Giant single crystal of isotactic polypropylene showing near-equilibrium melting temperature

Abstract

Giant single crystals of isotactic polypropylene (iPP) were obtained using a specific kinetic pathway through the mesophase of iPP; the pre-quenched iPP mesophase was heated to 166 °C at a rate of 75 °C min-1 and maintained at this temperature for 24 h. The obtained crystallites exhibited a very high melting temperature, Tm, of 183.7 °C, which is ∼19 °C higher than the iPP's nominal Tm (∼165 °C); namely, the observed Tm is immediately close to the literature value of iPP's equilibrium melting temperature, Tm 0 (186.2 °C). The crystallites have bamboo leaf-like or needle-like morphology and are ∼35 μm in length and ∼3.5 μm in width. The thickness of the crystallites was estimated to be 88 nm according to the melting temperature. The number density of the crystallites in a unit volume was controlled by adjusting the heating rate. As the result, well-isolated single crystals of iPP with the above-mentioned morphologies were obtained. © 2013 The Society of Polymer Science, Japan (SPSJ) All rights reserved.