Maurice Evans III
14 May 14
NSTI Marshall – Tuskegee
University Cluster
Dr. Mahesh Hosur
X ______________________
NSTI Professor Signature
Abstract
For the month of May, an investigation on viscoelastic properties of SC-15 epoxy resin infused
with nanoclay was conducted using dynamic mechanical analysis (DMA). Samples of SC-15
with added montmrrilonite I.30E nanoclay as reinforcement were produced. Neat samples
without nanoclay and those with nanoclay were tested and their values compared. The same
fabrication process was followed for producing the I.28E samples, but using I.30E
montmorrilonite nanoclay instead of I.28E montmorrilonite nanoclay. Results showed samples
infused with I.30E nanoclay performed better than neat and samples infused with I.28E.
Introduction
Nanocomposites are being implements in every facet of human life from medicines to
recreational sports. With the increase in popularity of nanocomposites, the demand for them has
increased too. In the present work, two nanoclays were explored in order to see which one would
improve the thermo-mechanical characteristics of the resin system that it was infused into.
Through research, epoxy-based mechanicals are proving themselves by giving outstanding
mechanical and thermal properties [1]. Reinforcing the resin systems with fillers is becoming a
common practice to strengthen epoxy resin systems. Fillers such as nanoclays are growing in
popularity due their inexpensiveness and their ability to absorb UV radiation and resist moisture
[2]. These statements are the basis for my research since I am trying to improve the epoxy resin
systems by adding nanoparticle fillers
The dynamic mechanical analysis (DMA) tests conducted in this experiment allow us to
characterize and understand the visco-elastic properties of the resin. Storage modulus, loss
modulus and the tan delta were the main properties observed to determine if there were any
improvements due to the addition of the nanoclay into the epoxy resin system.
Experimentation
Manufacturing
The epoxy resin, SC-15, was obtained from Applied Poleramic Incorporated. It is a lowviscosity, two-phased, toughened epoxy resin system consisting of part A (resin mixture of
diglycidylether of bisphenol-A, aliphatic diglycidlether epoxy toughener) and part B (hardener
mixture of cycloaliphatic amine and polyoxylalkylamine) [3]. The montmorillonite nanoclay was
obtained from Sigma-Aldrich. Three types of samples were made for the test, SC-15 neat
samples, neat refers to the resin system without any added fillers, SC-15 with 2% by weight
I.28E montmorillonite nanoclay, and SC-15 with 2% by weight I.30E montmorillonite nanoclay.
SC-15 epoxy resin sample infused with the montmorillonite nanoclay of dimensions
60mmx12.75mmx4mm roughly, were produced using a metal molding process at the Tuskegee
University Center for Advanced Mechanicals. The ratio of part A to part B of the resin system is
10:3. The nanoclay was added so that the final weight of the resin system has 2% nanoclay in the
system. 97.923 grams of SC-15 epoxy resin part A was poured and weighed. Then 2.6 grams of
the respective montmorillonite nanoclay was weighed and added to the resin. A Corning PC420D magnetic stirring hot plate was used to disperse the nanoclay throughout the resin. A
magnetic pill was placed in the resin that reacts to the stirring motion of the hotplate stirrer and
spins within the resin. The stirrer was set to 1000rpm and 21°C. These setting were selected to
optimize the dispersion of the nanocly into the resin. The system was allowed to stir for 24
hours. After 24 hours 29.377 grams of SC-15 epoxy resin part B was added to the system. A
Caframo Ultra Torque Model BDC1850 overhead stirred was used to mix the part A infused
with nanoclay with the part B. The stirrer spun at 1000rpm for five minutes (until thoroughly
mixed). The resin system was then poured into steel molds. Due to the cure behavior of SC-15
epoxy resin, the system was allowed to cure at room temperature for 24 hours. After 24 hours of
curing, the sample were removed from the molds and placed in an Across International Model
FO-19053 oven at 93°C for 2 hours to post cure. The post-curing ensures that the samples are
fully cured and that all of the polymer chains have linked. After post curing, the samples were
sanded using a Knuth Rotor form Struers to meet the dimensional specifications of
60mmx12.75mmx4mm. The neat samples were made very similarly to the SC-15 with nanoclay
samples. The nanoclay was not added to the neat samples, so the 24 hours of magnetic stirring
were negligible. The parts A and B of the SC-15 resin were mixed with a 10:3, A:B, ratio.
Test Procedure
The mechanical characteristics of the resin system were tested using dynamic mechanical
analysis. The DMA tests were performed using a TA Instruments DMA Q800 dynamic
Mechanical Analysis Machine. The specifications of the DMA machine are in source [4].The
DMA Machine program was on a data
acquisition system, or computer. The
machine was set up as follows:
Figure 1 - TA DMA Q800 w/ furnace open
The DMA machine was set up on
the MF Srain mode, with a 1 Hz frequency
and a ramp of 5˚C/min to 200˚C .
This procedure was used to test all of the resin samples
used in the investigation.
Results
The results of the samples are given in table 1. The curves of the best samples are shown in
figure 2. The software on the computer calculated and determined much of the data given in
table 1. Table 1 gives the data of the best samples from each group of resin samples tested. The
best samples were determined by those having high storage modulus. The equation below was
used to determine the storage modulus [5].
Strain: 𝜀 = 𝜀0 sin(𝑡𝜔)
Stress: 𝜎 = 𝜎0 sin(𝑡𝜔 + 𝛿)
Storage Modulus: 𝐸 ′ =
𝜎0
𝜀0
Where 𝝎: = 2πf; where f = frequency of strain oscillation
𝒕 ∶ time
𝜹 ∶ phase lag between stress and strain
cos 𝛿
Table 1 – Average ± Standard Deviation of Mechanical Results of Different Resin Systems
Storage Modulus (Mpa)
Loss Modulus (Mpa)
Tan Delta
2250 ± 294.59
1725 ± 363.93
2408 ± 267.08
213.8 ± 31.7
167.3 ± 36.49
222.8 ± 32.02
0.8247 ± 0.091
0.8326 ± 0.03
0.8703 ± 0.03
Neat
2wt% I.28E
2wt% I.30E
Discussion
Using the storage modulus as basis for
comparison of the resin samples, we
can see from figure 2 that the higher
initial stiffness and the steeper slope
given by the resin reinforced with
I.30E
Montmorillonite
outperformed
the
nanoclay
I.28E
Montmorillonite nanoclay and the neat
resin sample. Again in figure 3, we
can see that the I.30E nanoclay outperformed the other samples. The loss modulus or the
sample’s ability to dissipate energy through molecular motion [4] shows that this particular
nanoclay allows the SC-15 resin
system to absorb more energy
when subjected to a load. This is
evident by the higher peak of the
loss modulus curve.
If you take the ration of the two
moduli you will get the Tan Delta,
and
once
again
Montmorillonite
the
I.30E
nanoclay
outperformed the other two resin systems.
Conclusion
Based on the results of this study, thus far, on the three resins systems, the following conclusions
can be drawn. The SC-15 resin samples reinforced with I.30E Montmorillonite nanoclay showed
improved properties than SC-15 resin samples reinforced with I.28E nanoclay and the SC-15
neat samples. The nanoclays in this study, improved the properties of the resin system, while the
other degraded the properties.
From the test, the performance of the samples met my expectations. The storage modules, or
materials stiffness, of the samples assured me that my previous conclusions about the addition of
nanoclay fillers into the resin system were wrong. I believed that my previous results, showing
the nanoclay to deteriorate the properties of the resin system only applied to that specific
nanoclay being used. The fact that the company produces two different types nanoclay,
obviously means that they must perform differently and be applicable in different application,
and in my conclusion I suggest that the I.28E is used as a resin property lessener. Instead of
improving the properties of the resin system, it degrades the resin system’s properties. It allows
the user to produce a resin with lower mechanical and physical properties that may allow the
system to then be more suited for certain application. While on the other hand, the I.30E is a
property improving nanoclay and follows the patterns that many other nanoclays follow when it
comes to improving the mechanical and physical properties of resin systems.
References
1. Jones K., Zhou Y.X., Jeelani S.: Effect of polyhedral-oligomeric-sil-sesquioxanes on
thermal and mechanical behavior of SC-15 epoxy. eXPRESS Polymer Letters Vol.2,
No.7 (2008) 494–501
2. Zhou Y. Pervin F. Biswas M. Rangari V. Jeelani S.: Fabrication and characterization of
montmorillonite clay-filled SC-15 epoxy. Materials Letters 01/2006;
DOI:10.1016/j.matlet.2005.10.042
3. VARTM RESIN/ RTM RESIN - THERMAL CURE. (2008, August 4). . Retrieved ,
from http://www.appliedpoleramic.com/index.php?q=infusion_epoxy.html
4. Dynamic Mechanical Analysis. (2010, January 1). . Retrieved May 13, 2014, from
http://www.tainstruments.com/pdf/brochure/dma.pdf
5. Meyers and Chawla (1999): "Mechanical Behavior of Materials," 98-103.
6. TA Worldwide. (n.d.). Thermal Analysis & Analyzers. Retrieved May 13, 2014, from
http://www.tasupport.com/product.aspx?siteid=11&id=25&n=1
7. Zainuddin, S., Hosur, M. V., & Jeelani, S. (2013, January 1). Improving the durability of
advanced fiber-reinforced polymer (FRP) composites using nanoclay - Advanced FibreReinforced Polymer (FRP) Composites for Structural Applications - 21. Improving the
durability of advanced fiber-reinforced polymer (FRP) composites using nanoclay Advanced Fibre-Reinforced Polymer (FRP) Composites for Structural Applications - 21.
Retrieved May 13, 2014, from
http://www.sciencedirect.com/science/article/pii/B9780857094186500211