Determination Of Apparent Density Research Articles

Chlorine-Functional Silsesquioxanes (POSS-Cl) as Effective Flame Retardants and Reinforcing Additives for Rigid Polyurethane Foams.

The subject of the research was the production of silsesquioxane modified rigid polyurethane (PUR) foams (POSS-Cl) with chlorine functional groups (chlorobenzyl, chloropropyl, chlorobenzylethyl) characterized by reduced flammability. The foams were prepared in a one-step additive polymerization reaction of isocyanates with polyols, and the POSS modifier was added to the reaction system in an amount of 2 wt.% polyol. The influence of POSS was analyzed by performing a series of tests, such as determination of the kinetics of foam growth, determination of apparent density, and structure analysis. Compressive strength, three-point bending strength, hardness, and shape stability at reduced and elevated temperatures were tested, and the hydrophobicity of the surface was determined. The most important measurement was the determination of the thermal stability (TGA) and the flammability of the modified systems using a cone calorimeter. The obtained results, after comparing with the results for unmodified foam, showed a large influence of POSS modifiers on the functional properties, especially thermal and fire-retardant, of the obtained PUR-POSS-Cl systems.

New Flame Retardant Systems Based on Expanded Graphite for Rigid Polyurethane Foams

The effect of the addition of new flame retardant systems on the properties of rigid polyurethane (RPUF) foams, in particular, reduction in flammability, was investigated. The modification included the introduction of a flame retardant system containing five parts by weight of expanded graphite (EG) (based on the total weight of polyol), one part by weight of pyrogenic silica (SiO2) and an ionic liquid (IL): 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim] [BF4]), in an amount of 3:1 with respect to the weight of added silica. The kinetics of the synthesis of modified foams—including the growth rate and the maximum temperature—were determined and the physicochemical properties, such as the determination of apparent density and structure by optical microscopy, mechanical properties such as impact strength, compressive strength and, three-point bending test were determined. An important aspect was also to examine the thermal properties such as thermal stability or flammability. It has been shown that for rigid polyurethane foams, the addition of expanded graphite in the presence of silica and ionic liquid has a great influence on the general use properties. All composites were characterized by reduced flammability as well as better mechanical properties, which may contribute to a wider use of rigid polyurethane foams as construction materials.

Ash-and-Slag-Waste-based Porous Glass: Synthesis and Properties

In recent years, porous glass (sponge-glass) is becoming increasingly popular as an environmentally and hygienically safe non-flammable insulating material in the construction of civil and industrial buildings and structures. Composite materials with sponge-glass can be used for exterior insulation and facade finish. These materials are characterized by sufficiently high insulating effect, mechanical strength and chemical durability in combination with low cost of their production. Ash and slag waste from thermal power plants can be used as one of the main raw materials for the production of sponge-glass for construction purposes. The paper presents the results of research on the development and study of the properties of porous glass on the basis of ash and slag wastes of the Novotcherkasskaya GRES and bottled glass scrap: various compositions of the furnace charge have been synthesized, the influence of the fluxing agent and blowing agent on the functional properties of porous glass (density, porosity, strength and heat conduction) has been studied. Crystalline borax was used as the fluxing agent, and anthracite as the foaming agent. Standard methods were used for the study: electron microscopy methods, measurements of heat fluxes (tests were carried out in two modes: cooling and heating), determination of apparent density, etc., qualified equipment. The following was established in the course of study: the porosity of porous glass samples increases by more than two times with an increase in the anthracite additive; with an increase in the anthracite additive the strength of the porous glass decreases by more than 1.5 times; the optimal composition of the furnace charge, taking into account the effect of anthracite on the most important properties of the synthesized porous glass, is SHPS-B5 composition, which provides a sufficiently high porosity of 37.7% and a density of 466.8 kg/m3.

Validation of Rock Testing Methods in Determination of Apparent Density

Research on the physical properties of rock materials and aggregates used for construction should be based on standardized methods. Whereas scientific research is focused more on the development of new methods, testing and evaluation of new properties, etc. In case of own testing procedures and standardized but modified methods, they should be validated before being put into use. Validation is the confirmation of the ability to designate that method and tests its usefulness. In order to investigate the method's possibilities, the following assessment methods can be used: calibration or precision evaluation using reference standards or reference materials, systematic evaluation of factors affecting the result, resistance of the test method to variability of controlled parameters, comparison of test results obtained by various methods, inter-laboratory comparisons, and uncertainty of measurement. The paper presents mathematical formulas allowing to evaluate the precision of research methods and the consistency of results, which are the basis for validation of research methods. In the practical part of the article, own method of apparent density testing, was validated based on the analysis of repeatability, internal laboratory reproducibility and between laboratory reproducibility.

Modeling and Evaluation to Bone Tissue Based on Cellular Model

Aimed to modeling bone biomechanics removed from soft tissue, model is analyzed by using finite element method. The process of fresh swine thighbone biomechanical modeling include 3D geometry reconstruction of femoral CT image data, grid, determination of apparent density, transverse isotropic mechanical modeling of finite element and parameter selection of biomechanical model. Parameters selecting is the key work in this process. Specially, relational model between elastic modulus and apparent density is the most important step. A defined function model between elastic modulus and apparent density is developed based on cellular theory. Then load-axial strain and load-lateral strain data are got from mechanical model analysis results of femur. Finite element analysis results from empirical formula of elastic modulus and apparent density also are got and biomechanical test data are recorded. Simulation results from two kinds of models are compared to test results. To the one fresh swine thighbone, Under the same environment, the result of contrast show axial strain error between cellular theory mechanical model and test data is 25.92, lateral error is 10.04. Cellular theory mechanical model simulation results are more similar to test data than results from empirical formula mechanical model. Cellular theory mechanical model show clear advantage in accurate and scope of application for femoral modeling.

Efeito da adição de polímero precursor cerâmico na sinterização de alumina

Foram estudados os efeitos da adição de polímero precursor na sinterização, microestrutura e dureza da alumina. O polímero inorgânico polifenilmetilvinilhidrogenosilsesquioxano (PPS) foi utilizado como aditivo em cerâmicas de alumina sinterizadas a 1650 ºC. Os materiais sinterizados foram caracterizados por dilatometria, determinando-se a densidade aparente por picnometria de hélio, pela análise de carbono total, por difração de raios X, por microscopia eletrônica de varredura, espectrometria de energia dispersiva de raios X e por análise de indentação Vickers para determinação de dureza e tenacidade a fratura. Foram obtidas fases heterogêneas de Si2Al4O4N4 nas amostras com PPS. Dentre as amostras analisadas, a que contém 5% de PPS apresentou dureza e tenacidade à fratura superiores à da alumina pura. A preparação de compósitos cerâmicos com pequenas quantidades de polímero precursor mostrou-se um processo adequado para cerâmicas à base de alumina, sendo uma rota simples de conformação com grande potencial para a obtenção de peças com geometria complexa.

Manufacture of ceramic membranes for application in demulsification process for cross-flow microfiltration

This paper describes the manufacture of tubular ceramic membranes and the study of their performance in thedemulsification of soybean oil/water emulsions. The membranes were made by iso-static pressing method andmicro and macro structurally characterized by SEM, porosimetry by mercury intrusion and determination of apparentdensity and porosity. The microfiltration tests were realized on an experimental workbench, and fluid dynamicparameters, such as transmembrane flux and pressure were used to evaluate the process relative to the oil phaseconcentration (analysed by TOC measurements) in the permeate. The results showed that the membrane withpores' average diameter of 1.36 μm achieved higher transmembrane flux than the membrane with pores' averagediameter of 0.8 μm. The volume of open pores (responsible for the permeation) was predominant in the total porosity,which was higher than 50% for all tested membranes. Concerning demulsification, the monolayer membraneswere efficacious, as the rejection coefficient was higher than 99%.

Avaliação de propriedades físicas e mecânicas da madeira de cinco espécies florestais em função da deterioração em dois ambientes

Este trabalho teve por objetivo avaliar algumas propriedades físicas e mecânicas da madeira de Eucalyptus urophylla S.T. Blake "Eucalipto" (Myrtaceae), Melia azedarach L. "Cinamomo" (Meliaceae), Lophantera lactescens Ducke, "lanterneira" (Malpighiaceae), Pinus elliottii Engelm. "Pinus" (Pinaceae) e Inga marginata Wild "Inga" (Mimosaceae), submetidas ao processo de degradação em razão da exposição à intempérie no período de 12 meses, as madeiras foram colocadas em dois ambientes com características edafoclimáticas diferenciadas, isto é, foram montados dois campos de apodrecimento, sendo um dentro de uma mata secundária e outro a céu aberto, em um pasto formado por gramíneas rasteiras. Na avaliação, adotou-se um índice de deterioração médio, para expressar a degradação causada pelos fatores bióticos, nos corpos-de-prova oriundos de toras expostas nos respectivos ambientes. As determinações da densidade aparente, bem como da resistência à flexão (módulo de elasticidade (MOE) e ruptura (MOR)) e compressão paralela às fibras da madeira, foram realizadas antes e depois da exposição à intempérie. Os resultados indicaram que ocorreram reduções diferenciadas nas propriedades avaliadas. As diminuições significativas da densidade ocorreram somente nos corpos-de-prova oriundos das madeiras expostas dentro da mata, bem como as reduções nos módulos de elasticidade e ruptura foram mais acentuadas nas madeiras procedentes desse ambiente. A resistência à compressão da madeira apresentou-se com reduções maiores, também nesse ambiente.

Pellicular ion exchange resins based on divinylbenzene and 2-vinylpyridine

A semi-suspension polymerization process was used in this work in order to prepare ion exchange pellicular resins. This technique allowed us to produce cores of polydivinylbenzene or poly(divinylbenzene-co-2-vinylpyridine) with narrow particle size distribution. The shell structure was formed by a porous thin layer of a functional polymer based on poly(divinylbenzene-co-2-vinylpyridine) grafted to the core. The characterization of cores and pellicular resins was carried out through the determination of apparent density, surface area, particle average diameter and ion exchange capacity. The morphological characterization of the core-shell particles was carried out by electron microscopy.

Determination of the density of solids by means of a solid pycnometric substance

A new method has been developed for determination of apparent density of porous powdered materials, which uses a suitable plastic solid substance as the pycnometric medium. In this method a mixture of the tested and pycnometric substances is compressed in a pressing device up to the pressure, at which the pycnometric substance undergoes plastic deformation and fills completely all intergranular voids between particles of the tested material. The rheologic properties of the pycnometric substance prevent its penetration into coarse pores, which makes the method especially suitable for determination of apparent density of coarsely porous materials. The method can be used also for determination of true density of non-porous powdered materials.