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Title Powder Impregnation Studies for High Temperature Towpregs
Source Proc. 49th Int. SAMPE Symp. Exhib.
Year 2004
Author(s) Allred, R. E.; Wesson, S. P.; Babow, D. A.
Abstract Powder-impregnated fiber tows provide a means of producing composite precursor materials from otherwise intractable or difficult-to-process materials, which is common with high temperature resins [1,2]. Powder towpreg production entails measurement and control of polymer deposition, line tension, and line speed. A powder towline has been constructed that is capable of operation with small volumes of polymer for use with experimental materials. The line is also capable of producing production quantities of towpreg or tapes. Mechanical activities on the towline are monitored continuously, which also implements quality control, providing a certificate for each towpreg package showing that the batch is within established specifications. This paper also provides input data for subsequent analysis of polymer deposition uniformity. Specifically, application of fast Fourier transforms and autocorrelation algorithms shows if variations in polymer loading are periodic or random. If they are periodic, fluctuations in loading may correlate with changes in line tension and velocity or other mechanical effects from the production line. The objective is to manipulate line parameters to deliver the most uniform polymer loading, with all sources of periodic fluctuations tuned out. The essential objective of quality control is to minimize variation in polymer loading and to achieve the most homogeneous coating possible. Thermoset and thermoplastic powders have been processed with and without added fillers. Details of the powder towpreg process, including tension control, spreading, powder deposition, sintering, process control instrumentation, and packaging are discussed along with examples and characterization of various types of powder towpregs that have been prepared.
Keywords Preforms, prepregs, tape-unidirectional, powder towpreg, powder, deposition, polymer, sintering

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