The present invention relates to MgCl.sub.2.mROH.nH.sub.2 O adducts, where R is a C.sub.1 -C.sub.10 alkyl, 2.ltoreq.m.ltoreq.4.2, 0.ltoreq.n.ltoreq.0.7, characterized by an X-ray diffraction spectrum in which, in the range of 2.theta. diffraction angles between 5.degree. and 15.degree., the three main diffraction lines are present at diffraction angles 2.theta. of 8.8.+-.0.2.degree., 9.4.+-.0.2.degree. and 9.8.+-.0.2.degree., the most intense diffraction lines being the one at 2.theta.=8.8.+-.0.2.degree., the intensity of the other two diffraction lines being at least 0.2 times the intensity of the most intense diffraction line. Catalyst components obtained from the adducts of the present invention are capable to give catalysts for the polymerization of olefins characterized by enhanced activity and stereospecificity with respect to the catalysts prepared from the adducts of the prior art.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of Ser. No. 09/626,712, filed Jul. 26, 2000, now U.S. Pat. No. 6,323,152 which is a division of Ser. No. 09/050,612, filed Mar. 30, 1998, now U.S. Pat. No. 6,127,304.
A process for preparing spherical support particles used in the preparation of catalytic components for the polymerization of olefins by (a) forming an emulsion of an adduct of a Mg dihalide and a Lewis base compound in a liquid medium, and (b) cooling the emulsion by transferring it into a cooling bath containing a cooling liquid in motion wherein the cooling liquid is moving inside a tubular zone and the ratio V.sub.e /V.sub.ref of the velocity (V.sub.e) of the emulsion coming from step (a) to the velocity of the cooling liquid (V.sub.ref) of step (b) is between 0.25 and 4. The resulting spherical support particles have a very narrow size distribution and particularly regular morphology.
Articles, in particular non-pressure mono- or multi-layer pipes, prepared by extrusion, molding and combination thereof, comprising a heterophasic polyolefin composition comprising (1) 65-95% of a crystalline propylene polymer insoluble in xylene at ambient temperature in an amount over 85% and having a polydispersity index ranging from 4 to 13 and an intrinsic viscosity value ([.eta.].sub.1) of over 2.2 dl/g, and (2) 5-35% of an elastomeric olefin polymer of ethylene with a C.sub.3-C.sub.10 .alpha.-olefin having an ethylene content ranging from 15 to 85% and an intrinsic viscosity value ([.eta.].sub.2) of at least 1.4 g/ml. The [.eta.].sub.1/[.eta.].sub.2 ratio ranging from 0.45 to 1.6. The articles typically have modulus of elasticity in tension higher than 2000 MPa.The invention also relates to the said heterophasic polyolefin composition and an extrusion process for producing the said articles.
