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Determination of Gelation Zone Position in Reactive Thermoplastic Pultrusion by Analysis of Heating Power Consumption

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Abstract:

Process speed in pultrusion is significantly influenced by the exothermic reactions of the matrix materials used. The main reaction zone (gel zone) is a key indicator to describe and interpret the reaction behavior in pultrusion. It can be easily observed by elevated temperatures in the die, particularly for highly exothermic thermoset matrices like vinyl ester, epoxy, and polyurethane. However, this effect is not as pronounced in reactive thermoplastics. The exothermic reactions contribute to a reduction in power consumption of the heating plates within the different heating zones, each with its individual temperature. Analyzing the power consumption of the individual heating zones across different process parameter settings allows to determine the position of the gel zone. This information is foundational for pultrusion process optimization, as it allows for more efficient utilization of the die length, ultimately increasing the pull speeds and enabling higher production rates. In this study, a comparative analysis of the power consumption across the heating zones was performed. To validate the findings obtained from the power measurements, thermocouples were drawn through the die at the same process parameters to accurately measure the temperature evolution within the pultruded profile throughout the die length.

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Periodical:

Defect and Diffusion Forum (Volume 451)

Pages:

147-156

DOI:

https://doi.org/10.4028/p-S43Bos

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Cite this paper

Online since:

April 2026

Authors:

Michael Wilhelm*, Christoph Schelleis, Georg Zeeb, Frank Henning

Keywords:

Caprolactam, Gel Zone, Power Consumption, Pultrusion, Reactive Thermoplastic

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Creative Commons CC BY 4.0

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* - Corresponding Author

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