Papers by Keyword: Crystalline

Abstract: The paper deals with the use of concrete with crystalline admixture for special remedial structure which is exposed to intensive ground moisture and high level of air humidity. Additional protection of ground part of older buildings against subsurface water and ground moisture is one of the most important measures to ensure their long-time durability and satisfactory user properties. One of the most used remediation method are the air ducts which principle is to enable air flow along the moist structure surface to allow the sufficient evaporation of moisture from the structure. This group of methods includes also the ventilated underground tunnel along the perimeter walls. Presently the ventilated tunnels are designed as masonry structure whose durability in contact with the ground moisture is limited. The paper introduces a new technical solution of this method based on the special shaped concrete blocks whose durability is ensured by using of concrete with crystalline admixture. The waterproofing effect of the crystalline admixture is declared by the results of laboratory tests (in comparison with efficiency of crystalline coating).

Abstract: The use of polymeric matrices with different crystalline degree values for the design of polymer compounds for tribotechnical purposes is demonstrated. The wear resistance of the provided material in question trends significantly in favor of compounds with greater crystalline degree values. Considering the macrolevel data, the level of the sampled materials carry almost equal effective stress-strain properties. Therefore this difference may be associated with local material properties which influence the rearrangement of stress-strain state parameters in polymeric matrices with changing crystalline degree values.

Abstract: Nanoporous anodic WO₃ was annealed at three different times of 1h, 2h, and 3h at a constant temperature of 500oC. This was to investigate the intercalation and deintercalation behaviour of Li⁺ in this annealed nanoporous oxide. The as-anodised WO₃ is amorphous and after annealing, monoclinic WO₃ was observed with much higher degree of crystallinity when the time of annealing was increased from 1h to 3h. By electrodiffusion of Li⁺ in the nanoporous structure, an ion exchange between fully oxidized states (W⁶⁺) which is the octahedral coordination dominates (WO₆) and Li⁺ could happen. This causes changing of the colour of the yellowish WO₃ to bluish WO₃.Li₂O. This work showed the effect of annealing time on intercalation of Li⁺ ion with WO₃, however crystallinity can play a good role for electron movement, it cause a decrease in Li⁺ ion interaction with WO₃.

Abstract: A series of poly (butylenes succinate) with low Glycerol (GL) fraction ranging from 0 to 6‰ were synthesized by two step melting condensation. By this method, some three-dimentional branch or crosslink structure was introduced to the linear aliphatic chain of PBS. The sequence distribution, GL fraction, crystal structure and degradability were investigated. The degrability of PBS enhanced when GL was led into polymer chain as the crystalline (χ_c) decreased with GL increasing. And the degradation first happened in amorphous region and then crystal region.

Abstract: Main purpose of this research is to study the optical and electrical characteristic of zinc oxide material after undergoing annealing process at various time period. Hypothesis of this research have proved that the physical properties of zinc oxide material have changed by increasing time period for annealing process due to changes of optical and electrical characteristic of ZnO material. Morphological observation shows that, the transmittance properties of ZnO material on glass substrate varies after annealing at time period 5 hours compare to annealing time of 3 hours followed by annealing time of 1 hour. All the annealing process is conducted at temperature 200°C. Zinc oxide is synthesized through a facile method which is known as sol-gel method. Sol-gel solution is prepared based on mixture of zinc acetate dehydrate and stabilizer mono ethanolamine (MEA) with ratio 1:1 and the mixture solution is left for more than 24 hours for precipitation process to occur. The prepared solution is then coated with 3 layers on silicon oxide substrate and annealed at time period of 1 hour, 3 hours and 5 hours. The annealed samples with different period of time is further characterized through UV-Vis test and electrical test.

Abstract: To investigate transition metal precipitates in Si, synchrotron based measurements, like micro x-ray fluorescence (μXRF) or detailed transmission electron microscopy (TEM) studies, are usually necessary. Transition metals are among the most detrimental defects in multi-crystalline (mc) silicon material for solar cell applications, due to their impact on minority charge carrier lifetime and possible shunt formation. We present another possibility to investigate transition metal precipitates by 3-dimensional focused ion beam (3D-FIB) cutting using a combined scanning electron microscope (SEM) SEM-FIB-system. This method is able to detect transition metal precipitates down to 5 nm in radius and provides additional information about the 3D shape, size and spatial distribution of the precipitates.

Abstract: Ploy (N-hydroxymethyl acrylamide)/polyethylene glycol (PNHMPA/PEG) interpenetrating polymer network gel was prepared as new form-stable phase change thermal filler, and IPN distribute evenly in the new phase change thermal conversion coating. The polarizing microscope shows that IPN is crystalline, which proves its heat storage capacity. The DSC results indicate that the new PCM conversion coating has a good energy storage capability and an available phase transition temperature. The TG results show that the new coating has good thermal stability, and IPN effect of thermal decomposition is not affected by the coating composition.

Abstract: In Indonesia, a lot of wastes of glasses and metals have potency to be one of brake raw materials. For example, little bottles of used food packages are usually directly thrown into environment. The scraps of metal machining wastes are usually collected to be manufactured into other products. In this research, both wastes are used as fillers for brake friction materials, the effects of them on the thermal properties are studied in details. The glass wastes are crushed, grinded and filtered to simplify the mixing process with other raw materials when the fabrication of brake fiction materials done. During fabrication, samples are cured at 190°C for 3 hours. The samples are characterized using x-ray diffractometer and thermogravimetric analysis. Based on these characterizations, the increase of glass powders content plays role in increasing the percentage of crystalllinities. This is suspected the glass used as ingredient of friction material has crystalline structure. The glass waste quantity does not influence significantly on the thermal properties. During heating up to 1200°C, the mass loss occurs due to epoxy, bamboo fiber and styrene butadiene rubber decompose. The optimum composition is found at sample B2, a sample with lowest total mass loss (2 mg).

Abstract: There are continuous interests worldwide in zeolites and we can see it with increasing number of scientific publications of the zeolite. Zeolite is an inorganic material that has very special properties over it. They are characterized by framework structures with uniform pore and channel systems. The term zeolite can be defined as hydrated aluminosilicates belonging to the family of the tecto – silicates, whereas the SiO4 tetrahedral are from three – dimensional super cages. Therefore, the aim of this paper is to study about commercial synthetic zeolite that purchased from Fluka. The results cover by Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD).

Abstract: Concrete is the most widely used building material and due to its use, water tightness is one of the factors essential for many constructions. Materials applied on concrete surface as secondary protection can have various forms. One of the material group with waterproofing ability, are materials on so called "crystalline technology base". As this material is cement-based its wide world production brings significant effect on environment. To bring on building materials market new materials should be considered its environmental friendlier production. One of the ways for this group of materials with crystalline abilities is replacing cement by other substituent, at best by secondary raw material. This would bring double advantage, lowering usage of cement and on the other hand use of already produced secondary raw material. This article deals with new developed materials based on "crystalline technology" with cement partly replaced by fly-ash substituent. At this article are presented results of new developed screed and coating modifications and its effectiveness on concrete waterproofing.