CEE 3020 Lab 05 - Lee (1)
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Laboratory 5: Polymers and FRP
CEE 3020 Civil Engineering Materials
Submitted to:
Alex Wu
Savannah Lynn Howard
by:
Youngsoo Lee
Section B1 Group: B1A
Youngsoo Lee
Edwin Noel Gaona
Juan Martin Vanegas
Minjeong Jeong
and 5 others
Abstract
10%
Introduction
10%
Experiment
5%
Results
25%
Discussion
25%
Conclusion
10%
Technical Writing
10%
Graphics: Design
5%
TOTAL
Due Date: 11/14/22 5:00 PM
Lee 2
Abstract
Polymer is a frequently used material in the civil engineering industry. Similar to concrete and
metal, there are multiple types of polymer materials that have different behavior, so it is important to
understand those different characteristics. The objectives of this experiment are to observe the behavior
and measure the material properties of PVC, PMMA, HDPE, and FRP polymers under uniaxial tensile
stress, examine the effect of strain rate and temperature on the failure of polymers, compare isotropic
and anisotropic materials, and perform a microstructural evaluation of an FRP. All polymer specimens are
tested with 68
o
F temperature and 0.2 in/min strain rates. Additionally, PVC and PMMA samples at -94
o
F
and HDPE samples with strain rates of 0.2, 0.4, and 0.8 in./min are tested as well. The results of the
uniaxial tension test give values for PVC and PMMA that are consistent for thermoplastics and
thermosets, which means that the properties are dependent on the temperature of the material. HDPE
samples behave as expected based on the non-branching structure when subjected to different strain
rates, having higher toughness at lower strain rates, but higher tensile strength at higher strain rates. FRP
sample is viewed under the microscope in order to fully characterize the fiber and resin properties. The
result of the tensile strength test of polymers with different temperatures and strain rates states that it is
important to understand the environment where the polymeric materials will be placed because their
property can be influenced by temperature and strain rate. E-glass/polyester pultruded FRP contains six
layers of random and uniaxially oriented fibers, giving it anisotropic properties and higher strength.
Overall, the result indicates that FRP/E-glass is the stiffest and strongest material with an ultimate tensile
strength of 46,907.66 psi and a modulus of elasticity of 820,609.99 psi. HDPE at a strain rate of 0.2
in/min is the weakest, toughest and ductile material with the ultimate tensile strength of 3,320.46 psi, a
toughness of 10,427.3 psi, and a ductility of 500.37 %. PMMA at room temperature is the most brittle
material with a ductility of 3.91 %
.
Based on these behaviors, each polymeric material can be used in the
proper application based on applied load, climate, and necessary ultimate strength to maximize the
strength, durability, and efficiency of the project. Also, understanding the behavior of the polymer
materials can help to minimize the cost of repairing the damage due to using not suitable materials.
Lee 3
Table of Contents
Introduction:
4
Experiment:
5
Results:
6
Discussion:
13
Conclusions:
16
References:
17
Appendices:
18
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Lee 4
Introduction
Polymer is a material made up of molecules that contain many atoms linked by covalent bonds
(Dai, 2022b). Since the polymer has the characteristics of being durable and flexible enough for it to turn
into different shapes, it is widely used in civil structures such as pipes, sidings, sealants, adhesives, and
more (Dai, 2022b). Similar to concrete and steel, the behavior of polymers varies based on the
components, temperature, and external loading conditions, so it is important to understand how these
properties affect the polymer. The objectives of this experiment are to perform a tension test on
polymer specimens and observe the surface using a microscope. The objectives of this experiment are to
observe the behavior and measure the material properties of several types of polymers, including
polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), E-glass / polyester pultruded FRP Composite,
high-density polyethylene (HDPE), and a fiber-reinforced polymer (FRP), under uniaxial tensile stress, to
examine the effect of strain rate and temperature on the failure of polymers, to compare isotropic and
anisotropic materials, and to perform the microstructural evaluation. Based on these results, the
properties and uses of these materials will be able to be characterized. The results of the experiment
would provide insight into the polymer behavior which can help to understand how polymers used on
the project behave and the ability to identify which polymer is appropriate for the project that requires
high strength, toughness, ductility, or brittleness.
Lee 5
Experiment
Material
The materials are as described in the laboratory handout (Dai, 2022a). There was no deviation from the
prescribed materials.
Equipment
The equipment is as described in the laboratory handout (Dai, 2022a). There was no deviation from the
prescribed materials.
Procedure
The procedures are as described in the laboratory handout (Dai, 2022a). There was no deviation from
the prescribed materials.
Lee 6
Results
Table 1: Uniaxial Tension Test Data of PVC
Material 1a: Polyvinyl Chloride (PVC)
Gage Length (initial)
3.14 in
Width (initial)
0.532 in
Thickness (initial)
0.119 in
Cross Sect. Area (initial)
0.0633 in
2
Width (final)
0.4 in
Thickness (final)
0.08 in
Cross Sect. Area (final)
0.032 in
2
Maximum Load
470.83 lbf
Failure Load
331.77 lbf
Displ Rate
0.2 in/min
Temperature
68
o
F
Material 1b: Polyvinyl Chloride (PVC)
Gage Length (initial)
3.1305 in
Width (initial)
0.5293 in
Thickness (initial)
0.1175 in
Cross Sect. Area (initial)
0.0622 in
2
Width (final)
0.3695 in
Thickness (final)
0.0786 in
Cross Sect. Area (final)
0.0290 in
2
Maximum Load
568.20 lbf
Failure Load
339.34 lbf
Displ Rate
0.2 in/min
Temperature
-94
o
F
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Lee 7
Table 2: Uniaxial Tension Test Data of PMMA
Material 2a: Polymethyl methacrylate (PMMA)
Gage Length (initial)
3.284 in
Width (initial)
0.519 in
Thickness (initial)
0.133 in
Cross Sect. Area (initial)
0.0690 in
2
Width (final)
0.525 in
Thickness (final)
0.128 in
Cross Sect. Area (final)
0.0672 in
2
Maximum Load
560.81 lbf
Failure Load
560.81 lbf
Displ Rate
0.2 in/min
Temperature
68
o
F
Material 2b: Polymethyl methacrylate (PMMA)
Gage Length (initial)
3.36 in
Width (initial)
0.526 in
Thickness (initial)
0.128 in
Cross Sect. Area (initial)
0.0673 in
2
Width (final)
0.5345 in
Thickness (final)
0.1242 in
Cross Sect. Area (final)
0.0664 in
2
Maximum Load
546.80 lbf
Failure Load
546.80 lbf
Displ Rate
0.2 in/min
Temperature
-94
o
F
Table 3: Uniaxial Tension Test Data of Pultruded Polyester / E-Glass FRP
Material 3: Pultruded Polyester / E-Glass FRP
Gage Length (initial)
6.8 in
Width (initial)
1.051 in
Thickness (initial)
0.26 in
Cross Sect. Area (initial)
0.273 in
2
Width (final)
1.051 in
Thickness (final)
0.26 in
Cross Sect. Area (final)
0.273 in
2
Maximum Load
12805.79 lbf
Failure Load
N/A
Strain Rate
0.2 in/min
Lee 8
Table 4:Uniaxial Tension Test Data of HDPE
Material 4a: High Density Polyethylene (HDPE)
Gage Length (initial)
3.07 in
Width (initial)
0.53 in
Thickness (initial)
0.13 in
Cross Sect. Area (initial)
0.0689 in
2
Width (final)
0.198 in
Thickness (final)
0.048 in
Cross Sect. Area (final)
0.00950 in
2
Maximum Load
228.78 lbf
Failure Load
117.29 lbf
Strain Rate
0.2 in/min
Material 4b: High Density Polyethylene (HDPE)
Gage Length (initial)
3.14 in
Width (initial)
0.52 in
Thickness (initial)
0.13 in
Cross Sect. Area (initial)
0.0676 in
2
Width (final)
0.186 in
Thickness (final)
0.048 in
Cross Sect. Area (final)
0.00893 in
2
Maximum Load
243.16 lbf
Failure Load
126.83 lbf
Strain Rate
0.4 in/min
Material 4c: High Density Polyethylene (HDPE)
Gage Length (initial)
3.18 in
Width (initial)
0.52 in
Thickness (initial)
0.13 in
Cross Sect. Area (initial)
0.0676 in
2
Width (final)
0.214 in
Thickness (final)
0.0465
Cross Sect. Area (final)
0.00995 in
2
Maximum Load
263.88 lbf
Failure Load
N/A
Strain Rate
0.6 in/min
Lee 9
Table 5: Microscopy Data
Specimen ID
Image
Image(s)
Magnification
Description (Color, fiber orientation)
Polyvinyl
chloride (PVC)
16X
Dark grey color, reflects light, multiple
uniaxial layers stacked vertically,
Polymethyl
methacrylate
(PMMA)
16 X
White, transparent, multiple uniaxial
layers stacked vertically,
E-glass/Polyester
Pultruded FRP
Composite
8X
Light greenish color, multiple uniaxial
layers and random direction layers are
stacked horizontally
Acrylonitrile
Butadiene
Styrene (ABS)
10X
Yellowish white, beige color, no layers
and unibody construction
High density
polyethylene
(HDPE)
12.5X
White color, 3 large uniaxial layers with
different thickness are stacked
horizontally
Elongated High
density
polyethylene
(HDPE)
12.5X
White color, 3 uniaxial layers stacked
horizontally, became thinner, visible
cracks formed on the surface,
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Lee 10
Figure 1: Stress-Strain Curve of PVC at Varying Temperature
Figure 2: Stress-Strain Curve of PMMA at Varying Temperature
Lee 11
Figure 3: Stress-Strain Curve of FRP Material
Figure 4: Stress-Strain Curve of HDPE at Varying Strain Rates
Lee 12
Table 6: Properties of Polymer from Tension Test Data
Ultimate
Tensile
Strength (psi)
Modulus of
Elasticity (psi)
Rupture
Strength (psi)
True Stress at
Failure (psi)
Ductility
(%)
Toughness
(psi)
PVC (Room Temp)
7437.13
292167.10
628.51
1243.44
87.15
4616.76
PVC (-94
o
F)
9135.05
164623.86
952.67
2043.31
186.05
10322.67
PMMA (Room Temp)
8124.35
244788.40
808.38
830.36
3.91
163.34
PMMA (-94
o
F)
8234.81
157244.80
1549.63
1570.63
4.03
146.24
HDPE (0.2 in/min)
3320.46
167712.4
328.75
2383.31
500.37
10427.3
HDPE (0.4 in/min)
3597.04
154075.64
195.04
1476.81
253.86
5935.44
HDPE (0.8 in/min)
3903.55
141745.6
1998.70
13578.89
482.09
10203.23
E-Glass FRP
46907.66
820609.99
46907.66
N/A
N/A
1341.42
Sample Calculations
Ultimate Tensile Strength = (Max load) / (Initial cross sectional area)
= 470.83 / 0.063308 = 7437.13 psi
Modulus of Elasticity = SLOPE() function in excel from start to yield strength value and divided by the
initial cross sectional area = 18496.52 / 0.0633 = 292167.10
Rupture Strength = (Final Load) / (Initial cross sectional area)
= 39.79 / 0.0633 = 628.51 psi
True Stress at Failure = (Final Load) / (Final cross sectional area)
= 39.79 / 0.032 = 1243.44 psi
Ductility: = ((L
f
- L
i
) / L
i
)*100% / L
f
= (Failure Strain * L
i
) + L
i
L
f
= (0.8715 * 3.14) + 3.14 = 5.877 inch
((5.877 - 3.14) / 3.14)*100% = 87.15 %
Toughness = Area under stress versus strain curve, trapezoidal rule using Excel
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Lee 13
Discussion
1.
There are multiple sources of error introduced during the experiment. One is the polymer
specimen not at -94
o
F during the tensile test. The temperature could have dropped during the
process of transferring the polymer from the freezer to the testing machine and this could affect
the tension test values. Another possible error is incorrectly measuring the dimension of the
polymer specimen. The dimension values were measured and used to set up the tensile test
machine and calculate the initial and final cross sectional area. Incorrectly measuring the
dimension could affect the calculated values. The last source of error is calculating the cross
sectional area using wrong values. Calculation of cross sectional area requires multiplying the
width and thickness of the polymer specimen. Not following the valid calculation could result in
incorrect values.
2.
Table 7: Comparison of Calculated vs. Expected Values for Different Polymers
PVC
PMMA
FRP/E-glass
HDPE
Calculated
Expected
Calculated
Expected
Calculated
Expected
Calculated
Expected
Ultimate
Tensile
Strength
(psi)
7437-9135
542-8110
8124-8235
2800-
12300
46907.7
45000-
50000
3320-3904
1600-
3630
Modulus
of
Elasticity
(ksi)
165-292
163-700
157-245
200-550
820.7
2600-3000
142-168
89.9-189
Ductility
%
87-186
1.16-72
3.9-4
0.5-14
N/A
2-3
253-500
0-4
Measured strength, modulus, and ductility values were compared with typical strength,
modulus, and ductility values retrieved from MatWeb website (MatWeb, 2021). The tensile
strength of all 4 polymer specimens was within the typical range. Lowering the temperature of
PVC and HDPE caused the tensile strength to go over the typical range by a little. The modulus of
elasticity for HDPE was in the range of a typical value, but other specimens were mostly lower
than the typical range. The calculated modulus of elasticity for FRP/E-glass was significantly
lower than the typical value. The calculated ductility of PMMA was within the typical ductility
range, while PVC and HDPE were much greater than the typical range. The strain-stress graph of
FRP/E-glass was linear and does not have a failure strain needed to calculate the ductility.
Lee 14
3.
According to Table 6, the stiffest material is FRP/E-glass with a modulus of elasticity of 820609.99
psi, the strongest material is FRP/E-glass with the ultimate tensile strength of 46907.66 psi, the
weakest material is HDPE at a strain rate of 0.2 in/min with an ultimate tensile strength of
3320.46 psi, the most ductile material is HDPE at a strain rate of 0.2 in/min with the ductility of
500.37 %, the most brittle material is PMMA at room temperature with the ductility of 3.91 %,
and the toughest material is HDPE at a strain rate of 0.2 in/min with a toughness of 10427.3 psi.
4.
PVC and HDPE underwent ductile failure, while PMMA underwent brittle failure. The HDPE
material was more ductile than PVC. HDPE with a strain rate of 0.2 in/min elongated more than
any other polymer samples. Ductile polymer samples show more elongation and necking before
failure, while brittle samples experience sudden breaks and show less elongation. Polymers and
metals differ in their ductility as polymers exhibit more ductility than metals, which gets
elongated more than steel samples.
5.
Increasing the strain rate on the HDPE specimens led to higher ultimate tensile strength and
rupture strength, but lower modulus of elasticity, ductility, and toughness. HDPE experienced
these differences based on strain rate because HDPE has a non-branching structure. The
branching structure interferes with the movement of polymer chains and reduces the
deformation (Dai, 2022b). Polymers without branching are able to experience greater
deformation, which leads to changing properties.
6.
For both PVC and PMMA, reducing the temperature increases the strength and modulus of
elasticity but decreases rupture strength and toughness. According to the lab data, the modulus
of elasticity of cold PVC and PMMA samples was measured lower than the samples at room
temperature. These changes due to the low temperature occur because both PVC and PMMA
are thermoplastics, which lack a crystalline structure, making their properties dependent on
temperature (Mamlouk, 2017).
7.
Fiber and matrix constituents have multiple interacting methods. Anisotropic materials have
properties that are dependent on the direction, while Isotropic materials have properties that
are the same in all directions (Dai, 2022c). FRP is anisotropic, which means it will have varied
properties depending on if it experiences tension or compression in a certain loading direction.
Anisotropic materials like FRP will experience higher strength if loaded in the same direction as
the orientation of the fibers.
Lee 15
8.
Respective Tensile Strengths
46907.66 = (2000)V
m
+ (250000)V
f
V
m
+ V
f
= 1 -> V
f
= (1-V
m
)
46907.66 = (2000)V
m
+ (250000)(1-V
m
) -> 46907.66 = 2000V
m
+ 250000 - 250000V
m
V
m
= 0.819 * 100% = 81.9%
V
f
= 100 - 81.9 = 18.1%
Respective Moduli
820609.99 = (600000)V
m
+ (10 x 10
6
)V
f
V
m
+ V
f
= 1 -> V
f
= (1-V
m
)
820609.99 = 600000V
m
+ 10 x 10
6
- 10 x 10
6
V
m
V
m
= 0.977 * 100% = 97.7%
V
f
= 100 - 97.7 = 2.3%
The FRP sample is found to be 81.9% matrix material and 18.1% fiber based on the tensile
strength. It is 97.7% matrix and 2.3% fiber based on the modulus of elasticity.
9.
The difference between using tensile strength and moduli is that in tensile strength, there is an
assumption that the load is applied parallel to the fibers. In the test sample, the failure plane
was shown to be parallel to the fibers, so the tensile estimate is more believable.
10.
Microscopy data shows that the FRP sample had 6 different layers vertically stacked together.
Among those layers, 3 layers contained randomly oriented fibers and the other 3 layers
contained uniaxially oriented fiber. The randomly oriented fibers consist of loosely packed fibers,
whereas the internal uniaxial layers had fibers with tightly condensed packing. The overall color
of the FRP sample was green due to the randomly oriented layers having greenish color, but
uniaxial layers were closer to the color white.
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Lee 16
Conclusions
The objectives of this experiment were to perform tension and microscopy tests on the polymer
specimens, observe the properties of the polymer, and how they behave. There were PVC and PMMA
specimens with different temperatures, one at room temperature and the other at -94
o
F. Lowering the
temperature affected the strength, ductility, and toughness of the specimen compared to the specimen
at room temperature. This concludes that both PVC and PMMA are thermoplastic materials, which
means their physical properties are highly sensitive to changes in temperature. It is important to
understand these results as strain rates and temperatures will differ based on environments.
Understanding how temperature changes the property of a polymer is important since civil engineering
projects that are located outdoors can experience multiple temperature flux throughout the lifetime and
having material that can withstand temperature flux can extend the lifetime of the project. Among 8
polymer samples, the HDPE sample with a strain rate of 0.2 in/min exhibited the highest ductility with
500.37 % of ductility and the weakest strength with an ultimate tensile strength of 3320.46 psi.
Increasing the strain rate of HDPE from 0.2 in/min to 0.4 and 0.8 in/min caused the modulus of elasticity
and ultimate tensile strength to increase while a reduction in toughness. FRP is the strongest and stiffest
polymer with an ultimate tensile strength of 46,907.66 psi and a modulus of elasticity of 820,609.99 psi.
The most brittle material is PMMA at room temperature with a ductility of 3.91 %. Based on the
microscopic evaluation of the FRP sample shows that FRP is an anisotropic material consisting of
alternating layers of random and uniaxially oriented materials. Because it is anisotropic, it will exhibit
different properties based on the loading direction. When using polymer products, it is important to load
the material differently based on the orientation, as it will have higher strength if loaded along the
orientation of the fiber than if loaded perpendicular to the fiber orientation.
Lee 17
References
Dai, Sheng. (2022a).
Lab5: Polymetric Materials
. Atlanta, GA: Georgia Institute of Technology. Retrieved
from
https://gatech.instructure.com/courses/275110/files/folder/Lab/Laboratory%205%3A%20Polymers?pre
view=36339473
Dai, Sheng. (2022b).
Lecture 19: Polymer
. Atlanta, GA: Georgia Institute of Technology. Retrieved from
https://gatech.instructure.com/courses/275110/files/folder/Lecture?preview=36658061
Dai, Sheng. (2022c).
Lecture 21: FRP Properties
. Atlanta, GA: Georgia Institute of Technology. Retrieved
from https://gatech.instructure.com/courses/275110/files/folder/Lecture?preview=36785321
Mamlouk, M.S., & Zaniewski, J.P. (2017).
Materials for Civil and Construction Engineers
. Pearson
Education, Inc. Retrieved from
file:///D:/Users/Youngsoo%20Lee/Downloads/Materials-for-Civil-and-Construction-Engineering.pdf
MatWeb. (2021). Retrieved from https://www.matweb.com/index.aspx
Lee 18
Appendices
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Lee 19
Lee 20
Lee 21
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