Water uptake behavior of layered silicate/starch–polycaprolactone blend nanocomposites

The water uptake behavior of biodegradable layered silicate/starch–polycaprolactone blend nanocomposites was evaluated. Three different commercial layered silicates (Cloisite Na⁺, Cloisite 30B and Cloisite 10A) were used as reinforcement nanofillers. Tests were carried out in two different environments: 60 and 90% relative humidity using glycerol solutions. The clay/starch–polycaprolactone blend nanocomposites were obtained by melt intercalation and characterized by gravimetric measurements and tensile tests. The intercalated structure (determined by wide‐angle X‐ray diffraction) showed a decrease in water absorption as a function of clay content probably due to the decrease of the mean free path of water molecules. The diffusion coefficient decreased with clay incorporation but a further increase in the clay content did not show an important effect on this parameter. Elongation at break increased with exposure showing matrix plasticization. Mechanical properties of the nanocomposites deteriorated after exposure whereas they remained almost constant in the case of the neat matrix. Copyright © 2007 Society of Chemical Industry     

Topological modelling of large networks

In a complex network, there is a strong interaction between the network's topology and its functionality. A good topological network model is a practical tool as it can be used to test 'what-if' scenarios and it can provide predictions of the network's evolution. Modelling the topology structure of a large network is a challenging task, since there is no agreement in the research community on which properties of the network a model should be based, or how to test its accuracy. Here we present recent results on how to model a large network, the autonomous system (AS)-Internet, using a growth model. Based on a nonlinear preferential growth model and the reproduction of the network's rich club, the model reproduces many of the topological characteristics of the AS-Internet. We also identify a recent method to visualize the network's topology. This visualization technique is simple and fast and can be used to understand the properties of a large complex network or as a first step to validate a network model.