Published ahead of print in April 2022 in the journal Cannabis and Cannabinoid Research, this study examined the vaporization rates of cannabinoids and terpenes in cannabis and hemp flower (inflorescence).
They found that the temperatures typically used in commercial vaporizers are well below the actual boiling points of cannabinoids and most terpenes. However, due to evaporation, both cannabinoids and terpenes will almost completely evaporate over time at temperatures significantly below their actual boiling points.
THC needs at least 3 minutes to mostly evaporate at a temperature of 180°C [356°F]. The higher the temperature, the faster the evaporation. They also found that terpenes, which have much lower boiling points than cannabinoids, evaporate almost completely before the cannabinoids start to evaporate.
Monoterpenes are the terpenes with the lowest boiling points (when compared to sesquiterpenes), and their losses to evaporation begin at the moment of harvest.
Monoterpenes and monoterpenoids are mostly evaporated and the sesquiterpenes and sesquiterpenoids are markedly evaporated, before there is significant evaporation of THC.
The normal boiling points of the cannabinoids are much higher than what is usually considered, that is, above 400°C [752°F] rather than about 160°C [320°F], as mistakenly stated in many users' publications.
Yet, cannabinoids' evaporation at the temperatures of vaporizer operation is feasible.
at 180°C [356°F], more than 3 min are required for approaching complete evaporation of the THC.
The full text paper is here at Liebertpub.com.