A Mechanical Model for the Prediction of the Elastic Properties of Polymeric Resins Reinforced with Liquid Crystal Polymers

Abstract

The mechanical behavior of semicrystalline polymeric resins reinforced with short fiber liquid crystal polymers (LCP) under mechanical loading has been investigated. A micromechanical approach is considered and a representative unit cell model is developed and employed in conjunction with the finite element method of analysis to predict the effective elastic properties of the composite. The advantage of such an approach is that it could contain an improved reference to the microstructural elements by including their geometric description and their non-isotropic behavior. In the present work, the composite is assumed to be macroscopically homogeneous and linearly elastic with periodic fiber distribution array. The finite element method was used in the solution of the micromechanical boundary value problem. Three-dimensional models of the representative unit cell were generated. Models with varying short fiber geometry and volume fractions were developed and a number of boundary conditions and loading cases were used in the analysis. Displacement and stress fields in the composite are obtained and used in the calculation of the effective composite properties. Polypropylene composites reinforced with short fiber Vectra LCP in various volume fractions were fabricated. Tensile experiments were performed. The model predicted effective properties are in good agreement with micromechanical equations values and experimental results.

Keywords

short fiber composites liquid crystalline polymers micromechanics finite element analysis effective properties

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