This document describes a standard method to collect and report dielectric data for the purpose of monitoring or studying the cure of composites.

Systems Addressed:

Only systems commercially designed for dielectric cure monitoring are addressed.

Assumptions:

It is assumed that the purpose for recording dielectric (and electrical) parameters is one of the following:

a. Investigation

b. Quality assurance

c. Process control

A certain degree of computerization is required.

Correlation and Data Reduction:

The methods for correlation and data reduction are quite varied and out of the scope of this publication. The novice should refer to Section 4 and the references listed in Section 2 as required.

Field of Application:

The monitoring of electrical properties during cure has been found useful for bonded joints and composite materials. Variations of this procedure have been used to evaluate the cure on a wide variety of products including aircraft structure, printed circuit boards, automotive parts, and other applications where process monitoring can lead to greater knowledge of the process, cost savings, or product improvements.

Interpretation:

A detailed discussion of the interpretation of dielectric data and its application to the monitoring and control of cure is beyond the scope of this document. In general, a dielectrometer makes admittance measurements of the circuit that includes the dielectric sensor. If the geometry of the sensor is known, then the measured permittivity and loss factor of the material can be calculated and correlated to a change in the chemical and mechanical properties of the resins. The papers listed in Section 2 provide readings on industry studies.