Isotactic Poly(1-butene)/Hydrogenated Oligo(cyclopentadiene) Blends: Miscibility, Morphology, and Thermal and Mechanical Properties S. CIMMINO, M. L. DI LORENZO, E. DI PACE, C. SILVESTRE Istituto di Ricerca e Tecnologia delle Materie Plastiche, IRTEMP CNR, Via Toiano 6, 80072 Arco Felice (NA), Italy Received 27 February 1997; accepted 27 June 1997 ABSTRACT: The article discusses the influence of the oligomeric resin, hydrogenated oligo(cyclopentadiene) (HOCP), on the morphology and properties of its blends with isotactic poly(1-butene) (PB-1). PB-1 and HOCP are found to be partially miscible in the melt state. Solidified PB-1/HOCP blends contain three phases: (1) a crystalline phase formed by PB-1 crystals; (2) an amorphous PB-1-rich phase; and (3) an amor- phous HOCP-rich phase. The optical micrographs of the solidified blends show a mor- phology constituted by microspherulites and domains of the HOCP-rich phase homoge- neously distributed in the intraspherulitic region. DSC and DMTA results show two glass transition temperatures ( T g ) , different from the T g values of the plain components. The lower T g is attributed 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°C. At 25°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 ( s y ) and at rupture ( s r ). The 90/10 and 80/20 blends show high values of elongation at rupture ( 1 r ) . At 80°C, the blends show decreases of E  and s r values with the HOCP content. These decreases are attributed to the rubbery state of the phases and reduction of the blend’s crystallinity. At 80°C, all the blends show a high value of 1 r . This phenomenon is attributed to the fine-size domain dispersion of the phases and to sufficient densities of tie molecules and entanglements. Finally, the partial miscibility behavior proposed in this article is compared with the miscibility hypothesis reported elsewhere.  1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 1369– 1381, 1998 Key words: poly ( 1-butene ) ; hydrogenated oligo ( cyclopentadiene ) ; resin; blends; miscibility INTRODUCTION truded PB-1 is, in fact, used mainly in the manu- facture of pipes and tubes for its impact and corro- sion resistance. But other products, such as heavy- Isotactic poly(1-butene) (PB-1) is a semicrystal- line polyolefin with some interesting properties. duty bags, pressure-sensitive tapes, agricultural films, gaskets, and diaphragms can also be ob- Properly molded and processed articles made from poly ( 1-butene ) show excellent resistance to tained. In certain cases, such as applications at low temperature where high impact resistance is creep and environmental stress cracking. 1 Ex- needed, the PB-1 is preferred to iPP and P4MP1 for the production of house furnishings, electrical Correspondence to: S. Cimmino (cimmino@mail.irtemp. apparatus, automotive parts, and other articles. 2 na.cnr.it). PB-1 may crystallize in at least three distinct Journal of Applied Polymer Science, Vol. 67, 1369 – 1381 ( 1998 )  1998 John Wiley & Sons, Inc. CCC 0021-8995/98 / 081369-13 crystalline modifications. 1 From the melt, PB-1 1369 4672 / 8e07$$4672 12-19-97 12:45:27 polaal W: Poly Applied