ISOTACTIC POLY(1-BUTENE) HYDROGENATED OLIGO(CYCLOPENTADIENE) BLENDS -MISCIBILITY, MORPHOLOGY, AND THERMAL AND MECHANICAL-PROPERTIES/

The article discusses the influence of the oligomeric resin, hydrogena ted oligo( cyclopentadiene) (HOCP), on the morphology and properties o f its blends with isotactic poly(1-butene) (PB-1). PB-1 and HOCP are f ound to be partially miscible in the melt state. Solidified PB-1/HOCP blends contain three phases: (1) a crystalline phase formed by PB-1 cr ystals; (2) an amorphous PB-1-rich phase; and (3) an amorphous HOCP-ri ch phase. The optical micrographs of the solidified blends show a morp hology constituted by microspherulites and domains of the HOCP-rich ph ase homogeneously distributed in the intraspherulitic region. DSC and DMTA results show two glass transition temperatures (T-g), different f rom the T-g values of the plain components. The lower T-g is attribute d to the PB-1-rich phase, and the higher T-g, to the HOCP-rich phase. The tensile properties were investigated at 25 and 80 degrees C. At 25 degrees C, the PB-1-rich phase is rubbery and the HOCP-rich phase is glassy, so the addition of HOCP to PB-1 arouses a noteworthy hardening of the samples and this brings an increase of the Young's modulus, E' (although the blend crystallinity lessens), and decreases of stresses at yielding point (sigma(y)) and at rupture (sigma(r)). The 90/10 and 80/20 blends show high values of elongation at rupture (epsilon(r)). At 80 degrees C, the blends show decreases of E' and sigma(r) values w ith the HOCP content. These decreases are attributed to the rubbery st ate of the phases and reduction of the blend's crystallinity. At 80 de grees C, all the blends show a high value of epsilon(r). This phenomen on is attributed to the fine-size domain dispersion of the phases and to sufficient densities of tie molecules and entanglements. Finally, t he partial miscibility behavior proposed in this article is compared w ith the miscibility hypothesis reported elsewhere. (C) 1998 John Wiley & Sons, Inc.