Jorge Uribe-Calderon - Academia.edu (original) (raw)

Papers by Jorge Uribe-Calderon

Polymer Engineering and Science, Oct 14, 2022

During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, scientists from... more During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, scientists from different areas are looking for alternatives to fight it. SARS-CoV-2, the cause of the infectious respiratory disease COVID-19, is mainly transmitted through direct or indirect contact with infected respiratory droplets. The integrity of the virus structure is crucial for its viability to attack human cells. Quaternary ammonium salts are characterized by having antiviral capabilities which alter or destroy the structure of the viral capsid. In this work, polypropylene (PP)/(1-Hexadecyl) trimethyl-ammonium bromide (CTAB) composites have been prepared in order to create an antiviral material. The composites were melt processed and blown to produce thin films. The CTAB content on the antiviral effect was evaluated using antibodies and serum from infected patients with the SARS-CoV-2 virus. In addition, the mechanical and thermal properties of blown films were investigated, and CTAB release kinetics from the films was followed by UV-Vis. The results indicate that the virus tends to remain less on the polymer surface by increasing the amount of CTAB in the PP matrix.

Journal of Materials Science: Materials in Medicine

The surface of Tecoflex SG-80A Polyurethane (PU) films was modified by grafting polyethylene glyc... more The surface of Tecoflex SG-80A Polyurethane (PU) films was modified by grafting polyethylene glycol (PEG) chains at three different molar amounts (0.05, 0.10, and 0.15 mmol). The resulting substrata were characterized by FTIR-ATR, TGA, AFM, SEM and contact angle to assess the surface modifications occurred during the grafting reactions. Osteoblasts and fibroblasts were cultured with PU extracts for 24 h, and their cell viability and morphology were evaluated by CellTiterBlue assay, Crystal Violet staining and Live/Dead assay. FTIR and TGA results indicated that PEG chains were successfully grafted onto PU surfaces, specifically in the hard segment of PU forming allophanate groups as the PEG grafting density increased. SEM and AFM images suggest that PU substrata were partially covered by PEG, increasing the dispersive and basic components of the PU surface energy. It was found that extracts from PEG-grafted polyurethanes increased the osteoblast viability, although fibroblasts viabi...

e-Polymers, 2020

Tubular fibers (raw and wax-free) from Ceiba pentandra (CP) were cross-linked with butane-1,2,3,4... more Tubular fibers (raw and wax-free) from Ceiba pentandra (CP) were cross-linked with butane-1,2,3,4-tetracarboxylic acid (BTCA) at different concentrations to obtain a porous biodegradable medium for drug release applications. Chlorhexidine diacetate (CHX) was added to the cross-linked fibers for drug release studies. The Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy results indicated that the cross-linked fibers with a 5:1 fiber:BTCA ratio presented the higher cross-linking density. CHX was added at different concentrations (8% and 16% wt/wt); the elemental analysis indicated that CHX was loaded up to 7.99 wt%. In vitro studies showed a burst release of CHX within the first 3 h. CHX release kinetics was described using several models, with the Korsmeyer–Peppas equation, which adjusted better to the experimental data. The results indicated that the CP fibers are a feasible material for drug release applications.

Thermally Stable and Flame Retardant Polymer Nanocomposites

Journal of Polymers and the Environment, 2019

The effect of the incorporation of pristine and stearoyl chloride grafted CNCs on the chemical, m... more The effect of the incorporation of pristine and stearoyl chloride grafted CNCs on the chemical, mechanical, thermal and microstructural properties, during the thermo-oxidative aging, of LDPE blown films at 60 °C was studied. The success of the pristine CNCs grafting was assessed by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Thermal-gravimetric analysis (TGA), Atomic Force Spectroscopy (AFM) and contact angle measurements. The results show that chemical modification decreases both, the CNCs thermal stability and the polar component of surface energy, i.e. increases the nanocrystals hydrophobicity. Also, it was found that neither CNCs crystalline structure nor its dimensions changed with grafting. The changes on the blown film properties during thermo-oxidative aging were monitored using FT-IR, DSC, DRX and tensile testing. It was found that the CNCs catalyzed the production of carboxylic acids as a final degradation by-product, whereas the CNC-g-C 18 inhibits its formation, i.e. in presence of CNCs grafted with stearoyl chloride the catalytic effect attributed to the pristine CNCs was partially inhibited. The DSC, DRX and tensile testing results show the microstructural arrangements due to the annealing and the chains oxidation predominated during the first 30 days of aging and then chain scissions prevail. These findings suggest an analogous reduction in molecular weight at the end thermo-oxidative aging. In addition, the presence of a high concentration of carboxylic acid and the drop in molecular weight after LDPE aging will facilitate the biodegradation of these oxo-degradable films.

Polymer Composites, 2017

The effect of surface modification of Palygorskite (Pal) on the morphology and the mechanical and... more The effect of surface modification of Palygorskite (Pal) on the morphology and the mechanical and thermal properties of Nylon 6/Palygorskite nanocomposites, prepared by melt compounding, was investigated. A Pal mineral was purified, characterized, and surface modified separately with 3-Aminopropyl trimethoxysilane and tributylhexadecyl-phosphonium bromide in order to produce polymer nanoreinforcements. Organo-Pals were characterized through SEM/EDX, FTIR, TGA, and XPS; surface energy was also determined. Experimental evidence confirmed the grafting of surface agents on the Pal surface; as expected, organo-Pals exhibited high thermal stability and lower surface energy. Nylon 6/clay nanocomposites were melt-compounded with different Pals at low Pal loadings. Pal dispersion was assessed by SEM and the thermal and mechanical properties were determined. In general, Pal exhibiting lower surface energy produced Nylon 6/Pal nanocomposites with improved Pal dispersion and properties. Pal particles favored the formation of c crystalline form and increased the decomposition temperature of Nylon 6. The Pal aspect ratio in the Nylon 6/Pal nanocomposites was estimated from the experimental values of the elastic modulus using the Halpin-Tsai model; in addition, the Pal-Nylon 6 interactions were estimated from the experimental values of the yield strength of nanocomposites with the Pukanszky's model.

Journal of The Electrochemical Society, 2017

A nitrogen-doped reduced graphite oxide (rGO) has been prepared by high temperature pyrolysis fro... more A nitrogen-doped reduced graphite oxide (rGO) has been prepared by high temperature pyrolysis from a Polypyrrole/GO composite yielding high nitrogen content, with specific graphitic and pyridinic bonding as electrochemically active sites for the oxygen reduction reaction. The effect of the N-doped GO supports for CoSe chalcogenide nanoparticles on the electrochemical properties was evaluated in both half-cell, and micro-laminar flow fuel cells (μLFFC) in alkaline medium. The improved performance toward the oxygen reduction reaction (ORR) can be attributed to the availability of active sites on the N-doped rGO specific morphology, and successful coordination of the nitrogen bonds on the carbon lattice.

... PS. On a évalué l'influence de la température, de la masse molaire et de la ... préparat... more ... PS. On a évalué l'influence de la température, de la masse molaire et de la ... préparation. Le degré de dispersion de l'argile a été amélioré quand un mélange de polystyrène avec un copolymère de styrène et d'anhydride maléique (SAM) a été employé. ...

Polymer Bulletin, 2020

This work reports the easy production of hybrid organoclays composed of Cloisite 20A and modified... more This work reports the easy production of hybrid organoclays composed of Cloisite 20A and modified graphene oxide (r-mGO) at different proportions, and their effect on PP composites properties. In this way, it is proposed to evaluate both, the effect of the amount of r-mGO in the hybrid organoclay, and the effect of the amount of the hybrid organoclay on the PP composites. Morphological and structural details of PP composites were followed by scanning electron microscopy and X-ray diffraction, respectively. The thermal stability of the composites was analyzed by thermogravimetric analysis and differential scanning calorimetry, tensile mechanical properties were also tested. The results show that the obtained laminated hybrid material exhibited homogeneous intercalation of Cloisite 20A and r-mGO. The interactions among the clay intercalant molecules and graphene oxide grafting makes them remain united even in a polymeric matrix, acting as a good reinforcer and resulting in a rigid polymeric composite with improved mechanical properties at low content of the filler, mainly when having small amounts of r-mGO.

Polymers, 2020

Bis-GMA/TTEGDMA-based resin composites were prepared with two different types of nanoclays: an or... more Bis-GMA/TTEGDMA-based resin composites were prepared with two different types of nanoclays: an organically modified laminar clay (Cloisite® 30B, montmorillonite, MMT) and a microfibrous clay (palygorskite, PLG). Their physicochemical and mechanical properties were then determined. Both MMT and PLG nanoclays were added into monomer mixture (1:1 ratio) at different loading levels (0, 2, 4, 6, 8 and 10 wt.%), and the resulting composites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and mechanical testing (bending and compressive properties). Thermal properties, depth of cure and water absorption were not greatly affected by the type of nanoclay, while the mechanical properties of dental resin composites depended on both the variety and concentration of nanoclay. In this regard, composites containing MMT displayed higher mechanical strength (both flexural and compression) than those resins prepared with PLG...

Microporous and Mesoporous Materials, 2021

Abstract In this work the preparation and characterization of a multilayer film reservoir with cl... more Abstract In this work the preparation and characterization of a multilayer film reservoir with clay/essential oil (EO) composites is described. The goal is to analyze the potential use of these reservoirs with clay/EOs composites as aroma-controlled release for various applications such as pesticide or attractant for pest control as well as antimicrobial. Two types of clays were analyzed, porous halloysite (HNT) and octadecyl modified montmorillonite (MMT) nanoclay as well as two types of essential oils, orange (OO) and thyme oil (TO). The characterization was performed by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and gas chromatography (GC) analysis. FTIR confirmed that both clays adsorbed the EOs. The DRX and TGA results showed that MMT clay showed higher thyme oil adsorption and better interactions than with orange oil. The Clay/EO composites encapsulated in Polyethylene/tie/Polyamide/tie/Polyethylene multilayer film showed a continuous aroma release for longer periods. It was found that the Polyamide (PA) barrier layer thickness had has an effect on the liberation of the volatile compounds through the multilayer film. On the other hand, the highest cymene aroma release at 72 h was 800 μg for the MMT clay/thyme oil encapsulated in the multilayer film with lower PA layer thickness. This multilayer film encapsulated clay/EO composites could be an option to prepare aroma-controlled release systems for pest control and food packaging applications as antimicrobial or fungicidal systems.

Journal of Food Science, 2021

Ten native potato varieties grown in Cusco (at 3,672 m above sea level) were used for starches ex... more Ten native potato varieties grown in Cusco (at 3,672 m above sea level) were used for starches extraction (at a pilot scale), and their physicochemical, functional, morphological, and structural characteristics were assessed. The content of protein, apparent amylose and phosphorus ranged from 0.1% to 0.44%, 23.42% to 35.5%, and 0.07 to 0.10%, respectively. Starch granules revealed smooth surface, with ellipsoidal and spherical shapes, particle size analysis exhibited bimodal or multimodal distribution, while the averaged crystallinity was 27.7% assessed by XRD. Gelatinization temperatures of the starches ranged from 57.4 to 60.1 °C, 60.8 to 64.3 °C, and 68.4 to 71.1°C for To, Tp, and Tc, respectively; and the gelatinization enthalpies ranged from 15.4 to 17.1 J/g. Respect to pasting properties, the peak viscosity and setback viscosity ranged from 12,970 to 16,970 mPa⋅s and from 968 to 2498 mPa⋅s, respectively. Thermogravimetric analysis (TGA) revealed no significant relationship between apparent amylose content and thermal stability. Therefore, the results reveal subtle differences in the functional characteristics of the starches from the native varieties of potato studied, which can be recommended for food industry applications. PRACTICAL APPLICATION: This study contributes to show several varieties of native potatoes from Cusco and their valorization as nonconventional starch source. Describing the physicochemical, functional, and structural characteristics of these starches could be useful for food industry applications.

Synthetic Metals, 2020

The present work explores the synthesis of sulphate-polypyrrole (PPy/SO 4 2−) using MnO 2 as a re... more The present work explores the synthesis of sulphate-polypyrrole (PPy/SO 4 2−) using MnO 2 as a reactive template. Samples were characterized by different techniques, including SEM, CHNS, XRD, and XPS, which confirmed that MnO 2 acted as a reactive template during PPy synthesis. The materials obtained were characterized by cyclic voltammetry and electrochemical impedance spectroscopy techniques to evaluate their electrochemical properties as electrodes for electrochemical capacitors (ECs electrodes). Py50/M50 electrode exhibited the highest specific capacitance value being 1215 mF cm − 2 (or 125 F g − 1) at 5 mV s − 1. According to PEIS analysis, the enhancement of capacitive performance is attributed to the elongated shape morphology of Py50/M50 electrode that improves the ionic diffusion and reduces the charge transfer resistance on its surface. Furthermore, a symmetric ECs assembly using two identical pieces of Py50/M50 electrodes exhibited a maximum areal energy and power density of 13.5 mW h cm − 2 and 324 mW cm − 2 , respectively. These results suggest a new route of synthesis of PPy/SO4 2− with elongated shape morphology to produce electrodes for ECs with high electrochemical performance.

Journal of Vinyl and Additive Technology, 2020

the processing extruder. Therefore, this additives combination provides a favorable way to obtain... more the processing extruder. Therefore, this additives combination provides a favorable way to obtain efficient flameretardant materials with halogen-free, low smoke, and easy processing characteristics. J. VINYL ADDIT. TECHNOL., 2020.

International Journal of Polymer Science, 2018

The production and surface modification of cellulose nanocrystals (CNC) from Agave tequilana Webe... more The production and surface modification of cellulose nanocrystals (CNC) from Agave tequilana Weber waste (ATW) and their effect on the melt rheology of PLA were investigated. For that, CNC were obtained from ATW residues by acid hydrolysis and grafted with 2-ethyl hexyl acrylate (2-EHA) to promote compatibility with nonpolar polymers, such as PLA. The morphology of CNC occurred as rods, spheres, and the so-called porous network observed by scanning electron microscopy (SEM) and electron transmission microscopy (TEM), and the crystallinity of the cellulose fibers was ~73% and increased up to ~94% for CNC followed by X-ray diffraction (XRD). The acid hydrolysis and alkali extraction process produce changes on the native cellulose type I from ATW bagasse resulting in a mixture of cellulose type I and II and was preserved after CNC isolation and surface grafting. Polymer grafting was assessed using Fourier-transform infrared spectroscopy (FTIR) and X-ray electron spectroscopy (XPS). Upo...

Journal of Biomaterials Applications, 2019

Organoclays were prepared by means of cation-exchange reactions using different concentrations of... more Organoclays were prepared by means of cation-exchange reactions using different concentrations of chlorhexidine diacetate and two different types of clays: montmorillonite and palygorskite. The antibacterial activity against Escherichia coli was evaluated by means of disk diffusion tests as well as through bacterial growth inhibition (monitored by optical density measurements) in Luria broth media. Results indicate that modified palygorskites showed a greater antibacterial activity than those exhibited by modified montmorillonite, as latter only displayed antibacterial properties at the highest chlorhexidine diacetate loading. Modeling of chlorhexidine release was also performed and the models best described the drug release phenomena depended on the type of clay; being the Higuchi model and Korsemeyer–Peppas model for montmorillonite, whereas the zero-order model and Korsemeyer–Peppas model for palygorskite.

Journal of Drug Delivery Science and Technology, 2018

Characterization of clay-drug hybrid materials for antibacterial applications using montmorilloni... more Characterization of clay-drug hybrid materials for antibacterial applications using montmorillonite (MMT) and chlorhexidine diacetate (CA) has been reported; however, antibacterial clays based on palygorskite (PLG) have not been explored. Organoclays based on MMT (a laminar clay) and palygorskite (a microfibrous clay), are expected to differ in their chlorhexidine release profiles as the relevance of a specific mechanism depends on several factors. Therefore, CA was incorporated at various concentrations (50, 100 and 200% of Cation Exchange Capacity, CEC) and the resulting organoclays were characterized by Energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). In addition, in vitro release studies of CA from organoclays were carried out in phosphate buffered saline (PBS) media. EDS FTIR and TGA results confirmed that CA was successful incorporated into these nanoclays. XRD patterns of CA/MMT show an increase in d-spacing of MMT as CA concentration was increased suggesting CA intercalation within the MMT galleries; in contrast, the diffraction peak of CA/PLG remained unchanged upon the CA modification. The drug release studies showed an initial burst release within the first 5 hours and then a sustained release of CA up 24 h. CA released from MMT system was higher that observed for PLG ones.

$Research paper thumbnail of Improvement of fatigue strength and fracture toughness of bone cement by incorporation of aromatic structures to formulations$

International Journal of Polymeric Materials and Polymeric Biomaterials, 2018

It has been postulated that the incorporation of cyclic or aromatic groups to the chemical struct... more It has been postulated that the incorporation of cyclic or aromatic groups to the chemical structure of monomers/polymers could improve the mechanical performance of the polymeric materials prepared from them. In this work, N-methacryloyloxyethyl-m-toluidine (MEET) monomer, a compound whose chemical structure is similar to diethylamino ethyl methacrylate (DEAEM) but having an aromatic ring, was synthesized. Acrylic bone cements were prepared using either MEET or DEAEM as co-monomer and a systematic study of the potential influence of adding aromatic structures on the fatigue properties and fracture toughness of such bone cements was performed. Results indicated that the formulations prepared with the aromatic co-monomer (MEET) exhibited a higher fatigue resistance than those containing the aliphatic counterpart (DEAEM), at all comonomer concentrations. These results confirm the hypothesis that the inclusion of aromatic structures in the bone cement formulations increases the fatigue life of these materials. It was also found that presence of aromatic structures in bone cement formulations improve the fracture toughness of cements.