regular intervals for further analysis. The degradation process was discontinued
when samples snapped or flaked on bending. The degraded films were
homogenized by shredding the film into small pieces and re-melting into a single
film for a very brief time. Films removed from the oven at advanced stages of
degradation were brittle and shattered easily. Plasticity was, however, restored
after the re-moulding process.
2.1.3.3 Equipment
• SEC. Polymer Laboratories PL 220 high temperature chromatograph (Polymer
Laboratories, Church Stretton, UK) at 150
C, equipped with three 300 Â 7.5 mm
i.d. PLgel Olexis columns and a differential RI detector. The eluent was TCB
stabilized with BHT, at a flow rate 1 mL/min. Sample concentration was 0.5 mg/
mL in TCB and the injection volume was 200 μL. Calibration was done with PS.
• FTIR Spectroscopy. Nicolet Nexus 670 FTIR spectrometer (Thermo Electron,
Waltham, USA). Spectra were recorded from 4,000 to 650 cm
À1 . Spectra 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. Data obtained during the second heating cycle
were used for thermal analysis calculations. Measurements were conducted in a
nitrogen atmosphere.
• NMR. 600 MHz Varian
unity INOVA NMR spectrometer (Varian, 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.
• TREF. In-house built preparative TREF apparatus. For crystallization, 3 g of
polymer, ca. 2 wt% Irganox 1010 (Ciba Speciality Chemicals, Switzerland) and
300 mL of solvent were placed in a glass reactor and dissolved at 130
C. The
reactor was transferred to an oil bath maintained at 130
C. As the crystallization
support, pre-heated sea sand (white quartz; Aldrich, South Africa) was added to
the reactor. The reactor was cooled at the rate of 1
C/h. A stainless steel column
was packed with the crystallized mixture and transferred to a modified GC oven.
The temperature of the oven was increased at a steady rate 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.
• CRYSTAF. CRYSTAF apparatus Model 200 (Polymer Char, Valencia, Spain).
20 mg of the sample was dissolved in 40 mL ODCB. Stainless steel reactors for
crystallization were equipped with an automatic stirring and filtration device and
crystallization was carried out under agitation. The dissolution at 160
C was
38
2 Crystallization-Based Fractionation Techniques
when samples snapped or flaked on bending. The degraded films were
homogenized by shredding the film into small pieces and re-melting into a single
film for a very brief time. Films removed from the oven at advanced stages of
degradation were brittle and shattered easily. Plasticity was, however, restored
after the re-moulding process.
2.1.3.3 Equipment
• SEC. Polymer Laboratories PL 220 high temperature chromatograph (Polymer
Laboratories, Church Stretton, UK) at 150
C, equipped with three 300 Â 7.5 mm
i.d. PLgel Olexis columns and a differential RI detector. The eluent was TCB
stabilized with BHT, at a flow rate 1 mL/min. Sample concentration was 0.5 mg/
mL in TCB and the injection volume was 200 μL. Calibration was done with PS.
• FTIR Spectroscopy. Nicolet Nexus 670 FTIR spectrometer (Thermo Electron,
Waltham, USA). Spectra were recorded from 4,000 to 650 cm
À1 . Spectra 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. Data obtained during the second heating cycle
were used for thermal analysis calculations. Measurements were conducted in a
nitrogen atmosphere.
• NMR. 600 MHz Varian
unity INOVA NMR spectrometer (Varian, 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.
• TREF. In-house built preparative TREF apparatus. For crystallization, 3 g of
polymer, ca. 2 wt% Irganox 1010 (Ciba Speciality Chemicals, Switzerland) and
300 mL of solvent were placed in a glass reactor and dissolved at 130
C. The
reactor was transferred to an oil bath maintained at 130
C. As the crystallization
support, pre-heated sea sand (white quartz; Aldrich, South Africa) was added to
the reactor. The reactor was cooled at the rate of 1
C/h. A stainless steel column
was packed with the crystallized mixture and transferred to a modified GC oven.
The temperature of the oven was increased at a steady rate 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.
• CRYSTAF. CRYSTAF apparatus Model 200 (Polymer Char, Valencia, Spain).
20 mg of the sample was dissolved in 40 mL ODCB. Stainless steel reactors for
crystallization were equipped with an automatic stirring and filtration device and
crystallization was carried out under agitation. The dissolution at 160
C was
38
2 Crystallization-Based Fractionation Techniques