Materials Sciences and Applicatio n, 2011, 2, 1041-1048
doi:10.4236/msa.2011.28141 Published Online August 2011 (
Copyright © 2011 SciRes. MSA
Short Circuit Thermally Stimulated Discharge
Current Measurement on PMMA:PEMA:PVDF
Ternary Blends
A. K. Gupta1,2,4*, A. Tiwari1,3, R. Bajpai1, J. M. Keller1,2
1Department of Post Graduate Studies and Research in Physics & Electronics, R. D. University, Jabalpur, India;
2Macromolecular Research Centre, R. D. University, Jabalpur, India; 3Mata Gujari Mahila Mahavidyalaya, Jabalpur,
India; 4Department of Engineering Physics, Global Institute of Engineering, Patan Bypass Square, Karmeta, Jabalpur,
Email: *
Received August 6th, 2010; revised December 1st, 2010; accepted June 2nd, 2011.
The attainment of a better understanding and improvement of electrical properties of ternary blend is a task of particular
scientific and economic importance. Ternary films of Poly (methylmethacrylate), Poly (ethlymathacrylate) and poly
(vinlylidenefluoride) were prepared using solution cast technique. Thereafter, to study the hetro charges, homo-charges
and interfacial charge formation in ternary system, the short circuit thermally stimulated discharge current (SC-TSDC)
measurements were carried out on bilaterally metallized electrets. The ternary blend samples taken for the present in-
vestigations are hetrogeneous system involving three polymers differing in their conduction behaviour and dielectric
property. Thus, unequal ohmic conduction currents arriving at the interface are expected to result in accumulation of
charges at the interface or the Maxwell-Wagner effect. Clearly the Maxwell Wagner effect is expected to contribute
discernibly to the observed TSDC’s of the ternary blends. The PMMA: PEMA: PVDF: 100:100:50 blend exhibits highest
tendency while 100:50:100 the least, towards the anomalous current flow. Moreover, the conductivity of 100:100:50 is
found to be more and, therefore, a large amount of homocharge is injected leading to anomalous current.
Keywords: PMMA, PEMA, PVDF, Ternary Blend and SC-TSDC
1. Introduction
The study of electrical behavior to understand clearly
the electrical conduction mechanism origin of the inter-
facial charge formation and charge transport behavior of
ternary blended films, in order to determine the microe-
lectronics and engineering applications for industrial use
is of prime concern. As the field of polymer science con-
tinues to grow, new as well as existing techniques are
being developed to study the physical properties of these
materials. Most of the interesting physical properties of
polymers are attributed to molecular motions which are
very complex. These motions are evident by relaxations
which are observed during measurements such as me-
chanical and dielectric measurements etc. One favorable
method of assessing the physical properties of polymers
is to perform short circuit thermally stimulated depolari-
zation current (SC-TSDC) measurement. The SC-TSDC,
now a well known technique [1-8], has come to be re-
garded as a viable method for studying dielectric relaxa-
tion behaviour of polymers. After a conditioning phase
the sample is subjected to a chosen regime of electric
field and temperature changes. The result is assessed by
finally heating the sample (with absence of applied elec-
tric field), usually at a linear rate and analyzing the re-
sulting peaks of current thermograms. Originally this
technique was used to measure charge detrapping in
low-molecular-weight-organic and inorganic compounds.
The SC-TSDC thermograms also reflect the mechanical
behavior of polymers, and the resolution of SC-TSDC
and dielectric data is much better than many mechanical
measurements. The work reported earlier emphasizes on
different interpretations for the observed results but it
seems no ultimate view has yet been reached. The eluci-
dation of the underlying charge injection and carrier mi-
gration process is vital to the ever-growing future utility
of these materials. It has been shown that carrier mobility
can be greatly affected by impregnating the polymers
Short Circuit Thermally Stimulated Discharge Current Measurement on PMMA:PEMA:PVDF Ternary Blends
with suitable blending [9-12]. Thus, keeping this into
account the ternary blends of Poly (methylmethacrylate)
(PMMA), Poly (ethlymathacrylate) (PEMA) and poly
(vinlylidenefluoride) (PVDF) were prepared and
SC-TSDC characterization was carried out with different
charging temperatures, charging fields and charging pe-
riods to reveal clearly the contribution of different elec-
trical performance. However, combination of self-
existing structural-property relationship, single phase
compatibility and toughness, etc. of PEMA/PMMA/
PVDF ternary blends had already been explored by
Gupta et al. [13].
2. Experimental
2.1. Materials
For preparation of ternary blend specimens, commer-
cially available polymers; poly (vinylidene fluoride)
(PVDF) (Aldrich, USA) Mw 140000 (powder); poly
(methylmethacrylate) (PMMA) (Aldrich, USA) Mw
15000 (GPC); and poly (ethylmethacrylate) (PEMA)
(Aldrich, USA) Mw 34000 (GPC) were used.
2.2. Preparation of Ternary Films
The solution cast technique has been utilized to pre-
pare the ternary films of PMMA + PEMA + PVDF.
Calculated quantity of the three polymers was dis-
solved in dimethyl formamide (DMF) their common
solvent, at a temperature of 60˚C with constant stirring.
The blend films having ultimate desired concentrations
of PMMA: PEMA: PVDF: 100:100:100; 50:100:100;
100:50:100; and 100:100:50, were prepared and desig-
nated as FEMA-1, FEMA-2, FEMA-3 and FEMA-4,
respectively. The blends having different compositions
were cast on the glass substrate in a dust free chamber by
means of a spin coater (Model No. TP-1100 set) to en-
sure uniform ultimate thickness of 100 micron when
temperature of 60˚C was maintained. The solvent was
allowed to evaporate by keeping glass substrate inside
the oven for nearly 6 hours at same temperature. The-
reafter, the oven was switched off and allowed to
cool to room temperature (20˚C). The film specimen
so obtained was detached from the glass substrate. The
specimens obtained were in the forms of 100 ± 0.0002
micron thickness and 15 cm2 in size.
2.3. Experimental Technique
For SC-TSDC measurements the samples were bilater-
ally metallized over a central circular area of 5.0 cm di-
ameter. The TSDC measurement consists of following
1) The sample is polarized to saturation under a static
electric field Ep, at a temperature Tp.
2) The sample is cooled, with the field still applied,
down to a temperature T0, (room temperature) where the
dipole/charge carriers motion is hindered, i.e. where re-
laxation time (T0) becomes very long (of the order of
several hours) to years.
3) At T0
the external field is removed, and a sensitive
current detector is directly connected between the elec-
trodes; because of the low temperature the dipole/charge
carriers are frozen in their ordered position and the sam-
ple remains polarized even in the absence of field.
4) The sample is warmed up, usually, at a constant
heating rate
(convenient heating rates are between 1 -
10 K/min) while the current through the detector is re-
corded as a function of temperature.
5) The current measurement requires a sensitive elec-
trometer which has low detection limit of the order of
10–15 A. A Keitheley Electrometer model 61˚C was used
in the present investigation.
3. Result and Discussion
Various results describing the behaviour of ternary
blends investigated by short circuit thermally stimulated
discharge current (TSDC) are discussed below.
3.1. Temperature Dependence
Figure 1 shows the TSDC thermogram of FEMA-1 film
polarized with a field of 10 kV/cm at 40, 60, 80 and
100˚C. In case of FEMA-1 samples current flows in ano-
malous sense for low polarizing temperatures and even
for low field. Perhaps the anomalous peak appearing
around 90˚C in sample polarized at 40˚C appears as nor-
mal peak around 80˚C in case of sample polarized at 80˚C.
On changing composition tendency towards anomalous
behavior is found to become pronounced. For FEMA-2
films low field current is anomalous largely for all tem-
peratures. As the field increases, for low tempera-
Figure 1. TSDC thermogram of PMMA: PEMA: PVDF::
100:100:100 ternary film polarized with a field of 10 kV/cm
at 40, 60, 80 and 100˚C.
Copyright © 2011 SciRes. MSA
Short Circuit Thermally Stimulated Discharge Current Measurement on PMMA:PEMA:PVDF Ternary Blends1043
tures, current is normal but for high temperature current is
anomalous. At high field and high temperature the current
is always anomalous, similar as for FEMA-3 and 4.
3.2. Field Dependence
Figure 2 shows the TSDC thermogram of PMMA: PE-
MA: PVDF: 100:100:100 ternary film charged at 40ºC
with 10, 15, 20 and 25 kV/cm fields. In case of FEMA-1
films current flow in normal direction (except at lowest
temperature) up to moderate field values. The current
increases in magnitude with increase in field except for
very high field for which it decreases. For FEMA-2 films
current is anomalous for low polarizing temperatures and
low fields and also for high temperature for all field. For
moderate temperatures current is normal for all fields.
The FEMA-3 films, for low temperature and low field
current increase with the field. As the polarizing tem-
perature increases, the anomalous behaviour is also ob-
served at gradually increasing field values. Further, for
FEMA-4 films current is largely anomalous for all the
temperatures. Only in the case of very high field and high
temperature current is normal.
3.3. Composition Dependence
It is evident that for the composition, specimens polar-
ized at low temperature of 40˚C with low field 10 kV /cm
exhibits anomalous current flow, further anomalous cur-
rent peak observed around 90˚C (Figure 3). In case of
FEMA-4 composition sample is considerably weakened
in FEMA-3 sample composition. For samples charged at
60˚C with 10 kV/cm only in case of FEMA-1 (Figure 4)
composition anomalous current behaviour is observed
astonishingly the thermograms of samples with FEMA-2
and FEMA-4, composition are exact replica of each other.
From the thermograms of samples of various composi-
tions charged at high temperature 80 and 100˚C with low
fields it is evident that FEMA-2 and FEMA-4 composi-
Figure 2. TSDC thermogram of PMMA: PEMA: PVDF:
100: 100: 100 ternary film charged at 40˚C with 10, 15, 20
and 25 kV/cm fields.
Figure 3. TSDC thermogram of ternary blends having dif-
ferent composition charged at 40ºC with 10kV/cm field.
Figure 4. TSDC thermogram of ternary blends having dif-
ferent composition charged at 60˚C with 10kV/cm field.
tion samples have tendency towards anomalous current
flow more pronounced as compared to other samples.
Persistent polarization in a thermally charged dielectric
specimen may arise due to various mechanisms. The
important among these are orientation or dipolar polari-
zation, translational or space charge polarization and
interfacial polarization. The charge originated in SC-
TSDC due to dipolar orientation or trapping of space
charges in defect or dislocation sites is known to give
rise to a uniform polarization, which is heterocharge. On
the other hand, space charge build up by migration of
ions over microscopic distances or accumulation near
the electrodes, and interfacial or Maxwell Wagner ef-
fect gives a non uniform heterocharge, whereas trapped
injected space charge results in a nonuniform homo- or
hetero- charge depending upon the work function of the
metal electrode.
The decay of heterocharge during SC-TSDC gives a
current in a direction opposite to that of the charging
current i.e., negative normal current while decay of
homo charge results in a current in the same direction as
the charging current called positive or anomalous cur-
rent. The classical theory of Gubkin [14], Perlman [15]
and others for the decay of charge in polarizing dielec-
trics assumes the superposition of homocharge and het-
Copyright © 2011 SciRes. MSA
Short Circuit Thermally Stimulated Discharge Current Measurement on PMMA:PEMA:PVDF Ternary Blends
Polar polymers, in general, exhibit two main relaxa-
tions designated as
- and
- relaxations. The
- re-
laxation arises due to the main chain segmental motion
and occurs around and above Tg. The
- relaxation oc-
curs in the glassy state of the polymer and is due to the
hindered rotation of polar side groups around car-
bon-carbon link of the main chain. Sometimes - and
relaxations coalesce to give a single
- relaxation
around Tg as reported in the case of PMMA [16-18]. If
there are polar side groups in the polymers side chain,
capable of orienting in an electric field independent of
one another and having different relaxation times, two
- relaxations are observed. The relaxation
reported to occur due to the space charge is designated
as ρ- relaxation and occurs at high temperatures. When
the polymer is non-polar, it will exhibit no distinct di-
polar reorientation; however, it exhibits space charge
effects. Each relaxation process gives rise to a peak at
its characteristic temperature during SC-TSDC.
The depolarizing current recorded in the present in-
vestigation was found to flow, in general, in the direc-
tion opposite to that of the charging current i.e. in the
negative sense. Hence, processes responsible for het-
erocharge formation are primarily responsible for the
polarization of the ternary polymeric blends. All the
three polymeric components used for preparing the
blend samples are polar polymers. The polymers
PMMA and PEMA are branched amorphous thermo-
plastics. The two polymers differ only in the alkyl sub-
stituent’s (-COOCH3) and (-COOC2H5) of their ester
side groups. The ester side groups are polar- and so they
form permanent dipoles which can be oriented during
the electret formation.
It is well known that the ester side groups can rotate
singly or together with the main chain segments
–C-CH2. Evidently their cooperative motion with the
adjacent segments of the bulky main chain which may
contain all together at least 10,000 monomeric links,
requires more energy; hence it occurs well above the
room temperature when the polymer soften and become
rubbery. The polymers PMMA and PEMA, therefore
exhibit - transitions at 103 and 66˚C due to the dis-
orientation of ester side groups by their cooperative
motions with the adjoining segments of the main chains
which at these temperatures start to rearrange their
The local motions of the polar ester side groups by
rotation around their –C-C- links with the main chain
occur at much lower temperatures when the polymers
are in their glassy state. Their motions are sterically
hindered by the - methyl groups on the main chains.
The polymers PMMA and PEMA, therefore, exhibit
relaxation in their glassy state around –51˚C and –45˚C
due to release of part of their ester groups by local mo-
The third relaxation designated as ρ-peak has also
been observed at 115˚C for PMMA, and 85˚C for PE-
MA respectively and has been ascribed to thermally
stimulated space charge limited drift and diffusion of
frozen excess charges.
PVDF is a semicrystalline polymer. It exhibits at
least four crystalline phases α, β, γ, and δ. The α-form is
non polar while β-form is polar and is responsible for
all its useful electroactive properties [19-25]. In view of
the properties and relaxations of the three polymers dis-
cussed as above and the fact that the depolarization cur-
rent recorded in the present investigation was found to
correspond in general, to the normal current implies that
the dipolar orientation processes contribute significantly
to the hero charge formation. The thermograms, however,
do not show characteristic dipolar peaks. Further, the
TSDCs exhibit complex field and temperature depend-
ence. This indicates that the dipole relaxations are proba-
bly masked by strong space charge effects and other
phenomena. The space charges are excess charges which
will migrate during the electret formation towards the
electrodes. These charges may be ions or electrons and
they may originate from e.g. dissociation of impurities
(water, monomers, catalyst and initiation). The forming
field will drive the positive charges to negative electrode
and negative charges to the positive electrodes. The field
motion is opposed by diffusion; moreover, during their
transport parts of the charges are lost by recombination
with opposite carriers. However, the field drift will
dominate and charges will be piled up in the vicinity of
the electrodes.
In hetero- electrets the excess charges are intrinsic and
bipolar. They originate from those charges that first took
part in the conduction and were next accumulated near
the electrodes during the formation. The occurrence of
space charge polarization requires that there be enough
carriers of a sufficiently high mobility and this condition
is satisfied only if the conduction is reasonably high.
Hence, space charge formation occurs at high tempera-
ture close to and above Tg. The excess charges may also
be injected from the electrodes depending upon the work
function of the electrode material and the polymer. Under
the condition of high temperature, when the mobility of
charge carrier is high these charges may be localized in
various traps existing in the polymer. During the depo-
larization cycle the frozen in localized excess charges are
thermally mobilized and they start moving under their
own field towards the shorted electrodes and also by dif-
fusion generating hetro current.
Incidentally in hetrogeneous hetro-electrets of partially
Copyright © 2011 SciRes. MSA
Short Circuit Thermally Stimulated Discharge Current Measurement on PMMA:PEMA:PVDF Ternary Blends1045
crystalline polymers the intrinsic excess charges will
mainly pile up at the phase boundaries. They are supplied
there by unequal omic conduction currents within the
two components or phases (interfacial or Maxwell Wag-
ner charging). The ternary blend samples taken for the
present investigations are hetrogeneous system involving
three polymers differing in their conduction behaviour
and dielectric properties. Thus, unequal ohmic conduc-
tion currents arriving at the interface are expected to re-
sult in accumulation of charges at the interface or the
Maxwell-Wagner effect. Since the ohmic conductivities
are thermally activated, the Maxwell-Wagner effect pro-
duces permanent polarization when the sample is ex-
posed to field-temperature cycle. During SC-TSDC the
accumulated charge is neutralized by new carriers of
opposite polarity that are conveyed to the interface by
conduction currents which are created by the interfacial
charge itself. Clearly the Maxwell Wagner effect is ex-
pected to contribute discernibly to the observed SC-
TSDC of the ternary blends.
It has been observed that the depolarization current in
many cases is found to flow in the same direction as the
charging current. The depolarization current flowing in
the same direction as charging current is called positive
current or anomalous current while the depolarizing cur-
rent flowing in a direction opposite to the charging cur-
rent is called negative and normal current. Particularly
for samples charged at low temperatures or at high tem-
peratures with high field, the current exhibits the anoma-
lous behavior. Since the direction of the current is oppo-
site to that expected from the depolarization of dipoles, it
is likely to be due to electrode polarization or injected
homo space charge.
The anomalous behaviour of SC-TSDC current may be
understood in terms of localization of excess charges in
various available traps in the bulk of the polymers. At
low temperature when the mobility of the charge carriers
is low, the charge is largely localized in shallow traps.
However, at high temperature, the charge carriers with
high mobility are shifted to deeper traps. The number of
such trapped charge carriers increases with the increase
in the value of applied step field. It appears that owing to
the polar character of the three polymers, excess charge
carriers in sufficiently high concentration exist in the
ternary blend samples. With limited mobility at low po-
larizing temperature and under the directing action of the
field, these carriers in large number occupy the shallow
traps only in the bulk of the polymer. The releases of a
very large number of such charge carriers during the de-
polarization cycle may exceed the charge exchange rate
of the charging electrode resulting in the blocking of the
electrode and a consequent net carriers back flow to-
wards the near electrode. This gives rise to anomalous
SC-TSDC current.
As the temperature increases, mobility of the charge
carriers also increases; consequently the excess charge is
shifted to deeper traps. The release of charge carriers
from such traps requires more energy. Thus, release of
trapped charge carriers from deeper traps in limited
number may not be sufficient enough so as to cause
blocking of the charging electrode. Hence, carriers flow
towards the charging electrode resulting in normal cur-
rent in negative direction as has been observed from
samples polarized with moderate fields at moderate tem-
peratures. For high polarizing temperature, charge carri-
ers, with high mobility in large numbers under directing
action of high polarizing field occupy shallow traps as
well as deep traps. The release of trapped charge carriers
during TSD cycle in very large number may, therefore,
again surpass the carrier exchange rate of the electrode
causing its blocking and hence a net carrier flow towards
rear electrode giving positive anomalous current.
The anomalous current may also result from the in-
jected charge carriers. The anomalous current in terms of
injected homo space charges can be understood as fol-
lows. Considering one type of carrier, i.e. electrons for
simplicity, we may assume a distribution of injected
space charges just after charging such that its density n (x,
t) drops with increasing distance X from the injecting
electrode. Thus, the field F (0, t) at the injecting electrode
at any instant of time is greater than the field at any other
point of the dielectric (F (0, t) > F [d, t)], and there exists
a zero field plane at a distance say X0 towards the right.
The appearance of anomalous current requires the sup-
pression of the carriers to the left which results in a net
carrier flow to the right and the movement of zero field
plane X0 to the right.
As the carrier mobility increases with temperature and
the density of injected space charge increases with the
applied field, a strong space charge is expected near the
injecting electrode at high charging field and high tem-
perature. Such a situation is expected to result in a high
return rate of carriers to the injecting electrode. As a re-
sult, the return rate of the carriers may surpass the charge
exchange rate of the electrode leading to the blocking of
the electrode. This blocking suppresses the carriers flow
to the left (injecting) electrode and may result in the
movement of X0 towards right electrode causing anoma-
lous current. Figures 5 (a) and (b), shows the distribu-
tion of injected space charge and internal field.
The injected homo space charge may also produce a
non-uniform distribution of space charges. The injected
space charges may be localized in various trapping sites
available in the specimen. Under certain conditions of
charging field and temperature the positive charges in-
jected from the anode may migrate under the action of the
Copyright © 2011 SciRes. MSA
Short Circuit Thermally Stimulated Discharge Current Measurement on PMMA:PEMA:PVDF Ternary Blends
Figure 5. (a) and (b) distribution of injected space charge
and internal field.
internal field and pile up in front of the cathode and may
become immobilized on cooling during electrets forma-
tion. On removing the field and heating in short circuit,
this positive charge is released and the net flow will be
positive due to its accumulation in the vicinity of the
cathode. Similarly, the injected negative charges piled up
in front of the anode may flow towards the anode. The
flow of positive charges towards the cathode and nega-
tive charges towards the anode will lead to anomalous
current or homo charge flow.
From the various thermograms it is clear that the ten-
dency towards anomalous current flow depends on the
ternary blend composition. The FEMA-4 film exhibits
highest tendency while FEMA-3 the least, towards the
anomalous current flow. In case of FEMA-4 film the
current exhibits normal behavior only for highest form-
ing temperature and field. Thus, change in the wt%
composition of the ternary blend significantly modifies
the chemical structure and hence trap structure of the
It appears that reduction in wt% of PVDF in the blends
modifies the structure such that there results an increase
in the number of migration states or shallow traps. The
detrapping of charge carriers from these shallow states in
large number leads to blocking of near electrode and
consequently there results a net carriers flow towards
farther electrode. In case of FEMA-3 samples reduction
in the bulky ethyl group leads to increase in the density
of ester group and trapping sites. Detrapping of charge
carriers from these traps requires higher activation en-
ergy; this leads to decrease in the number of released
charge carriers not exceeding the charge carrier exchange
rate of the electrode, and hence to a normal current.
Increase in the tendency of depolarization current to-
wards anomalous behavior may also be understood in
terms of injected homocharge. It appears that the con-
ductivity of FEMA-4 is maximum so that a large amount
of homo charge is injected. PVDF is a semicrystalline
polymer while PMMA and PEMA both are amorphous.
Thus, in FEMA-4 blends amorphous content is relatively
more. We know that the conductivity of amorphous part
is more as compared to crystalline part. Hence, conduc-
tivity of FEMA-4 being more and a large amount of ho-
mocharge is injected leading to anomalous current.
From the SC-TSDC thermograms of ternary blends
polarized with the field of 10kV/cm at temperature 60˚C
(Figure 4), it is evident that thermograms of FEMA-2
and FEMA-4 films are exactly replica of each other. The
FEMA-2 blend exhibits normal current with a hump and
a well developed peak around temperatures 40 and 60˚C,
respectively. On the contrary FEMA-4 film shows ano-
malous current with hump and peak around the same
temperatures. Polymer PVDF is known to act as plasti-
cizer for PMMA and PEMA. Further, substituent ethyl
group is larger as compared to methyl group. The larger
ethyl group of PEMA which participates in the orienta-
tion of ester group of methacrylic polymer will push the
main chain in the polymer farther apart thereby causing
internal plasticization. Thus, the highly plasticized ter-
nary blend FEMA-2 exhibits increased mobility of the
main chain and the release of the dipolar ester group by
their cooperative motion with the adjoining segments of
the main chains is manifested in the form of hump and
peak in the normal direction.
It may also be inferred here that the hump and peak
appearing around 40 and 60˚C are actually the manifesta-
tion of dipolar relaxations associated with α-transitions
observed around glass transition temperatures of PEMA
and PMMA or β-relaxation associated with the chain fold
motion in the amorphous region of PVDF. The plastici-
zation is known to the lower the Tg, and it appears that
Tg’s of the PEMA and PMMA are shifted to around 40
and 60˚C [13]. Reduction in wt% of PVDF results in a
less plasticized ternary blend or conversely a relatively
hardened blend material. The hardening results in an im-
perfect contact between electrode and the sample. This
increases chances of breakdown in the electrode samples
interface and consequently enhances homocharging of
the sample. In the shorted homo-electrets the excess in-
jected homo charge localized in migration states and
deep traps will moves back to the near electrode on the
injection side. These homo-charge motions thus attract
image charges to this electrode rather than liberating
them. The resultant current is the net homo current and
the hump and peaks current are in fact the result of op-
posed dipolar and excess charge drift. Since the mobility
of the extrinsic carriers depends on the temperature and
free volume in a way similar to that of the chain seg-
ments of the polymer. Increased homocharge injection
may also be understood in terms if increased conductiv-
ity of FEMA-4 film. Reduction in the wt% content of
semicrystalline polymer PVDF entails decrease in the net
crystalline component and consequently an increase in
the net amorphous content in the ternary blends. Since
the conductivity of amorphous polymer is more so that in
Copyright © 2011 SciRes. MSA
Short Circuit Thermally Stimulated Discharge Current Measurement on PMMA:PEMA:PVDF Ternary Blends1047
this blend there is more injection of homo charge from
the electrode into the polymeric blend. Further, as said
earlier increase in the net amorphous content probably is
accompanied by increase in the density of migration
states (shallow traps) in which a large amount of excess
charge is localized. The delocalization and release of a
large amount of charge from these states results in ano-
malous SC-TSDC in FEMA-4.
4. Conclusions
The SC-TSDC measurement helps to understand the he-
trogeneous system involved in the three polymers which
are differ in their conduction behaviour and dielectric
properties. The SC-TSDC measurement shows the un-
equal ohmic conduction currents arriving at the interface,
which are expected to result in accumulation of charges
at the interface or the Maxwell-Wagner effect. Thus
Maxwell Wagner effect clearly expected to contribute
discernibly to the observed TSDC’s of the ternary blends
and hence making it useful material for microelectronics
and much special purpose insulation.
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