Mark–Houwink equation and GPC calibration for linear short‐chain branched polyolefines, including polypropylene and ethylene–propylene copolymers

Abstract

The reduction in molecular dimensions due to the presence of short side chains in otherwise linear polyolefins can very simply by calculated by assuming that the configuration of the main chain is not influenced by the side chains. This enables us to express the intrinsic viscosity–molar mass relationship as a function of the mass fraction of side chains (S): [η] = (1 − S)α+1KPEMνα and, with use of the universal calibration principle, to convert the GPC calibration for purely linear polymers samples into the calibration for short‐chain branched polymers: M* = (1 − S)M. Experimental data from literature on short‐chain branched poly‐ethylenes, and our own data on ethylene–propylene copolymers are used to verify the above assumption. It appears that the experimentally found relations between [η], Mw and M*w (GPC) within the usual accuracy justify this approach.

A Comprehensive Review on Controlled Synthesis of Long‐Chain Branched Polyolefins: Part 3, Characterization of Long‐Chain Branched Polymers

“…where α ≈ 0.710 [3,46,48] For linear HDPE, K = 2.8 and α = 0.73 were also reported in another study. [29] The weight-average intrinsic viscosity ( [ ] w η ) and hydrodynamic radius (R h, w ) can be obtained by an integration similar to the calculation of mass-average mean square radius of gyration ( r g 2 w 1/2 〈 〉 ) by Equation (6).…”

Chiral Fluorous Dialkoxy‐Diamino Zirconium Complexes: Synthesis and Use in Stereospecific Polymerization of 1‐Hexene

“…Polyethylene molecular weights were determined by reference to polystyrene (PSt) standards and are reported relative to polyethylene standards, as calculated by the universal calibration method using Mark-Houwink parameters (K = 14.1 10 À5 , a = 0.70 for PSt, K = 14.1 10 À5 , a = 0.70 for PE). [34] GPC of poly-1-hexenes was performed on a Waters instrument equipped with the double detection methods of UV spectrometry and differential refractometry using THF as solvent (1 mL min À1 ) at ambient temperature. The molecular weights of poly-1-hexene were determined by reference to polystyrene standards.…”

Copolymerization and characterization of ethene-1-hexene copolymers prepared by using the (Me5Cp)2ZrCl2-MAO catalyst system

“…21 Molar masses and molar mass distributions reported were determined by high-temperature size exclusion chromatography (Knauer) (135°C; 1,2,4-trichlorobenzene) with an universal calibration function [log (Mx[]) ϭ f (elution volume)] in connection with a Kuhn-Mark-Houwink equation. 22 Differential scanning calorimetry (DSC) was performed on a Seiko DSC 220. Each sample was heated from 25 to 160°C at a heating rate of 20°C/min and kept at this temperature for 5 min.…”