Polyethylene (PE) pipe material may degrade into lower carbon number volatiles quickly during thermal welding when the welding temperature rises up to very high temperature. However, PE may also degrade into lower molecular weight (MW) polymer when subjected to a lower temperature. As a result, determination of the allowable temperature during thermal welding is crucial for guaranteeing the quality of welding joint. In this paper, a typical commercial PE100 material was chosen to conduct thermogravimetic analysis (TGA) and gel permeation chromatography (GPC) tests. The thermal degradation behavior of PE100 was investigated in dynamic and isothermal mode. The composition of the residue after thermal degradation was also analyzed through MW and MW distribution (MWD) measurements. Based on the experimental results, the initial temperature of thermal degradation with volatilization was derived and the thermal degradation process was studied in detail. To limit the degree of thermal degradation within a certain range during thermal welding of PE pipe, the allowable welding temperature for typical commercial PE100 material was determined.

References

References
1.
Frederick
,
C.
,
Porter
,
A.
, and
Zimmerman
,
D.
,
2010
, “
High-Density Polyethylene Piping Butt-Fusion Joint Examination Using Ultrasonic Phased Array
,”
ASME J. Pressure Vessel Technol.
,
132
(
5
), p.
051501
.10.1115/1.4001212
2.
Kalyanam
,
S.
,
Krishnaswamy
,
P.
,
Shim
,
D. J.
,
Hioe
,
Y.
, and
Focht
,
E.
,
2012
, “
Structural Integrity of HDPE Piping and Joints in Nuclear Safety-Related Applications
,”
ASME
Paper No. ICONE20-POWER2012-54192.10.1115/ICONE20-POWER2012-54192
3.
Bowman
,
J.
,
1997
, “
A Review of the Electrofusion Joining Process for Polyethylene Pipe Systems
,”
Polym. Eng. Sci.
,
37
(
4
), pp.
674
691
.10.1002/pen.11712
4.
Shi
,
J.
,
Zheng
,
J.
,
Guo
,
W.
, and
Qin
,
Y.
,
2012
, “
Defects Classification and Failure Modes of Electrofusion Joint for Connecting Polyethylene Pipes
,”
J. Appl. Polym. Sci.
,
124
(
5
), pp.
4070
4080
.10.1002/app.35013
5.
Poutsma
,
M. L.
,
2003
, “
Reexamination of the Pyrolysis of Polyethylene: Data Needs, Free-Radical Mechanistic Considerations, and Thermochemical Kinetic Simulation of Initial Product-Forming Pathways
,”
Macromolecules
,
36
(
24
), pp.
8931
8957
.10.1021/ma0303768
6.
Holmström
,
A.
, and
Sörvik
,
E.
,
1974
, “
Thermal Degradation of Polyethylene in a Nitrogen Atmosphere of Low Oxygen Content. II. Structural Changes Occurring in Low-Density Polyethylene at an Oxygen Content Less Than 0.0005%
,”
J. Appl. Polym. Sci.
,
18
(
10
), pp.
761
778
.10.1002/app.1974.070181023
7.
Conesa
,
J. A.
,
Marcilla
,
A.
,
Font
,
R.
, and
Caballero
,
J. A.
,
1996
, “
Thermogravimetric Studies on the Thermal Decomposition of Polyethylene
,”
J. Anal. Appl. Pyrolysis
,
36
(
1
), pp.
1
15
.10.1016/0165-2370(95)00917-5
8.
Al-Salem
,
S. M.
, and
Lettieri
,
P.
,
2010
, “
Kinetic Study of High Density Polyethylene (HDPE) Pyrolysis
,”
Chem. Eng. Res. Des.
,
88
(
12A
), pp.
1599
1606
.10.1016/j.cherd.2010.03.012
9.
Wallis
,
M.
, and
Bhatia
,
S. K.
,
2006
, “
Kinetic Study of the Thermal Degradation of High Density Polyethylene
,”
Polym. Degrad. Stab.
,
91
(
7
), pp.
1476
1483
.10.1016/j.polymdegradstab.2005.10.003
10.
Aboulkas
,
A.
,
El Harfi
,
K.
, and
El Bouadili
,
A.
,
2010
, “
Thermal Degradation Behaviors of Polyethylene and Polypropylene. Part I: Pyrolysis Kinetics and Mechanisms
,”
Energy. Convers. Manage.
,
51
(
7
), pp.
1363
1369
.10.1016/j.enconman.2009.12.017
11.
Gao
,
Z. M.
,
Amasaki
,
I.
, and
Nakada
,
M.
,
2003
, “
A Thermogravimetric Study on Thermal Degradation of Polyethylene
,”
J. Anal. Appl. Pyrolysis
,
67
(
1
), pp.
1
9
.10.1016/S0165-2370(02)00010-4
12.
Ceamanos
,
J.
,
Mastral
,
J. F.
,
Millera
,
A.
, and
Aldea
,
M. E.
,
2002
, “
Kinetics of Pyrolysis of High Density Polyethylene. Comparison of Isothermal and Dynamic Experiments
,”
J. Anal. Appl. Pyrolysis
,
65
(
2
), pp.
93
110
.10.1016/S0165-2370(01)00183-8
You do not currently have access to this content.