fractionation occurs more or less strictly regarding the ethylene content of the
samples; see Fig. 3.26a, b. In CRYSTAF, on the other hand, fractionation occurs
regarding longer (crystallizable) homopolymer sequences. This is true for longer
propylene (low ethylene content) as well as longer ethylene (high ethylene content)
sequences; see Fig. 3.26c.
3.2.3 Analysis of 1-Alkene Copolymers [87]
Besides ethylene and propylene homo- and copolymers, the copolymers of these
monomers with higher 1-alkenes play an important role in technical applications.
The most important materials of this group are copolymers of ethylene and
1-butene, 1-hexene or 1-octene. They are known as linear low-density
polyethylenes (LLDPE) and they are mainly used as films in packaging. Other
interesting materials, although not frequently used in technical applications yet, are
copolymers of propylene with higher 1-alkenes.
3.2.3.1 Aim
Solvent gradient interaction chromatography has been shown to be a powerful tool
for the separation of olefin copolymers according to chemical composition. In
Sect. 3.2.2 the fractionation of ethylene-propylene copolymers has been presented.
In the present section, the fractionation of copolymers with higher 1-alkenes shall
be discussed. The focus will be on propylene copolymers with 1-butene, 1-hexene,
1-octene, 1-tetradecene and 1-octadecene. The behaviour of these copolymers will
be compared to the behaviour of ethylene-1-hexene copolymers which are typical
LLDPEs.
3.2.3.2 Materials
• Polymers. Copolymers of various origins were used. Their comonomer contents
and molar masses are summarized in Table 3.6.
3.2.3.3 Equipment
• Chromatographic system. High-temperature chromatograph PL-GPC 210 (Polymer Labs, Church Stretton, UK) containing a gradient HPLC pump model 1200
(Agilent). The flow rate was 0.5 mL/min; samples were dissolved in 1-decanol.
• Columns. Hypercarb (Thermo Scientific, Dreieich, Germany), 100 mm  4.6 mm
i.d., average particle size 5 μm, surface area 120 m
2 /g, average pore size 120 A ˚ .
• Mobile phase. 1-decanol-TCB.
• Detectors. ELSD PL-ELS 1000 (Polymer Laboratories, Church Stretton,
England). The air flow rate was 1.5 L/min, the nebulizer temperature was
160
C and the evaporator temperature was 260
C.
• Column temperature. 160
C.
• Sample concentration. 1–2 mg/mL. All samples were dissolved in 1-decanol.
• Injection volume. 13 μL.
3.2 Solvent Gradient Interaction Chromatography
107
samples; see Fig. 3.26a, b. In CRYSTAF, on the other hand, fractionation occurs
regarding longer (crystallizable) homopolymer sequences. This is true for longer
propylene (low ethylene content) as well as longer ethylene (high ethylene content)
sequences; see Fig. 3.26c.
3.2.3 Analysis of 1-Alkene Copolymers [87]
Besides ethylene and propylene homo- and copolymers, the copolymers of these
monomers with higher 1-alkenes play an important role in technical applications.
The most important materials of this group are copolymers of ethylene and
1-butene, 1-hexene or 1-octene. They are known as linear low-density
polyethylenes (LLDPE) and they are mainly used as films in packaging. Other
interesting materials, although not frequently used in technical applications yet, are
copolymers of propylene with higher 1-alkenes.
3.2.3.1 Aim
Solvent gradient interaction chromatography has been shown to be a powerful tool
for the separation of olefin copolymers according to chemical composition. In
Sect. 3.2.2 the fractionation of ethylene-propylene copolymers has been presented.
In the present section, the fractionation of copolymers with higher 1-alkenes shall
be discussed. The focus will be on propylene copolymers with 1-butene, 1-hexene,
1-octene, 1-tetradecene and 1-octadecene. The behaviour of these copolymers will
be compared to the behaviour of ethylene-1-hexene copolymers which are typical
LLDPEs.
3.2.3.2 Materials
• Polymers. Copolymers of various origins were used. Their comonomer contents
and molar masses are summarized in Table 3.6.
3.2.3.3 Equipment
• Chromatographic system. High-temperature chromatograph PL-GPC 210 (Polymer Labs, Church Stretton, UK) containing a gradient HPLC pump model 1200
(Agilent). The flow rate was 0.5 mL/min; samples were dissolved in 1-decanol.
• Columns. Hypercarb (Thermo Scientific, Dreieich, Germany), 100 mm  4.6 mm
i.d., average particle size 5 μm, surface area 120 m
2 /g, average pore size 120 A ˚ .
• Mobile phase. 1-decanol-TCB.
• Detectors. ELSD PL-ELS 1000 (Polymer Laboratories, Church Stretton,
England). The air flow rate was 1.5 L/min, the nebulizer temperature was
160
C and the evaporator temperature was 260
C.
• Column temperature. 160
C.
• Sample concentration. 1–2 mg/mL. All samples were dissolved in 1-decanol.
• Injection volume. 13 μL.
3.2 Solvent Gradient Interaction Chromatography
107