2.3.4. X-ray diffraction
Wide angle X-ray diffraction (WAXS) was used to
evaluate the influence of peroxide on the PP crystal
structure in the blend. WAXS was carried out in
Philips PW 1710 diffractometer (CuKα target). The
samples were scanned from 2θ = 10 to 50° with a
scanning rate of 30°/min.
2.3.5. Recycling study
The compression moulded TPV samples were
again melt-mixed in the internal mixer for 4 minutes.
Then they were remolded and finally properties
after recycling were determined.
2.3.6. Ageing test
Ageing test was carried out keeping the TPV samples
in an ageing oven at 100°C for 72 hours.
3. Results and discussion
3.1. Influence of peroxide at a fixed blend
ratio
3.1.1. Mechanical properties
Table 1 shows TPV compositions with different
DCP concentrations (0–3 phr) at a fixed blend ratio
and Table 2 shows their corresponding mechanical
properties. In this case, 10 phr (previously optimized
concentration) of m-PP was used as a compatibilizer
for m-EPM and PP blends; since
m-EPM is polar in nature whereas PP is a non-polar
polymer.
From Table 2, it is seen that tensile strength of m-
EPM based TPVs varies from 3.5 to 7.3 MPa and
elongation at break varies from 120 to 240%. Tensile
strength and elongation reach a maximum at
2 phr of DCP concentration. During vulcanization,
two competing processes take place simultaneously
in presence of DCP. One is cross-linking in rubber
529
Chatterjee and Naskar – eXPRESS Polymer Letters Vol.1, No.8 (2007) 527–534
( ) [mol/ml]
0.5·
ln 1
·
1
1/3
2
r r
r r r
s V V
V V V
V −
ν = − − + + χ
Table 1. TPV compositions (in parts per hundred rubber or
phr) with different DCP concentrations at a fixed
m-EPM/ PP blend ratio
Components N-01 N-02 N-03 N-04 N-05 N-06
m-EPM 100 100 100 100 100 100
PP 60 60 60 60 60 60
m-PP 10 10 10 10 10 10
Paraffinic oil 25 25 25 25 25 25
DCP (98%) 0 1.0 1.5 2.0 2.5 3.0
TAC (50%) 0 4 4 4 4 4