Structural Characterization of Syndiotactic Copolymers of Propene with 1-Butene

Rosa, Claudio De; Talarico, Giovanni; Caporaso, Lucia; Auriemma, Finizia; Galimberti, Maurizio; Fusco, Ofelia

doi:10.1021/ma981020c

Cited by 45 publications

(93 citation statements)

References 23 publications

(118 reference statements)

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“…Apparently, the characteristic crystalline peaks are present at the scattering angles 2θ = 12.18 ± 0.03 °, 15.93 ± 0.03 °, 20.64 0.11 ° and 24.56 0.04 °. By consulting all the publications dedicated to crystallographical studies of s‐PP,20–34 we strongly believe that the results shown in Fig 1 can be best described by the limit‐disordered form I26, 28, 30 (after the most recent nomenclature given by De Rosa et al 35), which has an orthorhombic unit cell with axes a = 14.5 Å, b = 5.6 Å and c = 7.4 Å and exhibits an antichiral packing of chains only along the a axis (see Fig 1B in ref 35). The space group proposed for this crystal modification was Pcaa 21.…”

Section: Resultsmentioning

confidence: 99%

Isothermal melt crystallization and melting behaviour of syndiotactic polypropylene

2000

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The lamellar morphological information and subsequent melting behaviour of syndiotactic polypropylene (s-PP) samples isothermally crystallized at crystallization temperatures ranging from 30 to 95 °C have been investigated using a combination of wide-angle X-ray diffraction (WAXD), smallangle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) techniques. Three known methods for determining the equilibrium melting temperature T m °, namely the Gibbs±Thomson extrapolation, the linear Hoffman±Weeks extrapolation and the non-linear Hoffman±Weeks extrapolation, have been employed to evaluate this important thermodynamic parameter, and the results obtained are compared. Finally, an estimate of the equilibrium melting temperature for a perfect s-PP sample (T m °)100% is given.

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Section: Resultsmentioning

confidence: 99%

Isothermal melt crystallization and melting behaviour of syndiotactic polypropylene

2000

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“…To date, four limit-ordered crystalline modifications of s-PP were proposed and described in the literature. [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] Of the four crystalline forms, only the molecular chain packing models of the limitordered form I 56 -59,64,66 and the limit-disordered form I 59,63,66 (after the most recent nomenclature given by De Rosa et al 70 ) are appropriate for characterizing s-PP samples that are crystallized under quiescent conditions from the melt state (or from solution).…”

Section: Dependence Of Subsequent Melting Endotherms On Crystallizatimentioning

confidence: 99%

Crystallization and melting behavior in syndiotactic polypropylene: Origin of multiple melting phenomenon

Supaphol

2001

J of Applied Polymer Sci

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ABSTRACT:The melting behavior of syndiotactic polypropylene (s-PP) after isothermal crystallization from the melt state was studied using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) techniques. Three melting endotherms were observed for isothermal crystallization at high degrees of undercooling. The minor endotherm, located closed to the corresponding crystallization temperature, was postulated to be the melting of the secondary crystallites formed at the crystallization temperature. The low-temperature melting peak was found to be the melting of the primary crystallites formed, and the high-temperature melting peak was a result of the melting of the crystallites recrystallized during a heating scan. The triple-melting behavior observed in subsequent melting endotherms of s-PP was therefore described as contributions from melting of the secondary crystallites and their recrystallization, partial melting of the less stable fraction of the primary crystallites and their recrystallization, melting of the primary crystallites, and remelting of the recrystallized crystallites formed during the heating scan. In addition, determination of the equilibrium melting temperature for this s-PP resin according to the linear and nonlinear Hoffman-Weeks extrapolations provided values of 143.1 and 185.6°C, respectively.

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“…Nevertheless, comonomers of some copolymers do cocrystallize. [15][16][17][18][19][20][21][22][23][24][25][26] For example, De Rosa et al 16 studied the cocrystallization behavior of propene and 1-butene. With increasing content of 1-butene, the increase of a and b axes from the values of s-PP to those of s-PB indicates that the comonomers (propene or 1-butene) are included in the unit cells.…”

Section: Introductionmentioning

confidence: 99%

Inducing New Crystal Structures through Random Copolymerization of Biodegradable Aliphatic Polyester

Li¹,

Sun²,

Huang³

et al. 2008

Macromolecules

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The crystal structures of poly(hexamethylene sebacate-co-hexamethylene adipate), P(HSe-co-HA), copolymers have been studied with Fourier transformation infrared spectroscopy (FTIR) and X-ray fiber diffraction. All characteristic FTIR absorption bands of the crystals of HSe and HA comonomers are present in all copolymers, and each copolymer has only one melt temperature, which supports that P(HSe-co-HA) copolymers cocrystallize in a whole range of comonomer compositions. In addition to peak shift, some new diffraction peaks were observed in X-ray fiber diffraction patterns of the copolymers, which correspond to new crystals with different unit cells from those of the homopolymers. The crystal structures of the copolymers were analyzed, which varied with the composition of HA and HSe comonomers. Interestingly, the lattice constants c of P(HSe-co-20 mol % HA) and P(HSe-co-35 mol % HA) crystals are even larger than those of either homopolymers, which implies a new length scale may be induced in the random copolymers. This supports the formation of new crystals instead of normal lattice distortion.

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Structural Characterization of Syndiotactic Copolymers of Propene with 1-Butene

Cited by 45 publications

References 23 publications

Isothermal melt crystallization and melting behaviour of syndiotactic polypropylene

Isothermal melt crystallization and melting behaviour of syndiotactic polypropylene

Crystallization and melting behavior in syndiotactic polypropylene: Origin of multiple melting phenomenon

Inducing New Crystal Structures through Random Copolymerization of Biodegradable Aliphatic Polyester

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