Electromagnetic and Dynamic Mechanical Properties of Extruded Cobalt Ferrite-Polypropylene Composites

Abstract

Cobalt ferrites of 0-45 wt% were incorporated in polypropylene by the extrusion technique. With increasing magnetic loading, the magnetizations were linearly increased according to the rule of mixture and the electrical permittivity was also proportional to the loading as described by Wagner's equation. The magnetic permeability may be increased but was reduced to minimal at high frequencies because of the substantial coercive field of cobalt ferrites after the extrusion. Without considerable adsorption of polymer matrix on magnetic fillers, the storage and loss modulus from 30 to 180 C of polypropylene were decreased by cobalt ferrites additions.

Effect of Cobalt Ferrite Loading on Differential Scanning Calorimetry of Magnetic Polymer Composites

“…This indicated that regular order chains in CoFe 2 O 4 -filled PP could also take place. The endotherms found for these filled samples, however, exhibited smaller magnitude (peak areas) when the amounts of CoFe 2 O 4 powders increased from 5 to 45 % (Table 1), due to the magnetic clusters in PP samples, as seen by SEM in [4]. They may inhibit the formation of order structures during sample preparation since they are embedded into the interchain spacing.…”

“…They may inhibit the formation of order structures during sample preparation since they are embedded into the interchain spacing. As a result, the nucleation of order chains become more difficult in the samples with heavier loading which explains the change in dynamic mechanical properties [4], and may To test this hypothesis, we systematically conducted DSC tests to the semi-crystalline polar polymer, PU. Thermogram of a PU sample without CoFe 2 O 4 displayed the endothermic peak, accounted for the melting of the order portion of chain segments, with a peak position at about 170°C (Fig.…”

“…For PU composites, poly[4,4 0 -methylenebis(phenylisocyanate)-alt-1,4 butanediol/di(propylene glycol)/polycaprolactone] beads (Sigma Aldrich) were turned into sheets by milling for 2 min and the milling continued for 12 min after the addition of CoFe 2 O 4 powders. Electromagnetic properties of these composites, referred to as PP-0…PP-45, PU-0…PU-45, NR-0…NR-45, were reported elsewhere [4,5]. Their thermal properties were characterized by means of differential scanning calorimeter (DSC7 Perkin Elmer) for the temperature ranging from 25 to 300°C with a heating rate of 10°C/min.…”

“…CoFe 2 O 4 powders with the particle size of the order of 100 nm [4] were incorporated in three different polymer matrices, i.e. PP, PU and NR.…”

“…Incorporation of magnetic fillers into polymeric matrices leads to unique properties which can be implemented in new specific proposes. Based on its magnetic, magnetostrictive, photomagnetic and catalytic properties, the effects of cobalt ferrite (CoFe 2 O 4 ) loading in polypropylene (PP), polyurethane (PU) and natural rubber (NR) were investigated [4,5]. The coercive field remained rather insensitive to the CoFe 2 O 4 loading but the magnetizations were proportional to the loading.…”