**5.1. Dielectric performance of virgin and electron beam irradiated SiR–EPDM blends**

For SiR–EPDM blends, it has been observed that cross-linking and chain scission may modify the macromolecular chains of the material. The consequence is the change in the dielectric parameters of the material. The effect of dominant mechanism can be noted from the changes in dielectric parameters.

#### **5.2. FTIR analysis**

FTIR spectra of electron beam irradiated samples of SiR–EPDM blends were obtained to identify the mechanism for the change in dielectric parameters after the electron beam irradiation. FTIR spectra of the virgin and electron beam irradiated samples of three compo‐ sitions of SiR–EPDM blends are depicted in **Figures 5**–**7** respectively.

**Figure 5.** FTIR spectra of electron beam irradiated samples of blend A. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

The FTIR investigations on electron beam radiated samples revealed that the radiation has induced the chemical and morphological changes. The variation in dielectric parameters was validated through FTIR spectra. It depicts the occurrence of new functional groups along with the % absorbance and the corresponding wave number. **Tables 1** and **2** list the correlation of variation in dielectric parameters of electron beam irradiated samples of SiR rich blends and EPDM rich blends and blend C using FTIR respectively.

**5. Discussion**

98 Radiation Effects in Materials

in dielectric parameters.

**5.2. FTIR analysis**

**5.1. Dielectric performance of virgin and electron beam irradiated SiR–EPDM blends**

For SiR–EPDM blends, it has been observed that cross-linking and chain scission may modify the macromolecular chains of the material. The consequence is the change in the dielectric parameters of the material. The effect of dominant mechanism can be noted from the changes

FTIR spectra of electron beam irradiated samples of SiR–EPDM blends were obtained to identify the mechanism for the change in dielectric parameters after the electron beam irradiation. FTIR spectra of the virgin and electron beam irradiated samples of three compo‐

**Figure 5.** FTIR spectra of electron beam irradiated samples of blend A. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

EPDM rich blends and blend C using FTIR respectively.

The FTIR investigations on electron beam radiated samples revealed that the radiation has induced the chemical and morphological changes. The variation in dielectric parameters was validated through FTIR spectra. It depicts the occurrence of new functional groups along with the % absorbance and the corresponding wave number. **Tables 1** and **2** list the correlation of variation in dielectric parameters of electron beam irradiated samples of SiR rich blends and

sitions of SiR–EPDM blends are depicted in **Figures 5**–**7** respectively.

**Figure 6.** FTIR spectra of electron beam irradiated samples of blend C. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

**Figure 7.** FTIR spectra of electron beam irradiated samples of blend E. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.


**Table 1.** Correlation of variation of dielectric parameters of electron beam irradiated samples of SiR rich blends using FTIR.

The BDV, DS, and DF of the SiR rich blends (A and B) found to reduce for all doses of electron beam irradiation. This is due to the disappearance of acid (COOH) group in them. The BDV and DS of the blend C is improved for all doses of electron beam irradiation. This is due to the appearance of Si–O–Si group at 1019, 1018, and 1019 cm−1 with 29, 20, and 23% absorbance in it. The dielectric constant is improved at 5 Mrad. This may be due to the appearance of =C–H (Alkene, bending, strong). The DF has been reduced at 15 Mrad. This may be due to the disappearance of =C–H (Alkene, bending, strong). The maximum improvement in DC of blend D occurred at 5 Mrad. This may be due to the increase in Si–O–Si group at 1018 cm−1 with 34% absorbance and also due to the shifting of alcohol (OH)-free group to higher wave number [16– 18]. The maximum improvement in DC of blend E has occurred at 25 Mrad. This may be due to the increase in alcohol (OH)-free group at 3795 cm−1 with 138% absorbance.



**Table 2.** Correlation of variation of dielectric parameters of electron beam irradiated samples of EPDM rich blends and blend C using FTIR.

#### **5.3. EDXA analysis**

**Behavior of dielectric parameter/doses**

B → Improvement in DC at 25 Mrad

100 Radiation Effects in Materials

Reduction in BDV, DS and DF

A → Reduction in DC

**Behavior of dielectric parameter/**

except at 15 Mrad D → 3445 cm−1 Improvement in DC at 5 Mrad

Improvement in BDV, DS Improvement in DF

FTIR.

**doses**

C (50:50)

Alcohol(OH) bonded, strong,

broad A → 3433 cm−1 with 150% B → 3427 cm−1 with 116% Si–O–Si A →1018 cm−1 with 18% B →1018 cm−1 with 10%

**5 Mrad 15 Mrad 25 Mrad**

Alcohol(OH) bonded, strong, broad A → 3427 cm−1 with 150% Alcohol(OH) bonded, strong, broad

A → 3438 cm−1 with 150% B → 3429 cm−1 with 150%

A → 1020 cm−1 with 4% B → 1018 cm−1 with 49%

Si–O–Si

B → 3446 cm−1 with

A → 1019 cm−1 with 15% B → 1018 cm−1 with 2%

Absence of alcohol (OH)-free, strong, sharp group and acid (COOH) group

**Table 1.** Correlation of variation of dielectric parameters of electron beam irradiated samples of SiR rich blends using

The BDV, DS, and DF of the SiR rich blends (A and B) found to reduce for all doses of electron beam irradiation. This is due to the disappearance of acid (COOH) group in them. The BDV and DS of the blend C is improved for all doses of electron beam irradiation. This is due to the appearance of Si–O–Si group at 1019, 1018, and 1019 cm−1 with 29, 20, and 23% absorbance in it. The dielectric constant is improved at 5 Mrad. This may be due to the appearance of =C–H (Alkene, bending, strong). The DF has been reduced at 15 Mrad. This may be due to the disappearance of =C–H (Alkene, bending, strong). The maximum improvement in DC of blend D occurred at 5 Mrad. This may be due to the increase in Si–O–Si group at 1018 cm−1 with 34% absorbance and also due to the shifting of alcohol (OH)-free group to higher wave number [16– 18]. The maximum improvement in DC of blend E has occurred at 25 Mrad. This may be due

**5 Mrad 15 Mrad 25 Mrad**

EPDM rich blends (D and E) Absence of =C–H Alcohol(OH) free, Alcohol(OH) bonded, strong,

Improvement in =C–H (Alkene), bending

strong at 673 cm−1 with 11%

group at 1416 cm−1 with 16%

Si–O–Si group at 1019 cm−1 with 23% (C–H) alkane

to the increase in alcohol (OH)-free group at 3795 cm−1 with 138% absorbance.

Absence of =C–H (Alkene),

bending strong

150% Si–o–Si

> **Figures 8**–**1**0 show the EDXA curves of the electron beam irradiated samples of blends A, C, and E respectively. The inferences from EDXA curves of all the irradiated samples of SiR– EPDM blends are listed in **Tables 3**and **4**.

**Figure 8.** EDXA curves of electron beam irradiated samples of blend A. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

**Figure 9.** EDXA curves of electron beam irradiated samples of blend C. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

**Figure 10.** EDXA curves of electron beam irradiated samples of blend E. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.


**Table 3.** Inferences from EDXA curves of electron beam irradiated samples of SiR rich blends (A and B).


**Table 4.** Inferences from EDXA curves of electron beam irradiated samples of EPDM rich blends (D and E) and blend C.

#### **5.4. Correlation of EDXA results with FTIR**

**Figure 9.** EDXA curves of electron beam irradiated samples of blend C. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

102 Radiation Effects in Materials

**Figure 10.** EDXA curves of electron beam irradiated samples of blend E. (a) 5 Mrad, (b) 15 Mrad and (c) 25 Mrad.

The interpretations between EDXA and FTIR of the electron beam irradiated samples of SiR– EPDM blends are listed in **Tables 5**–**7**.


**Table 5.** Interpretation between EDXA and FTIR of the electron beam irradiated samples of blend A.


**Table 6.** Interpretation between EDXA and FTIR of the electron beam irradiated samples of blend C.


**Table 7.** Interpretation between EDXA and FTIR of the electron beam irradiated samples of blend E.

#### **5.5. SEM analysis**

**Figure 11** (a1, b1, c1, d1, e1) and (a2, b2, c2, d2 , e2) are the SEM micrographs of the electron beam irradiated samples of SiR–EPDM blends exposed to 15 Mrad dose of electron beam irradiation for a magnification of 500 and 4000 respectively.

**Figure 12** (a1, b1, c1, d1, e1) and (a2, b2, c2, d2, e2) are the SEM micrographs of the electron beam irradiated samples of SiR–EPDM blends exposed to 25 Mrad dose of electron beam irradiation for a magnification of 500 and 4000 respectively.

It is observed from **Figure 1**1(a1, a2) that the surface of SiR rich blend (A) has larger number of cracks. This may be due to the decrease in silicon content for 15 Mrad dose of electron beam irradiation (inferred from EDXA analysis), but the surface of blend B and EPDM rich blends (D and E) has smaller number of cracks. This is validated through the increase in oxygen and silicon concentrations (inferred from EDXA analysis). The surface of blend C has smaller cracks. This may be due to the reduction in oxygen and silicon concentrations. The availability of white particles on the surface of the blends B, D, and E may be due to the decrease in carbon content in them (inferred from EDXA curves).

Electron Beam Irradiation Effects on Dielectric Parameters of SiR–EPDM Blends http://dx.doi.org/10.5772/62624 105

**Inference from EDXA 5 Mrad 15 Mrad 25 Mrad**

Appearance of C–H (alkane),

Appearance of C=C (asymmetric, stretch, strong)/C–H (alkane), bending, strong/=C–H (alkene),

bending, strong

Increase in Si–CH3–CH2/Si–H content

bending ,strong

Increase in CH3–CH2–CH Appearance of C=C (asymmetric, stretch,

Absence of Si–H (amorphous Si)

Absence of acid COOH group

**Table 6.** Interpretation between EDXA and FTIR of the electron beam irradiated samples of blend C.

**Inference from EDXA 5 Mrad 15 Mrad 25 Mrad**

**Table 7.** Interpretation between EDXA and FTIR of the electron beam irradiated samples of blend E.

**Figure 11** (a1, b1, c1, d1, e1) and (a2, b2, c2, d2 , e2) are the SEM micrographs of the electron beam irradiated samples of SiR–EPDM blends exposed to 15 Mrad dose of electron beam

**Figure 12** (a1, b1, c1, d1, e1) and (a2, b2, c2, d2, e2) are the SEM micrographs of the electron beam irradiated samples of SiR–EPDM blends exposed to 25 Mrad dose of electron beam

It is observed from **Figure 1**1(a1, a2) that the surface of SiR rich blend (A) has larger number of cracks. This may be due to the decrease in silicon content for 15 Mrad dose of electron beam irradiation (inferred from EDXA analysis), but the surface of blend B and EPDM rich blends (D and E) has smaller number of cracks. This is validated through the increase in oxygen and silicon concentrations (inferred from EDXA analysis). The surface of blend C has smaller cracks. This may be due to the reduction in oxygen and silicon concentrations. The availability of white particles on the surface of the blends B, D, and E may be due to the decrease in carbon

Absence of acid (–COOH) group

(amorphous Si) Increase in Si–CH3– CH2/Si–H content

Increase in oxygen content Increase in alcohol (–OH)-free group content

irradiation for a magnification of 500 and 4000 respectively.

irradiation for a magnification of 500 and 4000 respectively.

content in them (inferred from EDXA curves).

strong)

Increase in silicon content Appearance of Si–H

Increase in carbon

104 Radiation Effects in Materials

Decrease in silicon content except at 5

Decrease in oxygen

Decrease in carbon

**5.5. SEM analysis**

content

Mrad

content

content

**Figure 11.** SEM micrographs of electron beam irradiated (15 Mrad) samples of SiR–EPDM blends. 11 (a1), 11 (b1), 11 (c1), 11 (d1) and 11 (e1) -500 magnification; 11 (a2), 11 (b2), 11 (c2), 11 (d2) and 11 (e2) -4000 magnification.

**Figure 12.** SEM micrographs of electron beam irradiated (25 Mrad) samples of SiR–EPDM blends. 12 (a1), 12 (b1), 12 (c1), 12 (d1) and 12 (e1) – 500 magnification; 12 (a2), 12 (b2), 12 (c2), 12 (d2) and 12 (e2) – 4000 magnification.

It is observed from **Figure 1**2(a1, b1) that the surface of SiR rich blend (A) has large number of cracks. This may be due to the decrease in silicon content for 25 Mrad dose of electron beam irradiation (inferred from EDXA analysis), but the surface of blend B and EPDM rich blends (D and E) has smaller number of cracks. This is validated through the increase in oxygen and silicon concentrations from EDXA analysis. The surface smoothness of blend C is moderate. This may be due to the reduction in oxygen and silicon concentrations.
