Influence of the type of fluid and injection conditions on the processing of natural fiber composites

GASTON FRANCUCCI; ANALÍA VAZQUEZ; EDU RUIZ; EXEQUIEL RODRIGUEZ

Auckland

Conferencia; FPCM-11 - The 11th International Conference on Flow Processes in Composite Materials; 2012

In composites manufacturing, proper impregnation of the fibrous reinforcement is key for obtaining consistent mechanical properties of the components. The capillary flow taking place during resin injection is an important driving force for the infiltration of the fibers. Capillary flow is also a main mechanism on the void formation during resin injection. In the case of natural fibers, important capillary effects appear due to the hollow structure of the fibers, small diameter and molecular polarity. In a previous work presented at FPCM10, the authors have shown the characterization of the capillary effects arising during the infiltration of natural fiber preforms. In this work, the effect of the type of fluid used for the permeability test on the unsaturated permeability value was estimated and related to the capillary effects developed during the infiltration. In addition, the permeability of the fabrics was measured under different injection conditions, constant flow rate and constant pressure, and the differences observed could be explained taking into account the capillary effects developed in each case. Finally, the capillary pressure obtained in the constant pressure experiments was used to correct the applied pressure gradient in the transient unsaturated permeability tests and thus a corrected value of permeability independent of the tests fluid was obtained. The results obtained suggested that the processing conditions, such as type of fluid, injection method and flow velocity could affect significantly the measurements of unsaturated permeability.