Dependence of Tensile Strength on Polymer Chain Length

Graph of ultimate tensile strength vs. polymer chain length taken from simulation data

Abstract

Simulations were performed on polymers with varying chain length. A block of polymer was subjected to a uniaxial tensile strength test in order to determine its ultimate tensile strength. It was determined that the ultimate tensile strength of the polymer block increases with increasing polymer chain length.

Introduction

The tensile strength of a polymer is important in choosing what sort of application that polymer will be used for. When preparing polymers, a chemist can control the chain length of those polymers. The chemist would like to know what chain length to make a polymer in order for it to be an appropriate material for the application in question.

Simulation

To simulate this system I used Lennard-Jones potentials between polymers and a FENE type potential between segments on the chain. The simulations are performed at a constant temperature of 0.001 using a Nose-Hoover thermostat. They are also performed at a constant hydrostatic pressure of 0.40414 in two dimensions and a constant strain rate of 0.1 in the third dimension.

Data Analysis

The results from these simulations are shown to the left. The graph shows that the ultimate tensile strength of a block of polymers increases with increasing polymer chain length. The ultimate tensile strength of a block of polymer was determined by plotting the stress vs. strain for each simulation.

References

Tensile strength vs. chain length
http://plc.cwru.edu/tutorial/enhanced/files/polymers/synth/Synth.htm

Engineering Stress vs. Strain
http://www.engr.ukans.edu/~rhale/ae510/elasticity/sld002.htm