COLLABORATIVE RESEARCH AND DEVELOPMENT (CR&D). Delivery Order 0044: Accelerated Computational Approach to Multi-scale Relaxation in Nanoparticulate- polymer Composites

摘要

This research in support of the Air Force Research Laboratory Materials and Manufacturing Directorate was conducted at Wright-Patterson AFB, Ohio from 1 December 2005 through 1 April 2008. This task developed and validated Monte Carlo computational methods for the modeling of two-dimensional nanoplates in polymer/solvent matrix. Nano-particulate polymer composites consist of multi-component systems with such constituents as solvent, polymer chains, clay platelets etc. The vast parameter space includes molecular weight of constituents, their concentrations, temperature, and interaction apart from processing and driving mechanism (shearing, compression, etc.). The constitutive components can be described by particles, chains, and sheets in a coarse-grained modeling by computer simulations. Relaxation of each component and their cooperative dynamics lead to multi-scale responses resulting in self- organizing structures. While the stochastic dynamics of each component facilitate equilibration, the physical entanglement, local-crowding, and jamming cause entropic constraints that may hinder thermal equilibration. The evolving structure may or may not be in thermodynamics equilibrium depending on the time scales. Understanding the structure and dynamics of such a multi- component system is known for its complexities. Therefore, we proposed to address some of the issues by accelerated computational approach.