Polymeric Composites Tailored by Electric Field
- PDF / 1,486,310 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 17 Downloads / 221 Views
A solid composite of desirable microstructure can be produced by curing a liquid polymeric suspension in an electric field. Redistribution effect of the field-induced forces exceeds that of centrifugation, which is frequently employed to manufacture functionally graded materials. Moreover, unlike centrifugational sedimentation, the current approach can electrically rearrange the inclusions in targeted areas. The electric field can be employed to produce a composite having uniformly oriented structure or only modify the material in selected regions. Field-aided technology enables polymeric composites to be locally micro-tailored for a given application. Moreover, materials of literally any composition can be manipulated. In this article we present testing results for compositions of graphite and ceramic particles as well as glass fibers in epoxy. Electrical and rheological interactions of inclusions in a liquid epoxy are discussed. Measurements of tensile modulus and ultimate strength of epoxy composites having different microstructure of 10 vol% graphite, ceramic particles and glass fiber are presented. I. INTRODUCTION
Many applications will benefit from materials whose structure is designed and optimized to perform intended multi-functional tasks. To date, most composites having designed structures are mixtures of ceramic and metal constituents produced by variety of methods such as thermal spraying,1 powder processing,2 diffusion heat treatment,3 or sedimentation.4 Functionally graded polymers are also becoming prevalent. Lambros et al.5 obtained continuously varying mechanical properties in a polyethylene carbon monoxide copolymer by taking advantage of the susceptibility of the material to ultraviolet (UV) irradiation. Lee et al.6 and Krumova et al.7 created gradient materials from an epoxy resin filled with carbon fibers by controlling speed and duration of centrifuging. These technologies, while demonstrating the potential of polymeric composites with graded structure, are limited by critical processing conditions, e.g., high speed rotation of the mold or UV active pre-polymer. An electric field can be employed to modify the structure of polymeric composites. A liquid polymer intially containing randomly suspended micro- or nanosized inclusions can be cured in the presence of an electric field to produce a solid composite having locally microtailored structure. Direction, magnitude, and gradient of the applied field can vary from region to region of the manufactured part. The resulting material contains
DOI: 10.1557/JMR.2004.0151 1164
http://journals.cambridge.org
J. Mater. Res., Vol. 19, No. 4, Apr 2004 Downloaded: 13 Mar 2015
inclusions whose orietation and concentration changing from one region to another. This approach for local optimization of microstructure in polymeric composites is called field-aided micro-tailoring (FAiMTa) technology. FAiMTa technology targets multifunctional materials having desirable electroactive, thermal, or mechanical properties. To date, an extensive study of solid anisot
Data Loading...
