditions of alkali concentration (20, 30 and 40%), temperature (20, 45 and 75 °C) and contact time (1 and 2 h). Favourable conditions relative to the rheological response of a commercial lithium lubricating grease used as benchmark were found to be 40% NaOH, 20 °C and 2 h. Gel-like dispersions with acceptable lubrication properties in terms of consistency indices, mechanical stability, and frictional and wear performance, were obtained by using a 6–7% (w/w) proportion of cellulose pulp.

We present herein an unexpected selectivity in the reactions of castor oil with 1,6-hexamethylene diisocyanate (HMDI) in the absence of catalysts, heat or N2 protection to give monofunctionalized castor oil derivatives. The reagents were stirred at room temperature for 24 h, and the resulting formulations characterized with infrared spectroscopy, thermogravimetric analysis and NMR. In the highly viscous neat systems, the reaction stops at the formation of NCO-terminated urethane monomers. When the mass transfer limitations due to high viscosity are minimized, the NCO-terminated urethane monomers go on to form not di- or tri- urethane monomers, but cross-linked monourethane dimers. We propose that the selectivity of the functionalization reaction of castor oil originates from a hydrogen bonding mediated steric hindrance on two out of the three fatty acid moieties. This selectivity is normally associated with conformational preferences in crystallized triglycerides, and indicates an inherent level of struct...

This work advances the development and use of sustainable polyurethane elastomers as green adhesives by providing insights into the mechanisms of humidity-induced changes on adhesive performance. Using a model adhesive prepared from equimolar ratios of castor oil and hexamethylene diisocyanate under facile reaction conditions, we show that the subtle changes in the chemical composition which occur with curing under different humidity environments significantly impact the cohesive integrity of the adhesives and, thus, their performances with different substrates. The curing chemistry was evaluated based on the isocyanate consumption, which was followed using Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry. Thermal, mechanical and adhesion properties were evaluated from thermogravimetric analysis, differential scanning calorimetry, rheology, tacking and lap shear tests. Moisture-cured adhesives were less covalently crosslinked, harder, more resistant to deformation, and recovered faster upon shear deformation compared to those cured otherwise. These mechanical properties complimented adhesive lap shear performance with substrates which formed covalent bonds during curing. For substrates with which covalent bonds could not form during curing, however, decreased internal cohesive integrity and associated increased hardness by urea formation resulted in poorer adhesive lap shear performance. This is contrary better tack performances obtained for the moisture-cured adhesives, attributed to their increased polarity and the energy dissipating ability.

This work describes the solid-state fermentation(SSF) of wheat straw with Streptomyces sp. MDG147 and further soda-pulping process to obtain wheat straw soda lignins(WSLs). Subsequently, these WSLs were NCO-functionalized with 1,6-hexamethylene diisocyanate and then dispersed in castor oil to achieve stable oleogels. The WSLs were characterized using standard analytical methods, gel permeation chromatography, Fourier transform infrared spectroscopy,differential scanning calorimetry, and thermogravimetric analysis. Rheological properties of oleogels were determinedby means of small-amplitude oscillatory shear and viscous flow measurements. The enzymatic profile and production oflignin−carbohydrate complexes were recorded along the growth time of Streptomyces, whose life cycle was achieved after 7 days. NCO-functionalized WSL was able to chemically interact with castor oil via urethane bonding, providing oleogels with suitable rheological characteristics. Linear viscoelastic functions and viscosity values of oleogels were higher when wheat straw was submitted to SSF using Streptomyces, turning out in stronger oleogels., Ministerio de Economía, Industria y Competitividad

On account of the heavy reliance of the adhesive industry on petrochemical derivatives, there is a particular interest in the development of bio-sourced polyurethane adhesives. In this context, a moisture-curable polyurethane adhesive has been synthesized from cellulose acetate and castor oil, using 1,6-hexamethylene diisocyanate as a crosslinker. In particular, this research delves into the rheological and adhesion properties achieved by bio-inspired polyurethanes cured at 20 °C and under different relative humidity conditions (11, 33, 64, and 90.4%). Green shear and peeling strengths on wood and stainless steel as well as chemical structure variations were monitored over curing time. Moreover, fully cured polyurethane-urea adhesives were thermally (thermogravimetric and differential scanning calorimetric analyses) and rheologically characterized within the linear viscoelastic region. The results corroborated the noteworthy impact of environmental humidity throughout the curing process of the synthesized bio-sourced adhesives, favoring the formation of urea linkages, while sharply reducing the crystalline/amorphous ratio. All the bio-based polyurethane-urea copolymers showed a predominant elastic behavior and the time-Temperature superposition principle was found to be applicable up to around 120 °C, due to the thermal rearrangement of the hard segment units. The crosslinking density of the resulting supramolecular structure depends on the humidity-driven balance between the urethane and urea linkages production. As a consequence of the balance between the establishment of bidentate hydrogen bonds and the curing rate, moisture curable polyurethane adhesive cured at 33% relative humidity exhibited the most appropriate shear adhesion performance on wood, while the debonding shear strength on stainless steel increased with the relative humidity due to the higher urea:urethane ratio and larger proportions of non-bonded urethane and urea groups, thus enhancing secondary interactions. Therefore, on the basis of the present study results, it might be concluded that the synthesis of bio-inspired moisture-curable polyurethane can be tuned according to its end-use application through the control of the environmental conditions, and thereby optimizing their adhesion performance, while meeting the Green Chemistry tenets.

8 Pág. Instituto de Ciencias Forestales (ICIFOR), In this study, modified residual lignins from barley and wheat straws submitted to solid-state fermentation with diverse Streptomyces strains were targeted as binders in eco-friendly castor oil-based polyurethane adhesive formulations. The thermo-rheological and adhesion properties of these adhesives were examined and related to the solid-state fermentation yields. Viscoelastic properties were enhanced by lignin addition, and the Streptomyces action generally increased the values of the linear viscoelastic functions. Adhesion performance was dominated by lignin source and further Streptomyces activity and can be correlated with the resulting lignocellulosic composition. Wheat straw lignin-based polyurethane adhesives showed the best performance in metal-textile peeling tests, whereas barley straw lignin provided the best achievements in terms of shear strength in metal-metal and wood-wood joints. Overall, solid-state fermentation with Streptomyces demonstrated to be a suitable pretreatment to conveniently modify and improve residual lignin fractions for application as binders in environmental-friendly polyurethane adhesive formulations., This work was partially funded by two coordinated research MINECO-ERDF projects (CTQ2014-56038-C3-1R and CTQ2014-56038-C3-2R) and the ERDF-Junta de Andalucía 2014-2020 Operational Programme (project UHU-1252599). A.M.B-L. has received a Ph.D. Research Grant from the Ministerio de Educación, Cultura y Deporte (FPU16/03697). The authors gratefully acknowledge the financial support.

In this work, alkali lignin together with different diisocyanates (hexamethylene diisocyanate (HDI), isophorone diisocyanate (IDI), toluene diisocyanate (TDI) and 4,4′-methylenebis (phenyl isocyanate) (MDI)) have been tested as gelling agents in a castor oil medium. A two-step process comprising first lignin functionalization with a diisocyanate and then the formation of a bio-based polyurethane with gel-like characteristics by combining the functionalized lignin with castor was followed. FTIR and thermogravimetry analysis were carried out on both the gelling agents and resulting oleogels. Moreover, oleogel rheological properties were evaluated by means of small-amplitude oscillatory shear (SAOS) tests and viscous flow measurements. The influences of time-temperature processing conditions during oleogel formation, lignin/diisocyanate ratio and functionalized lignin concentration on the rheological properties of oleogels were analyzed using HDI as crosslinker. 30% (w/w) thickener concentration and room temperature processing were selected to prepare oleogels with the rest of diisocyanates considered. Under the same conditions, HDI-functionalized lignin-based oleogels showed the strongest gel-like behavior whereas TDI-, IDI- and especially MDI-functionalized lignin-based oleogels displayed weak gel-like, or even a liquid-like, behaviors as a consequence of the respective chemical structures, which guide to higher steric hindrance, diminishing the formation of urethane linkages and/or Van der Waals forces. In general, oleogels exhibited an internal curing process due to the progressive formation of urethane linkages, which is closely related to the evolving rheological properties. The kinetics of this curing process was studied and an empirical model has been proposed to predict the evolution of the rheological properties with time., This work is a part of two research projects (CTQ2014-56038-C3-1R and TEP-1499) sponsored by the MINECO-FEDER and Junta de Andalucía programmes, respectively.

It is well known that spontaneous oxidation is one of the main drawbacks for the industrial use of eco-friendly vegetable oil-based lubricants. Herein a quick and easy synthesis of different molecules belonging to stilbene family is reported, which together with a number of representative natural sources-derived products with antioxidant (AO) capacity have been tested as additives for improving the oxidative stability of a selected bio-lubricating grease formulation. Thus, different gel-like dispersions based on N-acylated chitosan in castor oil also including these additives have been prepared. Gel-like dispersions were characterized through thermogravimetric analysis (TGA), oxidation onset temperature (OOT) and small-amplitude oscillatory shear (SAOS) rheological measurements. These preliminary results demonstrate that, in general, these antioxidants delay N-acylated chitosan-based gel-like dispersions oxidation. However, the AO activity is more relevant in the case of propyl gallate and ascorbic acid palmitate and not so important in the family of stilbene derivatives. On the other hand, the addition of any antioxidant does not qualitatively affect the rheological response but unexpectedly may significantly modify the values of the SAOS functions. Remarkably, the delay of oxidation reactions occurs by exclusively employing natural resources-derived components, being these formulations environmentally acceptable as a whole and potentially employed in specific industrial applications.

The frictional and wear properties of novel bio-based greases consisting of epoxide-functionalized alkali lignins (EALs) dispersions in castor oil were examined. EALs used as thickeners were obtained by chemical modification of alkali lignin (AL) with poly (ethylene glycol) diglycidyl ether (PEGDE). The thickener concentrations and epoxy indices used spanned the ranges 2.5–10 wt% and 0.28–0.79 mol/kg, respectively. The influence of both variables on friction and wear was studied. Comparing the frictional behaviour of the biogreases and the base oil revealed that the influence of the thickener on lubrication performance differed with temperature, load, and sliding velocity. The thickener effectively reduced friction and wear, but especially at low concentrations (5 wt% or lower) and high epoxy indices (up to 0.79 mol/kg).

Considerable efforts are currently being made by the academic community and industry, aiming to develop environmentally friendly lubricants with suitable technical features for their performance. In this context, lignin could be considered a promising candidate to be used as a bio-sourced thickening agent to formulate eco-friendly lubricating greases. In this work, alkali lignin (AL) was chemically modified with poly(ethylene glycol) diglycidyl ether (PEGDE). Afterwards, the epoxidized lignin was properly dispersed in castor oil (CO) in order to obtain an oleogel for lubricant applications. The epoxidized lignins were characterized by means of epoxy index determination, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The epoxide-functionalized lignin-based oleogels were analyzed from both rheological and tribological points of view. It was found that the viscosity, consistency and viscoelastic functions of these oleogels clearly increased with the epoxy index of the epoxide-modified lignin compound. Thermo-rheological characterization of these oleogels revealed a slight thermal dependence of the viscoelastic moduli below 100 &deg, C, but a significant softening above that critical temperature. In general, these oleogels showed low values of the friction coefficient under the mixed lubrication regime as compared to the neat castor oil.

Several di- or tri-functional epoxides were used to chemically modify an industrial grade cellulose pulp from Eucalyptus globulus in order to thicken castor oil by dispersing epoxidized cellulose pulp fibers, resulting gel-like formulations with potential applications as biolubricants. Rheological properties of these colloidal suspensions were evaluated by analysing the effects of epoxidation degree and the epoxide chemical structure. With this aim, epoxidized cellulose pulp samples were characterized by means of epoxy index determination, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. It was found that linear viscoelastic functions, determined in small-amplitude oscillatory shear (SAOS), and viscosity values of epoxidized cellulose pulp gel-like dispersions decreased by increasing the epoxy index, whereas the shear-thinning character was dampened with the extension of epoxidation. Aromatic di-functional epoxides provide higher values of these rheological functions than aliphatic ones.

Several commercially available cellulose derivatives differing in the type of substituent and substitution degree (α-cellulose, methyl cellulose, 2-hydroxyethyl cellulose, methyl 2-hydroxyethyl cellulose and cellulose acetate propionate) have been functionalized with 1,6-hexamethylene diisocyanate (HMDI) and subsequently dispersed in castor oil to obtain chemical oleogels, which can be proposed as lubricating grease formulations completely based on renewable resources. NCO-functionalized cellulose derivatives used as thickening agents and corresponding oleogels were characterized by means of Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Oleogels were also rheologically investigated and gel microstructure determined by atomic force microscope (AFM) observations. Dispersions of the different cellulosic derivatives analyzed provide oleogels with a wide variety of rheological properties, thermal stability and physical appearance. Cellulose derivatives used as thickeners exhibited a reduced thermal resistance after NCO-functionalization due to the inclusion of the HMDI segments in the cellulose structure. However, the resulting oleogels presented suitable thermal resistance. The different rheological responses obtained, from solid-like to weak gels, were found to be basically dependent on the balance between the non-polar and polar substituents molar ratio in the biopolymer structure and the size of these substituents. The presence of non-polar groups reduces cellulose polarity and, therefore, increases the affinity by the oil medium, whereas large substituents seem to hinder the development of the three-dimensional gel network. An empirical correlation between the storage modulus, G ′, and a power function of both the molar ratio [− R polar /− R non-polar ] in each monomer,− R being the different substituents of cellulosic derivatives evaluated, and the ratio of average molecular weight of all substituents to cellulose monomer molecular weight has been proposed to predict the rheological behavior of resulting oleogel formulations.

In this work, several lignocellulose pulps from different origins and/or submitted to different treatments were cross-linked with hexamethylene diisocyanate (HMDI) and further dispersed in castor oil in order to obtain gel-like formulations based on renewable resources, which can be potentially applicable as semisolid lubricants. The rheological and tribological properties attained as well as physical and mechanical stability were suitable to consider these gel-like dispersions as efficient alternatives to traditional lubricating greases. The rheological behavior was evaluated by means of both small-amplitude oscillatory shear tests (SAOS) and viscous flow measurements, at different temperatures. The HMDI/cellulose pulp weight ratio applied in the cross-linking reaction can be used to modify and modulate the consistency and the values of rheological functions of these gel-like dispersions. However, the rheological behavior is not qualitatively affected by the amount of HMDI used as coupling agent. The the...

The overall objective of this work was to study the effect of reprocessing cycles of isotactic polypropylene (PP) on the rheological behavior and microstructure of gel-like dispersions in mineral oil. PP was subjected to 10 reprocessing cycles and oleogel samples were further prepared by using the mixing rheometry technique and characterized from a rheological point of view and polarized light optical microscopy (PLOM). Recycled polymer samples were also characterized by means of rheological measurements, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) to evaluate the property changes induced by reprocessing. The values of different linear viscoelastic functions (elastic modulus and complex viscosity) of recycled PP decrease with the number of reprocessing cycles, which influences oleogel rheological response. An empirical exponential correlation between the storage modulus (G′) of PP samples and the plateau modulus ( G N o ) of oleogels has been proposed to predict the rheological behavior of oleogels. Results were explained considering the scission of PP chains induced by the thermomechanical reprocessing treatment applied.

Summary This work deals with the development and characterization of new formulations based on different types of acylated chitosan, obtained using different acylation protocols and acyl chlorides, which are able to generate stable gel-like dispersions in castor oil. These dispersions can be proposed as promising candidates to replace current non-biodegradable lubricating grease formulations. The biopolymers and gel-like dispersions were characterized through Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). In addition to this, small-amplitude oscillatory shear (SAOS) measurements were performed on gel-like dispersions. The resulting oleogels demonstrated suitable thermal resistance although the inclusion of acyl segments into the polymer structure reduces thermal stabilities. The values of the linear viscoelastic functions and their evolution with frequency for gel-like dispersions of chitosans N -acylated with decanoyl chloride or N - and O -acylated with palmitoyl chloride were very similar to those exhibited for non-biodegradable commercial greases. A significant decrease in the storage and loss moduli was detected as the carbon chain length in the acyl group decreases in both N -acylated and N - and O -acylated chitosans. Moreover, both moduli decrease when the acylation reaction time increases, as a result of a major chitosan acylation degree, which provides weaker gels.

New oleogel formulations based on high-oleic sunflower oil (HOSO) and ethylene vinyl acetate copolymer (EVA)/polypropylene (PP) blends were prepared using the mixing rheometry technique and further characterized. The effects of PP tacticity and EVA vinyl acetate (VAc) content on the rheological, morphological, and thermal behavior of derived oleogels were investigated. Differential scanning calorimetry (DSC) and polarized-light optical microscopy (PLOM) observations indicated that VAc segments markedly influence the crystalline structure of polymeric fractions and phase morphology of oleogels. The normalized crystallinity of isotactic polypropylene (iPP) phase increased linearly with its concentration whereas syndiotactic polypropylene (sPP) content does not exert a significant influence. PLOM observations showed that VAc content plays an important role in the phase morphology of PP frictions (size and shape of crystals). The viscoelastic response of oleogels depended on PP tacticity and VAc content, which may be explained attending to the different microstructures attained. POLYM. ENG. SCI., 55:1429–1440, 2015. © 2015 Society of Plastics Engineers

Nowadays, different types of natural carbohydrates such as sugars, starch, cellulose and their derivatives are widely used as renewable raw materials. Vegetable oils are also considered as promising raw materials to be used in the synthesis of high quality products in different applications, including in the adhesive field. According to this, several bio-based formulations with adhesion properties were synthesized first by inducing the functionalization of cellulose acetate with 1,6-hexamethylene diisocyanate and then mixing the resulting biopolymer with a variable amount of castor oil, from 20% to 70% (wt). These bio-based adhesives were mechanically characterized by means of small-amplitude oscillatory torsion measurements, at different temperatures, and standardized tests to evaluate tension loading (ASTM-D906) and peel strength (ASTM-D903). In addition, thermal properties and stability of the synthesized bio-polyurethane formulations were also analyzed through differential scanning calorimetry and thermal gravimetric analysis. As a result, the performance of these bio-polyurethane products as wood adhesives were compared and analyzed. Bio-polyurethane formulations exhibited a simple thermo-rheological behavior below a critical temperature of around 80–100 °C depending on the castor oil/cellulose acetate weight ratio. Formulation with medium castor oil/biopolymer weight ratio (50:50 % wt) showed the most suitable mechanical properties and adhesion performance for bonding wood., This work is part of two research projects (CTQ2014-56038-C3-1R and TEP-1499) sponsored by MINECO-FEDER and Junta de Andalucía programmes, respectively. One of the authors (Adri án Tenorio) has also received a PhD. Research Grant from ‘Ministerio de Educación’ (FPU13/01114). The authors gratefully acknowledge the financial support.

13 páginas, 6 figuras, 7 tablas, The toxin profile and hemolytic activity of a strain of Ostreopsis cf. ovata (UFBA013) isolated from Todos os Santos Bay (northeastern Brazil) were evaluated under different levels of N and P. Phylogenetic analyses based on ITS rDNA region (ITS1-5.8S-ITS2) placed UFBA013 within the Atlantic/Mediterranean/Pacific clade of O. cf. ovata. Growth experiments were conducted in f/2 medium modified by adding N and P (P: 0–36 μM; N: 0–882 μM). The growth kinetics was adequately described by logistic equations. The best growth (highest Gm) was recorded under levels of N/P = 0/18, 129/5 and 441/36, while one of the lowest Gm was obtained under P-depletion. The maximum and specific maximum growth rates (as vm; cells mL−1 d−1 and μm; d−1) were achieved with N limitation (N/P = 441/36) and P-limitation/depletion (753/5.3 and 441/0) and are the highest values reported in the literature, most similar to isolates from Pacific and Mediterranean areas. The control experiment (N/P = 441/18) also yielded similar values to those from some Mediterranean isolates, but higher than formerly reported for Brazilian isolates. In all conditions assayed, no palytoxin (PLTX) was detected. The ovatoxins (OVTXs) a, b, c, d and e did not show significant differences in cell quota between exponential and stationary phases. A significant relationship was detected between OVTXs concentration and hemolytic activity, This study was supported by FAPESB - RED0006/2012 and CNPq (Productivity Scholarship in Research # 07368/2015-7) granted to J.M.C. Nunes; CNPq (research grant # 471303/2013-5) to M. Menezes; CAPES (PhD scholarship # 9947-14-14-0/2014) and FAPESB (PhD scholarship Bol. # 10685/2013) to M.C.Q. Mendes

The overall objective of this work was to study the influence of vinyl acetate (VAc) content on the rheological properties and microstructure of polymer gels based on conventional and high-oleic sunflower vegetable oils and ethylene-vinyl acetate copolymer (EVA). The mechanical properties during gel preparation can be in situ monitored through the evolution of torque with processing time by using the mixing rheometry technique. Linear viscoelastic measurements, as well as differential scanning calorimetry (DSC) tests and morphological observations, were performed on the resulting gels. From the experimental results, it can be concluded that VAc content and melt flow index of the EVA copolymer significantly affect the rheological and thermal responses of polymer gels. VAc content, mainly affecting EVA degree of crystallinity, and melt flow index influence the linear viscoelastic behaviour in opposite directions. On the contrary, the extension of the linear viscoelastic regime and gel-like to liquid-like response transition temperatures are mainly dominated by EVA degree of crystallinity, as confirmed through calorimetry tests and microscopy observations. The different fatty acid profile in sunflower oils tested does not exert an important influence on process rheokinetics and rheological behaviour.

This work deals with the influence of functionalization degree on the thermogravimetric and rheological behaviour of NCO-functionalized chitosan- and chitin-based oleogels. Chitosan and chitin were functionalized using different proportions of 1,6-hexamethylene diisocyanate (HMDI) and subsequently dispersed in castor oil to promote the chemical reaction between the –NCO group of the modified biopolymer and the –OH group located in the ricinoleic fatty acid chain of castor oil, thus resulting in different oleogels with specific thermogravimetric and rheological characteristics. Biopolymers and oleogels were characterized through Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Small-amplitude oscillatory shear (SAOS) measurements were performed on the oleogels. Oleogels presented suitable thermal resistance, despite the fact that the inclusion of HMDI moieties in the polymer structure led to a reduction in the onset temperature of thermal degradation. The insertion of low amounts of HMDI in both chitin and chitosan produces a drastic reduction in the values of oleogel viscoelastic functions but, above a critical threshold, they increase with the functionalization degree so that isocyanate functionalization results in a chemical tool to modulate oleogel rheological response. Several NCO-functionalized chitosan- and chitin-based oleogel formulations present suitable thermal resistance and rheological characteristics to be proposed as bio-based alternatives to traditional lubricating greases., This work is part of two research projects (CTQ2010-15338 and TEP-1499) sponsored by MINECO-FEDER (70% European cofunding rate) and Junta de Andalucia programmes, respectively. One of the authors (Rocio Gallego) has received a Ph.D. Research Grant from DIGICyT (MINECO). The authors gratefully acknowledge the financial support.

This work compares the thermal, rheological, and tribological properties of a new gel-like biodegradable formulation, prepared using an acylated chitosan thickener and castor oil, with properties exhibited by two conventional greases thickened with lithium and calcium soaps, respectively, taken as benchmarks. Thermogravimetric (TGA), rheological (small-amplitude oscillatory shear [SAOS], rheodestruction, and viscous flow) and tribological (friction and wear analysis) tests, as well as roll-stability measurements were carried out to characterize the three grease samples. In addition, infrared spectroscopy and differential scanning calorimetry (DSC) were used to chemically characterize the acylated chitosan thickener agent. From a thermogravimetric point of view, the new formulation displayed better thermal resistance than the calcium and lithium lubricating greases. The evolution of the linear viscoelasticity functions with frequency and viscosity values in the shear rate and temperature ranges studied wer...

This work deals with the development and rheological characterization of a variety of green lubricating grease formulations based on different combinations of vegetable oil-derived basestocks and biopolymers obtained from renewable resources. Castor oil, high-oleic sunflower acid oil (HOS-AO) and a ricinoleic acid-derived estolide were tested as basestocks, whereas chitosan and Kraft cellulose pulp, apart from traditional lithium soap, were selected as thickener agents. Rheological behaviour was characterized by means of small-amplitude oscillatory shear (SAOS) and viscous flow measurements. In addition to these, some standard mechanical tests were carried out in order to evaluate the suitability of these formulations for lubricant applications. The rheological response depends on the type of vegetable oil-derived basestocks and thickener agent. Higher values of the SAOS functions were obtained for chitosan-based formulations. High viscosity and consistency were particularly achieved by combining the estolide sample and lithium hydroxide. On the contrary, soft greases and generally higher flow indexes were found in cellulose pulp-based formulations. The effect of the different basestocks on the rheological response was explained attending to the influence exerted by oil viscosity and basestock-thickener polar interactions, as well as the chemical reaction between the basestock carboxylic moieties and lithium hydroxide to form different thickener structures.

In this work, the capability of organo-bentonite (OBent)/recycled polypropylene (PP) and mineral oil blends to form gel-like dispersions potentially applicable as lubricating greases was explored. Specifically, the effect of both thickener concentration ratios on the rheology, thermal and some lubricant performance properties of the resulting gel-like dispersions was studied. The rheological response was qualitatively similar for all the samples studied and also similar to that found in standard lubricating greases. The plateau modulus G°N, of OBent/PP dispersions in mineral oil showed negative deviation from the additivity line and minimum values were observed for intermediate OBent/PP concentration ratios, excepting at the highest temperature studied (150 °C), where a continuous increase of this viscoelastic parameter with OBent content was found. The degree of crystallinity of recycled PP in the sample was influenced by the presence of OBent. Samples formulated with lower values of OBent/PP concentration ratio yield gel-like formulations with appropriate mechanical stabilities to be used as lubricating greases. The friction coefficient evaluated in a ball-on-plate tribological contact decreased with OBent content.

In this study, cellulose acetate and castor oil have been used to synthesize new eco-friendly alternatives to traditional polyurethane adhesives. First, cellulose acetate (CA) was modified with diphenylmethane-4,4′-diisocyanate (MDI) at different NCO:OH molar ratios, ranging from 2 to 4.53, and then the resulting biopolymers were mixed with castor oil (CO) at 1:1 wt ratio. The fully cured bio-sourced adhesives were rheologically characterized by applying dynamic oscillatory torsional tests at different temperatures (from −30 up to 200 °C). Furthermore, their adhesion performance on stainless steel and poplar wood substrates was analyzed, by conducting standardized mechanical tests, namely single-lap shear and 180° peel strengths, at room temperature and 100 °C. Fourier transform infrared spectroscopy-attenuated total reflectance along with differential scanning calorimetry and thermogravimetric analysis were also performed. Above a critical NCO:OH ratio, a thermo-rheological simplicity was found within the whole temperature range considered, being able to apply the t-T superposition principle. However, an increase in the temperature led to a depletion in their mechanical performance, thus reducing their temperature range of application. Thermal and spectroscopic analysis corroborated the complete disappearance of free isocyanate during the first few days of curing, and a segmented structure, typical of polyurethanes. Optimum thermo-rheological behaviour and adhesion performance on wood and stainless steel of the bio-sourced polyurethanes studied were found for NCO:OH molar ratios higher than 3.5, which was related to the higher compatibility between hard and soft microdomains.

This work reports the influence of solid-state fermentation (SSF) of two agricultural residues, wheat and barley straws, by using Streptomyces MDG301 strain, on their capacity to thicken and structure castor oil via crosslinking with hexamethylene diisocyanate in order to obtain gel-like systems. The analytical composition of the lignocellulosic residues and the enzymatic profile of the strain on both substrates were screened in order to establish the best conditions to achieve optimal oleogel properties. A different rheological response was found for oleogels obtained from each residue. This result could be explained in terms of the different enzymatic profile observed when the microorganism grow on these substrates. Thus, a notable difference in the production levels of CMCase and xylanase activities were detected. The assessment of the resulting oleogels as potential lubricating grease formulations was carried out by means of rheological characterization at different temperatures and tribological and mechanical stability tests. Overall, these oleogels demonstrate to possess similar rheological and tribological characteristics compared to other commercial lubricating greases.

Practical steady-state flow curves were obtained from different rheological tests and protocols for five lubricating greases, containing thickeners of a rather different nature, i.e., aluminum complex, lithium, lithium complex, and calcium complex soaps and polyurea. The experimental results demonstrated the difficulty to reach &ldquo, real&rdquo, steady-state flow conditions for these colloidal suspensions as a consequence of the strong time dependence and marked yielding behavior in a wide range of shear rates, resulting in flow instabilities such as shear banding and fracture. In order to better understand these phenomena, transient flow experiments, at constant shear rates, and creep tests, at constant shear stresses, were also carried out using controlled-strain and controlled-stress rheometers, respectively. The main objective of this work was to study the steady-state flow behaviour of lubricating greases, analyzing how the microstructural characteristics may affect the yielding flow behaviour.

The rheological behavior of model and commercial borojo (Borojoa patinoi Cuatrec.) jams was analysed as a function of temperature (5–60°C). Model borojo jam formulations were prepared by modifying pectin concentration. Both small-amplitude oscillatory shear and steady flow measurements were performed. Rheological results were also compared with those obtained with a traditional commercial peach jam. The Herschel-Bulkley model was used to describe the steady flow behaviour. In general, all rheological parameters increased with pectin concentration and decreased with temperature. Arrhenius-type relationships were used to quantify the influence of temperature on several viscoelastic and viscous flow parameters. Model borojo jam formulations exhibited higher temperature dependence of linear viscoelastic functions than peach jam samples but lower than borojo commercial jam. The influence of temperature on the yield stress was more important in model borojo formulations than in both commercial jams.

The use of estolides as additives to increase the viscosity of vegetable oils for lubricant applications was investigated. For this purpose, high-oleic sunflower (HOSO) and castor (CO) oils were blended with estolides derived from acid oils resulting from vegetable oil refining process (HOSO and olive pomace acid oils). These blends were characterized from both viscous and tribological point of views. Significant increments in viscosity were generally found when added estolides were synthetized using sulphuric acid as catalyst, compared to p-toluensulphonic acid catalyst. Estolides prepared from these two by-products gave rise to similar viscosity modification in HOSO, yielding maximum viscosity increments of 322 and 362%, at 10°C, respectively. Smaller viscosity modifications were obtained for CO/estolide blends, with maximum increments in kinematic viscosity of 84 and 152%, respectively. Generally, the addition of estolides to HOSO yielded a significant increase in the temperature dependence of viscosity. The addition of acid oils-derived estolides slightly improved CO thermal dependence of viscosity for lubricant applications. Although wear was significantly reduced by adding these estolides to any of these vegetable oils, the addition of acid oils-derived estolides to CO increased the friction coefficient at low rotational speeds, extending the boundary lubrication regime to higher Sommerfeld number values. On the contrary, a single Stribeck master curve was obtained for HOSO/estolide blends.

This work deals with the viscous, thermal and tribological characterization of a variety of estolides, obtained from both oleic and ricinoleic acids, using different acid-catalysed synthesis protocols, and their blends with vegetable (high-oleic sunflower, HOSO, and castor, CO) oils. Estolides with molecular weights between 4.4 and 6.9 times higher than the originating fatty acids were obtained. Polymerization degree was larger when using the sulphuric acid-catalysed synthesis protocol. Estolides obtained from oleic acid displayed higher freezing temperatures than the fatty acid, whereas the crystallization process was delayed in estolides obtained from ricinoleic acid, yielding improved low-temperature properties. Ricinoleic acid-derived estolides showed much higher viscosity values than those prepared from the oleic acid, with values of kinematic viscosity up to around 6700 mm 2 /s. In general, viscosities were related to estolide molecular weight. Significant increments in HOSO and CO viscosities were found when they were blended with estolides, especially those prepared from the ricinoleic acid using the sulphuric and p -toluensulphonic acids-catalyzed methods. Relative increments in kinematic viscosities up to 1500% and 700% were obtained for HOSO and CO, respectively. HOSO's viscosity-temperature dependence was significantly improved when it was blended with different estolides, whereas CO/oleic acid-derived estolides blends showed a more moderate improvement of CO thermal dependence. The sulphuric acid-catalysed method influences friction and wear in the ball-on-plates contact lubricated with estolides. The addition of the different estolides to HOSO or CO does not modify their frictional behavior, resulting in just one single Stribeck curve for all samples, and significantly reduces wear.

This work focuses on the development of gel-like formulations for use as lubricating greases. These dispersions were formulated using mineral oil and recycled/amorphous polypropylene blends. In particular, the influence of the polypropylene concentration ratio (Wi) on the rheology, thermal and some lubricant performance properties of polymer/oil blends were studied. The rheological responses of these systems were quite different, influenced mainly by the concentration of amorphous polypropylene. At intermediate temperatures (25 °C, 50 °C) and high recycled polypropylene concentrations (Wi > 0.5), the evolution of small-amplitude oscillatory shear (SAOS) functions was very similar to those found with other commercial lubricating greases. Samples with lower concentrations of amorphous polypropylene (12.5%) present maximum G N ° values in the temperature range studied. An Arrhenius-type equation can be used to quantify the thermal dependence of the linear viscoelastic functions of these gel-like dispersions. In general, sample formulations studied exhibited values of the friction coefficient comparable to those found for traditional lithium lubricating greases.

This work has been focused on the development of polyolefins/oil blends potentially suitable as lubricating greases by studying the effect that some thermo-mechanical processing variables exert on their rheological properties and microstructure. Polyolefin/oil blends have been prepared by dispersing recycled and virgin polyolefins such as high-density polyethylenes (HDPEs) and polypropylenes (PPs) in mineral lubricating oil. Linear viscoelasticity functions have been significantly influenced by processing conditions. The nature of polymers used, specially the content of HDPE, has been found to modify the microstructure of blends yielding lower mechanical stability but, on the other hand, higher values of linear viscoelastic functions.

This work deals with the selective incorporation of reactive isocyanate groups into methyl cellulose in order to be used as reactive thickening agent in castor oil. Resulting gel-like dispersions may have potential applications as green lubricating greases formulated from renewable resources. Two different isocyanate-functionalized methyl cellulose-based polymers were obtained by reaction of methyl cellulose with 1,6-hexamethylene diisocyanate. The functionalization degree, from fully functionalized to a certain number of free hydroxyl groups (58:36:6 ratio between –OMe, –NCO and free –OH groups), was controlled by modifying the reagents molar ratio. These polymers were characterized through nuclear magnetic resonance of protons (1H-NMR), Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA). Thermal and rheological responses of oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA analysis and small-amplitude oscillatory shear measurements. The evolution of linear viscoelasticity functions with frequency of the oleogel containing isocyanate-functionalized methyl cellulose with lower –NCO content is quite similar to that found for traditional lithium lubricating greases. In relation to long-term stability of these oleogels, the values of viscoelastic functions significantly increase during the first 7 days of ageing and then remain almost constant.

7 páginas, 5 figuras, 1 tabla, Yessotoxins (YTXs) production along the culture growth of three strains of the dinoflagellate Protoceratium reticulatum isolated from seawater of Galician Rias Baixas, Spain was investigated. Quantification and toxin profile determination in both cells and culture medium along the growth curve were performed by liquid chromatography–mass spectrometry (LC–MS3) analysis. The YTX profile was very similar among strains, the three algal strains produce mainly YTX and also some YTX analogs. Among the strains the maximum toxin production ranged between 416 and 576 ng mL−1. This is the first report about YTX production by P. reticulatum isolated in Galician coast, NW Spain., This study was supported by project AGL2005-07924-CO4-01/02 with the collaboration of the project ACU-02-005 INIA and culture CCVIEO.[SS]

In this study, food emulsions of oil in water from sesame (Sesamum indicum) protein isolates and their oil were formulated and standardised. The effect of the concentrations of sesame (Sesamum indicum) protein isolates and base oil and the speed of the emulsification process for the food emulsion stability was studied. The protein isolates were achieved from the defatted sesame flour (DSF), obtaining a percentage of 80% ± 0.05% of protein. Emulsions were formulated through a factorial design 23. The rheological behaviour of sesame (Sesamum indicum) protein isolates-stabilised emulsions and microstructural composition were investigated. Stable emulsions with suitable rheological properties and microstructure were formulated at a concentration of 10% sesame oil and different concentrations of protein isolates, between 1.5% and 2.5%, with the best droplet distribution characteristics being shown for the 2.5% sesame protein isolates. The emulsions showed a non-Newtonian fluid behaviour, adjusting the Sisko model.

In this work, model renewable and biodegradable lubricating greases based on castor oil and chemically modified biopolymers (methylcellulose, chitin and cellulosic pulp) were tribologically characterized in a steel–steel ball-on-plates tribological cell coupled to a controlled-stress rheometer, and the results were compared to those provided by conventional lithium and calcium soap-based greases. Viscous flow, sliding velocity sweep and transient friction tests were carried out and resulting wear scars in the steel plates were evaluated by means of scanning electron microscopy (SEM). Different frictional responses were found depending on the thickener, especially at high temperature. Excepting for most severe conditions, wear is negligible when using chemically modified chitin and methylcellulose-based greases as lubricants., This work is part of two research projects (CTQ2014-56038-C3-1R and TEP-1499) sponsored by MINECO-FEDER and Junta de Andalucia programmes, respectively. One of the authors (Rocio Gallego) has received a Ph.D. Research Grant (BES-2011-045029) from DIGICyT (MINECO). The authors gratefully acknowledge the financial support. Maria Teresa Cidade acknowledges the support of the Portuguese Foundation for Science and Technology through Project PEst-C/CTM/LA0025/2013 and The Portuguese Society of Rheology (SPR) for her stay in University of Huelva.

This article deals with the influence of temperature on the rheological behavior of lithium lubricating greases modified with three different types of recycled polymers, high-density polyethylene (HDPE), low-density polyethylene, and polypropylene (PP), all deriving from waste plastic recycling plants. Grease formulations containing diverse polymers were manufactured and rheologically characterized. Small-amplitude oscillatory shear and viscous flow measurements over a temperature range of 25–175°C were carried out. The experimental results obtained suggest that a blend of HDPE and PP could be considered a suitable potential viscosity modifier for lithium lubricating greases in a wide range of in-service temperature. Thus, the lubricating greases studied modified by HDPE or PP show quite promising results at low or high temperature, respectively. In addition, thermomechanical reversibility has been studied by applying different combined stress–temperature protocols. Lubricating greases containing any of the recycled polymers studied show a significant irreversible structural breakdown when the sample is submitted to temperatures and stresses higher than 75°C and 200 Pa, respectively. Regarding lubricating grease viscous flow behavior, a minimum in the shear stress versus shear rate plots appeared at temperatures above 50°C, more pronounced as temperature increased, resulting from material flow instabilities. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.

In order to investigate the identity, abundance and toxicity of a distinctive Ostreopsis species present in the southern-central coast of Cuba, Ostreopsis field populations were examined during January-September of 2010. The morphological and partial LSU phylogenetic data suggested the presence of O. lenticularis, although a very close species like O. labens could not be discarded. Results indicated the presence of palytoxin-like molecules in a natural extract at concentration of 0.12 pg/cell. Ostreopsis populations were very stable through the course of the study, and a maximum of 7.9 × 104 cells/g of macroalgae fresh weight was recorded on June. Publicado 0