Papers by F. Martinez-boza
Journal of Industrial and Engineering Chemistry, 2014
ABSTRACT This paper studies the effect that both aqueous phase fraction and organoclay concentrat... more ABSTRACT This paper studies the effect that both aqueous phase fraction and organoclay concentration exert on the rheological properties of model suspoemulsions under pressure, commonly used in the formulation of invert oil muds for the drilling industry. These emulsions show a complex rheological behaviour that follows the Herschel-Bulkley's model. The yield stress shows a linear dependence with internal aqueous phase fraction for emulsions formulated with low organoclay concentration and power-law dependence for higher concentration. Barus’ model fits the pressure dependence of suspoemulsion viscosity, for different disperse phase volume fractions and organoclay concentration, fairly well.
Rheologica Acta, 2006
Knowledge of the kinetics of the manufacturing process of polymer-bitumen blends is of great inte... more Knowledge of the kinetics of the manufacturing process of polymer-bitumen blends is of great interest because it provides information on the behaviour of the binder at different stages of the mixing operation, which is useful for the establishment of the optimum processing conditions, involving temperature and operation time. The purpose of this research was to study the evolution of the rheological properties and microstructure of a polymer-modified bitumen during its processing. A 60/70-penetration grade bitumen and recycled EVA/LDPE were mixed under different processing conditions. Measurements of the evolution of viscosity with time, at different temperatures and agitation speeds, were carried out with an experimental device known as 'rheomixer', that is, a helical ribbon impeller inside a mixing vessel coupled with the transducer and motor of a conventional rheometer. Under the experimental conditions selected (within the laminar region, Re<10), temperature is the most important processing variable. Hence, low agitation speeds and a processing temperature of around 180°C should be chosen for bitumen modification with the polymer used.
Rheologica Acta, 2006
Transportation and consumption of petroleum products around the world have created a potential ri... more Transportation and consumption of petroleum products around the world have created a potential risk for oil spills in the environment. Knowledge of highpressure rheological behaviour of heavy crude oil fractions, which are usually transported in oil tankers, is very important to design deep recovering operations of the oil remaining in the tanks after an accident. The effect of pressure on the viscosity of these materials is not well understood, this is mainly due to experimental constraints involving high-pressure rheology measurements at low shear rates. Consequently, the overall objective of this work is to model the temperature-pressure-viscosity dependence of a selected heavy fuel oil in a wide range of pressure and temperature. With this aim, viscous flow tests at different temperatures and differential pressures and modulated differential scanning calorimetry tests were carried out on the heavy fuel oil selected. A temperature-pressure-viscosity model (FMT model) fits fairly well the experimental results obtained in the whole differential pressure range studied. However, viscosity values at temperatures lower than 10°C cannot be predicted due to microstructural changes associated with the solidification process of the heaviest components of the fuel oil tested.
Polymer Engineering & Science, 2007
ABSTRACT
Materials Chemistry and Physics, 2014
ABSTRACT Stable bituminous foams have been obtained by using a 35/50 penetration grade bitumen an... more ABSTRACT Stable bituminous foams have been obtained by using a 35/50 penetration grade bitumen and a reactive prepolymer (MDI-PPG) synthesized by the reaction of polymeric 4,4′-diphenylmethane diisocyanate (MDI) with a low molecular weight polypropylene glycol (PPG). In a first step, MDI-PPG and bitumen were allowed to react for up to 7 days. Foams were then obtained by adding an excess of water. The results obtained point out important changes in the material colloidal structure, as a consequence of the reactions between the –NCO groups and bitumen most polar fractions. Modification led to bituminous foams with low density and improved in-service properties (higher elasticity and resistance to deformation at high in-service temperatures, reduced thermal susceptibility and better flexibility at low temperatures), demonstrating their adequacy to be used in building applications. Properties were enhanced by subjecting the material to longer periods of curing prior to promote foaming.
Journal of Industrial and Engineering Chemistry, 2009
The main goal of this research was to compare the modification capability of two different types ... more The main goal of this research was to compare the modification capability of two different types of bitumen modifiers: non-reactive plastomers and elastomers, and reactive polymers. The group of nonreactive polymers included a block copolymer (SBS), recycled thermoplastic polymers (EVA/LDPE blends), and crumb tire rubber, which were mixed at a processing temperature of 180 8C. In the second group, a reactive MDI-PEG prepolymer, a low processing temperature modifier (90 8C), was considered. The study was mainly focused on the characterization of the thermorheological behaviour of selected modified bitumen samples. In addition, the thermal behaviour (by modulated DSC), and morphology (by optical microscopy) of these modified bitumen samples were also evaluated. All of these bitumen modifiers significantly improve the thermomechanical properties of the resulting binder, especially at high in-service temperatures. However, whereas bitumen modified by non-reactive polymers undergo marked oxidation events due to the high processing temperature used (180 8C), MDI-PEG modified bitumen does not experience this phenomenon because of the lower processing temperature involved (90 8C). In general, non-reactive polymers should be added in much larger concentrations than the reactive polymer to obtain similar results, although the latter requires a further period of curing, at room temperature, to induce suitable modification. Finally, only MDI-PEG modified bitumen is stable when stored at high temperature (163 8C), whereas all the non-reactive polymer-modified bitumen studied undergo either phase separation or particle precipitation.
Journal of Industrial and Engineering Chemistry, 2013
ABSTRACT Dimensionally stable bituminous foams were prepared by using 4,4′-diphenylmethane diisoc... more ABSTRACT Dimensionally stable bituminous foams were prepared by using 4,4′-diphenylmethane diisocyanate/polypropylene glycol (MDI–PPG) quasi-prepolymers, with different molecular weights. From the results obtained, it may be concluded that, after foam formation, the rheological properties are remarkably affected, especially at high temperatures. Paradoxically, the greater the molecular weight of MDI–PPG, the lower the values of viscosities at 60 °C, and the linear viscoelasticity functions of the resulting foams. This result seems to be related to the improved ability of small MDI–PPG molecules to interact strongly with polar bitumen compounds, leading to the formation of larger molecular-sized compounds.
Fuel, 2003
Mixing polymers into bitumen has important consequences on the engineering properties of bitumino... more Mixing polymers into bitumen has important consequences on the engineering properties of bituminous binders. Thus, structural and chemical changes may be observed during processing of polymer-modified bitumens. Chemical compatibility and processing conditions are crucial to obtain suitable properties. Most polymers occur to be insoluble, in some degree, in the bitumen matrix, and phase separation may result. Polymer stabilization can be
Fuel, 2007
A low-molecular-weight polyethyleneglycol functionalized with a polymeric MDI (4,4′-diphenylmetha... more A low-molecular-weight polyethyleneglycol functionalized with a polymeric MDI (4,4′-diphenylmethane diisocynate) was used as a modifying agent for a 60/70 penetration grade bitumen. The rheological properties of the resulting modified binder, at both low and intermediate temperatures, before and after curing at room temperature were studied and compared with those corresponding to a SBS modified bitumen. The analysis showed that the
Fuel, 2004
This paper deals with the viscous properties of recycled-polymer modified bitumens (PMBs) in a wi... more This paper deals with the viscous properties of recycled-polymer modified bitumens (PMBs) in a wide range of temperatures. With this aim, two different penetration grade bitumens (60/70 and 150/200) and recycled EVA copolymer (EVA R) from agriculture films were processed in an open reactor using a four blade propeller. Polymer concentration ranged from 0 to 9 wt%. Viscous flow and DSC measurements, from 5 to 165 8C, and optical microscopy, at room temperature, were performed on the samples. From the experimental results obtained, we may conclude that the viscous properties of bitumen, at high temperature, are improved by adding recycled EVA copolymer in amounts that depend on bitumen penetration grade. Moreover, significant microstructural changes, related to the development of a polymer-rich phase, tend to occur in the bitumen as polymer concentration increased. These changes in microstructure have a significant influence on the flow behaviour of the binder and on its in-service performance. As a consequence, the use of recycled EVA in PMBs can be considered a suitable alternative from both environmental and economical points of view.
European Polymer Journal, 2005
The influence that composition and processing variables exert on the linear viscoelastic properti... more The influence that composition and processing variables exert on the linear viscoelastic properties of model synthetic binders has been studied in a wide range of temperature and frequency. Model synthetic binders were prepared by blending a non-modified colophony resin (40-65%), a process aromatic oil and a styrene-butadiene-styrene (SBS) triblock copolymer (5-15%). At high SBS content (11% and 15%) and gentle processing conditions (i.e. 150°C and 60 rpm), a plateau region in G 0 is found in the mechanical spectrum. The microstructure of this binder is characterized by a continuous SBS-rich phase. On the contrary, a shoulder in G 0 is found at low polymer content. The resulting microstructure consists of a continuous resin-rich phase and a dispersed polymer-rich phase. Under severe processing conditions (180°C and 1200 rpm) and low polymer concentration, the polymer influence is dampened and the glassy region appears at higher temperatures or lower frequencies. At high polymer concentration, a phase inversion can be induced by processing (i.e. 180°C and 1200 rpm.). Both resin oxidation and SBS degradation may explain such microstructural changes.
Energy & Fuels, 2005
Bitumen is widely used in construction. Its applications go from binder for road asphalts to buil... more Bitumen is widely used in construction. Its applications go from binder for road asphalts to built-up roofing membranes and other waterproofing uses. The use of crumb tire rubber as a binder modifier may contribute to solving a waste disposal problem and to improving the ...
Construction and Building Materials, 2012
ABSTRACT Bitumen source is a key factor in the development of new bituminous products, such as di... more ABSTRACT Bitumen source is a key factor in the development of new bituminous products, such as dimensionally stable bituminous polyurethane foams, for building applications. With this aim, three neat bitumen samples, with very different chemical compositions and penetration grades, were modified with a reactive polymer, synthesized from the reaction of 4,4′-diphenylmethane diisocyanate with a low molecular weight polypropylene glycol (MDI–PPG). Firstly, modified bitumen were obtained by adding 10 wt.% MDI–PPG to each bitumen. Then, bituminous foams were achieved by adding an excess of water. Water reacted with the remaining NCO groups, generating CO2, which was used as a chemical foaming agent. The reactions involved in this bitumen modification were followed by using different techniques, such as thin layer chromatography (TLC–FID), and Fourier transform infrared spectroscopy (FTIR). The rheological properties of foamed bitumen are greatly improved by addition of small quantities of MDI–PPG and the degree of enhancement is dependent on bitumen characteristics. Thus, despite bitumen composition, dimensionally stable bituminous foams can be successfully obtained, even from the softest base.
Oil & Gas Science and Technology
The overall objective of this research was to study the combined influence of pressure and temper... more The overall objective of this research was to study the combined influence of pressure and temperature on the complex viscous behaviour of two oil-based drilling fluids. The oil-based fluids were formulated by dispersing selected organobentonites in mineral oil, using a high-shear mixer, at room temperature. Drilling fluid viscous flow characterization was performed with a controlled-stress rheometer, using both conventional coaxial cylinder and non-conventional geometries for High Pressure/High Temperature (HPHT) measurements. The rheological data obtained confirm that a helical ribbon geometry is a very useful tool to characterise the complex viscous flow behaviour of these fluids under extreme conditions. The different viscous flow behaviours encountered for both all-oil drilling fluids, as a function of temperature, are related to changes in polymer-oil pair solvency and oil viscosity. Hence, the resulting structures have been principally attributed to changes in the effective v...
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Papers by F. Martinez-boza