Experimental Characterization of the Influence of Tackifier Material on Preform Permeability

Abstract

Liquid composite molding processes use both simple and complex sets of preforms to produce high-performance composite parts. To produce these parts, binder materials known as tackifiers are used to shape the fabrics into complicated preforms prior to the resin injection. Tackifier materials enhance the formability and handling operations of dry reinforcements, and become an integral part of the composite laminate. A commercial tackifier was employed to form fiberglass preforms. Various preforms were prepared with different concentrations of the tackifier, and the effect on the permeability was studied. A permeability work-cell was used to continuously measure the permeability of the tackified preform for different fiber volume fractions. An analytical model based on a unit cell definition in combination with microscopic images was used to predict the permeability of tackified preforms. A comparison between the experimental measurement and the predicted results show the deficiencies in the unit cell approach to model permeability of preforms containing low concentrations of tackifiers.

Mechanical characterisation of the shear, bending and friction behaviour of bindered woven fabrics during the forming process

“…By using a binder, the fibre orientation and shape retention can be maintained during the trimming, handling and impregnation of the preform. The binder also prevents the layers from spring-back and shifting [14]. Furthermore, the binder influences the permeability of the textile semi-finished product and thus the resin infiltration into the preform.…”

“…The impregnation of the preform with the matrix material is influenced by the permeability of the fibre structure [14]. This can be expressed by Darcy's law:…”

“…In addition, the position and concentration of the binder in the reinforcing material has an influence on the permeability of the textile semi-finished product. Some scientists observed that binder particles settle in the channels between the fibre tows and increase the flow resistance of the textile semi-finished part [14]. It was demonstrated that the permeability of a preform increases when the binder is mostly within the rovings [13].…”

Experimental parametric study of flow‐induced fiber washout during high‐injection‐pressure resin transfer molding

“…This is termed as “fiber washout” which is flow‐induced and causes unacceptable deformation of the reinforcement, and introduction of excessive resin and/ or dry fiber zones . It may also change local fiber volume fraction and the permeability of preform and lead to inconsistent mechanical performance …”

Local Structure Fixation in the Composite Manufacturing Chain

“…It results from the thread displacement and falling apart the textile structure during formation [17,18]. In order to avoid these problems, structure fixing over the entire surface is being analyzed [19][20][21][22][23]. It is a good solution for the preforms with a low deformation degree.…”