ResumoEstudos têm comprovado a afinidade e a eficiência do fosfato de cálcio bifásico (BCP) em aplicações médicas e odontológicas, assim como elemento adsorvente para o gás CO2, devido a sua característica de material poroso. O BCP é composto pela combinação entre hidroxiapatita (HA) e beta fosfato tricálcico (-TCP), na proporção usual de 2/3 de HA e 1/3 de -TCP. Trata-se da mistura entre as fases solúvel, -TCP, e estável, HA, das biocerâmicas. O BCP é obtido por meio de tratamento térmico (para cristalização) do ACP (fosfato de cálcio amorfo), na mufla, em temperaturas variando de 600 a 1300ºC, por cerca de 24 horascalcinação. A caracterização e a comparação de amostras amorfas e amostras calcinadas, baseia-se na utilização de aparelhos DRX, MEV, FRX, difração de laser (Cilas) e análise de área superficial (BET). A seguir, na etapa de granulometria, BCP e ACP são peneirados em duas faixas de grãos: menores que 38μm e entre 53μm-38μm. As análises por microscopia eletrônica evidenciam que o ACP possui estrutura semelhante à hidroxiapatita (HA), mas como os seus cristais são muito pequenos, essa fase aparece como amorfa. As análises por DRX indicaram a ausência de impureza cristalina distinguível nas partículas de BCP e a presença de um pico característico de -TCP. Sabe-se que a produção de BCP demanda maior gasto energético em relação ao ACP, devido ao tratamento térmico (calcinação). Palavras-chave: Síntese; Caracterização; ACP; BCP. CHARACTERIZATION OF AMORPHOUS CALCIUM PHOSPHATE AND CALCIUM PHOSPHATE BIPHASIC (BCP) AbstractStudies have proven the affinity and efficiency of biphasic calcium phosphate (BCP) in medical and dental applications, as well as adsorbent for CO2 gas, due to its characteristic of porous material element. BCP is composed of a combination of hydroxyapatite (HA), and beta tricalcium phosphate ( -TCP) in the usual ratio of 2/3 of HA and 1/ 3 of -TCP. This is the mixing of the soluble phases -TCP, and stable HA of bioceramics. BCP is obtained by heat treatment (crystallization) of the ACP (amorphous calcium phosphate) in the muffle furnace at temperatures, ranging from 600-1300°C for about 24 hours -calcination. Characterization and comparison samples and calcined amorphous samples based on the use of XRD, SEM, XRF, laser diffraction (Cilas) and analysis of surface area (BET) apparatus. Then the grading stage, BCP and ACP are sieved into two grain bands: less than 38μm and 53μm -38μm across. Analyses by electron microscopy show that the ACP has similar to hydroxyapatite (HA) structure, but as its crystals are very small, this phase appears as amorphous. The XRD analyzes indicated the absence of crystalline impurity distinguishable particles BCP in the presence of a characteristic peak -TCP. It is known that the production of BCP demands higher energy consumption compared to PCA due to thermal treatment (calcination).

The strategy of combining the traditional reinforcement of glass fibers (GF) with lighter hollow glass microspheres (HGM) can afford to fulfill the need for potential light-weight and high-strength modern materials required in various sectors, such as automotive and aerospace industry applications. This work fabricated composites of PA6/GF/HGM by melting blending in a co-rotating twin-screw extruder, and subsequently, injection molded. The effects of HGM content on the density, morphological and mechanical properties were investigated and the PA6/GF/HGM composites properties were compared to the properties of the traditional PA6/GF (70/30) wt% composite, widely used today in automotive industries. With the increase of HGM amount in the formulations, a reduction of between 3 and 12% in density was achieved with a slight reduction in its mechanical properties, showing that this new strategy can be applied to replace the PA6/GF (70/30) wt% composite, providing a considerable weight reduction for these materials.

Abstract. We report results concerning the pattern formation during the capillary rising of a fluid front into a dense dry granular media. The system consists in a modified Hele-Shaw cell filled with grains of different gradings and confined in a narrow gap between the glass plates. This assembly is vertically installed over a water reservoir to allow an ascending front of liquid to percolate into the granular media. We acquire digital images of the liquid/air front which are treated by means of imaging analysis techniques. Thus, we are able to assess the temporal evolution of the air/liquid boundary profiles. We measure the roughness of the profiles, using a detrended fluctuation analysis technique, to obtain their fractal dimension. We compare our results with similar experiments reported in literature considering fluid displacement into heterogeneous media and directed percolation theory. However, the range of values for the Hurst exponent obtained from our experiments are odd to the measured/predicted values in experiments or theory.

Co‐cured parts usually have their application where large monolithic composite structures are desired. This study evaluated the mechanical response in monotonic tensile test of bidirectional glass fiber reinforced polymer (GFRP) co‐cured joints manufactured by Vacuum Assisted Resin Infusion – VARTM. All joints were designed with the same number of fiber plies and joint length, varying only the joint geometry. Three geometries were studied: single lap joint (SLJ), stepped lap joint (STJ), and a new concept proposed in this study called interspersed lap joint (ILJ), the latter provides higher shear area and interfacial contact area per layer. Tensile test pointed STJ as presenting 77% of the monolithic GFRP tensile strength, the highest ultimate tensile strength among the studied joints. Void content and failure analysis showed high levels of porosity in the joint region for the ILJ, and also a weak bond between the adherents, which may result in a poor mechanical performance. In summary, simple modifications, such as plies disposal prior infusion can benefit the mechanical properties achieved for co‐cured joints.