Molecular simulations of mechanical properties for polymer materials
Speaker: J.W. Andzelm, The U.S. Army Research Laboratory, Aberdeen, MD, USA
Date: Oct 12, 2018; Time: 2:30pm Location: BPB Rm. 131
The U.S. Army Research Laboratory (ARL) was activated 25 years ago with a mission to discover, innovate and transition science and technology to ensure dominant strategic land power. One of key research strategies at ARL is a development of superior protection systems for individual warfigter and vehicles. The protective systems often use polymers due to their low weight, good strength and toughness which improves resistance to ballistic penetration.
In this presentation, we will review fundamental research projects carried out at ARL and aimed at understanding and prediction of mechanical properties for polymers at high strain rates. We will focus on semicrystalline polyethylene discussing onset of crystallization in polymer melt upon drawing and cooling. Our model includes amorphous domains, explains experimentally known mechanics and supports fracture mechanism through chain pulling. We will discuss shock propagation in anisotropic semicrystalline models at atomistic level.
We also study emerging 2D polymers inspired by Kevlar(R) which is well known for its remarkable strength and stiffness facilitated by the hydrogen bonds formed between Kevlar chains. Molecular and micromechanical calculations predict that ensembles of 2D molecules bonded with hydrogen bonds will form stiff, strong and tough films of unprecedented mechanical performance.
Bio: Dr. Jan Andzelm serves as the Team Leader of the Multiscale Modeling Team in the Polymer Branch at ARL investigating properties of materials important for Soldier protection. The team is developing and applying novel computational techniques at quantum mechanical, atomistic and mesoscale levels aimed at understanding and predicting structural, mechanical and electronic properties of macromolecules and composite materials.
Dr. Andzelm has co-authored over 140 scientific papers and book contributions that attracted more than 14000 citations and generated h-index of 42. Dr. Andzelm was selected as a U.S. Army Research Laboratory Fellow in 2010.