Papers by Author: Wildor Theodoro Hennies

Abstract: The use of vulcanized rubber products is widely spread in the industry and in the society. Tires, shoes, tennis and other are examples of it. Most of the raw materials used in the formulations of vulcanized rubber products come from the synthesis of natural raw materials consuming time and energy and also generating CO₂ emissions during the respective transforming processes. The main reinforcing material used in rubber formulations is the carbon-black which is a petroleum derivative obtained by the incomplete burning of the fossil fuel. This paper show some results obtained after replacing all or part of the carbon-black by carbonaceous nanoparticle minerals in rubber formulations.

Abstract: The advantage of the incorporation of tire rubber powder and rice husk ash in the polymer compound is mainly due to the reduction of the products cost, as well as improving the essential properties for a great processing of the material, for example, its flow into a hole of a thin wall mold. The rice husk ash can replaces the carbon black in the new products, contributing with the improvement of the environment and the economy of the society. Main objectives of this work are: enhance the applications of the ashes from the rice husk and the waste from the tire rubber, as well as, study new methods of recycling of polymeric wastes, to incorporate an aggregated value to the recycled materials as well as obtaining compounds or nanocompounds materials.

Abstract: The paper describes the technique developed for applying garnet powder abrasive ultra-high pressure water jet advanced technology (AWJ) to build accurate models of artistic objects. The objects to be modeled have been selected through a cooperative initiative between the University of Sao Paulo and entities of the private sector. The first application was the reproduction of the artistic floor of marble at the St. Mark's Basilica, Venice, Italy. The other application was the production of official trophies for a technical awards ceremony for a national symposium that took place in Brazil. The trophies were made in stainless steel, whilst the floor reproduction was made in ceramic tiles. The floor was reproduced from high-definition photography of the original floor. The design concept and the blueprints of the trophies were originally conceived by the symposium organizers. Both models have been built using OMAX® CAD/CAM Software, which controls an AWJ unit installed at the University of São Paulo, where the procedures for building both models have been developed and executed with high success.

Abstract: The organo-clays have important industrial uses between others are: rheological additives for drilling fluids in oil bases, inks, glues, lubricants and cosmetics. At the moment and in a growing way, these materials are considered as important reinforcement fillers in the structuring of nano-composites clays/polymers. They are obtained by the smectite clay reaction with quaternary ammonium salts. In this work an organophillic clay sample prepared by a dry process at the PMT – EPUSP – Metallurgic and Materials Engineering Department of the Polytechnic School at the University of São Paulo, had been characterized basically by techniques of XRD, IR, Thermal Analysis, and by swell capacity of the clays in some oils and organic solvents.

Abstract: Smectites are clay mineral with a layered structure and nanometric thickness, high specific area and a huge variety of uses. Consisting on stacked layers of about 1nm thickness, including two silica tetrahedral and one octahedral sheet. Properties of natural Smectites can be enhanced by organic modification, due to the substitution of the exchangeable cations in the interlayer area. In fact, the properties of the modified smectite (organophilic clay) are related to its modified chemical composition and structural parameters. The interaction of smectite clays with surfactants has an important interest in the fields of drilling fluids, paints, cosmetic, ceramic industries and others. Recent applications are: remediation of contaminated areas and polymer/clay nanocomposites. The aim of this paper is to obtain organophilic clays using a bentonite from the Chiqui Gómez deposit in Central Cuba. The raw and organophilic clays were analyzed by DRX, SEM, swelling capacity in organic solvents and others.

Abstract: This paper studies the main well-know technological types of kaolins clays from the Republic of Cuba and compares it with one from Brazil. A simple description from the Cuban geology and from the involved kaolins deposits is showed. The basic characterization of each kind of kaolin, includes, chemical analyzes, grain size distribution, scanning electronic microscopy, X-ray diffraction and X-ray fluorescence for chemicals. For special assays it had conformed, by a simple axis hand press up to 5 t, test bodies, which had been burnt to the temperatures of 950, 1250 and 1450°C. These results include refractory and contraction results.

Abstract: The application of high-pressure abrasive water jets (AWJ) has evolved quickly in some fields of engineering. At Polytechnic School, University of São Paulo, one application has particular interest that is the cutting of friable materials, as rock and ceramics. The main aspect in this field is the cut at the beneficiation process of end product in dimension stone plates. How much the cut of plates, by different kind of AWJ methods, was the research of a PhD work of one of the authors. The abrasive water jet equipment, installed in the Laboratory of Rock Mechanics of the Mining and Petroleum Engineering Department, was used. Some fundamentals considerations regarding, the employed single and multiple passes methods of AWJ to cut rocks, are discussed.