Figure 19 shows the dielectric constant (top) and dielectric loss (bottom) of several
PP–OH copolymers (I) (Scheme 3) containing 0, 0.7, 1.8, and 4.2 mol% OH comonomer units, as well as the BOPP reference [69]. The dielectric constant increases
proportionally with the OH content. The ε value of PP–OH-3 with 4.2 mol% of the
OH comonomer content reaches about 4.6 (more than twice that of BOPP). It was a
pleasant surprise to observe all PP–OH dielectric profiles resembling the PP profile,
with a dielectric constant that is independent over a wide range of frequencies (between
100 and 1 MHz) and temperatures (between À20 and 100
C). These overlapping and
flat dielectric constant lines imply a fast polarization response for the PP–OH (I)
5
4
3
a
b
PP-OH-3
PP-OH-2
PP-OH-1
PP-OH-3
PP
Dielectric Constant
c
d
2
0
2 0
4 0
Temperature °C
Temperature °C
60
80
100
Hz
100
1K
10K
100K
1M
Hz
1K
10K
100K
1M
-20
0.10
0.08
0.06
0.04
tan
δ
0.02
0.00
-20
0
20
40
60
80
100
Fig. 19 (Top) Dielectric constants and (bottom) D–E loops for (a) PP and three PP–OH
copolymers containing (b) 0.7, (c) 1.8, and (d) 4.2 mol% OH content
270
T.C.M. Chung