Abdel Gawad, Wael Abdel Moez Mohamed Investigation of epoxy resins for application in different conditions /

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Nov 26, 2013 (3 years and 10 months ago)

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:فلؤملا

Abdel Gawad, Wael Abdel Moez Mohamed

:ناونعلا

Investigation of epoxy resins for application in different conditions

/

نايب
: ةيلوئسملا

Wael Abdel Moez Mohamed Abdel Gawad;Supervised by Abd EL
-
Monem A.
EL
-
Bassuoni,Aghareed Mohmoud Tayeb, Mohamed Kamel Mostafa
.

:رشنلا خيرات

6991
.

:صخلم

The present work is concerned with studying of the different


conditions affecting the final properties of the cured
resin, to identify to how


extent, the polymer will be effected by changing such conditions
.

The common use of epoxy resin systems, is usually as two components


systems which consist mainly of an epoxy resin and a selected hardener


(
curing agent
.)

In
this study different groups of hardeners were used which can be


classified as follows

:

6
-

Two different Modified cycloaliphatic polyamines and one adduct type

:

*
H
-
1266


*
H
-
1289


*
H
-
1310 (Adduct type
)

2

-

Modified ( aliphatic

&
heterocyclic ) polya
mines

:

*
H
-
1176


*
H
-
1492


(
Alipbatic

)

(
beterocyclic

)

3

-

Mannich
-
base ( Three different types
: )

*
H
-
1665


*
H
-
1675


*
H
-
1693


The proper mixing ratio between epoxy resin and hardener to achieve


the maximum mechanical properties (flexural,
tensile, and compressive


strength) for the [mal polymer was studied. Also it was proved that the


recommended mixing ratio (R.M.R) had not only a great effect on the tested


final mechanical properties of the cured polymer, but also on the pot life of


su
ch systems
.

The effect of deviation from R.M.R was found to differ from one


hardener to another.In all tested hardeners it was observed that the flexural,
tensile and


compressive strength increase with increasing the mixing ratio till a maximum


value a
t R.M.R. and then, the strength declines again after R.M.R. The


opposite behavior was observed for the pot life, where the pot life decreases


with increasing the mixing ratio till a minimum value (which differs from one


hardener to another) and increasi
ng again with increasing the mixing ratio
.

For H
-
1310, H
-
1492 and H
-
1693 any slight change in the mixing ratio


was found to have a great effect on the tested mechanical properties of the


cured polymer by using such hardeners
.

The effect of temperature
of the epoxy resins either in the curing state


or during the curing process was also studied. The tensile strength for neat


Thesis (M.SC)


Minia University.

resins and compressive strength for filled ones using silica fillers (1: 1) with


average diameter of 0.5 mm were found to decreas
e by increasing the


temperature till 220°C where the polymers destroy and change to dark
-
brown


color which indicated the charring process. For some samples it was


observed that at 60°C there is a slight increase in tensile strength which may


be due to
the unreacted portions of such epoxy systems. Also for compressive


strength an increasing for some tested samples at 220°C was observed, and


this may be due to the formation of new materials containing the fillers and


the destroyed polymers
.

Due to the

variation of the ambient temperatures all over the year and


from one site to another the effect of starting mixing temperature of the


components of epoxy systems was studied
.

It was reported that the maximum compressive strength (550 KglCm2
)

was recor
ded for the system which mixed at 45°C, while the minimum one


323

KglCm2) was reported for oOC starting mixing temperature. Therefore it


is recommended. to.,stan∙ilie
-

mixing process, at a higher temperature and
.

continuing either at the same temperatur
e or at normal one
.

A study was made on the behavior of the epoxy polymer when used as


a shear connector in steel beam
-
concrete composite sections as a new


application of epoxy resins
.

It was found that systems cured by H
-
1693 recorded the maximum


value of the shear strength (22.5 KglCm2) while the minimum


(
63.1

KglCm2) value recorded by H
-
1665. The shear strength was
improved.for

the first system (H
-
1693) by adding a silica filler (1:1) with 0.5
mm


average diameter reached to (28.2 Kg/Cm2). It wa
s also found that increasing


the filler ratio more than (1: 1) decreases the shear strength till a minimum


value (7.6 Kg/Cm2) at (1:3) epoxy system : silica fillers. For the second


system which cured by H
-
1665 the formulation process duplicated the shea
r


strength properties for such systems (19.1 Kg/Cm2
.)

l
<
inetic and thermodynamic studies were made to identify the thermal


properties and mechanism for such reactions between epoxy resins and curing


agents (hardeners) by using H
-
1492 and H
-
1693. It was

found that these


reactions are composed of two consecutive reactions, which were found to be


second order. A full mechanism for such reactions was suggested
.

The values of energy of activation were found to pass through a


minimum value at the recommen
ded mixing ratio, where the lower energy of


activation for the system cured by using H
-
1492 was found to be 2.785


Kcal./mole ”for the first reaction” and 3.262 Kcal./mole ”for the second


reaction” at R.M.R. For the system cured by H
-
1693 it was found to

be


3.2

Kcal./mole, and 1.5 Kcal./mole for the first and the second reactions


respectively

.

:عوضوملا

Epoxy resins

Faculty of Engineering.

Department of Chemical Engineering