Preferred Language
Articles
/
ijs-2871
UV-Exposure effect on the mechanical properties of PEO/PVA blends
...Show More Authors

 

     Poly ethylene oxide PEO / Poly vinyl alcohol PVA  blends were prepared by cast method at different ratios of (25%PEO/75%PVA, 30%PEO/70%PVA, 35%PEO/65%PVA, 40%PEO/60%PVA, and 50%PEO/505PVA). Samples miscibility ,and thermal stability were studied  by using differential scanning calorimetry(DSC),and thermo gravimetric analysis (TGA) analysis. The results proved that there was one glass transition temperature (Tg=160°C) at 25%PEO\PVA ratio
)that was attributed to its miscibility. This miscibility associated with (Hydrogen  bonds) between (Hydroxyl group) in PVA, and PEO, whereas there were two glass transition temperature for the blends ratio more than 30%PEO,that was due its immiscibility. The results proved increase in glass transition temperature (Tg) with PEO loading increase: whereas the melting point was fixed about(Tm=310°C). TGA results showed that  PEO loading caused overlapping between degradation stages ,and shifting in the second stage to higher degradation temperature, that was due to the good  PVA, and PEO compatibility, and thermal  stability improved of polymer blends. The mechanical properties of the samples  involved were studied :it was found  that  the tensile strength decreased with PEO ratio increase: whereas ,the elongation at break increased  with PEO ratio . 25% PEO/PVA proved  better tensile strength than the others blend ratios and elongation-at-break values in comparison with that ratio more than 25%,which was due  to good miscibility. These results were enhanced with optical microscope and FTIR analysis. 25%PEO/PVA was sellected to  study the UV-Weathering effect on the mechanical properties according to its ultimate strength(26.67MPa) in comparision with the blends envolved.The stress strain curves for 25%PEO/PVA before and after UV-Weathering with periods of time(25,60,and 90Hr.) showed little changes in ultimate strength up  to (60Hr) exposure time,then there were little decrese in ultmate strength in(90Hr) exposure time . Ultimate tensile strength decrease was attributed to premature failur induced by polymer photo degradation. UV-Weathering caused yelowish of  exposed samples that was due to long chain conjugated polymer sequencesbond formation induced by oxidative  photo degradation . The results proved little changes within (60Hr),that was attributed to polymer stability.It was folowed by little changes in tensile strength and   the elongation at break decreased that was due to sample brittlence increase,which was induced  by irradiation ,that caused modulus of elasticity increase. It was experimentally observed that the value of thermal conductivity of (PVA= 0.099W/cm.K).The results proved decrease in thermal conductivity with PEO loading increase.

Crossref
View Publication Preview PDF
Quick Preview PDF
Publication Date
Thu Dec 15 2022
Journal Name
Al-academy
Evaluating the education quality in the College of Fine Arts "Design Department as a model"
...Show More Authors

Education quality evaluation is one of the objectives of education quality. The evaluation includes assessing the education standards and academic program outcomes to develop intellectual, scientific and practical concepts for the educational structure. It considers the determination of the rates of the number of accepted students and graduates. The research focuses on "what are the levels of education quality according to the evaluation mechanisms in the design department" to enhance the quality system and the objectives of theoretical and applied education.
It is identifying the levels of education quality and evaluating it according to the numbers and rates of graduate students of the design department branches for morning and ev

... Show More
View Publication Preview PDF
Crossref
Publication Date
Sun Jul 01 2018
Journal Name
Journal Of Educational And Psychological Researches
The effectiveness of Barman model in acquiring the historical concepts among fourth-grade literary students
...Show More Authors

The researcher attempts to examine Barman model in acquiring the historical concepts among fourth-grade students at literary classrooms. To this end, the researcher held the null hypothesis, there is no significant difference between the experimental groups who was taught based on Barman model and the control group that taught based on the traditional method in acquiring the historical concepts on the post-test. To testify the effectiveness of Barman model, the researcher administered a questionnaire included (60) items on bunch of female-students who were selected from al-khamaeal preparatory school in al-hurriyah district in Baghdad. The author utilized different statistical tools to analyze the collected data.    &

... Show More
View Publication Preview PDF
Publication Date
Sun Nov 01 2020
Journal Name
Physics Of Atomic Nuclei
Study of the Halo Structure for Some Light Neutron-Rich Nuclei Using the Cosh Potential
...Show More Authors

The radial wave functions of the cosh potential within the three-body model of (Core+ 2n) have been employed to investigate the ground state properties such as the proton, neutron and matter densities and the associated rms radii of neutron-rich 6He, 11Li, 14Be, and 17B exotic nuclei. The density distributions of the core and two valence (halo) neutrons are described by the radial wave functions of the cosh potential. The obtained results provide the halo structure of the above exotic nuclei. Elastic electron scattering form factors of these halo nuclei are studied by the plane-wave Born approximation.

View Publication
Scopus (1)
Crossref (1)
Scopus Clarivate Crossref
Publication Date
Thu Jan 20 2022
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Posterior Estimates for the Parameter of the Poisson Distribution by Using Two Different Loss Functions
...Show More Authors

In this paper, Bayes estimators of Poisson distribution have been derived by using two loss functions: the squared error loss function and the proposed exponential loss function in this study, based on different priors classified as the two different informative prior distributions represented by erlang and inverse levy prior distributions and non-informative prior for the shape parameter of Poisson distribution. The maximum likelihood estimator (MLE) of the Poisson distribution has also been derived. A simulation study has been fulfilled to compare the accuracy of the Bayes estimates with the corresponding maximum likelihood estimate (MLE) of the Poisson distribution based on the root mean squared error (RMSE) for different cases of the

... Show More
View Publication Preview PDF
Crossref
Publication Date
Thu Dec 01 2011
Journal Name
Journal Of Economics And Administrative Sciences
Determine the optimal policy for the function of Pareto distribution reliability estimated using dynamic programming
...Show More Authors

The goal (purpose) from using development technology that require mathematical procedure related with high Quality & sufficiency of solving complex problem called Dynamic Programming with in recursive method (forward & backward) through  finding series of associated decisions for reliability function of Pareto distribution estimator by using two approach Maximum likelihood & moment .to conclude optimal policy

View Publication
Crossref
Publication Date
Tue Dec 31 2019
Journal Name
Journal Of Economics And Administrative Sciences
Prevent administrative and financial corruption behaviors by activating the functions of the organizational immunity system
...Show More Authors

The current research aims at testing the relationship between organizational immunity and preventing administrative and financial corruption (AFC) in Iraq. The Statistical Package for the Social Sciences program (R& SPSS) was used to analyse the associated questionnaire data. The research problem has examined how to activate the functions of the organizational immune system to enable it to face organizational risks, attempt to prevent administrative and financial corruption, and access the mechanisms by which to develop organizational immunity. A sample of 161 individuals was taken who worked in the Directorate General of Education, Karbala. Also, it was concluded to a lack of memory function for organizational immunity. In a

... Show More
View Publication Preview PDF
Crossref (2)
Crossref
Publication Date
Sun Aug 13 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
The Life Cycle and Larval Development of Neoechinorhynchus iraqensis (Acanthocephala: Neoechinorhynchidae) in the Intermediate Host
...Show More Authors

For the first time, the life cycle of Neoechinorhynchus iraqensis, a parasite of Liza abu and other freshwater fishes in Iraq and its larval development in the intermediate host, the copepod Cyclops hyalinus was given. Hatching took place in the intestine of the copepod host within 10 minutes of exposure to the infective eggs. Motile acanthor penetrated the wall of the intestine within 2-4 hr. after exposure and was found free in the hemocoel where it metamorphoses through the acanthella stage. Acanthella stage revealed changes in the entoblast where the anterior section gave rise to brain, proboscis and proboscis receptacle. The posterior section differentiation gave rise to the genital system. By  12 days, development in the copep

... Show More
View Publication Preview PDF
Publication Date
Mon Feb 04 2019
Journal Name
Journal Of The College Of Education For Women
Knowledge Management and Developing Human Resources in the Secretariat of the Central Library- Baghdad University
...Show More Authors

Knowledge management contribute to the overall private university libraries to develop libraries for the purpose of creating human and technological resources by investing research and development, as well as education and training for life.
This study followed the methodology of the descriptive and historical pillars of knowledge management for the years 1990 to the present day in 2017, depending on statistical figures obtained by the researchers from the General Secretariat of the Central Library at the University of Baghdad, and the Human Resources Division, which specialized human resources training after 2004 (and before those years from 1982 until 2002, where the continuing education was committee of the fixed committees are wor

... Show More
View Publication Preview PDF
Publication Date
Wed Mar 30 2022
Journal Name
Journal Of Educational And Psychological Researches
Content analysis of the chemistry textbook for the third intermediate grade according to visual thinking
...Show More Authors

The aim of this research is to identify the availability of visual thinking skills in the chemistry textbook scheduled for the third intermediate grade for the academic year (2020-2021) in the Republic of Iraq. The study sample consisted of all (85) images contained in the chemistry course for the third intermediate grade, which are (85) form using the curriculum.  Analytical descriptive A list of visual thinking skills was prepared, and the unit of form was adopted as a unit of analysis and repetition as a unit of counting, and frequencies and percentages were used for statistical treatment, and validity and reliability were calculated.  And using the Holste equation.  The following results were reached: The skill

... Show More
View Publication Preview PDF
Publication Date
Mon Nov 29 2021
Journal Name
Iraqi Journal Of Science
The Bulk of Solar Energetic Particles (SEP) Acceleration as Seen From the Intensity-Time Profile
...Show More Authors

In this work 27 events have been chosen for the period from (17 Feb 2000 to 10 Sep 2014) to analyze their intensity profile and find out what is the most effective reason behind the bulk of the accelerated SEPs as seen in the interval from the onset to the maximum intensity. It was found that the parameters of the associated eruptions (CME and solar flare) could play a major role in this acceleration. We considered some of these parameters such as: flare class related to soft X-ray flux, CME's speed and acceleration, site of the eruption (western, eastern) and particle transport in the IP medium. The shape of the profile showed a clear changing in ΔT1 (time from onset to maximum), as an inverse relation with the acceleration of coronal

... Show More
View Publication Preview PDF
Crossref