Post on 24-Feb-2016
description
transcript
Improving Performance of Rubber Materials Through Blending
C.M. RolandNaval Research Laboratory
Gary S. BuckleyCameron University
Outline
•A little terminology
•Work with hydrogels
•Can this shift to rubber materials?
•Materials used in rubber work
•Results
•Conclusions
A Little Terminology
Crosslink – a covalent bond between two separate polymer molecules
Work with Hydrogel Materials
Jing Ping Gong and Yoshinori Katsuyama, Advanced Materials, 15(14), 2003.
Single Network Double Network
Single Network Double Network (0.4 MPa) (17.2 MPa)
Key factors: 1. The two networks were homogeneous. 2. The difference in crosslink densities was maximized.
Can this idea translate to rubber materials?
Two selected rubber materials:
EPDM – contains double bonds and can be crosslinked with sulfur
EPM – contains no double bonds and cannot be crosslinked with sulfur
The idea:Blend EPDM and EPM followed by crosslinking with sulfur to see if mechanical properties are improved
0 0.5 1 1.5 2 2.5 3 3.5 40
0.5
1
1.5
2
2.5
3
3.5
Comparison of Higher Modulus Materials
0% EPM 0.625 phr S 50% EPM 1.4 phr S
Strain (mm/mm)
Stre
ss (M
Pa)
Tensile Strengths
Is the EPM chemically a part of the network?
Did EPM become a bonded part of the network?
All EPM should be soluble if not a chemical part of network
Soxhlet extraction to determine gel fraction
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60.50.60.70.80.9
11.1
Gel fractions vs. phr Sulfur
0% EPM 50% EPM
phr S
Gel
Fra
ctio
n
Gel fractions
Indicates that EPM was not a chemical part of the network
Network Density
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60.0E+001.0E-052.0E-053.0E-054.0E-055.0E-056.0E-057.0E-058.0E-059.0E-051.0E-04
Network Density vs. phr S
0% EPM 50% EPM
phr S
Netw
ork
Dens
ity (m
ol/c
c)
Tensile Strength and Network Density
0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05 6.0E-05 7.0E-05 8.0E-05 9.0E-050
0.5
1
1.5
2
2.5
3
3.5
4
Mechanical Properties vs. Network Density
0%EPM (TS) 50%EPM (TS)
Network Density (mol/cc)
Tens
ile S
tren
gth
(MPa
)
Is there a homogeneity issue?
Are EPDM and EPM homogeneous initially?
C-C bond length:
~ 0.15 nm
Potential Applications – Ballistics
Bad response Good response
Conclusions
•Blended EPDM and EPM crosslinked with sulfur provides better tensile strength than crosslinked EPDM
•Blended EPDM/EPM tensile strengths continue to increase even as the network density levels off
•The increase in tensile strength of the blended material is modest – not on the order of the hydrogel work
•The EPDM/EPM system is not particularly homogeneous - work remains to be done to see if its homogeneity increases as the cure package increases
Street lights
Fireworks