# Evidence: enthalpy relaxation

Parent: structural relaxation · class: kinetics · names merged here: enthalpy recovery; enthalpy relaxation

3 papers measured or used it, 1 only mentioned it (of 207 kept papers). Papers in year order; each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/concepts.csv and the cards; do not edit.

## 2006 Konno — Influence of Different Polymers on the Crystallization Tendency of Molecularly Dispersed Amorphous Felodipine · Solid state stability / Physical stability

[2006-konno-felodipine-polymer-crystallization-nucleation-solid-dispersions](../../../cards/2006-konno-felodipine-polymer-crystallization-nucleation-solid-dispersions/paper.html) · Solid state stability / Physical stability · measured · as: enthalpy relaxation

| id | kind | content | locator |
|---|---|---|---|
| R8 | record, measured | fraction unrelaxed 1−φ(t) versus ageing time (mean, error bars SD, n = 3) — 9:1 felodipine:polymer dispersions aged at 2 °C (P6) — sub-table below | Fig. 6, p.2698 |
| R9 | record, derived (E7) | KWW average relaxation time τ and stretch exponent β — 9:1 dispersions at 2 °C (P6); nonlinear regression, R² > 0.9 — PVP τ 208 h, β 0.42; HPMCAS τ 687 h, β 0.45; HPMC τ 319 h, β 0.47; no τ for felodipine alone reported | p.2698 |
| P6 | method | DSC enthalpy relaxation | p.2695; Fig. 6, p.2698 |

## 2010 Marsac — Effect of Temperature and Moisture on the Miscibility of Amorphous Dispersions of Felodipine and Poly(vinyl pyrrolidone) · Solid state stability / Physical stability

[2010-marsac-temperature-moisture-miscibility-felodipine-pvp-asd](../../../cards/2010-marsac-temperature-moisture-miscibility-felodipine-pvp-asd/paper.html) · Solid state stability / Physical stability · measured · as: enthalpy recovery

| id | kind | content | locator |
|---|---|---|---|
| R15 | record, measured | DSC heat–cool cycles to rising maximum temperature — 46.5 wt% PVP, 94% RH for 1 day, dried 15 h under N2 in the DSC; cycles to 60, 70, 80, 90, 100, 110 °C, then to 175 °C (P12) — first scan: strong enthalpic recovery (sharp endotherm ≈55 °C, read), largely absent in later scans; the thermal event moves to increasingly high temperature with each cycle; final heating: exotherm (peak ≈118 °C, read) followed by an endotherm (minimum ≈130 °C, read) | Fig. 10, p.177; text p.176-177 |

## 2010 Rumondor — Effect of Polymer Hygroscopicity on the Phase Behavior of Amorphous Solid Dispersions in the Presence of Moisture · Solid state stability / Physical stability

[2010-rumondor-polymer-hygroscopicity-moisture-phase-separation-asd](../../../cards/2010-rumondor-polymer-hygroscopicity-moisture-phase-separation-asd/paper.html) · Solid state stability / Physical stability · used · as: enthalpy relaxation

| id | kind | content | locator |
|---|---|---|---|
| C17 | claim, conclusion, authors: "can be attributed" | The endothermic peak with the single Tg after exposure is enthalpic recovery following enthalpy relaxation [rests on: R17] | p.487 |
| R17 | record, measured | DSC after humidity exposure — felodipine-, quinidine- and indomethacin-50% HPMCAS and indomethacin-50% PVPVA powders after 94% RH and drying (P7) — one Tg (R3.f-i) accompanied by an endothermic peak, peak minima at ≈57-68 °C (read from Figs. 7b-10b) | Figs. 7b-10b, p.486-487; text p.487 |

## Mentioned only

- 2017 Xie — [2017-xie-temperature-moisture-celecoxib-binary-ternary-asd-stability](../../../cards/2017-xie-temperature-moisture-celecoxib-binary-ternary-asd-stability/paper.html) · Solid state stability / Physical stability (ref 7)