Paula Mazo

Síntesis y caracterización de adhesivos reposicionables de poliuretano dispersos en agua, obtenidos a partir de aceite de castor maleinizado

This work focused on the production of aqueous dispersions of polyurethane using the emulsification method by phase inversion. For the synthesis two polyols were employed, viz. a commercial polyester and Maleinizated Castor Oil (MACO), with two diisocyanates: one aromatic, toluene diisocyanate (TDI) and another aliphatic, hexamethylene diisocyanate (HDI), which are not common for this application. Citric acid was used as internal emulsifier which is inexpensive and readily available. The parameters were the amount of citric acid and the mole ratio of isocyanate groups to hydroxyl (NCO/OH), generating a 32 factorial design, with minimization of the sedimented solids. The surface methodology was used to obtain a quadratic polynomial equation by multiple regression analysis. Polyurethanes synthesized were evaluated for their mechanical and adhesive properties (tack, loop tack, hold, peel). These measurements allowed classifying the polyurethanes synthesized as repositionable adhesives, for use in labels.

Síntesis y caracterización de espumas flexibles de poliuretano obtenidas a partir de aceite de castor maleinizado

In this work, the synthesis of polyurethane flexible foam is realized with the experimental design Taguchi, using castor oil with and without maleinization. The kinetic reaction of oil esterification was monitored by estimating the number of acid groups (ASTM D4662 - 03), and the mechanical properties of the foam were studied, including density, tensile resistance, % elongation, resilience and hardness (Norm NTC 2019 Icontec). The influence of various synthesis parameters was investigated, namely amount and type of catalyst, molar ratio of castor oil (CO) - maleinizated castor oil (MACO), amount of water and surfactant used. The foams were analyzed using FTIR and scanning electron microscopy (SEM). The results showed first order kinetics with respect to the anhydride. The maleinizated castor oil (MACO) increased the mechanical resistance of the foam due to the greater interweaving by the incorporation of acid groups.

Síntesis de espumas rígidas de poliuretano obtenidas a partir de aceite de castor y poliglicerol empleando calentamiento por microondas

In this work we showed the polyurethane rigid foams synthesis using a macropolyol synthesized from castor oil and polyglycerol. This process is optimized employing a response surface analysis and using a 32 factorial design. The factors evaluated were: amount of water and tartaric acid, where tartaric acid acts as crosslinking agent and catalyst; mechanical properties of foams were evaluated as bulk density (ASTM D1622-08), compressive strength (ASTM D1621), thermal conductivity (ASTM C177-04), and friability (ASTM C421-8); scanning electronic microscopic (SEM) and differential scanning calorimetry (DSC). The macropolyol was obtained from renewable sources by the transesterification of castor oil (CO) or maleinized castor oil (MACO) and polyglycerol (PG). The effect of microwaves on the reactions was evaluated, where there was a decrease in time. The monitoring and characterization of intermediate products were performed by quantifying the acid value by titration (ASTM D4662-03) and hydroxyl number (ASTM D4274-05).

Síntesis de poli ácido láctico y poli ricinoleato empleando calentamiento por microondas y su utilización en la producción de termoplasticos de poliuretano

In this paper we report on the synthesis of thermoplastic polyurethane (TPU) using oligomers synthesized from DL Lactic acid and ricinoleic acid. These polyols were obtained from renewable sources by polycondensation of monomers without catalysts. The effect of microwaves on the reactions was evaluated, where non-thermal effects were found to lower the activation energy and increase the rate constant in a third-order kinetics. The monitoring and characterization of intermediate products was done by quantification of acid value by titration (ASTM D4662 - 03) and hydroxyl number (ASTM D4274 - 05). Thermoplastics obtained are characterized by the following tests: tensile strength and elongation percentage (ASTM D882-97), analysis of differential scanning calorimetry (DSC), infrared spectroscopy (IR) and atomic force microscopy (AFM). TPU was obtained with a percentage of 50% soft segments, all have segmented morphology and segregation of phases. The formulations with poly(DL lactic acid) and Methylene diphenyl diisocyanate (MDI) have the highest stiffness and glass transition temperature (Tg).

Optimización de la Producción de Alquil Ésteres a partir de Aceite de Palma, empleando la Metodología de Superficie de Respuesta

Resumen En el presente articulo se estudia el efecto del porcentaje masico del catalizador y la relacion molar aceite:alcohol para diferentes sistemas de alcohol-catalizador, en la optimizacion de la produccion de alquil esteres de aceite crudo de palma. Se uso un diseno factorial 3 2 y la metodologia de superficie de respuesta, donde se obtuvieron las ecuaciones polinomiales cuadraticas mediante analisis de regresion multiple. La respuesta evaluada fue el porcentaje de conversion a glicerina empleando la norma de la Sociedad Americana de Quimicos de Aceites, AOCS Ca 14-56. Las dos variables afectan significativamente la conversion y el efecto de la relacion molar es mayor que el de la cantidad de catalizador. Las condiciones optimas varian para cada sistema, pero en general para los catalizadores homogeneos el porcentaje masico del catalizador es menor (1 a 2%) que para los heterogeneos (5 a 6%) y se requieren altas relaciones molares (1:12 a 1:40). Las propiedades de los combustibles obtenidos cumplen con los requerimientos de los estandares americanos para el biodiesel.

Síntesis de microcápsulas de poliurea a partir de aminas renovables, mediante doble emulsificación

This paper reports on the microencapsulation of a commercial perfume by means of a double emulsification, where the polyurea shell was synthesized by the reaction of lysine with two commercial di-isocyanates (aromatic and aliphatic). In the synthesis the factors evaluated were the amine:di-isocyanate molar ratio and the type of emulsifier. The particle size was optimized using a 32 factorial design and response surface analysis, with the following variables: amount of polyvinyl alcohol and the relationship of the disperse phase to continuous phase. The microcapsules were characterized using differential scanning calorimetry analysis (DSC), infrared spectroscopy (IR), scanning electron microscopy (SEM) and mean particle size. The double emulsification allows for a greater yield in the encapsulation of perfume. Furthermore, the microparticles have a smaller particle size when the aromatic di-isocyanate was used, also leading to an increase in the protective colloid (polyvinyl alcohol (PVA)) and reduction of the disperse phase.

Alternative Methods for Fatty Acid Alkyl-Esters Production: Microwaves, Radio-Frequency and Ultrasound

Biodiesel production is a very modern and technological area for researchers due to the relevance that it is winning every day because of the increase in the petroleum price and the environmental advantages (Mustafa, 2011). Biodiesel is a mixture of mono-alkyl esters of long chain fatty acids, is an alternative fuel made from renewable sources as vegetable oils and animal fats. It is biodegradable, nontoxic, show low emission profiles and also is beneficial environmentally. (Fangrui and Milford, 1999). Biodiesel is quite similar to petroleum-derived diesel in its main characteristics such as cetane number, energy content, viscosity, and phase changes. Biodiesel contains no petroleum products, but it is compatible with conventional diesel and can be blended in any proportion with fossil-based diesel to create a stable biodiesel blend. Therefore, biodiesel has become one of the most common biofuels in the world (Lin et al., 2011). There are four primary techniques for biodiesel production: direct use and blending of raw oils, microemulsions, thermal cracking and trans-esterification (Siddiquee and Rohani, 2011). Direct use of vegetable oil and animal fats as combustible fuel is not suitable due to their high kinematic viscosity and low volatility. Furthermore, its long term use posed serious problems such as deposition, ring sticking and injector chocking in engine. Microemulsions with alcohols have been prepared to overcome the problem of high viscosity of vegetable oils. Another alternative way to produce biodiesel is through thermal cracking or pyrolysis. However, this process is rather complicated to operate and produce side products that have not commercial value. The most commonly used method for biodiesel production is transesterification (also known as alcoholysis) reaction in presence of a catalyst. Transesterification is the process of exchanging the alkoxy group of an ester compound with another alcohol (Lam et al., 2010). Esterification is the sub category of trans-esterification. This requires two reactants, carboxylic acids (fatty acids) and alcohols. Esterification reactions are acid-catalyzed and proceed slowly in the absence of strong acids such as sulfuric, phosphoric, sulfonic-organic acids and hydrochloric acid (Vyas et al., 2010). The fatty acid methyl esters (FAME) are more used because of its facility of production, however, presents operating problems at low temperatures for its high content of saturated

ESTERIFICACIÓN DE LOS ÁCIDOS GRASOS LIBRES (FFA) DEL ACEITE CRUDO DE PALMA. CALENTAMIENTO CONVENCIONAL VS MICROONDAS

In contrast with conventional heating on the esterification reaction of the crude palm oil free fatty acids (FFA), the main effects of the microwave radiation are described. This reaction being carried out to decrease the palm oil acidity value from 13 to 1%, in order to prevent the formation of soap and emulsions that decrease the yield of the transesterification reaction for biodiesel production. The utilization of resins as heterogeneous catalyst as a viable technical, economic and environmental viable alternative is presented. The use of microwaves favors the reaction by located dielectric warming effects of the alcohol and the catalyst

OBTENCIÓN DE ESPUMAS FLEXIBLES DE POLIURETANO APARTIR DE ACEITES DE PALMA Y CASTOR MODIFICADOS

Very few studies have been made in the polyurethane flexible foam obtaining with modified palm oil and castor oil, by the great rigidity and hardness that present these products; in order to improve these properties, it is wanted modify by means of glycerol reactions and esterification. Optimization using Taguchi methodology, the following factors: relationship reagents, temperature and time, and in the obtaining of foam: poyol modified, amount of organometallic and aminic catalyst and amount water. The obtained foam present the required characteristics of comfort and durability, density, hardness, tensil resistance, percentage of elongation, percentage of resilience, tests of infrared spectroscopy and hydrolysis resistance