الفهرس 
Radiation processing of polymers
Interactions of Ionizing Radiation with polymerOnly 14 pages are availabe for public view
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Abstract
This work is divided into three parts
The first part include a study of the effect of fumed silica, zirconium
silicate and irradiation dose as well as N, N-m-phenylenedimaleimide
coagent on the physical and mechanical properties of EPDM rubber
nanocomposites. Ethylene-propylene-diene rubber (EPDM/ nanofiller) composites were prepared and crosslinked by gamma radiation.
The nanocomposites either containing 40 phr of fumed silica, 40 phr
of zirconium silicate, separately, or different ratios from both ranging
from 30:10 to 10:30, respectively. The effect of fumed silica and
zirconium silicate nanoparticles, on the thermal, electrical and
mechanical properties of the -irradiated EPDM rubber
nanocomposites was elaborated.
from the obtained result we can conclude the following:
1- The effect of irradiation dose (0 - 200 kGy) on the values of
TS for the all nanocomposites increased with increasing
irradiation dose reaching their maximum values at about 100
kGy and after that, the values of TS decreased on increasing
the irradiation dose up to 200 kGy. Whereas the values of (E
%) for the all nanocomposites decreased with increasing of
the irradiation dose.
2- The nanocomposite containing 40 phr fumed silica has the
highest tensile strength and by partially replacement of fumed
silica with zirconium silicate, the tensile strength decreased
but the elongation relatively increased and the nanocomposite
containing 40 phr fumed silica has the lowest elongation over
the all irradiation doses considered.3- The tensile strength values of the nanocomposites containing
coagent are better compared with those obtained for the
samples without coagent at the all absorbed doses considered.
4- The values of solubility in toluene of EPDM decreased
sharply with increasing the irradiation dose from 25 to 100
kGy then decreased with slow rate up to 200 kGy.
5- The values of the solubility for the EPDM composite
containing 40 phr zirconium silicate were the highest over
the all irradiation doses considered and at the same time, the
irradiated samples up to 25 kGy are completely soluble.
6- The solubility increased by the replacement of fumed silica by
zirconium silicate.
7- The Swelling (SW) in toluene noticeably decreased with
increasing irradiation dose from 25 to 100 kGy after that the
SW values have almost leveled off up to 200 kGy. This may
be due to the formation of cross-links under the effect of
radiation.
8- The swelling value of the nanocomposite samples containing
the highest content of fumed silica (40 phr) is the lowest and
by the replacement of fumed silica by zirconium silicate, the
swelling values increased reaching maximum value at zero
content of fumed silica (40 phr zirconium silicate).
9- The irradiated nanocomposites containing coagent has lower
swelling and solubility values than those nanocomposites
without coagent.
10- The nanocomposites irradiated to 100 kGy have the best
mechanical properties; hence the thermal, electrical and
morphology have been studied at that irradiation dose.11- The volume resistivity increased with increasing the level of
fumed silica. Hence, the nanocomposite containing 40 phr of
fumed silica has the highest volume resistivity.
12- The volume resistivity of the all nanocomposites decreased by
the addition of 5 phr N, N-m-phenylenedimaleimide coagent.
13- The TG and DTG curves shafted to higher temperature values
with the replacement of fumed silica by zirconium silicate,
T
comp and Tmax of the nanocomposites increased also. This
indicates that the thermal stability of the samples is increased
with the increasing of zirconium silicate content in the
irradiated nanocomposites.
14- T 10% of the all nanocomposites above 400 0C, indicating high
thermal stability.
15- T 10% of the nanocomposites increased with the increase of
zirconium silicate content; so the T 10%, of the sample
containing 40 phr zirconium silicate was 10 °C higher than
that of the sample containing 40 phr fumed silica. Besides,
Tonset, Tcomp and Tmax of the sample containing 40 phr
zirconium silicate are 22 °C, 21 °C, and 16 °C higher than
those of the sample containing 40 phr fumed silica,
respectively.
16- The Tonset, Tcomp and Tmax temperatures of the nanocomposites
with coagent shifted toward higher temperatures compared to
those of the nanocomposites without coagent, indicating the
enhancement of thermal stability of nanocomposites with
coagent.17- The char residue formation and the activation energy of the
composites have been increased with the increase of
zirconium silicate content in the samples.
18- It can be concluded that EPDM/fumed silica and zirconium
silicate composites irradiated to 100 kGy are characterized by
having good thermal and electrical insulation properties.
The second part include a study of the effect of - irradiation doses,
and fumed silica on the physical and mechanical properties of EPDM
rubber / nanocomposite containing 10 phr modified montmorillonite
nanoclay (OMMT). EPDM/ nanocomposites have been prepared by
incorporating various percentages of fumed silica (10, 20, and 30 phr)
onto EPDM/OMMT rubber nanocomposite and crosslinked by
gamma radiation. The effect of OMMT and fumed silica content on
the mechanical, electrical and thermal properties of the
nanocomposites was investigated.
from the obtained results we can conclude the following:
1- The effect of irradiation on the values of TS for the all
nanocomposites increased with increasing the irradiation dose
reaching their maximum values at about 50 kGy and after
that, the values of TS decreased on increasing the irradiation
dose up to 200 kGy. Whereas the values of (E %) for the all
nanocomposites decreased with increasing the irradiation
dose.
2- The nanocomposite containing 30 phr fumed silica has the
highest tensile strength and the lowest elongation over the all
irradiation doses considered.3- The tensile strength values of the nanocomposites containing
coagent are better compared with those obtained for the
samples without the coagent at the all absorbed doses
considered.
4- The SN values attained by the all nanocomposites have
decreased on increasing the irradiation dose.
5- The SN values have decreased with increasing the degree of
fumed silica loading at the same irradiation doses.
6- The values of solubility of EPDM decreased with increasing
the irradiation doses.
7- The solubility decreased by increasing of the fumed silica
concentration.
8- The nanocomposites containing coagent has lower swelling
and solubility values than the nanocomposites without the
coagent.
9- The nanocomposites irradiated to 50 kGy have the best
mechanical properties; hence the thermal, electrical and
morphology of the nanocomposites irradiated to 50 kGy have
been studied.
10- The volume resistivity increased with increasing the level of
fumed silica. i.e., the nanocomposite containing 30 phr of
fumed silica has the highest volume resistivity.
11- The volume resistivity decreased by the addition of 5 phr N,
N-m-phenylenedimaleimide coagent.
12- The TG and DTG curves shafted to higher temperature with
the addition of fumed silica, Tcomp and Tmax of the composites
increased also. This indicates that the thermal stability of the samples is increased with the increasing of fumed silica
content in the nanocomposites.
13- T 10% of the composites increased with the increase of fumed
silica content; so the T 10%, of the sample containing fumed
silica 30 phr was 23 °C higher than that of the sample without
fumed silica.
14- The Tonset, Tcomp and Tmax of the sample containing 30 phr
fumed silica are 22 °C, 13 °C, and 11 °C higher than those of
the sample without fumed silica, respectively.
15- The char residue formation and the activation energy of the
nanocomposites have been increased with the increase of
fumed silica content in the samples. The increase in the
activation energy indicate that some stable compounds was
formed during decomposition that required higher energy for
thermal decomposition.
16- The Tonset, Tcomp and Tmax temperatures of the nanocomposites
with coagent shifted toward higher temperature compared to
that of the nanocomposites without the coagent, indicating the
enhancement of thermal stability of the nanocomposites with
the coagent.
17- . It can be generally concluded that EPDM/nanoclay and
fumed silica composites irradiated to 50 kGy are
characterized by having good thermal and electrical insulation
properties and the nanocomposite containing 30 phr fumed
silica is the best.The third part include a study of the effect of N, N-mphenylenedimaleimide coagent and modified cerium oxide on the
physical and mechanical properties of -irradiated EPDM rubber/
montmorillonite clay nanocomposite. The high temperature resistant
EPDM rubber-nanocomposites containing 10 phr montmorillonite
nanoclay, different concentration of the modified cerium oxide (2, 5,
10 phr) and N, N-m-phenylenedimaleimide coagent were prepared.
from the obtained results we can conclude the following:
1- The effect of irradiation dose on the values of the TS for the
all nanocomposites increased with increasing irradiation dose
reaching their maximum values at about 50 kGy and after that,
the values of TS decreased on increasing the irradiation dose
up to 200 kGy. Whereas the values of (E %) for the all
nanocomposites decreased with increasing the irradiation dose.
2- The nanocomposite containing 5 phr modified cerium oxide
has the highest tensile strength and the lowest elongation over
the all irradiation doses considered.
3- The tensile strength values of the nanocomposites containing
coagent are better compared with those obtained for samples
without coagent at the all absorbed doses considered. The
increase of tensile strength value at the low irradiation doses is
higher than that at high irradiation doses.
4- The values of solubility of EPDM nanocomposites decreased
with the increase of the irradiation dose from 25 kGy to 50
kGy and the rate of decreasing of the solubility is high in the
range of the irradiation dose from 50 kGy to 100 kGy then
decreased with slow rate up to 200 kGy.5- The values of solubility for the EPDM nanocomposite
containing 5 phr cerium oxide were lower than those of the
others nanocomposites over the all irradiation doses range.
6- The solubility value decreased by increasing the cerium oxide
concentration up to 5 phr cerium oxide after that solubility
increased by increasing cerium oxide concentration.
7- The SW value decreased with increasing irradiation doses
8- The swelling value of the nanocomposite containing 5 phr
cerium oxide is the lowest.
9- The nanocomposites containing coagent has lower swelling
and solubility values than the nanocomposites without coagent.
10- The nanocomposites irradiated to 50 kGy have the best
mechanical properties; hence the thermal, electrical and
morphology of the nanocomposites irradiated to 50 kGy have
been studied.
11- The volume resistivity increased with increasing the level of
cerium oxide. Hence, the nanocomposite containing 10 phr of
cerium oxide has the highest volume resistivity.
12- The volume resistivity decreased by the addition of 5 phr N,
N-m-phenylenedimaleimide coagent and irradiated to 50 kGy.
13- The TG and DTG curves shafted to higher temperature with
the addition of cerium oxide, Tcomp and Tmax of the
nanocomposites increased also. This indicates that the thermal
stability of the samples is increased with the increasing of
cerium oxide content in the nanocomposites.
14- All the nanocomposites exhibit high initial weight loss
temperature (Tonset) up to 390 0C, indicating high thermal
stability.15- The temperature of the initial loss, Tonset of the composites
raised with the increase of cerium oxide content; i.e, the
T onset, of the sample containing 10 phr cerium oxide was 20 °C
higher than that of the sample without cerium oxide.
16- T10%, Tmax and Tcomp of the sample containing 10 phr cerium
oxide are 20 °C, 14 °C, and 23 °C higher than those of
nanoclay only, respectively.
17- The char residue formation and the activation energy of the
nanocomposites have been increased with the increase of
cerium oxide content in the samples.
18- The Tonset, Tmax and Tcomp temperatures of the nanocomposites
with coagent shifted towards higher temperature compared to
those of the nanocomposites without coagent, indicating the
enhancement of thermal stability of nanocomposites with
coagent.
19- It can be generally concluded that EPDM/nanoclay and cerium
oxide composites, enhanced with coagent and irradiated to 50
kGy are characterized by having good thermal and electrical
insulation properties and hence, it may has wide industrial
applications as good thermal and electrical insulating
materials.