(639d) Characterization of the Network Structure of Ancient Ambers

It is widely believed in the paleontology community that amber is a cross-linked polymer primarily based on the observation that it is difficult to dissolve in a solvent. However, presently, there have been few reports of the cross-link density or molecular weight between cross-links of these fascinating materials. In the present study we determined the cross-link density of a series of ambers having ages from 20 million years to approximately 100 million years by making measurements of the plateau modulus of the materials. By assuming that the ambers form tetrafunctional networks we estimate the cross-link density for the measured ambers to range from approximately 1800 g/mol to 3000 g/mol. It was also found that the age of the amber correlated better with the cross-link density than it does with the glass transition temperature. We will discuss the ambers and their thermomechanical properties as used to determine the cross-link density. Suggested network structures will also be shown.

Acknowledgements

The authors acknowledge the National Science Foundation under grants CBET 1603943 and DMR-1610495, and the J.R. Bradford endowment at Texas Tech University, each for partial support of this project. The authors also would like to give special thanks to Professor Xiaoyu Li at Beijing University of Chemical Technology for his support of this work.