The effects of polymeric binders on the processability and properties of composites made by suspension prepregging

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Virginia Tech


This thesis concerns the production of thermoplastic/carbon fiber composites via aqueous suspension prepregging. Suspension prepregging requires the use of a binder dispersant: i) to disperse the polymer particles so as to get good fiber-matrix distribution in the prepreg, and ii) to improve the handling characteristics of the prepreg, by holding the matrix to the fibers and the fibers to themselves. The effects of the binder on the processability, properties, and performance of composites were assessed.

It was found that the addition of the binder can affect both the matrix and the composite performance depending on the binder concentration and chemistry. For example an increase of 250 % on the complex dynamic viscosity of LaRC TPI matrix was measured upon the addition of 21.3 wt% of imidized LaRC TPI polyamic acid binder at a frequency of 1 Hz. The greatest fiber-matrix adhesion was observed for PEEK composites when BisP BTDA polyamic acid was used as a binder. A preliminary, qualitative study on the possibility of using suspension prepregging as means of manufacturing thermoplastic/carbon fabric composites was performed. Good penetration of PEEK polymer particles into the fabric was obtained when the fabric was previously desized by acid digestion.

A preliminary study was made on the binding and dispersing capabilities of a novel copolymer poly(pyridine ether-eo-ether ether ketone). The addition of the copolymer to PEEK drastically increased the melt viscosity due to an ionomer effect. This resulted in poorly consolidated panels with high void volumes.