română FLORINA-DIANA DUMITRU, MIHAELA-ANDREEA MONCEA, ANDREEA GEORGIANA BARAITARU, ANA-MARIA PANAIT, MARIUS VIOREL OLTEANU, GYÖRGY DEÁK
Abstract
Municipal and industrial waste discharges along with agricultural activities determines an increase of the toxic pollutants in the aquatic environments, affecting thus the living organisms. Due to the high porosities and large specific surface areas resulted from nanoscale size, mesoporous materials can be used for persistent pollutants removal. Therefore, SiO2-TiO2 and SiO2-ZnO mesoporous composites were synthesized using three different routes, to investigate their potential application as nanofilters for wastewaters. The obtained materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy (SEM). To assess the heavy metals retention efficiency, the nanopowders were stirred in a laboratory synthesized water enriched with cadmium, nickel and lead. The initial and at a certain time concentration (after 1, 2, 3, and 24h) being evaluated through atomic absorption spectroscopy (AAS). The results showed good retention efficiencies of the obtained nanocomposites for the investigated heavy metals.
Keywords
mesoporous composites, heavy metals removal, structural characterization
COSMIN MIHAI MIRIŢOIU, CRISTIAN OLIVIU BURADA
Abstract
In this paper there are presented researches regarding wool felt platbands with and without matrix. In the introduction, the state of are in the felt materials researches is presented. Then, there are built some samples made from felt without and with matrix (epoxy resin was used as a matrix). There are determined some mechanical parameters like: breaking strength, static Young modulus, elongation at break, maximum force at break, dynamic Young modulus, loss factor, damping factor and eigenfrequency.
Keywords
damping factor, loss factor, Young modulus,felt, epoxy resin
ANDREEA-IOANA ZAMFIRESCU, ADELA BANCIU, DANIEL BANCIU, SORIN-ION JINGA, CRISTINA BUSUIOC
Abstract
This work aims the obtaining of composite scaffolds based on polycaprolactone fibres loaded with inorganic powders, hydroxyapatite or/and barium titanate, through the electrospinning technique, as well as their characterization both from physicochemical point of view and biological side in order to establish the potential of such materials for integration in bone regeneration applications. The results confirmed the achievement of the designed materials, with a relative homogenous distribution of the mineral phases onto or inside the fibrous structures, together with a good response as respects the behaviour of fibroblast cells cultured in the presence of these multifunctional scaffolds with biocompatible, bioresorbable and bioactive features, combined with external stimulation capabilities (electric or/and magnetic).
Keywords
Polycaprolactone; Hydroxyapatite; Barium titanate; Composite scaffolds; Electrospinning
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Year
2020
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Issue
50 (2)
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Pages
161-165
ANDREEA HEGYI , CARMEN DICO, HENRIETTE SZILAGYI
Abstract
The aim of this paper is to present the performance of some composite panel products, in which, the core consists of a sheep wool mattress and the exterior is a closed cement based binder casing. The experimental results revealed the possibility of preserving the thermal insulation propertiy of the sheep wool mattress, together with the substantial improvement of both compressive and perpendicular tensile strength on the composite panel facings, but also impact resistance and penetration, while maintaining a low surface water permeability. The experimental results indicated a water permeability of the system of approximately 0.2 kg/m2h0.5, which satisfay classification requirements I2 for impact resistance and PE200 from the point of view of penetration resistance, while maintaining a thermal resistance in the field of 1.20-1.49 m2K/W. These performances contribute substantially to a wider range of applications which include outside thermal insulating products, without any further protection measures than plastering with a usual decorative plaster. A favorable framework is being developed for the production of new sustainable eco-innovative products for the construction field.
Keywords
thermal insulation; natural fibers of animal nature; mechanical resistances; water permeability; sustainability
MARIUS-GEORGE PÂRVAN, GEORGETA VOICU , OANA-CĂTĂLINA MOCIOIU, CRISTIAN HORNOIU
Abstract
This study presents the obtaining and characterization of some special mortars intended for smart constructions, having in composition Portland cement (PC) with addition of barium titanate nanopowder (BTNp). A main characteristic of these cementitious composites is piezoresistive behavior. These materials, based on PC with BTNp, can identify the stress within as a variation of electrical resistance; therefore, this type of cementitious composites (mortars and concrete) could have an important role in monitoring infrastructures as a nondestructive method. The BTNp was obtained by a combination of sol-gel and hydrothermal methods starting form tetrabutyl titanate and barium acetate. The mortars based on PC and BTNp were characterized from the point of view of specific properties (electrical resistance, mechanical strengths). Variation of electrical signal when applying a mechanical strain was the main specific property studied in terms of self-sensing materials.
The compositional and microstructural characteristics of mortars strongly influences the mechanical strength values and electrical signal. The compressive and flexural strength values were assessed on hardened mortars for 28 and 90 days; those of mortars containing barium titanate, are comparable with the ones of the mortar without BTNp. The values of electrical resistance are strongly correlated with the composition, morphology, and hardening time of mortars. The experimental results presented in this study demonstrate that BTNp addition can reduce the electrical resistance of cement-based matrices. Regardless of the hardening time, in all mortars, one can observe that the presence of BTNp does not change the nature of specific phases formed by hydration of Portland cement and does not lead to the formation of other new hydration phases.
Keywords
Portland cement, barium titanate, electrical properties, special mortars