DSC study of chlorosulphonated polyethylene
G. Janowska
•
A. Kucharska
•
W. M. Rzymski
•
A. Kasiczak
Received: 13 November 2009 / Accepted: 23 November 2009 / Published online: 18 December 2009
Ó Akade
´
miai Kiado
´
, Budapest, Hungary 2009
Abstract The results of thermal analysis of speciality
elastomers CSM with different chlorine and sulphur con-
tents is presented in the article. The thermal curves
obtained under the atmosphere of inert gas have been
interpreted from the point of view of phase transitions and
chemical reactions of the examined polymers during their
heating. It has been stated that from among the investigated
chlorosulphonated polyethylenes, only CSM24, which has
the lowest chlorine content, contains a crystalline phase,
clearly influences on its T
g
temperature. Results of the
thermal analysis obtained under inert gas atmosphere have
been compared with results obtained under termooxidative
atmosphere. Irrespective of the research atmosphere, the
thermal decomposition of investigated CSM takes place in
three stages. The maximum rate of thermal destruction of
modified by heating elastomers, dm/dt, decreases with the
increase in chlorine content in the sample having been
heated.
Keywords Chlorosulphonated polyethylene Á CSM Á
Crystallization Á Glass transitions Á Thermal analysis Á
Thermal curves Á DTA Á DSC Á DTG Á TG Á
Thermal properties Á Thermal cross-linking
Introduction
Thermal analysis methods play an important role for
characterization of structure–properties relationships in
individual polymers and polymer blends. Several tech-
niques are widely applied for the investigation of phase
structure, thermal properties of polymer blends [1–3]. In
the present work, two thermal analysis techniques, ther-
mogravimetric analysis (TG) and differential scanning
calorimetry (DSC) [4–16], were used for characterization
of modified polyethylene [17–27].
Chlorosulphonated polyethylene (CSM) is a specialty
elastomer, produced by modification and functionalization
of polyethylene (PE) performed during simultaneous
actions of chlorine and sulphur dioxide on PE (usually PE-
LD) dissolved in CCl
4
in the presence of radical initiators.
Commercial products contain 25–45 wt% of combined Cl
and 1.0–2.2 wt% of combined sulphur. This means that on
the average 1 Cl atom falls on 5–7 C atoms, while a single
chlorosulphonic group (–SO
2
Cl) falls on 80–100 °C atoms
in the main chain of CSM. Over 90% of Cl combined in
CSM occurs in secondary groups (R
1
R
2
CHCl) in the main
chain, up to 3.5%—in tertiary groups (RR
1
R
2
CCl), up to
3%—in RCH
2
Cl groups, including terminal groups, and
the remaining combined Cl—in chlorosulphonic groups.
The technological, performance and cohesive properties as
well as chemical reactivity of CSM depend on the quantity
of combined Cl and S [28–32].
The replacement of some number of H atoms in the PE
chain with –Cl and –SO
2
Cl groups distorts the structure of
regularity of its chain and consequently results in products
with different susceptibility to crystallization, dependent on
the quantity of Cl combined with the given CSM [33].
Based on fragmentary literature reports [34] and structural
condition-dependent properties of elastomers [32, 35], one
can also expect that the content of combined Cl and
chlorosulphonic groups will exert a significant influence on
their thermal properties, both in air and inert gas
atmospheres.
G. Janowska Á A. Kucharska (&) Á W. M. Rzymski Á
A. Kasiczak
Faculty of Chemistry, Institute of Polymers and Dye
Technology, Technical University of Lodz, Lodz, Poland
e-mail: agnieszka.kucharska-jastrzabek@p.lodz.pl
123
J Therm Anal Calorim (2010) 102:1019–1024
DOI 10.1007/s10973-009-0622-2