6 - Micromechanical modelling of wood–polymer composites

Abstract

This chapter provides an overview of existing micromechanical models to predict the hygroelastic and strength properties of wood fiber composites based on the properties of the fiber and matrix constituents, and the microstructure. It presents to refer the reader to relevant resources to find a suitable model. Most models have previously been developed for composite materials based on synthetic fibers. Those fibers generally have a simpler geometry and show less variability than wood fibers. If a model has not been validated thoroughly to be used for wood fiber composites, care must be taken when choosing models that have been developed for other materials. The particularities of the wood fibers that could affect the applicability of models developed for composites with synthetic fibers are their rather large variability in properties, helical structure, general anisotropy, pits, etc. The micromechanical models can be used to back-calculate a certain fiber property, since it may prove to be easier to test a composite than individual wood fibers. The models may also be used for simulations to identify which microstructural feature has the largest impact on the given macroscopic property. That could give processing engineers and chemists an indication of where to spend most of their efforts in materials development.