(E)-2-Methyl-1,3-pentadiene was polymerized with the AlEt2Cl-Nd(OCOC7H15)3-Al(iBu)3 system to a polymer consisting of 98–99% 1,4-cis-structure. The crude polymer was fractionated by successive extractions with boiling diethyl ether, heptane and toluene. Examination of the soluble fractions and of the residue to toluene extraction by NMR, X-ray and DSC techniques indicated that the crude polymer consists of macromolecules differing in stereoregularity. Evidence is reported that the crystalline residue after the toluene extraction has a 1,4-cis-isotactic structure. The existence of two different crystalline phases is shown and the respective cell parameters have been determined. α-Phase: a = 10,74, b = 13,04, c = 7,87 Å (−120°C), space group Pbca, Z = 8, Dc = 1,00 g · cm−3. β-phase: a = 9,30, b = 7,73, c = 7,90 Å (25°C), space group P212121 Z = 4, Dc = 0,96 g · cm−3.
THE STRUCTURE OF ONE CRYSTALLINE FORM OF ISOTACTIC 1,4-CIS-POLY(2-METHYL-1,3-PENTADIENE) - AN APPLICATION OF THERIETVELD METHOD
MEILLE, STEFANO VALDO;
1988-01-01
Abstract
(E)-2-Methyl-1,3-pentadiene was polymerized with the AlEt2Cl-Nd(OCOC7H15)3-Al(iBu)3 system to a polymer consisting of 98–99% 1,4-cis-structure. The crude polymer was fractionated by successive extractions with boiling diethyl ether, heptane and toluene. Examination of the soluble fractions and of the residue to toluene extraction by NMR, X-ray and DSC techniques indicated that the crude polymer consists of macromolecules differing in stereoregularity. Evidence is reported that the crystalline residue after the toluene extraction has a 1,4-cis-isotactic structure. The existence of two different crystalline phases is shown and the respective cell parameters have been determined. α-Phase: a = 10,74, b = 13,04, c = 7,87 Å (−120°C), space group Pbca, Z = 8, Dc = 1,00 g · cm−3. β-phase: a = 9,30, b = 7,73, c = 7,90 Å (25°C), space group P212121 Z = 4, Dc = 0,96 g · cm−3.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
