ORS2-0405
Topological Analysis of Load Transmission in Epoxy Networks with Different Reaction Conversion
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Oct 1, 2026
15:15 - 15:30
Room 103
Session Chairs
Jeong Min JI
Presenter(s)
Satoru Yamamoto (Kyushu University)
Co-Author(s)
Abstract
Understanding how incomplete curing affects the mechanical response of epoxy networks is essential for improving their reliability. In this study, all-atom molecular dynamics simulations combined with topological analysis were conducted to investigate load transmission in epoxy networks with systematically varied reaction conversion. Epoxy networks were represented as graphs, in which molecular segments were treated as edges and tertiary amine cross-linking sites as vertices. Network chains were classified into percolated load-bearing paths, dangling chains, and isolated chains based on graph connectivity. A virial-based approach was introduced to quantify the stress contribution of each path type. The results showed that load-bearing paths carried most of the applied stress, whereas dangling and isolated chains contributed less to load transmission. Increasing reaction conversion increased the number of load-bearing paths while reducing the fractions of dangling and isolated chains. Topological analysis across the gel point revealed that the cycle rank remained close to zero before gelation and increased markedly above the gel point, indicating the emergence of network cycles. Further curing increased the normalized cycle rank, demonstrating progressive densification of network cycles. Despite these substantial topological changes, the small-strain Young’s modulus remained nearly constant, whereas stress at moderate and large strain decreased systematically with decreasing conversion. These results demonstrate that network topology governs load transmission and elastic weakening in epoxy networks.
