Promolding (Netherlands)

Particle-reinforced polymer composites or compounds have been used for decades to increase the stiffness and strength of polymers and to reduce thermal expansion. Polymer nanocomposites based on exfoliated layered silicates have been developed more recently [11, 23, 24] for improved mechanical properties, barrier properties, and reduced flammability. Polymer nanocomposites are polymers filled with finely dispersed particles that have at least one dimension in the nanometer range. Compared to composites containing larger dispersed particles, nanocomposites have the advantage of achieving the optimal properties at relatively low filler content, resulting in a lower density and better surface smoothness and transparency. This is due to the large aspect ratio and high stiffness of the particles, resulting from the exfoliation of the layered silicate particles. This can be especially favorable for moisture-sensitive polymers like polyamides, which loose a lot of their stiffness under moist conditions [10, 12]. The types of polymer nanocomposite that will be discussed here are the plateshaped layered silicate nanocomposites, and polymer nanocomposites containing rod-shaped high aspect ratio boehmite needles. In both cases we will consider polyamide-6 (PA6) as the matrix material. For the layered silicate polymer nanocomposites, the increase in stiffness depends strongly on the degree of exfoliation of the silicate layers, see Fig. 1.