Crystallization of syndiotactic polystyrene under pressure

Zhan, Sun; Morgan, Roger J.; Lewis, David N.

doi:10.1016/0032-3861(92)90749-m

Cited by 41 publications

(48 citation statements)

References 4 publications

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“…The crystalline density of the ␤-crystalline form, 1.068 g/cm 3 , calculated from the parameters of the unit cell, is quite loose, and it is only slightly larger than the density of the amorphous s-PS, 1.045 g/cm 3 . 3 In the ␣-crystalline form, first the chains are packed in the clusters (triplets), each containing three chains. The backbones of these three chains make a core of the triplet, whereas the phenyl rings are pointed toward the periphery.…”

Section: Introductionmentioning

confidence: 82%

“…Two possible models of chain packing in the ␣-crystalline phase are shown in Figure 1 . 5 Despite the differences, both models predict the same density of the ␣ form, 1.033 g/cm 3 , which is smaller than the density of the amorphous phase as in the case with P4MP1. Two structural models predict different distribution of an unoccupied space in crystalline s-PS, which is responsible for the low density of the ␣ crystals.…”

Section: Introductionmentioning

confidence: 84%

“…2 This crystalline form is distinguished by orthorhombic chain packing with unit cell dimensions a ϭ 8.81 Å, b ϭ 28.82 Å, and c ϭ 5.1 Å. The crystalline density of the ␤-crystalline form, 1.068 g/cm 3 , calculated from the parameters of the unit cell, is quite loose, and it is only slightly larger than the density of the amorphous s-PS, 1.045 g/cm 3 . 3 In the ␣-crystalline form, first the chains are packed in the clusters (triplets), each containing three chains.…”

Section: Introductionmentioning

confidence: 99%

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Solid‐state structure of thermally crystallized syndiotactic polystyrene

Hodge¹,

Prodpran²,

Shenogina³

et al. 2002

J of Applied Polymer Sci

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ABSTRACT:The solid-state structure of syndiotactic polystyrene (s-PS) after crystallization from the melt and the glassy state was examined by differential scanning calorimetry (DSC), density, and X-ray diffraction analysis. It was possible to prepare semicrystalline s-PS containing either the pure ␣-or the pure ␤-crystalline form by melt crystallizing s-PS from 280 or 330°C. The measurements confirmed the low density of both crystalline forms, which in the case of ␣-crystalline form was smaller and in the case of ␤-crystalline form was only slightly larger than the density of the glassy amorphous s-PS. An endeavor to introduce the crystalline phase in s-PS through cold crystallization at constant temperature above the glass transition resulted in a complex ordered phase. This ordered phase, depending on the crystallization temperature, contained the planar chain mesomorphic phase and the ␣-crystalline phase with a low degree of perfection (cold crystallization in the range 120 -175°C) or a mixture of the ␣-and ␤-crystalline forms with a high degree of perfection (cold crystallization in the range 210 -260°C). The combination of DSC and X-ray measurements enabled us to resolve the complex ordered structure in semicrystalline s-PS after cold crystallization.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solid‐state structure of thermally crystallized syndiotactic polystyrene

Hodge¹,

Prodpran²,

Shenogina³

et al. 2002

J of Applied Polymer Sci

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show abstract

“…More recently, formation of the ␤ form is found to be favored in s-PS associated with pressure as in compression molding under pressure. 5 In addition, melt crystallization from high temperatures also favors its formation. 6,7 The ␥ and ␦ crystal forms can be obtained if dichloromethane treatment is imposed on the ␣-form crystal of s-PS.…”

Section: Introductionmentioning

confidence: 99%

Polymorphic crystal forms and morphology of syndiotactic polystyrene in miscible states

Woo

1998

J. Polym. Sci. B Polym. Phys.

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“…Because of the loose packing of chains, this phase has a theoretical density of only 1.03 g cm À3 , which has been reported to be even lower than that of amorphous sPS (1.04 g cm À3 ). [8][9][10][11][12][13][14][15][16][17] Barnes et al 18 showed that, as a result of the close resemblance of the densities of the amorphous and crystalline phase, the small-angle Xray scattering pattern hardly shows any contrast below the glass transition temperature. As a result, the density of the amorphous phase is intermediate between the densities of the a and b phases (i.e., q a < q am < q b ).…”

Section: Introductionmentioning

confidence: 99%

Solidification of syndiotactic polystyrene by a continuous cooling transformation approach

Carrubba

Piccarolo

Brucato

2007

J Polym Sci B Polym Phys

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Syndiotactic polystyrene (sPS) was solidified from the melt under drastic conditions according to a continuous cooling transformation methodology developed by the authors, which covered a cooling rate range spanning from approximately 0.03 to 3000 8C/s. The samples produced, structurally homogeneous across both their thickness and surface, were analyzed by macroscopic methods, such as density, wide-angle X-ray diffraction (WAXD), and microhardness (MH) measurements. The density was strictly related to the phase content, as confirmed by WAXD deconvolution. The peculiar behavior encountered (the density first decreasing and then increasing with the cooling rate) was attributed to the singularity of the phases formed in sPS; that is, one of the crystalline phases (a) was less dense than the amorphous phase, and the latter, in turn, was less dense than the other crystalline phase (b). With an increasing cooling rate, the thermodynamically stable phase (b) disappeared first, and it was followed by the a phase. On the other hand, the MH values remarkably depended on the amount of the b phase, the a-phase content influencing the mechanical properties only to a minor extent. The behavior of the crystallization kinetics was described through a modified multiphase Kolmogoroff-Avrami-Evans model for nonisothermal crystallization.

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Crystallization of syndiotactic polystyrene under pressure

Cited by 41 publications

References 4 publications

Solid‐state structure of thermally crystallized syndiotactic polystyrene

Solid‐state structure of thermally crystallized syndiotactic polystyrene

Polymorphic crystal forms and morphology of syndiotactic polystyrene in miscible states

Solidification of syndiotactic polystyrene by a continuous cooling transformation approach

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