*3.1.2. Dielectric constant and dissipation factor*

DC and DF were measured as per ASTM D 150 (IEC 60250) at 1 MHz. The sample dimensions were 5 × 5 × 0.3 cm.

### **3.2. Physicochemical investigations**

also to identify the elemental composition, scanning electron microscope (SEM) analysis and energy dispersive X-ray analysis (EDXA) were performed on SiR–EPDM blends. The effects of electron beam irradiation on the dielectric parameters of various compositions of SiR–

Commercially, available SiR and EPDM were used. Type of SiR-polydimethyl siloxane (PDMS). The composition of EPDM is ethylene-65%; propylene-25%; diene monomer-10%. Diene type is ethylidene norbornene (ENB). They are supplied by M/S Joy Rubbers, India. The

The five different compositions of SiR–EPDM blends were irradiated up to 5, 15 and 25 Mrad doses using an electron beam accelerator of 1.5 MeV rating at M/S Siechem Industries,

In order to analyze the dielectric behavior of SiR–EPDM blends in harmful environments,

As per standard ASTM D 149 (IEC 60243), BDV and DS were measured. The sample dimen‐ sions of 5 × 5 × 0.3 cm were placed between two electrodes, and the voltage was increased at a fixed rate of 500 V/s. The voltage at which dielectric breakdown occurs was measured as

five different compositions of SiR–EPDM blends were prepared [1–4, 9].

EPDM blends were reported.

**2.1. Preparation of SiR–EPDM blends**

**1.** Blend A—SiR 90%/EPDM 10%.

**2.** Blend B—SiR 70%/EPDM 30%.

**3.** Blend C—SiR 50%/EPDM 50%.

**4.** Blend D—SiR 30%/EPDM 70%.

**5.** Blend E—SiR 10%/EPDM 90%.

**3. Characterization of SiR–EPDM blends**

blends have been tested as per ASTM/IEC standards.

*3.1.1. Breakdown voltage and dielectric strength*

**2.2. Electron beam irradiation**

**3.1. Dielectric characterization**

BDV. DS was calculated.

Pondicherry, India.

**2. Experimental**

94 Radiation Effects in Materials

Various physicochemical techniques such as FTIR, EDXA and SEM were used to identify the nature of changes in the electron beam irradiated samples of SiR–EPDM blends.
