Polymeric stabilization of colloidal magnetite magnetic fluids

Author

Elkafrawy, S. ; Hoon, S.R. ; Lambrick, D.B. ; Bissell, P.R. ; Price, C.

Author_Institution

Dept. of Chem., Manchester Univ., UK

Volume

26

Issue

5

fYear

1990

fDate

9/1/1990 12:00:00 AM

Firstpage

1846

Lastpage

1848

Abstract

Stable colloidal suspensions of ~4.3-nm mean diameter magnetic particles have been prepared employing polystyrene-block-poly(ethylene/propylene) copolymer (M_n~100000) for steric stabilization. The potential of the copolymers as both dispersants and inhibitors of long-term oxygen degradation of the magnetic properties of the particles has been assessed. Magnetic changes due to oxidation, aggregation, and sedimentation consequent to prolonged exposure to atmosphere and gravitational and magnetic field gradients have been studied employing transmission electron microscopy, vibrating sample magnetometry, and scanning column magnetometry techniques. The flow properties in magnetic fields have also been investigated. Stable fluids of typically 5 J^-1T^-1kg^-1 have been obtained. It appears that the polymer competes with oxygen at the particle surface to decrease colloidal sensitivity to oxidation

Keywords

aggregation in substances; magnetic fluids; oxidation; polymer solutions; 4.3 nm; aggregation; colloidal magnetite magnetic fluids; colloidal sensitivity; dispersants; flow properties; inhibitors; oxidation; polystyrene-block-poly(ethylene/propylene) copolymer; scanning column magnetometry techniques; sedimentation; steric stabilization; transmission electron microscopy; vibrating sample magnetometry; Degradation; Electrokinetics; Inhibitors; Magnetic fields; Magnetic liquids; Magnetic particles; Magnetic properties; Oxidation; Polymers; Suspensions;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.104544

Filename

104544