Structure formation in low concentration magnetoactive polymers

Abstract

This paper concerns recent research into the autonomous formation of micro-structures in low carbonyl iron powder (CIP) concentration magneto active polymers (MAP). Higher concentrations of CIP show an isotropic distribution of magnetic filler throughout the entire sample, while autonomous structure formation is possible at mass concentrations lower than 3%. The formation of micro-toroids commences as CIP concentration approaches 1% wt. Further development of coherent rings with a defined order follow as CIP concentrations increase toward 2% wt, whilst exceeding 3% wt leads to the same isotropic distribution found in higher concentration MAP. Structured samples containing between 1% wt and 3% wt CIP were investigated using X-Ray tomography where solitary structures could clearly be observed. The ring structures represent microinductivities whose geometries can be manipulated during fabrication. In addition, these structures are magnetic field sensitive. This is not only relevant to applications in the GHz and THz areas but recent research has revealed implications for optical, thermal, acoustic and even chemical MAP sensors.

Self‐assembling structure formation in low‐density magnetoactive polymers

“…During vacuum evacuation, cavities rise to the surface before being dissipated. With very sparse filler particle concentrations, particles tend to gather on the boundary layers of ascending bubbles . A similar effect, previously intended for the attachment of much lighter talc particles, has been documented as has the self‐assembly of particles in ring structures in two phase fluids …”

“…The details are to be documented in later papers. Preliminary studies in the optical spectrum also reveal some interesting results …”

“…Since the self‐assembling effect is not magnetically driven, no further SQUID measurements were made on the nickel or silver particles (NP/SP). In particular, because the low CIP percentages show no extraordinary magnetic behaviour and further measurements will show the well‐known magnetization curves of the metals, since there is only a single material per sample used, as shown in Figure .…”

“…gives the volume of the torus formed. where R is the radius of the torus and α is the radius of the tubular section of the torus. However, cavities do not always rise vertically but also obliquely thus forming regular layers …”

Mini-Extruder for 3D Magnetoactive Polymer Printing

“…Cavity sizes are typically in the order of 80 μm to 120 μm diameter with rising velocities typically of the order of 0.1 m/s through medium with a dynamic viscosity of μ � 1500 mPa•s at 23°(polymer prior to curing). ese results in a Reynolds factor much lower than 1 thus ensure laminar flow [11]. In contrast to condensationcuring RTV-2 silicones, the vulcanization speed is controlled exclusively by temperature.…”