Multiscale morphological analysis of commingled PP/unidirectional glass fiber composites: Experiment and theory

Abstract

Quantitative 2D image processing has been performed to assess the morphology of commingled polypropylene composites reinforced by a range of glass fiber contents. Quantitative morphological probes, derived from both local and global analyses, point out the heterogeneous dispersion of unidirectional fibers within the polymer matrix, i.e., the presence of aggregates. It is found that more than 86% of fibers are packed into aggregates at a maximum packing fraction of 0.84 whatever the filler content. Moreover, accounting for these morphological characteristics and based on the percolation concept, prediction of the morphology behavior of such composites is proposed. A good agreement between theory and experiment is found.

Effects of fiber aggregates on the transverse mechanical behavior of commingled PP–glass fiber composites

“…On the basis of viscoelastic properties of aggregates, the prediction of the mechanical behavior of unidirectional composites can now be determined. A previous morphological analysis has shown that fiber aggregates are randomly dispersed within the polymer matrix, whatever the content of fillers 19…”

“…Using a 2D image processing, Dubouloz‐Monnet et al19 have shown that the composites exhibit a heterogeneous morphology characterized by both isolated fibers and aggregates. In fact, more than 86% of glass fibers are packed into aggregates randomly dispersed within the polymer matrix.…”

“…Moreover, different geometric characteristics of such clusters have been determined, such as the surface fractions of fibers and aggregates, S f and S ag , and a morphological parameter, χ 0 , defined by the following relationship9, 19 (Table II): To define the phase considered as the reinforcing one, micromechanical modeling is performed. Benzarti20 and Vendramini et al7 have shown that if glass fiber is assumed as the reinforcing phase, embedded in the polymer, important differences can be observed between theoretical and experimental values.…”

“…On the basis of a previous morphological analysis,19 we tried to define the key parameters governing the initiation of damages in the commingled composites. For this, a linear evolution of ε c versus the interaggregate surface‐to‐surface distance, Δ ag , is plotted in Figure 10, whatever the temperature range.…”

A preliminary study on bladder‐assisted rotomolding of thermoplastic polymer composites

“…The average diameters of E-glass and iPP fibers are 17.5 and 30 µm, respectively. 17 TWINTEX plies can be formed into rigid laminates under the simultaneous application of heat and pressure. According to technical datasheets from Vetrotex, the compacted material has an average tensile modulus of 13.8 GPa and a tensile strength of 280 MPa.…”