Compounding, sheeting and vulcanization of rubber blends
were carried out in accordance with ASTM D3182. All rubber
blends were prepared on a two-roll laboratory mill (diameter
200 mm and working distance of 750 mm). The roll temperature
was kept at 70 1C during mixing. Mixing time was 12 min andmixing speed was 60 rpm. After compounding, the sheeted rubber
compounds were conditioned at a temperature of 23 1C for 24 h.
For sulfur curing, cure characteristics of mixes, scorch time (tS2),
cure time (tC90), minimum torque (ML) and maximum torque
(MH) were determind using a Hiwa Rheometer model 100
according to ASTM D2084. Sulfur curing was carried out in an
electrically heated press at 160 1C under pressure (1 MPa) to
obtain optimum cure time to prepare sheets (2 mm thick).
Dumbbell test specimens were cut from the sheets. For electron
beam curing, fixed formulation of master batch compounds was
compression-molded between aluminum foil at 160 1C under
pressure (1 MPa) in an electrically heated press to prepare sheets
of 2 mm thickness. Dumbbell shape test specimens were cut from
the sheets. The samples were marked 100–400 referring to
irradiation in kGy