Pablo Montemartini | Universidad Nacional de Mar del Plata- CONICET (original) (raw)
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Papers by Pablo Montemartini
Fil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro ... more Fil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Mar del Plata. Instituto de Investigacion en Ciencia y Tecnologia de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingenieria; Argentina
Materials Research Innovations, 2002
Materials Research Innovations, 2002
We have placed a copolymer of poly(ethylene terephthalate + 0.6 mole fraction of p-hydroxybenzoic... more We have placed a copolymer of poly(ethylene terephthalate + 0.6 mole fraction of p-hydroxybenzoic acid) in magnetic fields up to 1.8 Tesla, heated it to the molten state (at several temperatures in the range 240-315°C) and cooled to the room temperature under the field to maintain the orientation so acquired. Then the extent of the orientation has been determined with an anisotropy parameter a based on the ultrasound criticalangle reflectometry (UCR); the parameter is calculated from the ratio of the maximum velocity to the minimum velocity of the reflected wave at critical incidence angles at which total internal reflection occurs. A significant orientation effect is found. As expected, anisotropy increases with time, magnetic field strength and to a lesser extent with the temperature. Large changes in the extent of the anisotropy are connected to phase transitions determined before. The Freederickscz transition is observed. The influence of the orientation effect on the mechanical properties of samples has been established by flexural tests. The strengthening observed has been explained using an extension of the statistical-mechanical theory of Flory in terms of channeling of flexible sequences in the polymer liquid crystals (PLC) and changes in phase structures under the magnetic field. The strengthening effect depends strongly on the presence, size and distribution of liquid crystal (LC) islands in the material. The islands act similarly as dispersoids in other types of materials. Maxima of the strengthening effect with respect to the alignment are found and related to the size of LC-rich islands in the structure.
Journal of Polymer Science Part B: Polymer Physics, 1996
Load separation is the theoretical basis for the single-specimen J-integral experiment and the in... more Load separation is the theoretical basis for the single-specimen J-integral experiment and the incremental calculation of J-integral crack growth resistance (J-R) curves. This criterion has been experimentally studied in nongrowing crack records in several materials, and more recently a new method to extend the applicability to growing crack experiments has been proposed in testing steel. This article examines the applicability of the load separation criterion for evaluating ductile fracture mechanics parameters in rubber-modified polystyrenes and thermally treated polypropylene in the bending configuration. This criterion allows the load to be represented as the multiplication of two independent functions: a material deformation function and a crack geometry function. Its validity is evaluated with both stationary and growing crack experiments. q-factor calculation for smooth and sidegrooved specimens was also tried using the simple method of Sharobeam and Landes, in order to identify material dependency. This article also investigates the applicability of the normalization method, based on the load separation criterion for evaluating J-R curves on PP and PS. A simple approach which combines a blunt notched and a precracked specimen experiment is proposed to determine the J-R curve of the materials studied. The resulting J-R curves are compared with multiple specimen results available in the literature for these materials. A good agreement between the J-R curves obtained from this simple method and from the multiple specimen technique was found.
The Journal of Chemical Physics, 2011
By means of electric force microscopy, composition depth profiles were measured with nanometric r... more By means of electric force microscopy, composition depth profiles were measured with nanometric resolution for a series of fluorinated networks. By mapping the dielectric permittivity along a line going from the surface to the bulk, we were able to experimentally access to the fluorine concentration profile. Obtained data show composition gradient lengths ranging from 30 nm to 80 nm in the near surface area for samples containing from 0.5 to 5 wt. % F, respectively. In contrast, no gradients of concentration were detected in bulk. This method has several advantages over other techniques because it allows profiling directly on a sectional cut of the sample. By combining the obtained results with x-ray photoelectron spectroscopy measurements, we were also able to quantify F/C ratio as a function of depth with nanoscale resolution.
Journal of Biomedical Materials Research, 1999
Page 1. Polymethylmethacrylate-Based Bone Cement Modified with Hydroxyapatite Claudia I. Vallo, P... more Page 1. Polymethylmethacrylate-Based Bone Cement Modified with Hydroxyapatite Claudia I. Vallo, Pablo E. Montemartini, Maria A. Fanovich, Jose´ M. Porto Lo´ pez, Teresita R. Cuadrado Institute of Materials Science and ...
International Journal of Polymeric Materials, 2005
ABSTRACT Results of an experimental evaluation of commercial propylene polymers' performa... more ABSTRACT Results of an experimental evaluation of commercial propylene polymers' performance under cyclic loading are reported. Experiments were conducted on one extrusion grade homopolymer and one impact block copolymer. The influence of thermal annealing was taken into account on the homopolymer. A laboratory-made mechanical fatigue unit capable of applying sinusoidal displacement was used to conduct fatigue tests on precracked specimens in three points bending at room temperature. Materials exhibit different crack propagation modes. The neat homopolymer displays discontinuous-catastrophic crack propagation. Both copolymer and annealed homopolymer show longer fatigue lifetime but faster propagation rates than the neat homopolymer. The annealed homopolymer also propagates in a step-like way whereas the block copolymer displays a continuous crack propagation mode in which the crack advances regularly as cycling proceeds. A noticeable crack front damage (identified as stress whitening) is developed at the crack root, which seems to control the crack propagation rate
Polymer, 2001
Morphology, elastic modulus, static and dynamic friction of a commercial epoxy resin 1¯uorinated ... more Morphology, elastic modulus, static and dynamic friction of a commercial epoxy resin 1¯uorinated poly(aryl ether ketone) (12F-PEK) system have been studied. The system was cured at 24 and 708C. We have obtained signi®cant friction lowering, namely 30% less than the value for the plain epoxy at the 12F-PEK concentration of only 10 wt% after curing at 248C. By contrast, after curing at 708C, increases in both static and dynamic friction are observed. At 248C, the SEM analysis shows that a phase separation starts at 10% 12F-PEK; completely phase-inverted morphology was found above 30% of the¯uoropolymer. The system cured at 708C has more compact structure and the phase separation process is shifted towards higher¯uoropolymer concentrations. We explain the phase inversion at low¯uoropolymer concentrations by the low free surface energy of 12F-PEK; as a consequence, we observe its accumulation on the surfaces of the samples. The samples with high 12F-PEK concentrations exhibit elevated elastic modulae and are highly ductile.
Polymer Degradation and Stability
Journal of Materials Science and Chemical Engineering
Glass fiber reinforced epoxy (GFRE) composite materials are prone to suffer from water absorption... more Glass fiber reinforced epoxy (GFRE) composite materials are prone to suffer from water absorption due to their heterogeneous structure. The main process governing water absorption is diffusion of water molecules through the epoxy matrix. However, hydrolytic degradation may also take place during components service life specially due high temperatures. In order to mitigate the effects of the water diffusive processes in the deterioration of in-service behavior of epoxy matrix composites, the use of chemically modified nanoclays as an additive has been proposed and studied in previous works [1]. In this work, an Artificial Neural Network (ANN) model was developed for better understanding and predicting the influence of modified and unmodified bentonite addition on the water absorption behavior of epoxy-anhydride systems. An excellent correlation between model and experimental data was found. The ANN model allowed the identification of critical points like the precise temperature at which a particular system's water uptake goes beyond a predefined threshold, or which system will resist an immersion longer than a particular time.
Journal of Applied Polymer Science
Polymer Degradation and Stability
Polymers for Advanced Technologies
International Journal of Polymeric Materials, 2001
A Zn-polycarboxylate biocompatible adhesive was synthesized from polyacrylic acid and Zn-acetate ... more A Zn-polycarboxylate biocompatible adhesive was synthesized from polyacrylic acid and Zn-acetate solutions. The influence of reactant concentration, from 1 to 3 N, on the properties of this compound, was studied. The reaction product was characterized by both infrared (IR) and Raman spectroscopies and scanning electron microscopy. Adhesion behavior was evaluated by 90° and 180° peel-out testing using wood and cowhide
Handbook of Materials Failure Analysis with Case Studies from the Oil and Gas Industry, 2016
Journal of Applied Polymer Science, 2015
ABSTRACT
Journal of controlled release : official journal of the Controlled Release Society, Jan 3, 2005
Journal of materials science. Materials in medicine, 1999
Fracture and mechanical characterization of bone composite composed of polymethylmethacrylate and... more Fracture and mechanical characterization of bone composite composed of polymethylmethacrylate and hydroxyapatite (HA) at different contents was carried out. Hydroxyapatite is added in order to improve cement biocompatibility, but it is expected that it also affects mechanical properties. Specimens were either stored in air at 37 degrees C for 120 h or in physiological solution (PhS-37), in order to establish the influence of storage conditions upon mechanical behavior. One set of specimens was also postcured at 120 degrees C for 4 h to take into account the influence of free monomer. Fracture experiments revealed some non-linearity in load-displacement records and differences in trends between initiation and propagation values of the fracture surface energies. The trends in the data shows that HA acts as a rigid filler enhancing fracture resistance, flexural modules and yield stress, up to a certain content. Beyond the latter limit, properties suffer a deterioration because the addi...
Fil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro ... more Fil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Mar del Plata. Instituto de Investigacion en Ciencia y Tecnologia de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingenieria; Argentina
Materials Research Innovations, 2002
Materials Research Innovations, 2002
We have placed a copolymer of poly(ethylene terephthalate + 0.6 mole fraction of p-hydroxybenzoic... more We have placed a copolymer of poly(ethylene terephthalate + 0.6 mole fraction of p-hydroxybenzoic acid) in magnetic fields up to 1.8 Tesla, heated it to the molten state (at several temperatures in the range 240-315°C) and cooled to the room temperature under the field to maintain the orientation so acquired. Then the extent of the orientation has been determined with an anisotropy parameter a based on the ultrasound criticalangle reflectometry (UCR); the parameter is calculated from the ratio of the maximum velocity to the minimum velocity of the reflected wave at critical incidence angles at which total internal reflection occurs. A significant orientation effect is found. As expected, anisotropy increases with time, magnetic field strength and to a lesser extent with the temperature. Large changes in the extent of the anisotropy are connected to phase transitions determined before. The Freederickscz transition is observed. The influence of the orientation effect on the mechanical properties of samples has been established by flexural tests. The strengthening observed has been explained using an extension of the statistical-mechanical theory of Flory in terms of channeling of flexible sequences in the polymer liquid crystals (PLC) and changes in phase structures under the magnetic field. The strengthening effect depends strongly on the presence, size and distribution of liquid crystal (LC) islands in the material. The islands act similarly as dispersoids in other types of materials. Maxima of the strengthening effect with respect to the alignment are found and related to the size of LC-rich islands in the structure.
Journal of Polymer Science Part B: Polymer Physics, 1996
Load separation is the theoretical basis for the single-specimen J-integral experiment and the in... more Load separation is the theoretical basis for the single-specimen J-integral experiment and the incremental calculation of J-integral crack growth resistance (J-R) curves. This criterion has been experimentally studied in nongrowing crack records in several materials, and more recently a new method to extend the applicability to growing crack experiments has been proposed in testing steel. This article examines the applicability of the load separation criterion for evaluating ductile fracture mechanics parameters in rubber-modified polystyrenes and thermally treated polypropylene in the bending configuration. This criterion allows the load to be represented as the multiplication of two independent functions: a material deformation function and a crack geometry function. Its validity is evaluated with both stationary and growing crack experiments. q-factor calculation for smooth and sidegrooved specimens was also tried using the simple method of Sharobeam and Landes, in order to identify material dependency. This article also investigates the applicability of the normalization method, based on the load separation criterion for evaluating J-R curves on PP and PS. A simple approach which combines a blunt notched and a precracked specimen experiment is proposed to determine the J-R curve of the materials studied. The resulting J-R curves are compared with multiple specimen results available in the literature for these materials. A good agreement between the J-R curves obtained from this simple method and from the multiple specimen technique was found.
The Journal of Chemical Physics, 2011
By means of electric force microscopy, composition depth profiles were measured with nanometric r... more By means of electric force microscopy, composition depth profiles were measured with nanometric resolution for a series of fluorinated networks. By mapping the dielectric permittivity along a line going from the surface to the bulk, we were able to experimentally access to the fluorine concentration profile. Obtained data show composition gradient lengths ranging from 30 nm to 80 nm in the near surface area for samples containing from 0.5 to 5 wt. % F, respectively. In contrast, no gradients of concentration were detected in bulk. This method has several advantages over other techniques because it allows profiling directly on a sectional cut of the sample. By combining the obtained results with x-ray photoelectron spectroscopy measurements, we were also able to quantify F/C ratio as a function of depth with nanoscale resolution.
Journal of Biomedical Materials Research, 1999
Page 1. Polymethylmethacrylate-Based Bone Cement Modified with Hydroxyapatite Claudia I. Vallo, P... more Page 1. Polymethylmethacrylate-Based Bone Cement Modified with Hydroxyapatite Claudia I. Vallo, Pablo E. Montemartini, Maria A. Fanovich, Jose´ M. Porto Lo´ pez, Teresita R. Cuadrado Institute of Materials Science and ...
International Journal of Polymeric Materials, 2005
ABSTRACT Results of an experimental evaluation of commercial propylene polymers' performa... more ABSTRACT Results of an experimental evaluation of commercial propylene polymers' performance under cyclic loading are reported. Experiments were conducted on one extrusion grade homopolymer and one impact block copolymer. The influence of thermal annealing was taken into account on the homopolymer. A laboratory-made mechanical fatigue unit capable of applying sinusoidal displacement was used to conduct fatigue tests on precracked specimens in three points bending at room temperature. Materials exhibit different crack propagation modes. The neat homopolymer displays discontinuous-catastrophic crack propagation. Both copolymer and annealed homopolymer show longer fatigue lifetime but faster propagation rates than the neat homopolymer. The annealed homopolymer also propagates in a step-like way whereas the block copolymer displays a continuous crack propagation mode in which the crack advances regularly as cycling proceeds. A noticeable crack front damage (identified as stress whitening) is developed at the crack root, which seems to control the crack propagation rate
Polymer, 2001
Morphology, elastic modulus, static and dynamic friction of a commercial epoxy resin 1¯uorinated ... more Morphology, elastic modulus, static and dynamic friction of a commercial epoxy resin 1¯uorinated poly(aryl ether ketone) (12F-PEK) system have been studied. The system was cured at 24 and 708C. We have obtained signi®cant friction lowering, namely 30% less than the value for the plain epoxy at the 12F-PEK concentration of only 10 wt% after curing at 248C. By contrast, after curing at 708C, increases in both static and dynamic friction are observed. At 248C, the SEM analysis shows that a phase separation starts at 10% 12F-PEK; completely phase-inverted morphology was found above 30% of the¯uoropolymer. The system cured at 708C has more compact structure and the phase separation process is shifted towards higher¯uoropolymer concentrations. We explain the phase inversion at low¯uoropolymer concentrations by the low free surface energy of 12F-PEK; as a consequence, we observe its accumulation on the surfaces of the samples. The samples with high 12F-PEK concentrations exhibit elevated elastic modulae and are highly ductile.
Polymer Degradation and Stability
Journal of Materials Science and Chemical Engineering
Glass fiber reinforced epoxy (GFRE) composite materials are prone to suffer from water absorption... more Glass fiber reinforced epoxy (GFRE) composite materials are prone to suffer from water absorption due to their heterogeneous structure. The main process governing water absorption is diffusion of water molecules through the epoxy matrix. However, hydrolytic degradation may also take place during components service life specially due high temperatures. In order to mitigate the effects of the water diffusive processes in the deterioration of in-service behavior of epoxy matrix composites, the use of chemically modified nanoclays as an additive has been proposed and studied in previous works [1]. In this work, an Artificial Neural Network (ANN) model was developed for better understanding and predicting the influence of modified and unmodified bentonite addition on the water absorption behavior of epoxy-anhydride systems. An excellent correlation between model and experimental data was found. The ANN model allowed the identification of critical points like the precise temperature at which a particular system's water uptake goes beyond a predefined threshold, or which system will resist an immersion longer than a particular time.
Journal of Applied Polymer Science
Polymer Degradation and Stability
Polymers for Advanced Technologies
International Journal of Polymeric Materials, 2001
A Zn-polycarboxylate biocompatible adhesive was synthesized from polyacrylic acid and Zn-acetate ... more A Zn-polycarboxylate biocompatible adhesive was synthesized from polyacrylic acid and Zn-acetate solutions. The influence of reactant concentration, from 1 to 3 N, on the properties of this compound, was studied. The reaction product was characterized by both infrared (IR) and Raman spectroscopies and scanning electron microscopy. Adhesion behavior was evaluated by 90° and 180° peel-out testing using wood and cowhide
Handbook of Materials Failure Analysis with Case Studies from the Oil and Gas Industry, 2016
Journal of Applied Polymer Science, 2015
ABSTRACT
Journal of controlled release : official journal of the Controlled Release Society, Jan 3, 2005
Journal of materials science. Materials in medicine, 1999
Fracture and mechanical characterization of bone composite composed of polymethylmethacrylate and... more Fracture and mechanical characterization of bone composite composed of polymethylmethacrylate and hydroxyapatite (HA) at different contents was carried out. Hydroxyapatite is added in order to improve cement biocompatibility, but it is expected that it also affects mechanical properties. Specimens were either stored in air at 37 degrees C for 120 h or in physiological solution (PhS-37), in order to establish the influence of storage conditions upon mechanical behavior. One set of specimens was also postcured at 120 degrees C for 4 h to take into account the influence of free monomer. Fracture experiments revealed some non-linearity in load-displacement records and differences in trends between initiation and propagation values of the fracture surface energies. The trends in the data shows that HA acts as a rigid filler enhancing fracture resistance, flexural modules and yield stress, up to a certain content. Beyond the latter limit, properties suffer a deterioration because the addi...