Crystallization behaviour of fractions of a copolymer of propene and 1-hexane

Pérez, Ernesto; Benavente, Rosario; Bello, A.; Pereña, José M.; Zucchi, Debora; Sacchi, Maria Carmela

doi:10.1016/s0032-3861(97)00064-5

Cited by 31 publications

(21 citation statements)

References 23 publications

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“…This might be because the comonomer unit disrupts the regularity of the chain, thus lowering the chain crystallizability and rate of crystallization; similar observations have been reported in the literature. [16] Parameters A and B were found to be relatively independent of the cooling rate used, but strongly dependent on comonomer content. The trends show that both parameters A and B decrease as comonomer content increases.…”

Section: Resultsmentioning

confidence: 91%

A Mathematical Model for the Kinetics of Crystallization in Crystaf

Anantawaraskul

Soares

Jirachaithorn

2007

Macromolecular Symposia

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Summary: A series of ethylene homopolymers and ethylene/1-hexene copolymers with different molecular weight distributions (MWD) and chemical composition distributions (CCD) was analyzed by crystallization analysis fractionation (Crystaf) at several cooling rates to investigate the effect of MWD, CCD, and cooling rate on their Crystaf profiles. Using these results, we developed a mathematical model for Crystaf that considers crystallization kinetic effects ignored in all previous Crystaf models and can fit our experimental profiles very well.

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Section: Resultsmentioning

confidence: 91%

A Mathematical Model for the Kinetics of Crystallization in Crystaf

Anantawaraskul

Soares

Jirachaithorn

2007

Macromolecular Symposia

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“…The values of r a ¼ 0.852 g Á cm À3 and r c ¼ 0.936 g Á cm À3 were used [21,22] for the amorphous and crystalline phase densities, respectively. Wide-angle X-ray scattering (WAXS) patterns were recorded in the reflection mode, at room temperature, using a Philips diffractometer with a Geiger counter, connected to a computer.…”

Section: à3mentioning

confidence: 99%

Metallocenic Isotactic Poly(propylene) and its Copolymers with 1‐Hexene and Ethylene

Arranz-Andrés

Suárez

Peña

et al. 2007

Macro Chemistry & Physics

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A comprehensive study of the structure and properties has been performed for copolymers of propylene‐1‐hexene, CiPH, and propylene‐ethylene, CiPE, synthesized by an isotactic metallocene catalyst system. The comonomer content constitutes the most important factor affecting the structure and properties of these CiPH and CiPE copolymers, although the length of the comonomer is also very important. Thus, a considerable decrease in crystallinity is observed in the two kinds of copolymers as the comonomer content increases. The structure in the CiPH copolymers evolves, however, from the typical, monoclinic crystal lattice to mesomorphic‐like, ordered entities for the highest 1‐hexene molar fraction, whereas in the CiPE copolymers the structural evolution with molar fraction goes from a monoclinic lattice to an almost amorphous material. All of these variations in crystal structure significantly influence the viscoelastic and mechanical behavior of these CiPH and CiPE copolymers. Consequently, the location and intensity of the different relaxation mechanisms, as well as the rigidity parameters (storage and Young's moduli and microhardness) and deformation mechanism are strongly dependent upon composition.magnified image

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“…The copolymers here examined have molecular weight comparable with that of homopolymer (M v ¼ 1.94 Â 10 5 Da), with the exception of the sample E/H-5, which displays a lower molecular weight. [7] Perez et al [27] have investigated the effect of molecular weight on the melting behaviour of copolymers of propene with 1-hexene and reported a depression of the melting temperature in the order of a few degrees for polymer fractions with lower molecular weight.…”

Section: Thermal Behaviourmentioning

confidence: 99%

“…Similar findings have been reported for various random copolymers of ethylene or propylene with a-olefins. [27][28][29] M. Pracella, A. D'Alessio, S. Giaiacopi, A. Raspolli Galletti, C. Carlini, G. Sbrana Figure 7.…”

Section: Crystallisation Kineticsmentioning

confidence: 99%

FTIR Microanalysis and Phase Behaviour of Ethylene/1‐Hexene Random Copolymers

Pracellà¹,

D’Alessio

Giaiacopi

et al. 2007

Macro Chemistry & Physics

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Ethylene/1‐hexene random copolymers with 1‐hexene content in the range of 1–5 mol‐%, synthesised in the presence of new heterogeneous catalyst systems based on bis‐carboxylato and ‐bis‐chloro‐carboxylato titanium chelate complexes, have been characterised by FTIR microspectroscopy (FTIR‐M), DSC calorimetry and X‐ray scattering. The co‐monomer content and sequence distribution in the various samples were determined by means of both FTIR‐M and 13C NMR spectroscopy. The deformation bands of methyl groups in the region of 1 400–1 330 cm−1 were used for the structural analysis of these copolymers. The effect of composition on the crystallinity and phase transitions of copolymers was analysed both in 1 500–1 300 and 760–690 cm−1 frequency ranges as a function of the annealing temperature. A neat variation of the absorbance ratio of methyl band at 1 378 cm−1 was recorded between 110 and 130 °C corresponding to the melting range of the copolymer crystals. The crystallisation behaviour of the copolymers was examined by DSC in dynamic and isothermal conditions; the isothermal kinetics were analysed according to the Avrami model. A marked decrease in the bulk crystallisation rate, accompanied by changes in the nucleation and growth of crystals, was found with an increase in the co‐monomer content. The melting behaviour of isothermally crystallised samples was also investigated and the melting temperatures of the copolymers at equilibrium conditions were related to the composition; the experimental data were consistent with the Flory exclusion model of side branches from the crystalline phase. The lowering of crystal growth rate in the copolymers has been accounted for by an increase in the free energy of formation of critical size nuclei due to the effect of the side branches.magnified image

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Crystallization behaviour of fractions of a copolymer of propene and 1-hexane

Cited by 31 publications

References 23 publications

A Mathematical Model for the Kinetics of Crystallization in Crystaf

A Mathematical Model for the Kinetics of Crystallization in Crystaf

Metallocenic Isotactic Poly(propylene) and its Copolymers with 1‐Hexene and Ethylene

FTIR Microanalysis and Phase Behaviour of Ethylene/1‐Hexene Random Copolymers

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