A comparison of the temperature dependence of the modulus, yield stress and ductility of nanocomposites based on high and low MW PA6 and PA66

Nanocomposites with both organically modified and unmodified silicate have been prepared by an extrusion process using low and high molecular weight grades of PA6 and a low MW grade of PA66. Mechanical properties have been tested at temperatures ranging from 20 to 120 degrees C. The modulus increase in all nanocomposites with organically modified nanocomposites is similar: at room temperature an increase in the modulus of approximately 10% for each wt% of silicate is found. PA66 nanocomposites display an identical normalized modulus increase as PA6 nanocomposites, while unmodified silicate nanocomposites show a smaller increase in the modulus. The yield stress also increases with the addition of layered silicate. Low MW PA6 and PA66 nanocomposites show brittle fracture behaviour at room temperature, while high MW PA6 nanocomposites are ductile. With increasing temperature all nanocomposites become ductile at a certain temperature. (c) 2005 Elsevier Ltd. All rights reserved.