**4. Results**

### **4.1. Dielectric characterization of virgin SiR–EPDM blends**

The virgin SiR rich blends (A and B) have higher breakdown voltage (BDV) and dielectric strength (DS), when compared to remaining blends. This may be due to the occurrence of maximum self cross-linking during the blending process itself. During the blending process, the cross-linking reaction has taken place between the side chains of SiR and EPDM. The blend C and EPDM rich blends (D and E) were found to have lesser values of BDV, DS, and higher values of DC and DF in comparison with SiR rich blends (A and B).

### **4.2. Effect of electron beam irradiation on dielectric behavior of SiR–EPDM blends**

#### *4.2.1. Effect on breakdown voltage and dielectric strength*

**Figures 1** and **2** depict the variations in breakdown voltage and dielectric strength of five different compositions of SiR–EPDM for various doses of electron beam irradiation.

**Figure 1.** Variations in breakdown voltage of SiR–EPDM blends for various doses of electron beam irradiation.

**Figure 2.** Variations in dielectric strength of SiR–EPDM blends for various doses of electron beam irradiation.

The BDV and DS of SiR-rich blends (A and B) and EPDM-rich blends (D and E) reduced for all doses of electron beam. The BDV and DS of the blend C improved for all doses of electron beam. The DC of the blend D and E has been improved at 5 and 5/25 Mrad respectively.

#### *4.2.2. Effect on dielectric constant and dissipation factor measurement*

**Figures 3** and **4** depict the variations in dielectric constant and dissipation factor of five different compositions of SiR–EPDM blends for various doses of electron beam irradiation.

**Figure 3.** Variations in dielectric constant of SiR–EPDM blends for various doses of electron beam irradiation.

**Figure 1.** Variations in breakdown voltage of SiR–EPDM blends for various doses of electron beam irradiation.

96 Radiation Effects in Materials

**Figure 2.** Variations in dielectric strength of SiR–EPDM blends for various doses of electron beam irradiation.

*4.2.2. Effect on dielectric constant and dissipation factor measurement*

The BDV and DS of SiR-rich blends (A and B) and EPDM-rich blends (D and E) reduced for all doses of electron beam. The BDV and DS of the blend C improved for all doses of electron beam. The DC of the blend D and E has been improved at 5 and 5/25 Mrad respectively.

**Figures 3** and **4** depict the variations in dielectric constant and dissipation factor of five different compositions of SiR–EPDM blends for various doses of electron beam irradiation.

**Figure 4.** Variations in dissipation factor of SiR–EPDM blends for various doses of electron beam irradiation.

The DC of the blend A reduced for all doses of electron beam. The DC of blend B reduced at 5 and 15 Mrad. The DF of SiR-rich blends (A and B) reduced for all doses of electron beam. The DC and DF of the blend C improved at 5 and 15 Mrad respectively. The blend D has the improved DF at 25 Mrad.
