SEM722 Assignment 1: Epoxy Resin Cure Kinetics and Rheology

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SEM722
Assignment 1

Table of Contents
1. Abstract.............................................................................................................................................2
2. Introduction.......................................................................................................................................3
3. Experiment Profile.............................................................................................................................4
4. Cure Kinetic and Rheology Constants................................................................................................6
4. Flow Stack for Optimization of flow.................................................................................................10
5. Quality Control Testing....................................................................................................................11
6. Conclusion.......................................................................................................................................14
7. Reference........................................................................................................................................15
Table of Figure
Figure 1: K-factor and Reynolds number graph....................................................................................4
Figure 2: change in cure reaction graph................................................................................................6
Figure 3: viscosity of the Resin..............................................................................................................8
Figure 4: resin graph..............................................................................................................................8
Figure 5: Volume of the resin................................................................................................................9
Figure 6: flow stack..............................................................................................................................10
Figure 7: graph1...................................................................................................................................10
Figure 8: Quality Control Testing.........................................................................................................11
Figure 9: Cure Degree..........................................................................................................................12
Figure 10: Fatigue Testing....................................................................................................................12
Figure 11: Internal Porosity Testing.....................................................................................................13

1. Abstract
This is one of the close mould processes that is used to enhance the RIM235 Hexoin Epikote
by the method of the subjection of polymer chain reaction. The chain reaction makes the
linkage hard and forms a 3D network. The chain reaction makes the difference in the
molecule subjection like in their viscosity, hardening, melting temperature etc. The Kinetic
and Rheology Constants can be calculated by the viscosity curve.
In this report calorimeter analysis and Viscosity analysis of resin is also been discussed,
along with the above method the optimization is also done to improve the glass transmission
temperature of the resin. The standard testing method that is used over the resin to its quality
is also been discuss in the further part to assure the best quality of the resin. There are two
different types of testing are used to be done over the resin i.e. destructive and non-
destructive testing. The optimized temperature that is used for the flow of resin is also
determined in this report along with the porosity of the resin structure. The bond strength,
fatigue life and various different testing procedure are also been discussed in this report.

2. Introduction
The use range of composite material is very vast as compared to non-composite material but
on the other hand, the non-composite material has many different advantages. There is a
disadvantage in the availability of a method from which we can use the non-composite
material in vast use. To analyse the issue the epoxy resin is tested and analysed in the practice
to maximise their uses.
In practical 1, the major focused is done over to increase the cure level of resin in order to
reduce their counterpart so that it can be used in the maximised way. The optimization is
done over the cost of resin, viscosity profile, temperature profile with the help of various
testing methods. The bond strength and the bond structure are cured with the help of
calorimeter that is a mathematical tool that helps the resin to cure their structure into a 3D
lattice. The calorimeter reaction applied over the resin help them to enhance their quality.

3. Experiment Profile
To calculate the heat profile of the resin differential scanning calorimeter is used. In this
method, the rise in temperature is calculated along with the reference temperature. The rise in
temperature help into the determination of kinetic and rheological profile of the resin. The
differential scanning calorimeter is generally work in two different ways first one is when the
temperature is kept constant that is also known as an isothermal process along with with this
the second one when the temperature is variable that is also known as dynamic scanning.
Experiment Setup
Resin (RIM 255) 10 Mg
Room Temperature 0 C
Variable Temperature Rate 5, 10, 15, 20 C/min
Coolant R22 (Liquid State)
Experiment Procedure: To perform this experiment the Hexion epidote RIM 235 is poured
into the aluminium pan. Gradually while performing the experiment the pan is heated with on
constant temperature, during the initial setup of the calorimeter is placed with the aluminium
pan. After the change in the temperature, the iso scanning is done over the setup over a period
of time after checking the temperature the sample is cool down with the help of R22 coolant
which requires near about 45 min to cooling the cure reaction. The heat released from the
reaction is given be H=∫
0
t
( dQ
dt ) dt.
Where dQ is changed in heat and dt is changed in time.

Figure 1: K-factor and Reynolds number graph
Now the dynamic testing is done over the cooled resin that is cooled to 0 C temperature.
When the resin is placed in the heated furnace than it is noted that the heat change in the
dynamic scanning of the resin is noted near to 300 C. Hence total heat of the reaction is been
calculated from the above equation i.e. H=∫
0
t
( dQ
dt ) dt. When the functions are the
differential of d.

4. Cure Kinetics and Rheology Constants
The hardening and strengthening of the polymer are done with the help of chemical reaction
of resin that is known as the curing process of the resin. In this curing process, the cross-
linking of the resin is converted into the 3D lattice structure that strengthens the polymer. The
time taken by the resin to convert their polymer structure into the 3D structure is known as
kinetics. This kinetic cure method is used for industrial use to enhance the quality of resin
used in their process. In the mathematical form, the α represents the degree of cure that has
been done over the epoxy resin, as it includes the heat evolution during the formation of a
new bond and it is denoted by the α= H
Hu . Where Hu is the heat that is released up to a
certain limit of time.
For the calculation of the change in the cure reaction d ∝
dt =K ( 1−∝ )n. In this equation, K is
the rate constant and order of the reaction is given by the n.
Figure 2: change in cure reaction graph
For the calculation of K, it is denoted by K= Ko exp (−∆ E
RT ). In this equation Kois the
frequency of Archimedes factor, E is the cure activation energy. For the maximum utilization
of the cure rate, this model is used in the curing process which forms the 3D structure from
the cross-linkages that strengthen the whole lattice structure of the resin. There also another

advantage of this method that reaction rate increases by this model along with this help in the
diffusion process that result in the low kinetic energy of the molecule particles. This
mathematical model also upgrades the parameter of diffusion that helps the cross-linkage to
transfer in the 3D linkage.
The rheology constant is the property of a fluid that generally deals with the specific property
of a fluid that is non-new tonic fluid. The fluid property is defined with their viscosity and the
temperature at which it shows their maximum viscosity. In the cure reaction when the
temperature increases the viscosity of the fluid is also increases that help the resin to for
diffuse their cross-linkage. When the temperature increase cure reaction in the resin starts and
the molecules of the resin start creating their cross-linkage when the links created then the
molecules of resin become hinder and strict the movement of the molecules. Due to the
hinder in the molecules, the molecules start increasing their size which results in the increase
in the viscosity of the resin.
The viscosity of the material and temperature are directly proportional to each other, as the
temperature increases the viscosity of the material increase on the other hand when the
temperature decreases the viscosity of the resin decreases. By the practical 1, it is also been
observed that this model help in the understanding of kinetic reactions for this the empirical
model is been applied in the cure reaction for that the formula is given
μ=μ∞ exp ( U
RT ). exp ( K0
α ), on the other hand for the empirical constant.
ETotal=P∗R∗μ∗A∗GTotal
In the above equation μ∞is a constant, K is also constant and U is the activation energy.
Observations: After analysing all the cure reaction of rheology and kinetic constant we
received the following result that is as follows, the practical 1 is done under the several
conditions of the environment where the behaviour of the resin is measured. The practical is
performed under Pour, Bag, Leaks, Flip, Wet and Wet Out whose result are given below:
Time (Sec) UD[ 0]4
UD [ 0,90 ]5
UD [ 0,90 ]8 Mix
Pour 0 0 0 0
Bag 23 23 23 23
Leaks 30 30 30 30
Flip 41 41 41 41

Wet 65 97 99 60
Wet Out 30 Min 30 Min 30 Min 30 Min
There are also several methods to calculate the viscosity of the Resin other than DSC is using
Viscometer, in which the torque is applied over the resin in the apparatus name rotational
rheometer. In this apparatus the resin is placed in two different plates of apparatus and then
they are put together by the force of torque, hence where the torque is lower it depicts that
viscosity of that particular resin is high on the other hand where the torque force is high it
depicts that the viscosity of that liquid is low.
Figure 3: viscosity of the Resin
The result that is obtained by the application of torques over the resin can be depicted as
below:

Figure 4: resin graph
The other method to calculate the above constant is capillary viscometer that is used to
calculate the viscosity of the resin. In this apparatus the resin is passed through the small
diameter tube, the viscosity is calculated as compared to the time in which it rises in a
capillary tube.
To determine the viscosity by this method it is compulsory that all the dimensions of the
apparatus are pre-defined with the volume of the resin.

Figure 5: Volume of the resin

4. Flow Stack for Optimization of flow
The proper cure of resin is done by the proper optimization of temperature. The most
preferable temperature that is used for the optimization of resin is room temperature. For the
optimization of resin to maintain the temperature thermostats are used in which hot air is
blown to maintain the room temperature. There is also another method in which the resin is
flown in the hot tube surrounded with hot flowing water to maintain the temperature.
Figure 6: flow stack
Achieving the proper stack flow of resin the transition temperature is achieved, at this
temperature the viscosity of the resin increases which help them to flow easily. When the
temperature of the resin decreases to the transition temperature then it will show ductility in
their nature.