while pre-heated solvent was pumped through the column. Fractions were
collected at pre-determined intervals, solvent was evaporated, fractions were
recovered by precipitation in acetone and then finally dried to a constant weight.
• Solvent. Xylene
• TREF column temperature. Temperature gradient between 130
C and 30
C.
• TREF sample concentration. 3 g of polymer in 300 mL of solvent.
• SEC. PL 220 high temperature chromatograph (Polymer Laboratories, Varian
Inc., Church Stretton, UK) at 150
C equipped with three 300 Â 7.5 mm
i.d. PLgel Olexis columns and a differential RI detector. BHT stabilized TCB
was the eluent at a flow rate of 1 mL/min. Sample concentration was 0.5 mg/mL
in TCB and injection volume in all cases was 200 μL. Narrowly distributed
polystyrene (PS) standards (Polymer Standards Service GmbH, Mainz,
Germany) were used for calibration.
• FTIR spectroscopy. Attenuated total reflectance (ATR) measurements were
recorded on a Nicolet Nexus 670 FTIR spectrometer (Thermo Electron,
Waltham, USA) with a SensIR ATR attachment, equipped with a diamond
reflective crystal, incidence angle of 45
. Spectra recorded from 4,000 to
650 cm
À1 were obtained from a collection of 64 scans at a resolution of 2 cm
À1 .
• DSC. Mettler 822 DSC instrument (Mettler Toledo, Greifensee, Switzerland),
calibrated with indium metal according to standard procedures, heating rate of
10
C/min from 25
C to 200
C. Second heating cycle data were used for
thermal analysis calculations. Measurements were carried out in a nitrogen
atmosphere.
• NMR. 600 MHz Varian
unity INOVA NMR spectrometer (Varian Inc., Palo Alto,
USA) operating at 125 MHz for carbon at 120
C, 5 mm PFG switchable
broadband probe, samples were prepared to a concentration of 6 wt% in
deuterated tetrachloroethane (Aldrich, South Africa), 90
flip angle of approximately 6 μs, continuous proton decoupling, acquisition time 1.8 s, pulse delay
time 15 s.
• SEC-FTIR. PL XT-220 (Polymer Laboratories, Church Stretton, UK) operating
at 140
C was coupled to a solvent evaporation FTIR interface LC-Transform
(Series 300, Lab Connections, Carrboro, USA), stage and nozzle temperatures
160
C and 150
C, respectively, transfer line temperature 150
C, solutes
deposited on heated germanium disc and subsequently analysed by FTIR,
analysis of SEC-FTIR results using Omnic software package (Thermo Electron,
Waltham, USA).
2.1.2.4 TREF Fractionation
The preparative TREF fractions of the sample were collected at 30
C, 60
C, 80
C,
90
C, 100
C, 110
C, 120
C and 130
C. Figure 2.12 depicts the weight
distribution (W i %) and weight fraction per temperature increment (W i %/ΔT ) of
the eight P-TREF fractions. The 30
C fraction and fractions eluting in the range
110–130
C constitute the largest weight percentage of sample 3V, as is shown by
the fractionation diagram. The principle of TREF fractionation is based on
crystallizability; therefore, fractions collected at 30
C are expected to be
2.1 Temperature Rising Elution Fractionation
27
collected at pre-determined intervals, solvent was evaporated, fractions were
recovered by precipitation in acetone and then finally dried to a constant weight.
• Solvent. Xylene
• TREF column temperature. Temperature gradient between 130
C and 30
C.
• TREF sample concentration. 3 g of polymer in 300 mL of solvent.
• SEC. PL 220 high temperature chromatograph (Polymer Laboratories, Varian
Inc., Church Stretton, UK) at 150
C equipped with three 300 Â 7.5 mm
i.d. PLgel Olexis columns and a differential RI detector. BHT stabilized TCB
was the eluent at a flow rate of 1 mL/min. Sample concentration was 0.5 mg/mL
in TCB and injection volume in all cases was 200 μL. Narrowly distributed
polystyrene (PS) standards (Polymer Standards Service GmbH, Mainz,
Germany) were used for calibration.
• FTIR spectroscopy. Attenuated total reflectance (ATR) measurements were
recorded on a Nicolet Nexus 670 FTIR spectrometer (Thermo Electron,
Waltham, USA) with a SensIR ATR attachment, equipped with a diamond
reflective crystal, incidence angle of 45
. Spectra recorded from 4,000 to
650 cm
À1 were obtained from a collection of 64 scans at a resolution of 2 cm
À1 .
• DSC. Mettler 822 DSC instrument (Mettler Toledo, Greifensee, Switzerland),
calibrated with indium metal according to standard procedures, heating rate of
10
C/min from 25
C to 200
C. Second heating cycle data were used for
thermal analysis calculations. Measurements were carried out in a nitrogen
atmosphere.
• NMR. 600 MHz Varian
unity INOVA NMR spectrometer (Varian Inc., Palo Alto,
USA) operating at 125 MHz for carbon at 120
C, 5 mm PFG switchable
broadband probe, samples were prepared to a concentration of 6 wt% in
deuterated tetrachloroethane (Aldrich, South Africa), 90
flip angle of approximately 6 μs, continuous proton decoupling, acquisition time 1.8 s, pulse delay
time 15 s.
• SEC-FTIR. PL XT-220 (Polymer Laboratories, Church Stretton, UK) operating
at 140
C was coupled to a solvent evaporation FTIR interface LC-Transform
(Series 300, Lab Connections, Carrboro, USA), stage and nozzle temperatures
160
C and 150
C, respectively, transfer line temperature 150
C, solutes
deposited on heated germanium disc and subsequently analysed by FTIR,
analysis of SEC-FTIR results using Omnic software package (Thermo Electron,
Waltham, USA).
2.1.2.4 TREF Fractionation
The preparative TREF fractions of the sample were collected at 30
C, 60
C, 80
C,
90
C, 100
C, 110
C, 120
C and 130
C. Figure 2.12 depicts the weight
distribution (W i %) and weight fraction per temperature increment (W i %/ΔT ) of
the eight P-TREF fractions. The 30
C fraction and fractions eluting in the range
110–130
C constitute the largest weight percentage of sample 3V, as is shown by
the fractionation diagram. The principle of TREF fractionation is based on
crystallizability; therefore, fractions collected at 30
C are expected to be
2.1 Temperature Rising Elution Fractionation
27