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BACKGROUND Zein as a sole material is not suitable for technological applications since it is not flexible. A possible solution to extend the applications of zein is the formation of zein-polysaccharide complexes. As a first step, sonication parameters were optimized to obtain finer emulsions formulated with zein, rosemary essential oil as food preservative, and sunflower oil, by means of response surface methodology. After the formation of these guar- or diutan-zein complexes the rheological properties of these food emulsions were evaluated. RESULTS An increase in sonication power, sonication time and cycles provoked a decrease in mean droplet size and a lack of recoalescence. The optimized emulsion was the starting point to form two different complexes: zein with diutan gum and zein with guar gum at different concentrations. Rheological properties as well as the microstructure observed by field emission scanning electron microscopy (FESEM) were analyzed. Interestingly, zein-guar gum complexes did not form a rheological gel; as a consequence, emulsions containing them seem to undergo a destabilization process with aging time. In contrast, emulsions formulated with zein-diutan gum presented a 3D network, observed by FESEM technique and proved by rheological measurements. CONCLUSION While emulsions containing zein-guar gum complexes did not form networks to stabilize oil droplets, zein-diutan gum complexes did. This work brings to light the importance of the selection of polysaccharide used in food emulsions formulated with zein. © 2021 Society of Chemical Industry.

Grout injection is a useful repair and strengthening technique to intervene in old masonry buildings. Until now, a very limited amount of work has been reported on the potential of geopolymers for consolidation of old stone masonry walls. In the last decades there has been several research initiatives focus on the development of materials involving a higher volume of supplementary cementitious materials that substitute the traditional binders. Geopolymers that were developed as a part of these efforts, can not only reduce the dependence on traditional binders, but also potentially present materials with less environmental impacts and improved performance. This study investigates the fresh and hardened properties of grouts composed of natural hydraulic lime (NHL) and geopolymer. The experiments were conducted using a geopolymer made of fly ash, sodium hydroxide and water. The effects of the replacement of NHL by the fly ash-based geopolymer (at the dosages of 0, 20, 50, 80 and 100%) on the rheological parameters, stability, water absorption, compressive strength and durability were investigated. The results showed that the geopolymer-based grout has several advantages regarding the mechanical strength, durability and fresh stability, but the improvement of their rheological performances proved to be a challenging task. Overall, the findings of this study will be useful in assessing the design of grouts incorporating alternative binders and consequently contribute to the improvement of the grouting technique.

Several problems and limitations faced in the treatment of many diseases can be overcome by using controlled drug delivery systems (DDS), where the active compound is transported to the target site, minimizing undesirable side effects. In situ-forming hydrogels that can be injected as viscous liquids and jellify under physiological conditions and biocompatible clay nanoparticles have been used in DDS development. In this work, polymer&ndash, clay composites based on Pluronics (F127 and F68) and nanoclays were developed, aiming at a biocompatible and injectable system for long-term controlled delivery of methylene blue (MB) as a model drug. MB release from the systems produced was carried out at 37 &deg, C in a pH 7.4 medium. The Pluronic formulation selected (F127/F68 18/2 wt.%) displayed a sol/gel transition at approx. 30 &deg, C, needing a 2.5 N force to be injected at 25 &deg, C. The addition of 2 wt.% of Na116 clay decreased the sol/gel transition to 28 &deg, C and significantly enhanced its viscoelastic modulus. The most suitable DDS for long-term application was the Na116-MB hybrid from which, after 15 days, only 3% of the encapsulated MB was released. The system developed in this work proved to be injectable, with a long-term drug delivery profile up to 45 days.

Rheology, defined as the science of the deformation and flow of matter, is a multidisciplinary scientific field, covering both fundamental and applied approaches [...]

The injection of grouts is a consolidation technique suitable for overcoming the structural deterioration of old stone masonry walls. Grouting operations involve introducing a suspension (grout) into a masonry core with the aim of improving the load capacity of the wall, as well as reducing its brittle mechanisms. The yield stress of injection grouts will affect the injection pressure and their flow inside the masonry. However, the determination of some rheological properties such as yield stress in hydraulic grout is challenging, due to the combined effects of hydration reactions and interactions between the particles present in the suspension. In this study, the determination of the yield stress of natural hydraulic lime-based grouts with polypropylene fibers was carried out. The changes in yield stress with time, fibers content and hydration were evaluated by two measurement methods using a rotational rheometer. Additionally, the static and dynamic yield stress as well as the critical shear&ndash, strain rate were determined, which provided useful information on the grout design in order to achieve successful grouting operations.

Pluronic PE9400/water binary systems at different concentrations were characterized by means of rheological and microstructural techniques. Temperature ramps revealed a structural transition defined by three zones, which determine time-dependent behaviors. Thus, non-time-dependent, antithixotropic, and thixotropic behaviors were observed depending on Pluronic’s concentration and temperature. These phenomena were analyzed resorting to rheological tools, namely hysteresis loops and transient tests, and supported by Cryo-SEM. The results obtained demonstrated the shear-sensitive character of these systems. All properties presented by these systems make them adequate and interesting for many applications such as injectable systems for tissue repair.

This study discusses the effect of the filler on the fatigue behaviour of bitumen-filler mastics by means of strain controlled fatigue tests, with constant and variable load amplitude, implemented in the DSR. Diluted and concentrated mastics were fabricated with two fillers and two bitumens. The results showed that though the generic behaviour is highly dependent on the bitumen, the effect of the filler is not only related to the increase of stiffness but, more importantly, it is seen in the response to repeated loading. Hence, the fatigue performance was significantly more affected by the increase in content of hydraulic lime than of limestone filler.

Several calamitic reactive mesogens containing only two benzene rings in the molecular core and with or without lateral substitution by the methyl/methoxy groups have been designed and their mesomorphic behaviour was characterised. Depending on the molecular structure, some of the materials exhibit the nematic and the orthogonal smectic mesophases. The reactive mesogens are aimed for further design of the macromolecular materials like polysiloxane-based polymers and elastomers. Beyond the mesomorphic and structural properties, the electrorheological properties within the temperature range of the nematic and smectic A mesophases were studied with and without applied electric field for the selected reactive mesogen. The increase of viscosity was found not to be higher than three times under applied electric field strength of 2 kV/mm. The mesomorphic, structural and rheological properties of the newly designed reactive mesogens are discussed in order to contribute to better understanding of the molec...

Multi-leaf stone masonry walls are among the most vulnerable elements of historic constructions. Grout injection is a common and efficient technique to consolidate such masonries. It consists of introducing a grout into the masonry inner core in order to upgrading the cohesion of the wall by ensuring the transversal bond between the external leaves and improving its monolithic behaviour. Notwithstanding, the recrystallization of salts due to changes in moisture content causes several damages in these masonries, even after the consolidation intervention. This paper aims to assess the potential use of linseed oil in natural hydraulic lime-based grouts to mitigate the water penetration and therefore the damages from salts crystallization. Linseed oil was used in former times as an additive for mortars in order to grant hydrophobicity. In this study several properties of the grouts were evaluated: rheology, mechanical strength, water absorption, adhesion and durability assessed by testing the resistance to sodium chloride. Moreover, this paper also analyses the correlation between non-standard specimens (with reduced size) and standard specimens (40x40x160 mm3). The experimental results revealed that the grouts durability and water transport are significantly improved with added linseed oil. It was also possible to observe a small reduction in mechanical resistance with the presence of linseed oil; however, acceptable strength values to promote an appropriate consolidation were ensured. Furthermore, the reduced size specimens revealed to be a viable alternative to the standard ones.

Rheology, defined as the science of deformation and flow of matter, is a multidisciplinary scientific field, covering both fundamental and applied approaches [...]

A (model) composite system for drug delivery was developed based on a thermoresponsive hydrogel loaded with microparticles. We used Pluronic F127 hydrogel as the continuous phase and alginate microparticles as the dispersed phase of this composite system. It is well known that Pluronic F127 forms a gel when added to water in an appropriate concentration and in a certain temperature range. Pluronic F127 hydrogel may be loaded with drug and injected, in its sol state, to act as a drug delivery system in physiological environment. A rheological characterization allowed the most appropriate concentration of Pluronic F127 (15.5 wt%) and appropriate alginate microparticles contents (5 and 10 wt%) to be determined. Methylene blue (MB) was used as model drug to perform drug release studies in MB loaded Pluronic hydrogel and in MB loaded alginate microparticles/Pluronic hydrogel composite system. The latter showed a significantly slower MB release than the former (10 times), suggesting its potential in the development of dual cargo release systems either for drug delivery or tissue engineering.

Tissue engineering is responsible for developing biological substitutes that restore, maintain or improve tissue function. A solution to achieve this is to implant scaffolds on the affected tissue. These support structures will be responsible for cell protection, oxygenation and nutrition, while supporting mechanical loads during the regeneration process. They should also be biodegradable in order to be gradually replaced by healthy tissue. From the available scaffolds manufacturing techniques, fused filament fabrication has been used recently. This technique does not use organic solvents and has the ability to produce complex geometries. In this paper the influence of manufacturing parameters was assessed. Different temperatures, extrusion speeds, filament offset distances and layer thicknesses were tested and their effect analyzed regarding scaffold morphology and mechanical properties. By decreasing the filament offset distance, three different scaffolds porosities were obtained, increasing the mechanical properties. Combining higher printing temperatures with slow extrusion speeds and low layer thickness, a maximum yield stress of 28 ​MPa and apparent compressive modulus of 942 ​MPa were obtained. With these preferred parameters, two different manufacturing schemes and geometries were tested. While using a double layer printing scheme one obtains an average of 70% increase in mechanical properties, using a staggered configuration can decrease mechanical properties up to 84%.

The newest generation of lubricants needs to adapt to stricter environmental policies. Simple and sustainable formulations with tunable rheological properties under the action of electric potentials may be the key. The present research explored the feasibility of producing electro-sensitive ecolubricants based on nanocellulose (crystalline and fibrillar) or nanoclay (Cloisite 15A montmorillonite and halloysite nanotubes) dispersions in castor oil, at concentrations that ranged from 2 to 6 wt.%. Broadband dielectric spectroscopy (BDS) measurements allowed for a first estimate on the electro-responsive potential of the nanofluids. The nanocelluloses and the montmorillonite suspensions presented a relaxation event in the dielectric loss, &epsilon, &Prime, centered at ca. 2&ndash, 4 kHz, which is related to interfacial polarization. Moreover, their actual electro-rheological (ER) effect under high electric potentials up to 4 kV/mm was assessed by determining the magnitude of the yield stress from steady flow curves at 25 &deg, C. It was found that the nanocelluloses and the montmorillonite showed an enhancement of three orders of magnitude in their yield stress values at 4 kV/m. This enhancement was much greater than in the halloysite nanoclay, which did not exhibit any polarization). This is the starting point for the development of environmentally friendly ER lubricating fluids, based on nanocellulose and montmorillonites (layered nanosilicates), which might assist in reducing the friction and wear through the application of controlled electric fields.

The oscillation frequencies produced by oscillation-type density meters during the density measurements suffer damping due to the viscosity of Newtonian liquids. The effect of viscoelastic behaviour of non-Newtonian liquids in the damping of these oscillations is still not known. So, 7 viscoelastic liquids were rheologically characterized, resorting to a rheometer, and their density measured in order to provide a deeper insight into the damping effects produced by these types of fluids. To do so, oscillatory data was related with the obtained density deviations. The results of this study will give further insights for the knowledge of the measuring behaviour of these density meters when measuring viscoelastic fluids, one of the scopes of the EMPIR Project 17RPT02-rhoLiq.

Fatigue testing of binders is an important subject in asphalt research and in recent decades several test procedures and analysis methods have been proposed. This paper discusses the application of several analysis methods to two different strain-controlled tests, implemented with the DSR. The fatigue laws obtained from the time sweep (TST) and the linear amplitude sweep (LAS) tests with the traditional failure limits, based on a fixed stiffness reduction value, are quite different. Using LAS, with maximum shear stress as failure criterion, gives rise to better results that can be further improved when changing the failure criterion to one based on the dissipated pseudo strain energy evolution.

Two room temperature ionic liquids (ILs) bearing coumarin and p-hydroxycinnamic acid moieties are synthesized, and their photochemistry is studied in solution and neat conditions. Irradiation at absorption maxima leads to photochemical transformations and results in changes of their rheological properties which are evaluated by rotational rheometry. Samples of ionic liquids are also studied by Hyper-Rayleigh scattering, and the effect of their photochemistry on ionic nanoaggregation is discussed.

Gums are often used to increase the viscosity of the continuous phase of oil-in-water emulsions in order to reduce or inhibit some destabilization processes such as creaming. A new type of xanthan gum, advanced performance xanthan gum, which possesses improved rheological properties, has been used as a stabilizer. The addition of advanced performance xanthan gum to egg protein-based emulsions prepared at different homogenization pressures in Microfluidizer was studied. These emulsions showed different droplet size distributions and flocculation degrees. However, all the emulsions studied exhibited the same viscoelastic properties, characterized by a crossover point in the mechanical spectra. This work demonstrates the essential role of this novel gum in the rheology of emulsions. In addition, there is a direct relation between homogenization pressure and flocculation degree. This flocculation led to destabilization by coalescence in these emulsions, being the emulsion processed at the smallest homogenization pressure the most stable.

The financial support received from the Portuguese Foundation for Science and Technology through the strategic project 288 UID/CTM/50025/2013 (Cenimat/I3N) and from the Spanish Ministerio de Economia y Competitividad as well as from V Plan Propio Universidad de Sevilla, and the European Commission (FEDER Programme) is kindly acknowledged. In this paper the rheological characterization of Pluronic/water systems filled with alginate microparticles is presented. The rheological characterization of the Pluronic/water systems allowed for the choice of the best Pluronic concentration taking into account its applications as injectable hydrogels for tissue repair. The effect on the rheological behavior of the addition of alginate microparticles, to be loaded with the drug, was analyzed and the maximum concentration of microparticles determined. publishersversion published

(FCT/MCTES) through the scholarship SFRH/BPD/108427/2015. The authors would like to acknowledge the support from the strategic project UID/CTM/50025/2013. This paper puts forward a new hydrophobic silica fume and assesses its contribution to the performance improvement of grouts for stone masonry consolidation. The experiments were conducted using different dosages of hydrophobic silica fume with natural hydraulic lime grouts in the presence of a polycarboxylate-based high-range water reducer. Results revealed that the effects of hydrophobic silica fume on properties of natural hydraulic lime grouts optimize the use of ordinary silica fume. Remarkable rheological performance was obtained in the presence of hydrophobic silica fume: the plastic viscosity and yield stress were reduced compared with the ordinary silica fume. For mechanical strength aspects, it was found that hydrophobic silica fume slightly affected the flexural and compressive strength; however, the values obtained are suitable for the old stone masonry consolidation purposes. It was also observed that water capillarity was substantially reduced as a result of the water-repellent behavior of hardened grouts. This study suggests that the promising effectiveness of this new silica fume for injection grouts opens the way for it to be used in many other applications. authorsversion published

The oscillation frequencies produced by oscillation-type density meters during the density measurements suffer damping due to the viscosity of newtonian liquids. The effect of viscoelastic behaviour of non-newtonian liquids in the damping of these oscillations is still not known. So, 5 viscoelastic liquids were rheologically characterized, resorting to a rotational rheometer, and their density measured in order to provide a deeper insight into the damping effects produced by these types of fluids. To do so, oscillatory data was related with the obtained density deviations. The results of this study are one of the first insights for the knowledge of the measuring behaviour of these density meters when measuring viscoelastic fluids, one of the scopes of the EMPIR Project 17RPT02-rhoLiq.

Grouting is a current repair technique for consolidating and strengthening old masonry buildings. Grouts can be seen as mixtures of binder with water, admixtures and/or additives, which should present low viscosity and high penetrability. The grout specification involves the knowledge of the flow capacity within the masonry inner core and physic-chemical compatibility with the original materials. Nevertheless, the grout properties are affected by a large number of parameters, including binder type and composition, mixing procedure, type and dosage of admixture, environmental conditions such as temperature that may lead to different grout injection capacities, as reported by several authors. This paper deals with the effect of environmental temperature over superplasticized hydraulic lime-based grouts with partial replacement of lime by silica fume. Grout performance was analysed in fresh and hardened state by testing its rheological behaviour, injectability as well as its hydration reactions kinetics. In spite of the considerable amount of information that exists for cement based mixtures with superplasticizers, there is little information about the effects of superplasticizers when used in natural hydraulic lime mixtures proportioned with silica fume. This study aims to contribute to a better understanding of the behaviour that superplasticized hydraulic lime grouts present under different temperatures. The results showed that hydraulic lime grouts performance could be improved, regarding rheological parameters and strength capacity if they are properly design and a suitable processing temperature were ensured.

The injection of grouts inside multi-leaf stone masonries is a technique widely used for structural consolidation. To ensure an adequate flow of the grout inside the masonry, it is crucial to assure good fresh grout properties, such as good rheological behaviour. The scope of this paper is to provide preliminary indications and valuable data about the effects of specific hydraulic lime grout composition on their rheological behaviour with the purpose of a successful injection process. Through the use of rotational rheometer together with the Taguchi method, it was possible to study the influence of water/binder ratio, the type and dosage of superplasticizer and the partial replacement of hydraulic lime by silica fume, upon the grout rheological properties. The study leads to the conclusion that polycarboxylate-based superplasticizers present better performance from a rheological point of view than the naphthalene-based superplasticizer and that the water/binder ratio and superplasticizer dosage are the most determinant factors in the fresh grout rheological behaviour. On the other hand, silica fume dosage turned out to be the factor with the least contribution to improve the grout rheological behaviour compared to the other two factors reported in this study. The results summarised in this paper are part of a larger study and precede the analysis of the performance of those grouts when injected into different porous media that simulate old masonries.

Due to several advantages over traditional approaches (e.g. sutures and staples), surgical adhesives are excellent materials for wound closure. For several decades intensive research activities have been carried out to enhance the efficiency of the adhesives in different tissues and application conditions. This article provides a concise literature review of different types of adhesives in order to understand their structure–properties relationship. Some of the most important commercial adhesives available are presented and discussed in terms of limitations and applications. The recent advances reported in the literature that could provide new avenues to the development of more efficient adhesives inspired in nature strategies are also discussed.

A combined analysis of Pressure–Volume–Temperature (PVT), Dynamic Mechanical Thermal Analysis (DMTA) and oscillatory flow measurements for blends of a polypropylene (PP) with a commercial liquid crystalline polymer (Rodrun LC3000) is presented. This analysis allows the determination of the pressure–viscosity coefficient b = ∂lnη 0 /∂P. This coefficient depends on the Rodrun LC3000 content, increasing with it and is of the same order of magnitude as values reported for several commercial polymers showing a similar dependence of the viscosity on pressure. The analysis of the pressure dependence of Tg (related to b ) leads to the conclusion that the number of segments involved in the glass transition of PP increases with the Rodrun LC3000 content, thus demonstrating that the polymers are not totally immiscible. As far as the authors know, this is the first time that the dependence of the viscosity on the pressure has been reported for thermoplastic/liquid crystalline polymer blends.

In the present work the rheological characterisation (steady-state and oscillatory data) of a non-chiral low molecular weight liquid-crystalline diol (denoted as HBP 6/6) exhibiting the nematic and smectic phases over a broad temperature range is presented. A non-Newtonian flow behaviour was found. This result, together with the progressive increase of the viscosity observed near the nematic–isotropic transition, suggests that the material behaves like a polymer, due to hydrogen bonding. The effect of an electric field applied normal to the flow direction, on the steady state in the nematic phase, was established. An electrorheological effect shows up, as an enhancement of the apparent viscosity, due to the positive dielectric anisotropy of this material. It was found that the increase of the apparent viscosity scales linearly with the applied field strength.

In this work we study the electro-rheological behaviour of a series of four liquid crystal (LC) cyanobiphenyls with a number of carbon atoms in the alkyl group, ranging from five to eight (5CB–8CB). We present the flow curves for different temperatures and under the influence of an external electric field, ranging from 0 to 3 kV mm−1, and the viscosity as a function of the temperature, for the same values of electric field, obtained for different shear rates. Theoretical interpretation of the observed behaviours is proposed in the framework of the continuum theory of Leslie–Ericksen for low molecular weight nematic LCs. In our analysis, the director alignment angle is only a function of the ratio between the shear rate and the square of the electric field – boundary conditions are neglected. By fitting the theoretical model to the experimental data, we are able to determine some viscosity coefficients and the dielectric anisotropy as a function of temperature. To interpret the behaviour of the flow curves...

The combined analyses of pressure–volume–temperature tests and oscillatory flow measurements for three thermotropic liquid crystalline cellulose derivatives, one acetoxypropylcellulose and two hydroxypropylcelluloses, are presented. This combined analysis allows for the determination of the pressure–viscosity coefficient b = ∂lnη0/∂P. It was observed that the activation energy of flow, dT g /dP, the compressibility coefficient and the pressure–viscosity coefficient obtained for the investigated thermotropic systems lie within the range of the values of these parameters reported for conventional polymers. However, the values of the thermal expansion coefficient below T g are considerably lower, reflecting the effect of the liquid crystalline order. The differences found between the three systems are explained considering microstructural factors, such as (average molar substitution), length of branching and hydrogen bonds.

The preparation of smart polymeric particles in supercritical carbon dioxide (scCO 2 ) presents many advantages for biomedical applications over conventional processes due to the easy elimination of trace contaminants rendering highly pure particles. Herein we report the successful optimization of poly( N -isopropylacrylamide) (PNIPAAm) synthesis strategy to obtain cell-sized hydrogel microbeads with defined and systematically varied mechanical properties. The effect of using different hydrophilic cross-linkers such as N , N -methylenebisacrylamide (MBAm), di(ethylene) glycol dimethacrylate (DEGDMA) and glycerol dimethacrylate (GDMA), on beads morphological, physico-chemical and mechanical properties was investigated. In agreement with a larger water uptake ability beads cross-linked with DEGDMA are more compliant than those containing MBAm or GDMA, having lower stiffness as accessed through oscillatory measurements on a rotational rheometer. Cytotoxicity assays showed that the obtained cross-linked PNIPAAm microbeads do not present any toxic effect on fibroblast cell cultures. Microbeads biocompatibility and adequate mechanical compliance enable their potential application on biomedical settings.

An experimental and theoretical study of the electro-rheological effects observed in the nematic phase of 4-n-heptyl-4′-cyanobiphenyl has been conducted. This liquid crystal appears to be a model system, in which the observed rheological behaviour can be interpreted by the Leslie–Ericksen continuum theory for low molecular weight liquid crystals. Flow curves are illustrated at different temperatures and under the influence of an external electric field ranging from 0 to 3 kV mm−1, applied perpendicular to the direction of flow. Also presented is the apparent viscosity as a function of temperature, over similar values of electric field, obtained at different shear rates. A master flow curve has been constructed for each temperature by dividing the shear rate by the square of the electric field and multiplying by the square of a reference value of electric field. In a log–log plot, two Newtonian plateaux are found to appear at low and high shear rates, connected by a shear-thinning region. We have applied t...

The purpose of the present communication is to study the metrological compatibility of measurement results of mass fractions of sodium chloride in aqueous solutions, by different analytical techniques: refractometry and oscillation-type densimetry. In complement pH measurements were made in solutions of NaCl of 3,5 cg g−1 and in a synthetic seawater standard (OSIL). Previously, metrological compatibility of measurement results with refractometer and oscillation-type density meter was showed for aqueous solutions of glucose, from 2 cg g−1 to 42 cg g−1. Due to its interest for the food science and health science, sodium chloride mass fraction in aqueous solution between 0,5 cg g−1 and 7 cg g−1 and for brine systems were also measured. Comparison was displayed between potentiometric pH and pH deduced by salinity experimental value.

The purpose of grout injection is to increase the compactness of the masonry and its injection optimization is a task of major importance for masonry consolidation. Fresh grout properties seem to be as important as the ones in the hardened state since grout consistency is an essential characteristic to allow the filling of voids. Since the grout rheological behaviour is associated with its fresh properties, they should be well understood and controlled so that the fluid may be pumped and flow correctly inside the porous media. This paper analyses some relevant rheological properties for natural hydraulic lime grouts, such as yield stress, plastic viscosity, consistency and power-law index. The study envisage to increase the understanding of the influence of environmental temperature and of the addition of fly ash in fresh grouts behaviour. An attempt was made to achieve an optimal grout composition by using the Taguchi method. The paper shows that fly ash is capable of substantially changing the grout rheological parameters, while the effect of temperature is negligible for the parameters tested.

The asymmetric membranes based on cellulose acetate are mainly applied for separations in aqueous systems and in reverse osmosis processes, although they can also be used in the so-called salinity process of energy generation. These applications require membranes with considerable water permeability and high salt rejection. In this paper the improvements resulting from the addition of two different types of fibers on the permeability performance of the membranes (water permeability and salt rejection) as well as on mechanical properties are presented. Concerning the water permeability and salt rejection, the influence of four different contents of cellulosic fibers (CF) and anionic diethylaminoethyl cellulose (DEAE) fibers has been studied and the optimum value was chosen after measuring water permeability and salt rejection of the membranes. To study the mechanical performance, membranes with six different contents of these two types of fibers were produced. Both permeability and mechanical test results obtained for membranes with different contents of fibers were compared with the ones for the membranes produced from the same solution but without fibers. In terms of permeability tests, the membranes with 0.5 wt % CF fibers present the best results, with water permeability 22.8% higher than the membrane without fibers, while the salt rejection only decreases by 7.3%. Concerning the mechanical properties, the best membrane would be the one with 3 wt % CF fibers, however the membrane with 0.5 wt % CF fibers still present a toughness 18.9% higher than the membrane without fibers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The use of thermoplastic/liquid-crystalline polymer (LCP) blends is recognized as a good strategy for reducing viscosity and improving mechanical properties relative to pure thermoplastics. This improvement, however, is only noticeable if the LCP fibrillates, in situ, during processing and the fibrils are kept in the solid state. In this article, we report a morphological, rheological, and rheo-optics study performed with two blends of poly(ethylene terephthalate) with a LCP, Rodrun LC3000 (10 and 25 wt % LCP content), and we show that the obtained droplet-shape relaxation time (the time the deformed droplet took to regain its spherical form after the cessation of flow) allowed for the explanation of the morphological observations. In fact, the droplet-shape relaxation time was higher for the blend with higher LCP content, for the higher experimentally accessible shear rates, and still increased at the highest shear rate, which explained the fibrils of the LCP dispersed phase observed in this blend, whereas for the lower LCP content blend, the droplet-shape relaxation time reached a low-value plateau for higher shear rates, which explained the absence of fibrillation in this blend. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

The addition of a liquid crystalline polymer (LCP) to a matrix of a flexible thermoplastic (TP) has been used in the last two decades as an in situ reinforcement of the matrix. Owing to the immiscibility of the two phases and the high degree of orientation typical of LCPs, the dispersed phase is, after processing, essentially constituted by fibrillar structures, which are responsible for the reinforcement of the matrix and the decrease of viscosity with respect to the matrix. The low degree of adhesion typical of LCP/TP blends often requires the use of compatibilizers, which will act reducing the interfacial tension between the two components. In this work, we present the synthesis of three different compatibilizers, as well as the mechanical characterization of the corresponding compatibilized blends. Some scanning electron microphotographs will be also presented to better explain the mechanical results. The mechanical properties of these blends were compared with the noncompatibilized blend, as well as with the ones presented by blends obtained with two commercial compatibilizers, leading to the conclusion that, considering our compatibilizer C, the one that leads to the higher enhancement of the Young's modulus, when compared with the noncompatibilized blend, we obtain a Young's modulus 27% higher than the one presented by the noncompatibilized blend. Comparing this result with those presented by the blends compatibilized with the two commercial compatibilizers, D and E, we conclude that this enhancement is higher than those presented by those blends (increase in Young's modulus of 16% for both compatibilizers). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Received 7 July 2006; accepted 23 February 2007DOI 10.1002/app.26412Published online 23 April 2007 in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: The main aim of this work is to study theinfluence oftheapplication ofdifferent processingconditionson the morphological and mechanical properties of thermo-plastic/LCP blends, in which the viscosity ratios are inferiorto unity and decrease with increasing temperature. The waythe microstructure evolves along the extruder determines thefinal morphology and thus, the mechanical performance ofthesystems.Inthepresentcase,themechanicalpropertiesarerelated with the degree of fibrillation in the final composites.The best degree of fibrillation was obtained for low screwspeeds and temperatures and for intermediate outputs. Theuseofhighscrewspeedsandprocessingtemperaturesresultsin a decrease of the viscosity ratio, in the former case via anincrease in the viscous dissipation, at the regions of highershear rates (kneading-elements). The application of a lowerprocessing temperature is advantageous for deformation,break-up,andfibrillarformationbecauseofthehigherviscos-ity ratios and higher shear stresses involved.