Testing the Electrical Resistivity of Wax and Copper Composites: An Experiment for Simulating the Electrical Behavior of Metal-Filled Plastics
Gabriel Pinto
Departamento de Ingenieria Quimica Industrial, E.T.S.I. Industriales, Universidad Politecnica de Madrid, Jose Gutierrez Abascal 2, 28006-Madrid, Spain
A study is reported with the aim of providing teachers at many levels with both theoretical and practical information for classroom use, through an experiment simulating the typical variation in electrical behavior of metal-filled plastics. The use of wax-copper systems is proposed because wax is easier to process in most teaching laboratories than a polymer. The overall dependence of the electrical resistivity of these wax-copper composites on filler concentration, showing a percolation transition, is similar to that observed on powder polymer composites. This experiment, inexpensive to construct and easy to perform, allows students to study more important and interesting aspects of chemistry than the usual experiments. In addition, this experiment can serve as an introduction to materials science, polymer chemistry, or electrical properties of solids.
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