Crystal structure of syndiotactic polypropylene

Corradini, Paolo; Natta, G.; Ganis, Paolo; Temussi, Piero Andrea

doi:10.1002/polc.5070160503

Cited by 202 publications

(265 citation statements)

References 4 publications

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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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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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“…The less stable form is the trans-planar conformation [8]. For the polymorphs, four crystalline forms are known: the t 2 g 2 (Forms I and II) [9], planar zigzag (Form III) [10,11], and t 2 g 2 t 6 g 2 (Form IV) conformations [12]. Form I was discovered by Lotz et al and Lovinger et al [13,14].…”

Section: Introductionmentioning

confidence: 99%

Diffusion and morphological properties of syndiotactic polypropylene (sPP) films

Yamashita

Fujiwara

Fujikawa

et al. 2009

Polymer Engineering & Sci

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Four different fabrication procedures were used for casting thin films of syndiotactic polypropylene (sPP). A hot press system operated at 200°C and 30 MPa pressure was used to melt polypropylene powder and make the cast films. Different cooling procedures were used to anneal the films, including cooling in liquid nitrogen (LN), ice water, and air at room temperature (RT). The morphological and mass transfer properties of the films were studied with XRD, polarized optical microscopy, bulk flow, and diffusion experiments. All sPP films contained amorphous and crystalline phases. The crystalline phase was determined to be disordered Form I. The sPP films annealed with LN had the lowest crystallinity whereas the sPP films cooled in air at RT had the highest crystallinity. Diffusion of toluene in the films and comparison with Maxwell's equation indicated that the crystalline phase mass permeability is much lower than the amorphous phase, which causes films with low crystallinity to have a higher effective diffusion constant and permeability compared with high crystallinity films. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

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“…the bc growth plane). At the time of publication though, only the high temperature orthorhombic form I (Cell I) [30] was available, and they accordingly assumed that the growth plane occurred on the (110) plane. With this in mind, we re-evaluated the crystal growth parameters, based on a 0 7.77 × 10 Ϫ8 cm and b 0 5.22 × 10 Ϫ8 cm, and found that they are s 4.4 erg cm Ϫ2 , s s e 259.5 erg 2 cm Ϫ4 , s e 58.7 erg cm Ϫ2 , and q 6:9 kcal mol Ϫ1 , which is extremely close to their published values.…”

Section: Further Discussion Of the Literaturementioning

confidence: 99%

Regime crystallization in syndiotactic polypropylenes: re-evaluation of the literature data

Supaphol

Spruiell

2000

Polymer

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The Lauritzen and Hoffman secondary nucleation theory was applied to linear growth rate data of syndiotactic polypropylene taken from the literature. Observation of the distinctive upward change of slope in plots of log G ϩ U ‫ء‬ /2.303R(T c Ϫ T ∞ ) versus 1/2.303T c (DT)f suggested the regime II 3 III transition at the crystallization temperature of 110ЊC. Based on the input parameters judged to be the most accurate, the ratios of K g,III /K g,II were found to range from 1.7 to 2.2. Regardless of the crystal structure, if the growth is assumed to occur on the bc plane, the lateral surface free energy, s 11.3 erg cm Ϫ2 and the fold surface free energy s e 63.7^7.1 erg cm Ϫ2 were found. The latter leads to the average work of chain folding of q 7:4^0:8 kcal mol Ϫ1 . If the growth is assumed to occur on the ac plane, the fold surface free energy is found to be s e 82.4^9.1 erg cm Ϫ2 , while the lateral surface free energy is the same as previously noted. In this case, the work of chain folding of q 9:6^1:1 kcal mol Ϫ1 is found. These values are applicable to both regimes II and III. A detailed evaluation of the effects of changes in input parameters was also carried out. ᭧

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Crystal structure of syndiotactic polypropylene

Cited by 202 publications

References 4 publications

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

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

Diffusion and morphological properties of syndiotactic polypropylene (sPP) films

Regime crystallization in syndiotactic polypropylenes: re-evaluation of the literature data

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