{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"90482aea68309d0064f0ebf90c56086e05513efaca67f9181d65f24b3cc8ec7b","created":"2026-10-03T07:17:57Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"9827a03e5f083006878183af007c3b937d3390dfe9c75e77e45401b1c6286236","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"bio.glass-transition.fragility-origin","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Some liquids, such as molten silica, slow down smoothly as they approach the glass point, while others, such as many organic liquids and polymers, slow down abruptly; this steepness is called fragility. Why liquids differ so much is not known.","posed_since":"","precise":"The kinetic fragility m = d log10(tau_alpha) / d(T_g/T) evaluated at $T = T_g$ ranges from about 20 for SiO2 to above 150 for some polymers. Identify the microscopic determinants of $m$ (softness of the repulsion, network connectivity, vibrational anharmonicity, the heat-capacity jump $\\Delta C_p$ at $T_g$) and give a predictive relation for $m$ tested across a set of chemically different liquids.","problem_ref":null,"references":"","settled_by":"A relation predicting m from microscopic or thermodynamic inputs that holds within experimental error across a large database of molecular, network, polymeric and metallic glass formers.","status_note":"","title":"What sets the fragility of a glass-forming liquid","topic_ref":"b6cec0edf29a3e5b5b7b70395d6ca2460f15dfb7644125d881ab5595366caa14"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"169f0b6faa7371dd3302978930e1cf39753a62e4d7ee2fc66902aa52c5751135","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"593234b63f198eff25c62aedb1a342156facff50942187d20ef33c9d1eae8fd4","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"xDQ8-SwjBcfSilYF5gXKLLCAQPlxivG2kBLlMmK1Op_iISyB-3XePIyZ7tuPxEFAwXOPP_Kl3-eozW9NF7oADg"},"schema":"pubphys.envelope/1"},"record_hash":"169f0b6faa7371dd3302978930e1cf39753a62e4d7ee2fc66902aa52c5751135","leaf_index":776}