Influence of the quenching temperature on the crystallization of the trans-planar mesomorphic form of syndiotactic polypropylene
β Scribed by Claudio De Rosa; Odda Ruiz de Ballesteros; Michele Santoro; Finizia Auriemma
- Publisher
- Elsevier Science
- Year
- 2003
- Tongue
- English
- Weight
- 270 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0032-3861
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β¦ Synopsis
The crystallization from the melt of the trans-planar mesomorphic form of syndiotactic polypropylene is investigated at different quenching temperatures. The formation of the trans-planar mesomorphic form at 25, 0 and 6 8C is followed as a function of the residence time at these temperatures by X-ray diffraction and FTIR spectroscopy. The quenching temperature influences the rate of formation of the mesomorphic form as well as the maximum amount of the obtained mesomorphic form. By increasing the quenching temperature, in the examined range between 25 and ΓΎ6 8C, an increase in the rate of formation of the mesomorphic form is observed. The maximum amounts of mesomorphic form obtained at 6 and 25 8C are lower than the amount achieved at 0 8C, which corresponds to nearly 100% of the total crystalline phase.
π SIMILAR VOLUMES
The packing of the chains in (T 6 G 2 T 2 G 2 ) n conformation of the form IV of s-PP is revisited on the basis of packing energy and structure factor calculations. According to this analysis, an alternative mode of packing has been suggested. A monoclinic structural model, with the unit cell center
Fractionated syndiotactic polypropylene (sPP) samples with homogeneous tacticity were annealed at diΓΎ erent temperatures. The inΓ½uence of syndiotacticity and annealing temperature on the double melting peak phenomena were investigated. It is found that all fractions show double melting peaks at 75ΓC