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ω
(CH
2
)
τ
(CH
2
)
1050
1100
1150
1200 1250
Raman shift (cm
-1
)
1300
1350
1400
1450
Figure 3.4
Raman spectrum of polyethylene fi lm in 1000-1500 cm
−
1
range.
10000
809 cm
-1
841 cm
-1
8000
6000
4000
2000
750
800
850
900
Raman shift (cm
-1
)
950
1000
1050
1100
Figure 3.5
Raman spectrum of an isotactic polypropylene fi lm in 750-1150 cm
−
1
range.
conformation of the chains in the crystalline region and the isomeric
defect phase, respectively. These two bands arise from the nonhelical
conformation at 830 cm
− 1
present in melt or amorphous phase. Nielsen
et al. [11] reported that the sum of band intensities at 809, 830, and
841 cm
− 1
(I
809
+ I
830
+ I
841
) is independent of chain conformation or crys-
tallinity. Therefore, the total integrated intensity under the 809- to
841 - cm
− 1
band is invariant of the state of the polymer, and is used
as a standard.
The crystallinity values of PP were calculated by dividing the inte-
grated intensity of 809- cm
− 1
peak (helical chain conformation) by the
total integrated intensity under the 809- to 841 - cm
− 1
band:
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