Concentration Regimes of Fiber Suspensions

A sustained industrial interest has been shown in fiber-filled polymers. When fibers are combined with a polymer matrix that provides cohesion, the fibers become the load bearing component of the composite, and enhance the strength and stiffness of the material. Many articles made from the fiber-reinforced composites are produced by injection molding or compression molding. The thermo-mechanical properties of the end-product highly depend on the fiber orientation distribution induced by the flow of fiber suspension during processing. Therefore, the flow of fiber suspensions needs to be understood in order to predict the fiber orientation distribution and its effects on the end properties of the products. 

The concept of a suspension is only meaningful when the typical dimension of the suspended particles is much smaller than the typical dimension of the apparatus. When these two length scales differ by several orders of magnitude, we speak of a suspension rather than a collection of discrete individual particles suspended in a medium. 

The concentration of fiber suspensions is classified into three regimes dilute, semi-concentrated (or semi-dilute) and concentrated. A suspension is called dilute 

Zheng et al.. Injection Molding, DOI 10.1007/978-3-642-21263-5 5, Springer-Verlag Berlin Heidelberg 2011 

5 Flow-Induced Alignment in Short-Fiber Reinforced Polymers 

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