Development of High Temperature Fiber and ETFE Tight Buffered ...

Development of High Temperature Fiber and ETFE Tight Buffered Fiber
Zhixiong Sun Zhuang Xiong Dingfang Xu Zheng Xu Bing Wan
Yangtze Optical Fiber and Cable Co. Ltd.
Wuhan, Hubei, P. R. China
+86-27-67887644 · sunzhixiong@yofc.com
Abstract
The fibers used in some specific fields such as aeronautics and
astronautics, should work under the circumstances with the
temperature range from -60°C to +150°C. Ordinary fibers with
normal UV cured acrylate coating can not meet the demand. Thus, a
high temperature fiber and corresponding ETFE tight buffered fiber
are developed. In this paper, the structure of ETFE tight buffered
fiber is presented. In addition, a lot of performance tests including
thermal shock test, temperature cycling test and ageing test are
carried out to verify the reliability of the products. The results of
these tests are also introduced in the paper.
Keywords: High temperature fiber; Tight buffered fiber; ETFE,
Thermal shock test; Temperature cycling test; Ageing test
1. Introduction
The coating, physically in contact with the fiber, will greatly
affect the optical performance of the fiber. The operational
temperature of silica fiber depends on what kind of coating it
comprises. Such temperature of the fiber with normal UV cured
acrylate coating ranges from -60°C to +85°C. However, high
temperature fibers, which should be used in the environment with
higher temperature, for example, 150°C, plays an important role
in aeronautics and astronautics as well as military and equipment
industry.
Compared with normal fibers and their tight buffered structure,
high temperature fibers utilize special fiber coating and polymer
for tight buffer. In this paper, a high temperature fiber and its
ETFE tight buffered structure are developed, which can satisfy
the requirement of surrounding temperature from -60°C to
+150°C. Then reliability tests are carried out on these fibers.
Results of thermal shock test, temperature cycling test and ageing
test are also presented in the paper. In addition, fiber strippability
is tested before and after those reliability tests, but the test results
will be given in another paper.
2. High Temperature Fiber
The selection of coating is the key to the development of high
temperature fibers. Table 1 shows the comparison of different
coatings. The high temperature fiber product features dual coating
system on 100kpsi proof-tested fiber, including silicone layer
followed by high temperature acrylate layer. Inner silicone
coating is a thin layer which is bonded directly to the glass
surface of an optical fiber while outer coating is high temperature
acrylate, which makes the fiber up to the diameter of 250µm and
allows the fiber to be used in the environment with the
temperature up to +150°C.
Results of thermal shock test and temperature cycling test will be
given later while the test conditions are shown in Table 2.
Temp. Upper
Limit(°C)
Table 1. Comparison of different coatings
Table 2. Test conditions
2.1 Thermal shock test
Thermal shock test simulates the environment in which
temperature changes instantly from high to low and vice versa.
Temperature(℃)
Temperature(℃)
Test Item
Thermal
shock test
210
180
150
120
90
60
30
0
-30
-60
-90
210
180
150
120
90
60
30
0
-30
-60
-90
Acrylate
High Temp.
(°C)
High Temp.
Acrylate
A7305109AB1(Silicone&KS2-004)-CJ-1310nm
0
-0.01
-0.02
0 2 4 6 8 10 12 14 -0.03
Time(h)
Temperature
0.05
0.04
0.03
0.02
0.01
Change of
attenuation(dB/km)
-0.04
-0.05
Change of attenuation
Figure 1. Induced attenuation change at 1310nm in
thermal shock test
A7305109AB1(Silicone&KS2-004)-CJ-1550nm
0
-0.01
-0.02
0 2 4 6 8 10 12 14 -0.03
Time(h)
Silicone
Temperature
Polyimide
85 150 200 300
Low Temp.
(°C)
Humidity
(%)
150 -60 --
TCT 150 -60 55
Details of Test
Requirements
Without tension,
attenuation is measured.
Then thermal shock test
is carried out. Keep at
both temperature
extremes for 30 minutes.
After that, attenuation is
monitored online.
3 cycles, 1°C /min,
attenuation is monitored
and recorded
automatically.
Strippability is tested
after TCT.
0.05
0.04
0.03
0.02
0.01
Change of
attenuation(dB/km)
-0.04
-0.05
Change of attenuation
Figure 2. Induced attenuation change at 1550nm in
thermal shock test
International Wire & Cable Symposium 431 Proceedings of the 58th IWCS/IICIT

The test is used to examine the fiber’s resistance to rapid
temperature changes, to determine the reliability and stability of
its optical performance, and to improve the product quality.
Figure 1 and Figure 2 show induced attenuation changes at
1310nm and 1550nm respectively during the thermal shock test.
The maximum change of attenuation in the test at 1310nm
wavelength is +0.008dB/km while that at 1550nm wavelength is
+0.011dB/km.
2.2 Temperature cycling test
Figure 3 and Figure 4 show induced attenuation changes at
1310nm and 1550nm during the temperature cycling test. The
maximum change of attenuation in the test at 1310nm wavelength
is +0.009dB/km while that at 1550nm wavelength is
+0.011dB/km.
Temperature(℃)
Temperature(℃)
A7305109AB1(Silicone&KS2-004)-TCT-1310nm
210
180
0.05
0.04
150
0.03
120
0.02
90
0.01
60
0
30
-0.01
0
-0.02
-30 0 11 22 33 -0.03
-60
-0.04
-90
-0.05
Time(h)
Temperature Change of attenuation
Figure 3. Induced attenuation change at 1310nm in
temperature cycling test
A7305109AB1(Silicone&KS2-004)-TCT-1550nm
Change of
attenuation(dB/km)
210
180
0.05
0.04
150
0.03
120
0.02
90
0.01
60
0
30
-0.01
0
-0.02
-30 0 11 22 33 -0.03
-60
-0.04
-90
-0.05
Time(h)
Temperature Change of attenuation
Figure 4. Induced attenuation change at 1550nm in
temperature cycling test
3. ETFE Tight Buffered Fiber
An ETFE buffer is extruded on the fiber to 900µm in diameter, as
shown in Figure 5.
Figure 5. Structure of ETFE tight buffered fiber
The selection of buffer polymer is very important in the
development of high temperature tight buffered fibers. The
coating and the buffer may be mechanically removed from the
fiber in one step, which is convenient for direct termination with
connectors. Mechanical stripping in short length (about 15mm) is
Change of
attenuation(dB/km)
also permitted to remove the buffer and leave the coating intact,
which can facilitate the splicing with 250μm fibers from gel-filled
cables with loose tube structure.
In this section, the properties of ETFE resin are introduced.
Thermal shock test, temperature cycling test and ageing test are
performed on the tight buffered fiber. Test conditions are shown
in Table 3.
Table 3. Test conditions
Test Item
Thermal
shock test
High Temp.
(°C)
Low Temp.
(°C)
Humidity
(%)
150 -60 --
TCT 150 -60 55
Ageing test 150 -- --
Details of Test
Requirements
Without tension,
attenuation is measured.
Then thermal shock test
is carried out. Keep at
both temperature
extremes for 30
minutes. After that,
attenuation is monitored
online.
3 cycles, 1°C /min,
attenuation is monitored
and recorded
automatically.
Strippability is tested
after TCT.
Without tension,
duration is 30 days.
Attenuation is measured
once a week.
Strippability is tested
after ageing test.
3.1 Properties of ETFE Resin
ETFE (Ethylene tetrafluoroethylene) is used for the
applications requiring good impact resistance and stress cracking
resistance. The resin maintains these properties even at
continuous working temperature over 150°C. These features make
ETFE an excellent candidate for the materials used in chemical or
mechanical industry.
The main properties of ETFE are:
• Excellent impact resistance;
• Enhanced durability and stiffness against other fluoropolymers;
• Higher pressure rating than other fluoropolymers;
• Higher tensile strength and creep resistance than other
fluoropolymers;
• Better crush resistance than other fluoropolymers.
Additional Properties of ETFE are:
• Sterilizable by Gamma ray, ETO and e-beam;
• Working temperature up to 150°C;
• Chemical resistant;
• Flame retardancy: UL-94 V0;
• Limiting oxygen index: 30.
Due to its excellent flame retardancy and good flexibility at low
temperature as well as the retention of properties after ageing at
elevated temperatures up to 150°C, ETFE is the best RoHS
compliant polymer for fiber protection as the tight buffer. The
comparison of different tight buffer materials is shown in Table 4.
International Wire & Cable Symposium 432 Proceedings of the 58th IWCS/IICIT

Table 4. Comparison of different tight buffer polymers
3.2 Thermal Shock Test
Figure 6 and Figure 7 show induced attenuation changes at
1310nm and 1550nm during the thermal shock test for ETFE tight
buffered fibers.
The maximum change of attenuation in the test at 1310nm
wavelength is +0.016dB/km while that at 1550nm wavelength is
+0.020dB/km.
Temperature(℃)
Temperature(℃)
Material
A7305109AA4(Silicone&KS2-004&ETFE900um)-CJ-1310nm
210
180
0.05
0.04
150
0.03
120
0.02
90
0.01
60
0
30
-0.01
0
-0.02
-30 0 2 4 6 8 10 12 14 -0.03
-60
-0.04
-90
-0.05
Time(h) Temperature Change of attenuation
210
180
150
120
90
60
30
0
-30
-60
-90
Typical
Temp.
Rating
(°C)
Flame
Retardancy
Figure 6. Induced attenuation change at 1310nm in
thermal shock test
A7305109AA4(Silicone&KS2-004&ETFE900um)-CJ-1550nm
-0.02
0 2 4 6 8 10 12 14 -0.03
Time(h)
Limiting
Oxygen
Index
(LOI)
Abrasion
Resistance
Temperature
Radiation
Resistance
PVC -30~+105
Self
extinguish
23-42 Poor Poor
Hytrel
Flammable
-40~+120
5556
UL-94 HB
20 Very good Poor
LSZH -30~+90
Self
extinguish

Because of the reliability of high temperature fiber and ETFE
material and the stability of tight buffering process, ETFE tight
buffered fiber can be used in aeronautics and astronautics as well
as military and equipment industry.
5. Acknowledgments
Special thanks should be given to those who extend their kind
assistance to the development of these products.
6. Pictures of Authors
Dingfang Xu
Yangtze Optical Fiber
and Cable Co., Ltd.
4 # Guanshan Er Road
Wuhan
P. R. China
430073
Zhixiong Sun
Yangtze Optical Fiber
and Cable Co., Ltd.
4 # Guanshan Er Road
Wuhan
P. R. China
430073
Mr. Dingfang Xu graduated from Xi’an Jiaotong University in
Cable and Insulation major in 1992. He has been engaged in the
research and manufacture of cables for 15 years. He is the
technical manager in Cable Production Department of YOFC. As
a member of China Institute of Communications, he has published
about 30 papers.
Mr. Zhixiong Sun got his M.E. degree in Chemical Engineering
from Hubei University of Technology in 1995. He joined Yangtze
Optical Fiber and Cable Co., Ltd. in 2001. He has been engaged
in research and development of optical fiber cables. As an R&D
engineer, he has obtained ten patents and has published 20
technical papers.
Zheng Xu
Yangtze Optical Fiber
and Cable Co., Ltd.
4# Guanshan Er Road
Wuhan P. R. China
430073
Zhuang Xiong
Yangtze Optical Fiber
and Cable Co., Ltd.
4# Guanshan Er Road
Wuhan P. R. China
430073
Mr. Zheng Xu received B.E. degree in cable technology and
materials at Harbin Institute of Electrical Technology, China in
1983. He was a research engineer at Chengdu Cable Plant, China
(1983–1988), a chief engineer at YOFC, China (1989–1997) and
a design engineer at General Cable New Zealand Ltd., New
Zealand (1999–2002). Now he is the manager in Cable Production
Department of YOFC.
Dr. Zhuang Xiong got his B.E. degree in Mechanical Engineering
from Wuhan Institute of Technology in 1994 and received his
Ph.D. in Mechanical Manufacture and its Automation from
Huazhong University of Science and Technology in 2000. Since
then, he has been working in Yangtze Optical Fiber and Cable
Co., Ltd., engaged in the research and development of optical
fiber cables. Now he is the assistant manager in Cable Production
Department. He has obtained eighteen patents while other three
are still awaiting authorization. Moreover, he has published nearly
50 technical papers. He is also a senior member of China Institute
of Communications and an expert in Chinese Delegation to ITU-T
and IEC.
Bing Wan
Yangtze Optical Fiber
and Cable Co., Ltd.
4 # Guanshan Er Road
Wuhan
P. R. China
430073
Mr. Bing Wan got his B.S. degree in Mechanical Engineering
from Tsingdao University of Science & Technology in 1990 and
his M.S. degree in Computer Application (CAD) from Wuhan
University in 2000. Since 2001, he has been working in YOFC as
a senior R&D engineer in Cable Production Department.
International Wire & Cable Symposium 434 Proceedings of the 58th IWCS/IICIT