{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"edb9faa752aaf6ff2612a5e0177d2686b53d1eb233a7eabef07b44b8ab4996b7","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["169f0b6faa7371dd3302978930e1cf39753a62e4d7ee2fc66902aa52c5751135","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"879502f7ff4636678d4d6026b0233f48f9609fe73bdafb46330a9aa051d0a7de","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":["ai:gpt-5.5"],"external_id":"bio.glass-transition.fragility-origin","kind":"phenomenon","literature_status":"open","n":"2","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 $\\mathrm{SiO_2}$ 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":"169f0b6faa7371dd3302978930e1cf39753a62e4d7ee2fc66902aa52c5751135","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":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"e9095ecdd007afca021da73cc8263c798f6b761e59f6f377a4dff19a2cc21c54","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"0357d05e1366c2caba4c432410d4cd1988d62e02cf1ef4721c39679543f9c4a7","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"AoaBj7dVC5rghCB-PD3UIgHPzUPBlKkcbc_M99yx-nVvdU2dNAdFb9Kor7azZOEBYZyy3UDKoh2CRFpW_ZQIAg"},"schema":"pubphys.envelope/1"},"record_hash":"e9095ecdd007afca021da73cc8263c798f6b761e59f6f377a4dff19a2cc21c54","leaf_index":2568}