✦ LIBER ✦

The thermal expansion of the monoclinic unit cell of isotactic polypropylene

✍ Scribed by J. R. Isasi; R. G. Alamo; L. Mandelkern

Publisher: John Wiley and Sons
Year: 1997
Tongue: English
Weight: 119 KB
Volume: 35
Category: Article
ISSN: 0887-6266
DOI: 10.1002/(sici)1099-0488(199712)35:17<2945::aid-polb17>3.0.co;2-7

No coin nor oath required. For personal study only.

✦ Synopsis

The lattice parameters of a highly stereoregular metallocene polypropylene crystallized at 145ЊC were obtained after cooling and heating cycles in a temperature interval between 25ЊC and 165ЊC. The b dimension undergoes a large thermal expansion with temperature (0.6 A ˚) while the change of the a axis is relatively small (0.1 A ˚). The unit cell dimension along the molecular (c) axis appears less sensitive to temperature than are the intermolecular distances. The difference in dimensions between the a and c axis at low and high crystallization temperatures is small, varying from 2.3 to 3.5%. This small difference allows the formation of daughter, crosshatched lamellae in the complete interval of crystallization temperatures. The thermal expansion coefficient of the unit cell specific volume is also reported.

📜 SIMILAR VOLUMES

A study of the dilation of the unit cell

A study of the dilation of the unit cell of metallocene isotactic poly(propylenes): The monoclinic form

✍ J. R. Isasi; R. G. Alamo; L. Mandelkern 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 199 KB 👁 2 views

The lattice parameters of a series of monoclinic metallocene poly(propylenes) of constant molecular weight are measured as a function of defect content, that vary between 0.3 and 2.35 total defects per 100 monomeric units. The parameters are also measured as a function of molecular weight for a fixe

The degree of crystallinity of monoclini

The degree of crystallinity of monoclinic isotactic poly(propylene)

✍ José R. Isasi; Leo Mandelkern; María J. Galante; Rufina G. Alamo 📂 Article 📅 1999 🏛 John Wiley and Sons 🌐 English ⚖ 194 KB 👁 2 views

The degree of crystallinity of a set of monoclinic (alpha) isotactic poly(propylenes), prepared by a metallocene-type catalyst, were determined at room temperature. Three different methods were used: density, enthalpy of fusion, and wide-angle X-ray scattering, and the results compared. The relation

Influence of regioirregular structural u

Influence of regioirregular structural units on the crystallization of isotactic polypropylene

✍ Antonio Marigo; Carla Marega; Roberta Saini; Isabella Camurati 📂 Article 📅 2000 🏛 John Wiley and Sons 🌐 English ⚖ 186 KB 👁 2 views

The morphology of irradiated isotactic p

The morphology of irradiated isotactic polypropylene

✍ X. C. Zhang; R. E. Cameron 📂 Article 📅 1999 🏛 John Wiley and Sons 🌐 English ⚖ 301 KB 👁 1 views

The research in this article explores the response of semicrystalline isotactic polypropylene to gamma radiation in air, and relates the morphological changes of the polymer to corresponding changes in mechanical properties. The effect of the initial morphology of the polymer on its response to irra

The effects of atacticity, comonomer con

The effects of atacticity, comonomer content, and configurational defects on the equilibrium melting temperature of monoclinic isotactic polypropylene

✍ Eric Bryan Bond; Joseph E. Spruiell 📂 Article 📅 2001 🏛 John Wiley and Sons 🌐 English ⚖ 128 KB 👁 1 views

Effect of various triazine derivatives o

Effect of various triazine derivatives on the thermal oxidative degradation of isotactic polypropylene

✍ Zenjiro Osawa; Ng Mok Seng; Yoshitaka Ogiwara; Yukio Oto; Koji Matsui 📂 Article 📅 1973 🏛 John Wiley and Sons 🌐 English ⚖ 379 KB 👁 1 views

## Abstract A number of triazine derivatives, mostly aryloxy‐__s__‐triazines, were prepared, and the effects of these compounds on the thermal oxidative degradation of isotactic polypropylene were examined by conventional oxygen uptake. Almost all triazine derivatives prepared showed a more or less