To enhance interfacial bonding between carbon fibers and epoxy matrix, the carbon fibers have been modified with multiwall carbon nanotubes (MWCNTs) using the dip- coating technique. FT-IR spectrum of the MWCNTs shows a peak at 1640 cm−1 corresponding to the stretching mode of the C=C double bond which forms the framework of the carbon nanotube sidewall. The broad peak at 3430 cm−1 is due to O–H stretching vibration of hydroxyl groups and the peak at 1712 cm−1 corresponds to the carboxylic (C=O) group attached to the carbon fiber. The peaks at 2927 cm−1 and 2862 cm−1 are assigned to C–H stretching vibration of epoxy produced at the defect sites of acid-oxidized carbon fiber surface. SEM image shows a better interface bonding between the fiber and the matrix of modified composites (MWCNTs-CF/Ep) than those of unmodified composite. The loss factor curve of CF-MWCNTs/Ep composites is the narrowest compared with neat epoxy and CF/Ep composites which evinces that the length distribution range of molecular chain segments in the matrix is the narrowest. From the dependence of the AC conductivity on temperature, we can see that σAC increases when temperature increases. The increase in electrical conductivity of the composites may be a result of the increased chain ordering due to annealing effect. The use of MWCNTs to modify the surface of carbon fiber resulted in a large amount of junctions among MWCNT causing an increase in the electrical and thermal conductivity by forming conducting paths in the matrix. The MWCNTs-CF/Ep composite shows better thermal stability than unmodified composites. The strong interaction between CF and MWCNTs can retard diffusion of small molecules from the resin matrix at high temperature and hence, result in the improved thermal stability of the modified CF/Ep composite.
In this research, optical communication coding systems are designed and constructed by utilizing Frequency Shift Code (FSC) technique. Calculations of the system quality represented by signal to noise ratio (S/N), Bit Error Rate (BER),and Power budget are done. In FSC system, the data of Nonreturn- to–zero (NRZ ) with bit rate at 190 kb/s was entered into FSC encoder circuit in transmitter unit. This data modulates the laser source HFCT-5205 with wavelength at 1310 nm by Intensity Modulation (IM) method, then this data is transferred through Single Mode (SM) optical fiber. The recovery of the NRZ is achieved using decoder circuit in receiver unit. The calculations of BER and S/N for FSC system a
... Show MoreThe Mesopotamian soil is muddy and fertile, and so from ancient eras Iraqis used mud in their building, settlements and architecture in different methodologies according to the nature and the function of the building that was either in its pure form or by mixing it with other materials such as straw . also as raw bricks in different ways either for the whale building or parts of it, or for the finishing parts such as roofing for instance. In this research these different forms and methodologies will permeate through out a chosen examples of historical building, rural buildings and settlements and ancient buildings as well as some current uses of mud in the structures and building in standing cities, this in order to conclude some
... Show MoreA lotic ecosystem is considered a source of carbon dioxide (CO2) in the atmosphere where it becomes supersaturated with CO2, which contributes to the global carbon cycle. To enhance our comprehension of the roles of CO2 in rivers, an outdoor experiment was designed with controlled carbon source inputs to investigate the roles of the dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in the phytoplankton community. Plastic enclosures were installed in the Tigris River within Baghdad for that goal. Samples were collected on the first day, as well as on the 5th and the 12th days from 14 enclosures. The enclosures were treated by artificial glucose (C6H12O6) (10, 20, 30mg/ l) as DOC sources, while sodium bicarbonate (NaHCO3) (1
... Show MoreRotating blades are the important parts in gas turbines. Hence, an accurate mathematical estimation (F.E.M) of the stresses and deformations characteristics was required in the design applications to avoid failure. In recent year’s there are researchers interest in the effect of temperature on solid bodies has greatly increased, The main of this study investigated the thermal and rotational effects. So, the thermal stresses due to high pressure and temperature are studies, also determine the steady state stresses and deformations of rotating blades due to mechanical effect. Many parameters such as thickness and centre of rotating are investigated in this paper. The
... Show MoreIn the present investigation two different types of fiber reinforced polymer composites were prepared by hand lay-up method using three different parameters (curing temperature, pressing load and fiber volume fraction). These composites were prepared from the polyester resin as the matrix material reinforced with glass fibers as first group of samples and mat Kevlar fibers as the second group, both with different volume fractions (4%, 8%, and 12%) of fibers. They were then tested by tensile strength and impact strength. The main objective in this study is to use Taguchi method for predicting the better parameters that give the better tensile and impact strength to the composites, and then preparing composites at
... Show MoreMany faces are exposed to degradation, discoloration, changes in humidity. The primary objective has improved some properties of hybrid nanocomposites materials that used for restoring of the function maxillofacial prosthesis and improving the esthetic. In the present research different lengths chopped and continuous of ultrahigh molecular weight polyethylene (UHMWPE) fiber was added at selected percentage (0.0, 0.2% and 1%) to polymer blend composite (95%SR /5%PMMA: 0.2% Pomegranate Peels Powder (PPP)) for developing the properties of silicone rubber used for the maxillofacial prosthesis applications. Some mechanical and physical properties were done on the all prepared samples. The results showed that all properties have improved when add
... Show MorePolymeric hollow fiber membrane is produced by a physical process called wet or dry/wet phase inversion; a technique includes many steps and depends on different factors (starting from selecting materials, end with post-treatment of hollow fiber membrane locally manufactured). This review highlights the most significant factors that affect and control the characterization and structure of ultrafiltration hollow fiber membranes used in different applications.
Three different types of polymers (polysulfone PSF, polyethersulfone PES or polyvinyl chloride PVC) were considered to study morphology change and structure of hollow fiber membranes in this review. These hollow fiber membranes were manufactured with different pro
... Show MoreThe Moisture damage is considered as one of the main challenge for the experts in the field of asphalt pavement design. The aims of the present study is to modify moisture resistance of the asphalt concrete by utilizing ceramic fibers as a type of reinforcement incorporated with hydrated lime. For this purpose, a penetration grade of the asphalt cement (40-50) was utilized as a binder with an aggregate of the maximum nominal size of 12.5mm and mineral filler limestone dust. A series of specimens has been fabricated by utilizing 0.50, 1.0, 1.5, and 2.0 percentages of ceramic fibers. For each of these contents, another subsequent group of specimens with hydrated lime with 0.0, 1.0, 1.5, and 2.0 percentages were moulded. For the additi
... Show MoreA particulate composite material was prepared by adding the Titanium dioxide (TiO2) with a particle size of (75-150) µm to Epoxy resin at weight percentage of (10%,20%,30%,40%,50%).The following some mechanical properties were studied,fracture toughness, hardness.casting preparation methods were used in this study includes preparing plate of matrix and composites. specimens were prepared according to ASTM for the Mechanical properties tests. After that Another samples were heat treated for three and six hour at 65C?. Fracture toughness (Kic) represent for stress intensity factor results were showed that the curve of three hours aging increases in fracture toughness (Kic) for composites but for six hours aging increases fracture tough
... Show MoreIn this work (paper), we investigate about the robustness of the modified divergence Information Criterion (MDIC), which proposed by Mantalos, Mattheou and Karagrigoriou (2008), to determine the probability of the Criterion picking up the true lag for Autoregressive process, when the error term of this process is normally and Non normally distributed. We obtained the results for different sample sizes by using simulation.