Influence of natural exposure on castor oil based polyurethane reinforced with waste tire rubber.

Waste tire rubber (WTR) has been extensively generated worldwide due to mobility needs growth. About 1.5 billion units are generated annually, constantly discharged in the environment with a few reusability alternatives. Therefore, rubber recovery methods and these residues' transformation into a cost-effective product have gained attention. Aiming to minimize the usage of fossil resources and contributes to a circular economy, it was analyzed the usage of WTR particles (5-20% by weight) in castor oil-based polyurethane foams under natural aging to promote a holistic view of all factors involved in the performance of the foams. Morphological, thermal, chemical, and mechanical properties were determined before and after exposure to open air to observe the impact of photo-oxidation and hydrolysis. The increase in viscosity of pre-polymer during the rubber loading produced greater density foams with smaller cell sizes than neat PU, in which the average cell size increased after the weathering. The rubber contributes to enhancing the compressive behavior in the non-exposed samples. After exposure, the results suggest that degradation may act to increase the crosslinking density even with the presented structural changes such as yellowing and voids. Regarding thermal stability, the rubber promotes a slight decay in the ability to resist a heat flow before and after weathering. Still, the char yield increased, showing a possibility of better fire retardancy for composites. FTIR and UV-vis showed chemical structure changes as Photo-Fries network rearrangement, Norrish I random chain scission, and Norrish II ß-scission. Besides, UV-vis revealed the maximum absorbance in the UVB region, showing that the PU reinforced by WTR can be a promising material for civil coatings.

Evaluation of rubber powder waste as reinforcement of the polyurethane derived from castor oil.

Waste tire rubber is produced on a large scale in the automotive industry and is considered difficult to recycle because they have iron, nylon, polyester, and chemical structure formed by cross-links. In this way, the waste is almost always deposited in inappropriate places or incorrectly burned, causing a series of environmental problems. The objective of this work was to analyze the viability of the use of waste tire rubber (5, 10, and 20% m/m) reinforced in polyurethane foam (PU) derived from castor oil to obtain composites, as an alternative for raw materials petrochemical industrial. The materials were characterized by scanning electron microscopy (SEM), optical microscopy (OM), apparent density, contact angle, water absorption, X-ray diffractometry (XRD), spectroscopy infrared (FTIR), thermogravimetry (TGA) techniques, and mechanical tests. The results showed that the residue of the rubber powder reinforced with polyurethane caused an increase in the density of the composites when compared to pure PU, which directly influenced the morphological, physical, thermal, and mechanical properties. This fact occurred because with the insertion of rubber powder in the PU there was a decrease in cell size and increase of pore volume. The TG and DTG analyzes showed that the insertion of the rubber powder improved the thermal stability of the composite when compared to pure PU, as well as impact tests and contact angle.

Controlling practical stability and safety of mechanical systems by exploiting chaos properties.

In this paper, a method for controlling the global nonlinear dynamics of mechanical systems is applied to two models: the model of Augusti and an inverted guyed pendulum. These simplified models represent a large class of structures liable to buckling exhibiting interacting buckling phenomena. These structures may fail at load levels well below the theoretical buckling load due to complex nonlinear phenomena that decrease the safety and the dynamic integrity of the structure; this often occur as a consequence of imperfections and of the erosion of the basins of attraction of the safe pre-buckling solutions. So, it is of paramount practical importance to increase the safety of these structures in a dynamic environment. This can be achieved by increasing the integrity of the basins of attraction of the safe solutions, a goal that is attained by a control method which consists of the (optimal) elimination of homoclinic (or heteroclinic) intersection by properly adding superharmonic terms to a given harmonic excitation. By means of the solution of an appropriate optimization problem, it is possible to select the amplitudes and the phases of the added superharmonics in such a way that the manifolds distance is as large as possible. The results show that this methodology increases the integrity of the basins of attraction of the system and, consequently, the practical safety of the structure.

Licuefaccion y exportacion de gas natural al Pacifico

Contenido: Cap.1 Bases teoricas del transporte de gas natural por tuberias.Naturaleza de flujo en tuberias.Perdidas de presion por fabricacion en tuberias.Propiedades fisicas del fluido que intervienen.Deduccion de las ecuaciones para flujo de gas natural Cap.2 Conversion del oleoducto OSSA en gasoducto.Introduccion.Caracteristicas del oleoducto OSSA.Caracteristicas del gas a transportar.Estudios y calculos hidraulicos.Analisis de inversiones y costos.Costos anuales de operacion del gasoducto al Pacifico "GAP".Costo unitario de transporte.capital de inversion y financiamiento Cap.3 Licuefaccion del gas natural.Introduccion.Caracteristicas del gas natural.Propiedades del gas natural.Fundamentos termodinamicos de la licuefaccion del gas natural.Funcion del refrigerante o Agente Refrigerante Cap.4 Gas natural licuado "GNL".Introduccion.Naturaleza del GNL.Usosdel GNL.Usos del frio del GNL.Plantas de GNL Cap.5 Almacenaje de GNL.Introduccion.Tipos de almacenaje de GNL.Tanques de GNL.Aislamiento termico de los tanques de GNL.Optimizacion del diseno de almacenaje de GNL Cap.6 Planta de licuefaccion en Arica.Caracteristicas del gas de alimentacion.Aspectos generales de la Planta.Procesos de la Planta.Licuefaccion.Almacenaje y carguio de GNL.Otras instalaciones de la Planta Cap.7 Concepto de una terminal receptora de GNL.Introduccion.Caracteristicas principales.Descripcion de las diferentes secciones.Resumen de instalaciones y equipo Cap.8 Analisis comercial.Comercio mundial de GNL.Mercado potencial de exportacion del GNL.Precios internacionales de exportacion de GNL.Precio "FOB" del GNL Boliviano puesto en Arica Cap.9 Estimacion de costos.Introduccion.Estimacion de los costos de las secciones de la planta.Costos anuales de operacion.Costo unitario de licuefaccion Cap.10 Estudio economico y financiero.Introduccion.Resumen de los costos anuales de operacion.Parametros financieros.Metodo de analisis de "Flujo en efectivo descontado" Cap.11 Conclusiones y recomendaciones.