Viscosity-molecular weight relations for an isotactic polybutene-1

Abstract

Dilute solution studies of polymers in these laboratories have recently been extended to studies of some stereoregular polymers in solution. This paper reports results of an investigation of viscosity-molecular weight relations for an isotactic polybutene-1. ExperimentalThe polybutene-1 was furnished by the Sun Oil Co. The material was soluble in pentane at room temperature. The x-ray pattern, using the powder technique, clearly indicated that the polymer is crystalline. FractionalionFractionation was carried out by the fractional precipitation method from 1.5% solution in cyclohexanone at 115°C. A 3:l (volume) mixture of cyclohexanol-glycol was used as the nonsolven t. Melting Point DeterminationMelting points of several of the fractions were determined with a Bausch and Lomb microscope equipped with a Kofler micromelting apparatus. The crystals were prepared by heating slowly to 165°C. on the hot stage, followed by slow cooling over a period of several hours. The spherulites thus formed were viewed through crossed prisms and the temperature was raised slowly until the field disappeared. This temperature was taken as the melting point of the polymer. Fraction 8 melted at 121.4"C. while fractions 5,6, and 7 melted at 127°C. Viscosity and Light ScatteringIntrinsic viscosities were determined in decalin a t 115°C. and in heptane at 35 and at 60°C. An Ubbelohde dilution viscometer was used. Flow times for the reagent-grade solvents exceeded 100 sec. in all cases.Refractive index increments (dnldc) were determined with a BricePhoenix differential refractometer. For polybutenel in heptane at 60°C.) dn/dc was found to be 0.115 ~m.~g.-lfor X = 5460 A. and 0.120 cm.3g.-lfor X = 4360A.

Dynamics in the crystalline polymorphic forms I and II and form III of isotactic poly-1-butene

“…The PBu1 studied was a commercial sample from Aldrich. Its measured intrinsic viscosity of 1.04 dL/g in heptane at 35 °C corresponds to a weight‐average molecular weight of 270,000 g/mol 20. The tacticity of the sample was determined by 13 C NMR in solution 21.…”

Infrared characterization of polymorphism in polybutene‐1

“…A viscosity-average molecular weight approximating lo6 was derived from intrinsic viscosity measurements. 8 The infrared spectra were recorded with a Perkin-Elmer Model 421 spectrometer.…”

1H NMR studies of molecular relaxations of poly‐1‐butene

“…In form 111, 41 helices are packed in an orthorhombic lattice12 with a T , between 105 and 110°C and a density of 0.894 g/cm3, close to the 0.868 g/cm3 density of the amorphous p01yrner.l~ Form I' can be obtained by crystallization under high or from specific solvent^.^ It shows a g in heptane at 35°C corresponds to a weight-average molecular weight of 270,000. 22 The tacticity of the sample was determined by 13C NMR in solut i~n .~~ The side-chain methylene peak splitting in the spectra recorded at 100 MHz in a 20% (w/v) odichlorobenzene-deuteriobenzene ( 9 : 1 volume ratio) mixture at 100°C indicated an isotactic content of at least 96%.…”