ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 7, pp. 1258!1261. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + M.F. Galikhanov, I.A. Zhigaeva, A.K. Minnakhmetova, R.Ya. Deberdeev, 2008, published in Zhurnal Prikladnoi Khimii,
2008, Vol. 81, No. 7, pp. 1178!1181.
AND POLYMERIC MATERIALS
Biodegradability of Electret Polymer Materials
M. F. Galikhanov, I. A. Zhigaeva, A. K. Minnakhmetova, and R. Ya. Deberdeev
Kazan State University of Technology, Kazan, Tatarstan, Russia
Received November 1, 2007
Abstract-Corona electrets based on composites of shockproof polystyrene and starch were studied.
Utilization of spent polymer electrets is a topical
problem because of their wide use in various con-
verters, air filters and individual respirators, tribo-
technical and sealing systems, etc. . In Russia,
polymer items are usually disposed of with solid
domestic wastes. However, since polymers are
extremely resistant to degradation, studies should be
carried out to develop new biodegradable polymers.
One of the ways to impart biodegradability to poly-
mers is addition of fillers, which can act as a source
of food for bacteria and fungi and simultaneously
promote degradation of polymer chains to oligomer-
ic fragments easily assimilated by the same micro-
organisms [4, 5].
Our previous studies  showed that, from
polymers and dispersed fillers, it is possible to
prepare electrets considerably surpassing in char-
acteristics those based on unfilled polymers. How-
ever, as shown in , electric fields negatively affect
the vital activity of various microorganisms. In this
case, electret as a material producing an electrostatic
field cannot undergo biodegradation even when
modified with various fillers.
In this work we studied biodegradation of elec-
trets based on polymers and fillers.
In our studies we used shockproof polystyrene
(SPPS) of 0801 brand [GOST (State Standard)
20250389E] and potato starch (GOST 7699378).
The polymer and filler were mixed in a Brabender
blender at 190+2oC for 5 min. The composite plates
with a thickness of 0.8 mm were pressed in accor-
dance with GOST 12019366 at 190+5oC for 5 min.
Then, the resulting plates were heated at 100oC for
10 min and cooled in the field of the negative corona
discharge. The corona discharge was obtained with
an electrode of 196 needles uniformly distributed
over the square area (7 0 7 cm). The polarization
voltage and time were 35 kV and 60 s, respectively.
The electret and straight polymer plates were
stored in paper envelops at ambient temperature
and humidity. The electret characteristics were
measured every day on an IPEP-1 meter whose
operation is based on intermittent shielding of the
measuring probe located at some distance from the
electret surface. The measurement errors of the sur-
face potential V
, electric field strength E, and sur-
face density of the electric charges s
were no more
To perform the biodegradation studies, the plate
was placed into a Petri dish with the Saburo model
culture medium containing spores of Aspergillus
niger mycelial fungi. The biodegradation was
monitored by the outward appearance and weight
loss of the plates.
Shockproof polystyrene is one of the most widely
used structural polymeric materials. However, its
electret properties are analyzed only in a few studies
[10, 11]. At the same time, corona electrets based on
polystyrene, exhibiting high electret properties, were
studied fairly extensively [638, 12, 13]. Electrets
with a stable external electric field are prepared by
corona discharge using specifically nonpolar poly-
mers, which are characterized by the presence of
the energy trap of charge carriers (impurity ions),
free polymer volume, and specific surface defects
formed in the course of oxidation. It should be
noted that shockproof polystyrene has a two-phase
structure typical for composites in which the matrix
phase of polystyrene incorporates microgel particles