Paula Mazo

Bio: Paula Mazo is an academic researcher from University of Antioquia. The author has contributed to research in topics: Castor oil & Transesterification. The author has an hindex of 8, co-authored 20 publications receiving 209 citations.

Kinetics of the Transesterification of Castor Oil with Maleic Anhydride Using Conventional and Microwave Heating

Abstract: The transesterification of castor oil with maleic anhydride was studied using conventional and microwave heating. Reactions were followed by measuring the acid value and the reaction products were characterized by FTIR and 1H NMR. A kinetic model that fit the experimental data was derived. The transesterification was non-catalytic and first-order with respect to each reactant. Non-thermal effects of microwaves were not observed. Activation energy, enthalpy of activation, entropy of activation and free energy of activation were similar regardless of the heating method. Rate constants and the pre-exponential factor were lower with the use of microwave heating, which could be a consequence of the decrease in the dielectric constant of the reaction liquid as the reaction progresses.

Carbonation of Epoxidized Soybean Oil Improved by the Addition of Water

Abstract: Carbonated soybean oil was synthesized from epoxidized soybean oil and CO2 at atmospheric pressure and with tetrabutylammonium bromide (TBABr) as catalyst. Kinetic parameters, i.e., rate constants, activation energy and pre-exponential factors were determined. The effects of catalyst concentration and water content were studied. The reaction followed first-order kinetics with respect to epoxide at 100–140 °C. A steep increase in conversion (ca. 30 %) was obtained by increasing the amount of catalyst from 3 to 5 %. Further increasing the amount of catalyst to 7 % increased the conversion less than 10 %. The reaction proceeded faster when water was added; reaction times with water were ca. 70 % of the reaction times without water. Titration, FTIR and 1H-NMR analyses indicated ca. 90 % conversion and ca. 88 % selectivity towards the carbonate after 70 h at 120 °C with 5 % mol TBABr and 1:3 molar ratio of water to epoxide.

Esterification and transesterification assisted by microwaves of crude palm oil: Heterogeneous catalysis

Abstract: -- The principal objective of this study was to obtain alkyl ester from crude palm oil (CPO) , using microwaves like heating source, in a process of two stages by means of heterogeneous catalysis; the first stage (esterification), was made using Dowex 50X2, Amberlyst 15 and Amberlite IR-120 resins catalysts, to diminish the acid value of the oil, a voiding the soap formation and facilitating the separation of the phases. The second stage (transesterifi cation) was made using potassium carbonate catalyst. The behavior in the crystallization of the product using differential scanning calorimetry, cloud point ASTM D2500 (2005) and pour point ASTM D97 (2005) was evaluated. The obtained biofuels fulfill the requirements of the American standards for biodiesel and the propose methodology for the synthesi s presents environmental advantages and of increase in the reactivity, as opposed to the traditional me thods of heating.

Lignin utilization: A review of lignin depolymerization from various aspects

Abstract: Lignin is the most abundant aromatic polymer in nature. Due to its high amount of phenolic compounds storage, lignin is considered as an alternative source for various polymers and biomaterials production. Except for the native lignin in lignocellulose, a massive amount of technical lignin is being produced daily all over the world. However, the complex structure and low reactivity of lignin limit its further applications and currently, most of the lignin is burned for generating energy. Therefore, the depolymerization of lignin is considered one of the important challenges in lignin utilization. Methods for lignin depolymerization can be divided into thermochemical treatment, mechanical treatment, chemical catalysis, and biological treatment. Different methods for lignin depolymerization, their characteristics and products are extensively discussed in this review.

Polyurethane Foams: Past, Present, and Future

Abstract: Polymeric foams can be found virtually everywhere due to their advantageous properties compared with counterparts materials. Possibly the most important class of polymeric foams are polyurethane foams (PUFs), as their low density and thermal conductivity combined with their interesting mechanical properties make them excellent thermal and sound insulators, as well as structural and comfort materials. Despite the broad range of applications, the production of PUFs is still highly petroleum-dependent, so this industry must adapt to ever more strict regulations and rigorous consumers. In that sense, the well-established raw materials and process technologies can face a turning point in the near future, due to the need of using renewable raw materials and new process technologies, such as three-dimensional (3D) printing. In this work, the fundamental aspects of the production of PUFs are reviewed, the new challenges that the PUFs industry are expected to confront regarding process methodologies in the near future are outlined, and some alternatives are also presented. Then, the strategies for the improvement of PUFs sustainability, including recycling, and the enhancement of their properties are discussed.

Non-isocyanate polyurethanes: synthesis, properties, and applications†

Abstract: Conventional polyurethanes are typically obtained from polyisocyanates, polyols, and chain extenders. The main starting materials—isocyanates used in this process—raise severe health hazard concerns. Therefore, there is a growing demand for environment-friendly processes and products. This review article summarizes progress that has been made in recent years in the development of alternative methods of polyurethane synthesis. In most of them, carbon dioxide is applied as a sustainable feedstock for polyurethane production directly or indirectly. The resulting non-isocyanate polyurethanes are characterized by a solvent-free synthesis, resistance to chemical degradation, 20% more wear resistance than conventional polyurethane, and can be applied on wet substrates and cured under cold conditions. Three general polymer synthetic methods, step-growth polyaddition, polycondensation, and ring-opening polymerization, are presented in the review. Much attention is given to the most popular and having potential industrial importance method of obtaining non-isocyanate polyurethanes, poly(hydroxy-urethane)s, based upon multicyclic carbonates and aliphatic amines. It is evident from the present review that considerable effort has been made during the last years to develop environmentally friendly methods of obtaining polyurethanes, especially those with the use of carbon dioxide or simple esters of carbonic acid. Copyright © 2015 John Wiley & Sons, Ltd.