This work represent synthesis of new benzoxazines polymers based on
either phenol or hydroquinone as a phenolic compounds and para
aminophenol as primary amine and paraformaldehyde.
In this work, three new compounds of benzoxazine monomers were
synthesized based on (phenol, hydroquinone, 2-naphthol) and
triethoxysilyl propyl amine (TESPA) and paraformaldehyde. (TESPA)
were used to study its effect on the thermal stability of
polybenzoxazine
resulting from the ring opening polymerization of prepared monomers.
تم في هذا البحث اصطناع كل من كرومات الزنك الصفراء اللون وكرومات النيكل ذات اللون البني المصفر بطريقة الترسيب المشترك
To evaluate the ultimate load of composite columns " steel – concrete "
having square or circular steel tubes filled hollow section with concrete
and Longitudinal reinforcing steel bars and subjected to centrical load and
Exposed to the standard f
ire in accordance with ISO 834 curve along and
from all sides,Fire duration ,buckling length of the column , geometrical
and mechanical properties of each material for structural and reinforcing
steels and concrete were in the base of the method, given in the French
National Annex of EN 1994-1-2.
This study was achieved to identify some characteristics of clay minerals of
soils in the southern of region (provinces of Daraa, Sweida). Several soils
profiles were selected, forming a toposequence, including the western slope of
Jabal Al Arab a
nd part of Huran plateau which rise about 500-1200m a.s.L.
and rainfall between 250-350mm. These soils usually are planted with rainfed
crops and some trees. Three samples were collected from each profile at depth
0-25 cm, 25-50cm and 50-100cm in order to determine some physical and
chemical of soli characteristics and x-ray and Differential Thermal Analysis
(DTA) were applied to determine the mineralogical composition of clay
minerals. Results indicated that the soils had an clayey texture (37.9 % in Tafas
Dr2 to 67.5% in Tal al Haded SW2), rather high CEC (35-49.4) meq /100g soil,
neutral pH in Sahwa blata SW1 soil (7.1) to slightly alkaline pH (8) in other
soils, low content of organic matter (1)%. CaCO3 ranged of (3.16)% in Sahwa
blata SW1 soil to (25.35)% in Tafas Dr2. Cacium was the dominant cation on
the exchange complex (33.11mq/100g) in TafasDr2, and followed by magnesium
(13.99 mq/100g) in Tal al Haded SW2. Mineralogical analsis by x-ray and DTA
showed the presence of three main clay minerals, Smectites (montmurillonite),
Kaolinite and Mica (probablly illite).
errite (x=0.5) was prepared by a well-known conventional ceramic double sintering method (CCDS). Force constant K was calculated for tetrahedral and octahedral sites. The elastic constant C11, bulk modulus B , longitudinal and shear wave velocities w
ere calculated. Threshold frequency for electronic transition was determined using IR spectra. In addition, the drift mobility for tetrahedral and octahedral sites, as well as magnetic dipole moment changes for bond were determined. The area beneath endothermic peaks was correlated to the weight change TG%. On the other hand, the heat capacity under constant pressure CP was correlated to sample treatment temperature. It has been noticed that the CP has a critical value at 175.
Calculation of fire resistance for any structural member divided in two independent steps . The first step involves predicting the temperature distribution inside the structural members, referred to as ‘thermal analysis’. The second step of the analy
sis, termed the ‘structural analysis’, is carried out for the main purpose of determining the response of the structure due to static and thermal loading. The first stages of analysis are discussed in this paper, using finite element method by a structural analysis program " ANSYS "
