applications of LLDPE, random copolymers of propylene and higher α-olefins are
less frequently investigated and used. Most of the work that has been done over the
years has dealt with copolymers of propylene and ethylene, one example being
IPCs; see, e.g. Sect. 2.1.2.
As has been discussed earlier (Sect. 2.2.1) there is a direct correlation between
the crystallization temperature and the copolymer composition. This has been
documented for LLDPEs with butene, hexene or octene as comonomers. The
crystallization behaviour of random copolymers of ethylene was reviewed by
Alamo and Mandelkern [111]. According to them, a linear relationship describes
the melting temperature of ethylene/higher α-olefin copolymers versus the comonomer content up to 4 mol%. The type of comonomer has no effect on the melting
temperature. In agreement with these findings, the CRYSTAF and TREF analysis
of narrow LLDPE fractions revealed a linear correlation between crystallization
temperature and comonomer content [8, 16]. The CRYSTAF and TREF apparatus
were calibrated by the crystallization temperature of single-site ethylene-1-octene
(EO) copolymers and the calibration was subsequently used for the analysis of
broadly distributed industrial LLDPE samples [103].
2.2.3.1 Aim
There are numerous studies on the melting and crystallization behaviour of
ethylene-α-olefin copolymers. However, copolymers based on propylene have not
received much attention. In the present study, these copolymers shall be
investigated by DSC and CRYSTAF. The influence of the comonomer shall be
investigated for propylene copolymers with 1-octene, 1-decene, 1-tetradecene and
1-octadecene.
2.2.3.2 Materials
• Polymers. The copolymerizations were conducted according to the procedure
described in [110]. The catalyst was (CH 3 ) 2 Si(2-methylbenz[e]indenyl)ZrCl 2 .
The copolymer compositions are summarized in Table 2.6. The molar masses
were determined by SEC.
2.2.3.3 Equipment
• CRYSTAF system. CRYSTAF instrument model 200 (Polymer Char, Valencia,
Spain).
• Detector. Built-in dual wavelength IR detector with heated flow-through micro
cell at 150
C.
• Solvent. TCB.
• Crystallization protocol. Crystallization between 100
C and 30
C at a rate of
0.1
C/min.
• Sample concentration. 20 mg in 30 mL TCB.
• DSC. Pyris 1 (Perkin-Elmer, Waltham, USA). Samples were cooled to À50
C
and then heated to 180
C. From 180
C, samples were again cooled to À50
C.
The cooling rate was kept at 10
C/min. T c was determined from the maximum
60
2 Crystallization-Based Fractionation Techniques
less frequently investigated and used. Most of the work that has been done over the
years has dealt with copolymers of propylene and ethylene, one example being
IPCs; see, e.g. Sect. 2.1.2.
As has been discussed earlier (Sect. 2.2.1) there is a direct correlation between
the crystallization temperature and the copolymer composition. This has been
documented for LLDPEs with butene, hexene or octene as comonomers. The
crystallization behaviour of random copolymers of ethylene was reviewed by
Alamo and Mandelkern [111]. According to them, a linear relationship describes
the melting temperature of ethylene/higher α-olefin copolymers versus the comonomer content up to 4 mol%. The type of comonomer has no effect on the melting
temperature. In agreement with these findings, the CRYSTAF and TREF analysis
of narrow LLDPE fractions revealed a linear correlation between crystallization
temperature and comonomer content [8, 16]. The CRYSTAF and TREF apparatus
were calibrated by the crystallization temperature of single-site ethylene-1-octene
(EO) copolymers and the calibration was subsequently used for the analysis of
broadly distributed industrial LLDPE samples [103].
2.2.3.1 Aim
There are numerous studies on the melting and crystallization behaviour of
ethylene-α-olefin copolymers. However, copolymers based on propylene have not
received much attention. In the present study, these copolymers shall be
investigated by DSC and CRYSTAF. The influence of the comonomer shall be
investigated for propylene copolymers with 1-octene, 1-decene, 1-tetradecene and
1-octadecene.
2.2.3.2 Materials
• Polymers. The copolymerizations were conducted according to the procedure
described in [110]. The catalyst was (CH 3 ) 2 Si(2-methylbenz[e]indenyl)ZrCl 2 .
The copolymer compositions are summarized in Table 2.6. The molar masses
were determined by SEC.
2.2.3.3 Equipment
• CRYSTAF system. CRYSTAF instrument model 200 (Polymer Char, Valencia,
Spain).
• Detector. Built-in dual wavelength IR detector with heated flow-through micro
cell at 150
C.
• Solvent. TCB.
• Crystallization protocol. Crystallization between 100
C and 30
C at a rate of
0.1
C/min.
• Sample concentration. 20 mg in 30 mL TCB.
• DSC. Pyris 1 (Perkin-Elmer, Waltham, USA). Samples were cooled to À50
C
and then heated to 180
C. From 180
C, samples were again cooled to À50
C.
The cooling rate was kept at 10
C/min. T c was determined from the maximum
60
2 Crystallization-Based Fractionation Techniques