# Formula: water plasticization rule of thumb

Parent: — · class: glass transition · names as written: Tg depression by sorbed water (rule of thumb); water plasticization Tg rule of thumb; water plasticization rule for wet Tg; water plasticization rule of thumb

5 instances in 5 papers (of 207 kept papers). Each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/formulas.csv; do not edit.

## 2013 Ilevbare · E15 · Tg depression by sorbed water (rule of thumb) · Dissolution / C. Amorphous solubility and LLPS

[2013-ilevbare-llps-supersaturated-poorly-water-soluble-drugs](../../../cards/2013-ilevbare-llps-supersaturated-poorly-water-soluble-drugs/paper.html) · Dissolution / C. Amorphous solubility and LLPS

- expression: Tg falls by about 10 °C for each 1% of water sorbed
- symbols and units: Tg glass transition temperature (°C); water content (%)
- assumptions stated: cited from refs 22, 34
- used for: R5, R6
- status: printed in words · recomputed: reproduces (dry 50.4 °C, dispersed phase 0.4 °C with 4.87% water at 37 °C: 50.0 / 4.87 = 10.3 °C per 1%, within rounding)
- locator: p.15

## 2017 Indulkar · E6 · Tg depression by sorbed water (rule of thumb) · Dissolution / A. Release mechanism and LoC

[2017-indulkar-origin-nanodroplet-formation-asd-isotope-scrambling](../../../cards/2017-indulkar-origin-nanodroplet-formation-asd-isotope-scrambling/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: wet Tg = dry Tg − about 10 °C for each 1% of water sorbed (stated in words)
- symbols and units: dry Tg 42 °C; water content 2.5% (M1)
- assumptions stated: typical observation (ref 25, indomethacin)
- used for: M1 wet Tg; C16
- status: printed in words · recomputed: reproduces (42 − 10 × 2.5 = 17 °C; text "approximately 17°C")
- locator: pdf p.9, p.13

## 2020 Saboo · E6 · water plasticization rule for wet Tg · Dissolution / A. Release mechanism and LoC

[2020-saboo-congruent-release-hbond-crystallization-tg-pvpva-asd](../../../cards/2020-saboo-congruent-release-hbond-crystallization-tg-pvpva-asd/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: Tg decreases by 10 °C for each 1% of water sorbed (in words)
- symbols and units: dry Tg from DSC; water content of the water-saturated amorphous drug extrapolated to 100% RH
- assumptions stated: linear decrease; experimental observation from ref 27
- used for: M1 (wet Tg 29 °C)
- status: printed in words · recomputed: inputs not printed (water content of water-saturated amorphous IND)
- locator: p.12; SI p.4

## 2021 Yang · E3 · water plasticization Tg rule of thumb · Dissolution / A. Release mechanism and LoC

[2021-yang-asd-nanodroplet-release-drug-properties-polymer-selection](../../../cards/2021-yang-asd-nanodroplet-release-drug-properties-polymer-selection/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: Tg lowered by 10 °C for every 1% w/w water absorbed
- symbols and units: Tg (°C); water content (% w/w) of the amorphous drug at 100% RH from a 37 °C sorption isotherm extrapolated from 95% to 100% RH
- assumptions stated: approximation cited from ref 28
- used for: wet Tg of M2, M3, M4
- status: printed in words · recomputed: inputs not printed (water contents not printed)
- locator: p.2069

## 2022 Hiew · E3 · water plasticization rule of thumb · Dissolution / A. Release mechanism and LoC

[2022-hiew-combining-drug-salt-formation-asd-double-edged-sword](../../../cards/2022-hiew-combining-drug-salt-formation-asd-double-edged-sword/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: Tg decreases by 10 °C for every 1% w/w of water absorbed (stated in words)
- symbols and units: Tg in °C; water in % w/w
- assumptions stated: cited from ref 48
- used for: R3, R5
- status: printed in words · recomputed: reproduces (highest dry ASD Tg ≈105.5 °C, R3.x, minus 10 °C × 35%, the lowest stated uptake in R5, lies far below 37 °C, as stated for all ASDs)
- locator: p.58