The crystalline structure, spherulitic crystallization and melting behaviour of isotactic polypropylene (iPP) is comprehensively reviewed, illustrated and discussed. It is demonstrated and summarized how the nucleation, development and growth of the different spherulites depend on the crystallization and melting conditions both in quiescent and sheared melt. Based on the results the microtexture development during real processing conditions is elucidated for selected examples. Several subjects of intense debate on the above topics are clarified using evidence from polarized optical micrography and differential scanning calorimetry.

Supermolecular structure of isotactic polypropylene

Infrared spectra of polyethylene terephthalate and three of its deuterated analogs have been obtained in the region of 70 to 3600 cm-i, polarized spect,ra having been obtained down to 330 cm-l On the basis of analysis of the predicted spectrum, and with the aid of data from benzene and substituted benzenes, a complete assignment of the spectrum has been made This assignment suggests a modification of the proposed chain structure of this polymer It also leads to the conclusion that the changes in the spectrum which occur upon crystallization of the polymer are not associated with different isomeric forms of the -OCH2CH20portion of the chain, but rather with changes in the symmetry and resonance characteristics of the substituted benzenoid ring framework

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Infrared spectra of high polymers

Epitaxial crystallization and crystalline polymorphism of polylactides

Polymorphism in isotactic polypropylene

Microstructure of polypropylene

The crystal structure of isotactic polypropylene and its chemical-physical properties are described here. The polymer crystallizes in the Cc space group with the following constants of the unit cell: a = 6.65 ± 0.05 A ; b = 20.96 ± 0.15 A ; c = 6.50 ± 0.05 A β = 99 ° 20 ′ ± 1 ° .

Structure and properties of isotactic polypropylene

Crystal Structure of Isotactic Poly-alpha-Butene.

Vorläufige Mitteilung: Über die Kristallstruktur des isotaktischen Poly‐α‐butens

Die Kettenstruktur des kristallinen Polyvinylisobutylathers, der nach Schildknecht und Mitarbeitern gemas einem kationischen Katalysenmechanismus hergestellt worden ist, wird diskutiert. Die rontgenographischen Daten werden mit Hilfe der Methoden der Molekulartransformation interpretiert und es wird daraus geschlossen, das das Polymere im kristallinen Zustand isotaktisch ist (das heist, das die asymmetrischen Kohlenstoffatome alle die gleiche sterische Konfiguration besitzen), und das die Polymerenkette eine ternare Helixsymmetrie besitzt (Typ (AB)3 gemas Bunn).



Es wird eine vollstandige Analogie der Molekularstruktur des kristallinen Polyvinylisobutylathers mit der des isotaktischen Poly-5-methyl-hexen-1 beobachtet. Letzteres Polymere wurde nach einem anionischen Mechanismus hergestellt.



On discute la structure de la chaine du polyvinylisobutylether, prepare avec un mecanisme de catalyse cathionique, d'apres Schildknecht et coll.



Les donnees roentgenographiques sont interpretees a l'aide des transformees moleculaires, et on conclu que le polymere a l'etat cristallin est isotactique (c'est-a-dire que les atomes de carbones asymetriques ont tous la meme configuration sterique) avec une symetrie ternaire helicoidale de la chaine (type (AB)3 de Bunn). On observe une totale analogie entre la structure moleculaire du polyvinylisobutylether cristallin et celle du poly-5-methylhexene-1 isotactique, prepare ce dernier avec un mecanisme de catalyse anionique.

Über die kettenstruktur des kristallinen polyvinylisobutyläthers

Many types of helical chains present in the crystals of different isotactic polymers have been described in the past few years. They all correspond to successions of more or less distorted trans and gauche bonds. The chains of the polymers, which have an identity period along the fiber axis comprised between 6·4 and 6·7 A, generally correspond to successions of undistorted trans (σ 1 = 180°) and gauche (σ 2 ∼ 60°) bonds, repetition being achieved along a three-fold helix 2 [(AB) 3 or (AC) 3 ]. This chapter presents an evaluation of the structure and mode of packing of the isotactic polyvinyl cyclohexane. The isotactic structure of polyvinyl cyclohexane is confirmed by the fact that through hydrogenation of isotactic polystyrene, and hydrogenation and dehalogenation of isotactic amorphous polychloro-styrenes, the products obtained exhibit the same X-ray diffraction lines as crystalline polyvinyl cyclohexane. All X-ray reflections given by a fiber of this polymer may be indexed on the basis of a tetragonal unit cell, with a = 21·9 A.

P. Corradini

Papers

Structure and properties of isotactic polypropylene

Crystal Structure of Isotactic Poly-alpha-Butene.

Vorläufige Mitteilung: Über die Kristallstruktur des isotaktischen Poly‐α‐butens

Über die kettenstruktur des kristallinen polyvinylisobutyläthers

Chain structure of isotactic polyvinyl cyclohexane