In this study a polymeric composite material was prepared by hand
lay-up technique from epoxy resin as a matrix and magnesium oxide
(MgO) as a reinforcement with different weight fraction (5,10,15,
and 20)% to resin. Then the prepared samples were immersed under
normal condition in H2So4(1 M) solution, for periods ranging up to
10 weeks. The result revealed that the diffusion coefficient
decreasing as the concentration of MgO increase. Also we studied
Hardness for the prepared samples before and after immersion. The
result revealed that the hardness values increase as the concentration
of MgO increase, while the hardness for the samples after immersion
in H2SO4 decreased as compared to those before immersion. In
addition, the dielectric strength decreasing by increasing the MgO
concentration with time immersion.
This paper examines the mechanical properties of a composite material made of modified Iraqi gypsum (juss) reinforced with polypropylene fibers. The modified juss was prepared by adding two percentages of cement (5, 10) %. Two percentages of polypropylene fibers were used, to reinforce the modified juss (1, 2) %. The water/dry compound ratio used was equal to 0.53%. The composite was evaluated based on compressive strength, flexural strengths, absorption percentage, density, acoustic impedance, ultra - pulse velocity, longitudinal shrinkage and setting time tests. The results indicated that the inclusion of cement on to juss increases the compressive strength, absorption percentage, density, acoustic impedance, ultra - pulse velocit
... Show MoreThe lead-acid battery has become so dependable in its used applications of automobile starting, emergency lighting and telecommunications, which left an impression that no further investigation is necessary or desirable. While there has been slow continuous improvements in lead-acid battery performance and mainly limited to design and material engineering. This work is mainly devoted to the properties of the active mass of the positive electrode and the acid/water ratio during the manufacturing process. A field study is carried out at the State Battery Manufacturing Company located in Baghdad, to prepare batches of lead mono-oxide with predefined quantities of liquid additives (i.e. sulfuric acid and water). Quality control and laborator
... Show MoreThis research study the effect of surface modification and copper (Cu) plating carbon fiber (CF) surface on the thermal stability and wettability of carbon fiber (CF)/epoxy (EP) composites. The TGA result indicates that the thermal-stability of carbon fiber may be enhanced after Cu coating CF. TGA curve showed that the treatment temperature was enhanced thermal stability of Ep/CF, this is due to the oxidation during heating. The Cu plating increased the thermal conductivity, this increase might be due to reduce in contact resistance at the interface due to chemical modification and copper plating and tunneling resistance.
The increase of surface polarity after coating cause decreas
... Show MoreIn this research study the effect of irradiation by (CW) CO2 laser on some optical properties of (Cds) doping by Ni thin films of (1)µm thickness has been prepared by heat evaporation method. (X-Ray) diffraction technique showed the prepared films before and after irradiation are ploy crystalline hexagonal structure, optical properties were include recording of absorbance spectra for prepared films in the range of (400-1000) nm wave lengths, the absorption coefficient and the energy gap were calculated before and after irradiation, finally the irradiation affected (CdS) thin films by changing its color from the Transparent yellow to dark rough yellow and decrease the value absorption coefficient also increase the value of energy gap.
The CdSe pure films and doping with Cu (0.5, 1.5, 2.5, 4.0wt%) of thickness 0.9μm have been prepared by thermal evaporation technique on glass substrate. Annealing for all the prepared films have been achieved at 523K in vacuum to get good properties of the films. The effect of Cu concentration on some of the electrical properties such as D.C conductivity and Hall effect has been studied.
It has been found that the increase in Cu concentration caused increase in d.c conductivity for pure CdSe 3.75×10-4(Ω.cm)-1 at room temperatures to maximum value of 0.769(Ω.cm)-1 for 4wt%Cu.All films have shown two activation energies, where these value decreases with increasing doping ratio. The maximum value of activation energy was (0.319)eV f
Background: Impression materials, impression trays, and poured stone cast have been said to be the main source of cross infection between patients and dentists. However, it was observed that disinfection of the impression is not performed systematically in routine dental practice. Disinfection of alginates either by immersion or spray technique was found to cause dimensional inaccuracies, although with proper disinfection of alginates there were small dimensional changes. A variety of fluoride releasing products designed for topical use is currently available. Following their use, varied amount of fluoride is systemically absorbed depending on the fluoride concentration and the manner of its use. The objective of this study was to evaluate
... Show MoreBackground: Dental stone casts come into contact with impression materials and becomes susceptible to cross contamination from saliva and blood. This study was done to evaluate the physical and mechanical properties of dental stone type IV after treatments with various disinfecting agents and regimes (methods). Materials and Methods: Type IV dental stone and different types of disinfecting agents were used and divided into seven groups: G1: dental stone without disinfection (control group), G2: dental stone mixed with silver nitrate powder 0.5% , G3: dental stone mixed with silver nitrate powder 1%, G4: dental stone mixed with copper sulfate powder 0.5%, G5: dental stone mixed with copper sulfate powder 1% ,G6: dental stone immersed in prop
... Show MoreIn recent years, nano-modified asphalt has gained significant attraction from researchers in the design of asphalt pavement fields. The recently discovered Titanium dioxide nanoparticles (TiO2) are among the most exciting and promising nanomaterials. This study examines the effect of 1, 3, 5, and 7% of nano-TiO2 by weight of asphalt on some of its rheological and hardened properties. The experimental study included physical and rheological properties. The asphalt penetration, softening point, ductility, and rotational viscometer tests indicate that 5% nano-TiO2 is the ideal amount to be added to bitumen as a modifier. The
The researchers have recently noticed the interest in the problem of overweight and how to find solutions to it until it is now at the forefront in terms of innovating various and different methods and treatment methods, and the interest in developing health fitness is one of the most important requirements of physical activity for the trainees, which led to the multiplicity of sports activities that promote the health aspect For the individual, in addition to the aesthetic aspect, the problem lies in not adopting training programs according to codified scientific foundations aiming, in addition to reducing weight, to raise the general health level of the trainee participating in fitness institutes, as the trainers do not follow the
... Show More