samples, a cooling rate of 0.20
C/min was used; the heating rate was 0.25
C/min.
For the elution step, a flow rate of 0.75 mL/min was used.
The TREF-FTIR curve of a random EO copolymer is presented in Fig. 2.10.
‘dWf/dT’ is the differential mass per temperature increment; the accumulative
weight fraction is calculated based on the mass profile. The comonomer content
is expressed as CH 3 /1,000C.
Figure 2.10 shows a typical TREF profile with a component that elutes at high
temperature, producing a sharp elution peak and a range of components that elute in
a broad peak between 30
C and 90
C. A different TREF profile is obtained for a
blocky EO copolymer produced by chain shuttling technology, see Fig. 2.11
[50]. This sample shows no elution peak at high temperature but a broad elution
peak between 30
C and 90
C. Different from the random sample, the olefin block
copolymer exhibits a narrow elution peak at 25
C.
The TREF curve of the random EO copolymer is quite representative for a
LLDPE. The online FTIR detection shows that the octene content of the copolymer
decreases with increasing TREF elution temperature. The highest eluting fraction
does not contain octene and is, therefore, PE. The elution temperature of 96
C is in
agreement with linear (high density) PE. The copolymer components eluting
between 30
C and 90
C are due to EO copolymer molecules with different EO
contents. The lowest eluting fractions have an octene content of about 40 CH 3 /
1,000C. It is interesting to note that the TREF elution temperature is linearly
dependent on the octene content of the copolymer. This makes it very easy to
produce a calibration curve that stretches towards higher octene contents. The
online FTIR detection also provides the total concentration of the sample
components. Figure 2.10 indicates that the present sample contains about 10 %
of PE.
Fig. 2.10 TREF–FTIR profile of a random EO copolymer (reprinted from [46] with permission of
Wiley-VCH)
24
2 Crystallization-Based Fractionation Techniques
C/min was used; the heating rate was 0.25
C/min.
For the elution step, a flow rate of 0.75 mL/min was used.
The TREF-FTIR curve of a random EO copolymer is presented in Fig. 2.10.
‘dWf/dT’ is the differential mass per temperature increment; the accumulative
weight fraction is calculated based on the mass profile. The comonomer content
is expressed as CH 3 /1,000C.
Figure 2.10 shows a typical TREF profile with a component that elutes at high
temperature, producing a sharp elution peak and a range of components that elute in
a broad peak between 30
C and 90
C. A different TREF profile is obtained for a
blocky EO copolymer produced by chain shuttling technology, see Fig. 2.11
[50]. This sample shows no elution peak at high temperature but a broad elution
peak between 30
C and 90
C. Different from the random sample, the olefin block
copolymer exhibits a narrow elution peak at 25
C.
The TREF curve of the random EO copolymer is quite representative for a
LLDPE. The online FTIR detection shows that the octene content of the copolymer
decreases with increasing TREF elution temperature. The highest eluting fraction
does not contain octene and is, therefore, PE. The elution temperature of 96
C is in
agreement with linear (high density) PE. The copolymer components eluting
between 30
C and 90
C are due to EO copolymer molecules with different EO
contents. The lowest eluting fractions have an octene content of about 40 CH 3 /
1,000C. It is interesting to note that the TREF elution temperature is linearly
dependent on the octene content of the copolymer. This makes it very easy to
produce a calibration curve that stretches towards higher octene contents. The
online FTIR detection also provides the total concentration of the sample
components. Figure 2.10 indicates that the present sample contains about 10 %
of PE.
Fig. 2.10 TREF–FTIR profile of a random EO copolymer (reprinted from [46] with permission of
Wiley-VCH)
24
2 Crystallization-Based Fractionation Techniques