Location

Williamsburg, VA

Start Date

1-1-1988 12:00 AM

Description

Dielectric measurements are becoming increasingly important as a means for feedback control in the area of polymer processing. The changes in dielectric response as a function of changing molecular weight or cross link density have been the subject of much research for the last 50 years [1]. Only now is process control through dielectric feedback becoming a reality due to recent advances in dielectric measurement capability [2]. Microdielectric sensors are now available which function down to frequencies characteristic of mechanical measurements (less than 1Hz) and can be inserted directly into curing composite structures. By monitoring the dielectric properties (permittivity and loss factor) at several frequencies, the ionic conductivity can be extracted [3] with the aid of commercial software packages in real time. This paper investigates the use of first and second derivative information (log ionic conductivity with respect to time) for controlling certain key processin-ing steps during composite curing.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

7B

Chapter

Chapter 7: Characterization of Materials

Section

Process Control

Pages

1573-1579

DOI

10.1007/978-1-4613-0979-6_84

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Cure Control: Strategies for Using Dielectric Sensors

Williamsburg, VA

Dielectric measurements are becoming increasingly important as a means for feedback control in the area of polymer processing. The changes in dielectric response as a function of changing molecular weight or cross link density have been the subject of much research for the last 50 years [1]. Only now is process control through dielectric feedback becoming a reality due to recent advances in dielectric measurement capability [2]. Microdielectric sensors are now available which function down to frequencies characteristic of mechanical measurements (less than 1Hz) and can be inserted directly into curing composite structures. By monitoring the dielectric properties (permittivity and loss factor) at several frequencies, the ionic conductivity can be extracted [3] with the aid of commercial software packages in real time. This paper investigates the use of first and second derivative information (log ionic conductivity with respect to time) for controlling certain key processin-ing steps during composite curing.