| Several types of reinforcement have been traditionally added to polymers in order to enhance their stiffness. In recent years, a new type of reinforcement based on exfoliated mineral layered crystals has begun to be employed commercially. Each such crystal has a sheet-like form, with typical dimensions of approximately 100 nm in length and 1 nm in thickness. Typically, adding 2-wt% of these nanoparticles into a semicrystalline polymer such as dried polyamide 6 (PA6) increases Young's modulus by 50% but decreases markedly the ductility and fracture toughness.; With the main research objective of determining the effect of the addition of nanoparticles on the fatigue behavior of a dried PA6 matrix, axial fatigue and fatigue crack propagation (FCP) tests were carried out employing non-notched and pre-cracked injection-molded specimens of the polymer nanocomposite (PNC) studied and of the corresponding non-filled PA6 matrix. A detailed literature review on the structure of the materials under consideration and on their behavior under monotonic or constant loading was carried out and is presented before the review related to fatigue. The two types of quantitative results obtained from the axial fatigue tests were the macroscopic stress-strain-time response and the fatigue life. (Abstract shortened by UMI.)... |
