Thermal ageing, degradation and swelling of acrylate rubber,
ﬂuororubber and their blends containing polyfunctional acrylates
M. Abdul Kader
, Anil K. Bhowmick*
Rubber Technology Centre, Indian Institute of Technology, Kharagpur-721 302, India
Received 19 July 2002; accepted 12 August 2002
The thermal ageing and degradation behaviour of acrylate rubber (ACM) ﬂuoroelastomer (FKM), and blends of ACM and
FKM containing polyfunctional acrylates were studied in air and nitrogen atmospheres. The blends were also subjected to swelling
in diﬀerent solvents. Thermogravimetric analysis of the blends containing polyfunctional acrylate indicated higher thermal stability
of the blends by shifting initiation of degradation to higher temperature. The ageing and degradation of FKM-containing blends
resulted in elimination of hydrogen ﬂuoride and formation of some lower molecular weight components. Polyacrylates with higher
functionality showed multi-step degradation. Higher levels of polyacrylate in the blend resulted in an additional step of degradation
compared to polyacrylate. Swelling studies indicated higher swelling resistance of ACM and FKM containing polyacrylate in sol-
vents having diﬀerent solubility parameters. Maximum swelling of the blends was observed with the solvents having solubility
parameter values comparable to that of blends i.e. in the range of 9–10 MPa
. The swelling index of the blends decreased with
increasing level of polyfunctional acrylates. Higher functionality of polyfunctional acrylates decreased the swelling index.
# 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Ageing; Thermal degradation; Fluoroelastomer; Acrylate rubber; Polyfunctional monomers; Thermogravimetry; Solvent swelling;
Fluoroelastomers (FKM) are well known for their
resistance to heat and aggressive ﬂuid environments ,
while acrylic rubber (ACM) is extensively used where
lower resistance is required . Blending of these two
rubbers and their miscibility have been discussed in our
earlier work . Polyacrylates containing poly-
functionality have been mixed with some polymers to
prepare polymer blends [4–6]. These polyfunctional
acrylates are involved in grafting and crosslinking of
polymers [7,8]. In our earlier publication  we reported
that the mechanical and dynamic mechanical properties
of ACM/FKM blends are improved by the addition of
polyfunctional acrylates. The morphology of the above
blends shows a phase-separated microstructure, with
ACM and polyacrylate together as continuous phase
and FKM as the dispersed phase . These novel
blends are expected to display superior heat and solvent
Many researchers have extensively studied thermal
behaviour and ﬂuid resistance of FKM and polyacrylate
rubbers [11–14]. Likewise, data on swelling and solvent
transport phenomena of these two elastomers are also
available in the literature [15–17]. Arnold et al  have
reported the heat and ﬂuid swelling of blends of acrylate
rubber and ﬂuoroelastomers. Jha and Bhowmick 
have shown improved swelling resistance of dynamically
vulcanized blends of acrylate rubber and Nylon-6. The
thermal degradation mechanism of polyacrylate-poly-
methacrylic acid blend has been proposed by Bajaj et al.
. Though degradation of many single polymers has
been extensively studied [21–27], degradation behaviour
of many blends is still obscure.
In our present investigation, we deal with the ageing
and thermal degradation behaviour of binary and tern-
ary blends of ACM/FKM containing polyfunctional
acrylates having functionality in the range of 2–6.
0141-3910/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
Polymer Degradation and Stability 79 (2003) 283–295
* Corresponding author. Tel.: +91-3222-83180; fax: +91-3222-
E-mail address: firstname.lastname@example.org (A.K. Bhowmick).
Present address: Crescent Engineering College, Vandalur Chen-
nai-600 048, India.