Kinetic and Rheology Constants of Hexion Epidote RIM 235 Epoxy Resin

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Research Paper - Kinetic and Rheology
Constants

Abstract
The technique named Resin infusion is
mainly used to enhance Hexoin epidote RIM
235 epoxy resin that leads to a cure by
subjecting this resin to cure polymer
reactions. This cure includes conversion of
resin, it's hardening by a method of cross-
linking molecules so as to develop a 3D
network which is interlinked. Some of the
components for hardening of these cure
reactions and factors that lead to changes
like change in viscosity and temperature of
resin are being described below. Several
methods are being performed for the
analysis of viscosity that determines the
profile of viscosity through visualizing
viscosity curve and its constituents that are
kinetic and rheology constant of resin. Apart
from the differential scanning calorimeter,
the analysis of viscosity is performed via
alternative processes which are being
discussed along with the method of
optimization so as to enhance temperature
range.
Some methods of quality assurance are also
being described. It even analyses the best
quality of resin that could be used for
industrial purpose and must be assured by
standardized testing. These testing of resin
can be carried out in destructive as well as in
a non-destructive manner for better
assurance of quality. This paper determines
glass transition temperature, apparatus, and
procedures used for this purpose and
methods for internal porosity testing. It
determines testing procedures, their bond
strength, and resin’s fatigue life along with a
deep analysis through differential scanning
calorimeter determining the infusion of the
Hexion epidote RIM 235 epoxy resin.
Introduction
When comparing different materials type
like composite materials which seem to offer
more in accordance with non-composite
type materials. Despite composite being
advantageous, several issues are even being
faced because of lack source to standardize
methods. In order to preserve day resin, a lot
of practice is being done on infusion in
various laboratories so as to cure the
occurring problems. The study of these
materials focuses on various techniques that
lead to resins cure so as to improve it along
with countering its side effects. It even
optimizes the temperature, time and cost
along with highlighting methods for both
non-destructive as well as destructive testing
for infusion of resin. It uses Differential
scanning calorimeter to determine the
purpose and develops various mathematical

models of cure and rheology in order to
manage cure reaction parameters that need
to be applied to enhance the quality of the
composite resin.
Experimental Setup
In order to fulfill the intent of heat flow
profiling of thermosetting, differential
scanning calorimeter or infusion resins DSC
is mainly used as it determines through
calculation the difference between the
amount of heat per raise in temperature and
the reference temperature. It will help in
determining cure degree for cure reactions
and its kinetics. The DSC process mainly
works in two conditions, one when the
temperature is constant and another when it
varies. The initial process is named as
thermal scanning and the latter one as
dynamic scanning. The parameters based on
experiments majorly include the following.
The storage of resin is usually done in
hermetic pans which are of aluminium and
also the temperature profile is being
recorded when isothermal calorimeter
functions or runs. When temperature
changes with 50C from 1250C to 1450C it
can be defined as the range defined for
isothermal scanning. Once the sample is
completely scanned, it is then cooled using
coolant to 00C instantly and time taken for
completion of this reaction is 30 minutes
approx. The equation for the heat of the
reaction can be represented as
H=∫
0
t
( dQ
dt ¿) dt ¿
Further, the sample of resin is cooled to 00C
from the ambient by using coolant and later
is kept in a furnace to perform dynamic
testing. As cure reaction takes place, for
dynamic heating rate the temperature goes
increasing. It observes a heat change of
2500C for change in every heat rate, for each
completed cure reaction in dynamic testing
or scanning. HU =∫
0
td
¿ ¿
td = time taken to complete cure reaction
Hu = Total heat of cure reaction
Rheology constants and Cure
kinetics
Polymer’s cure chemistry is defined as
various chemical process or reactions of

polymers. In this particular case, the
polymer named epoxy resins is strengthened
and hardened by material strands cross-
linking and generated 3D cross-linked and a
more strengthened resin. The study about
the ability of conversion time relationship
that is analysing the relationship among time
acquired during the conversion of resin cure
into the better and more strengthened resin,
such a conceptual analysis is called as
Kinetics. The purpose behind the model of
cure kinetics is to develop a core
understanding at the industrious base of cure
applied. α= H
Hu
α = Degree of cure which determines the
amount of released heat in cure reaction
done for the formation of the bond.
Hu = Heat of the reaction
H = Released amount of heat by the time (t).
d α
dt =K (1−α )n
This equation acts as a model of kinetic cure
where,
α = Degree of cure
K = Reaction rate constant
n = Order of the reaction, the representation
of K is
K= K0 exp (−∆ EA
RT )
EA= Activation Energy
T= Absolute temperature
K0= Arrhenius factor of frequency
R= Gas constant
The above model provides the highest rate
which could be achieved by the cure
reaction with an aim of consuming up the
reactants and formation of building up 3D
cross-linking networks, excluding reaction
rate and decisive factor from key factors.
The result of resins diffusion is low for

kinetic reactions which upgraded to its
diffusion parameters and making changes in
the model of mathematics.
Rheology has contributed to materials fluid
dynamics which deals with material's fluid
characteristics as well as the non-Newtonian
flow of fluid which accounts the concerns of
viscosity. Viscosity defines resin flow
fluency which relies on temperature and
cures degree. After preceding the cure
reaction, cross-links starts generating, resins
start becoming dense which hinders the
movements of the molecule. The molecule's
size starts increasing resulting in raise in
viscosity which defines thermosetting resin
flow that does not comes out to be that
fluent.
Increase in temperature leads to a rise in a
molecular movement that directly impacts
the resin viscosity. With this, it can be
determined that the rheology model is
required for contributing to the enhancing
knowledge regarding kinetic reaction. An
empirical model is being commonly used
that is
μ=μ∞ exp ( U
RT ). exp ( K0
α )
U = Viscosity activation energy
K0 = Constant
R = Gas constant
μ∞= Constant
T = Absolute temperature
The calculative results of rheology and
kinetic constant are being determined by
differential scanning calorimeter (DSC)
which are provided below

Viscosity measurement even has an
alternative method so as to formulate the
curve of viscosity without the use of the
DSC method of viscosity measurement but
through the application of torque using
viscometer or rotational rheometer.
Rheometer here not only provides a
measurement of viscosity but also gives its
access by placing samples in 2 plates. Also,
the shear rate is being measured by applying
torque on the upper sample of the plate that
will strain the lower sample plate's material.
Shear rate here will give viscosity for the
non-Newtonian thermosetting resin.
Using capillary viscometer is another
technique that initiates the passage of
sample via capillary tube having a small
diameter. Time taken by the sample to pass
via tube relies on the viscosity of resin
taking into consideration the volume and
dimensions before experiments.
Optimization of flow through fiber
stack
In order to achieve the purpose, glass
transition temperature acts as a key factor
temperature over that the material
consistency or viscosity gets changed
leading to better flow of resin. At
temperature below the glass transition
temperature, resin experiences great
strength.
The temperature optimization enables in
epoxy resins cure and the suitable
temperature for this purpose is above room
temperature. Heat boxes which are
controlled using thermostat are mainly used
for temperature increase. Alternatively, the
epoxy is made to pass from hot water or
storing in it hot rooms which provide better
movement of epoxy resin.
After the visualization of experiments, the
stored epoxy in hot circumstances was
analyzed to have smooth and better flow
along with enhancement of glass transition
temperature.
Testing for quality control
The testing for quality control possesses
several factors of composite materials like
epoxy resins etc. Some of them are
described below
1. Internal porosity measurement
In order to measure porosity various
techniques used like ultrasonic testing,
infrared imaging, and autography NDE
method. Ultrasonic testing is done by
machines of ultrasonic testing that provides
with the bulk of tests which cause various

ultrasonic waves for resin propagation that
hits and reverts back providing the
estimation of porosity by comparing the
density of material with air. Similar to that,
the method of infrared imaging uses infrared
rays to get an estimated analysis by
comparing the difference in reflected waves
and its results are generated on thermograms
by using electromagnetic spectrum for better
imagination.
Acoustography is a method of evaluation
majorly used for measurement of porosity
which recommends that with an increase in
resin porosity the ultrasonic attenuation even
increases. Acoustography utilizes ultrasound
as a real-time image which is similar to X-
rays. The testing of ultrasonic with
ultrasonic machine comprises of the bulk of
tests which cause the movement of
ultrasonic waves, hits and reverts back
providing the estimation of porosity by
comparing the difference in material density
with air.
2. Carbon Bond Strength
For the test of resin bond, the universal
testing machine is used for the quality
assurance of carbon bond strength. It is the
attraction between the two different
molecules of resin that are present in the
lattice of the 3D structure.
3. Fatigue of Material
In this quality assurance method, the fatigue
of the resin is tested from the fatigue testing
machine. When the resin is placed in the
machine then it is applied under a certain
amount of fatigue to calculate their life span.
When a certain amount of fixed load is
applied in this machine, then the fatigue test
is done over several time to test the life of
the resin.
4. Degree of Cure
The degree of cure is the calculation of the
glass temperature of the resin. This testing is
done with the help of calorimeter which
determines the glass transition temperature
of an epoxy resin. Generally, two different
factors are calculated in this method one of
the glass transition methods and the other
one is the cure of residual. This also helps in
the determination of 3D lattice of the
molecule.
Conclusion
The resin is undergone in the curing process
for the hardening and strengthening of resin.
The standardized method is defined for the
curing of resin that is known as Differential
scanning calorimeter, it helps in the
development of successful infusion resin in
the practical 1. Along with this also help in

the settlement of viscosity profile of resin in
which it helps to flow of resin and also their
cure temperature.
Further, the resin properties are classified
properly with the help of rheology constant,
when the cross-linkage in between the
molecules of resin increase then the
diffusion rate in between the molecules
decreases. The degree of cure stands over
the critical point after that the viscosity of
the resin decreases at the critical point the
viscosity of the resin is maximum and the
cure temperature is at their minimum point.
Further, in the report, the quality assurance
method is defined that defines the quality of
resin it also determines the resin is fit for the
particular use or not.
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