Is the softening point of ointment related to the storage time?
Here is the English translation of the provided text:
The softening point of plasters is indeed correlated with storage time, with specific impacts as follows:
I. Mechanism of Storage Time on Softening Point
Room Temperature Storage Time
After melting, plaster ring samples must be stored at room temperature for more than 1 hour to ensure test data accuracy. Prolonged storage may lead to oxidation or volatilization of matrix components, indirectly affecting softening point stability.
Storage Time and Matrix Aging
Long-term storage (e.g., over 3 months) can cause oxidation of the plaster matrix, potentially increasing the softening point (due to resin cross-linking) or decreasing it (due to oil rancidity). For example, black plasters stored in winter may exhibit a softening point reduction of approximately 1.8°C compared to summer due to oxidation.
II. Key Influencing Factors
Ambient Temperature and Humidity: High summer temperatures and humidity accelerate matrix component changes, shortening the effective application time of plasters (5-7 days), requiring a softening point of around 50.70°C. In winter, low and dry conditions allow a slightly lower softening point (48.90°C).
Matrix Ratio: Plasters with higher oil content have lower softening points and are more prone to softening point decline with prolonged storage.
III. Industry Recommendations
Testing Standards: Standardize storage time (e.g., 1 hour) before softening point measurement to minimize errors.
Storage Conditions: Store in a cool, dry place in sealed containers to avoid exceeding the recommended shelf life (typically 1-3 months), which may cause abnormal softening points.
ST104A Plaster softening point meter/tester is designed and manufactured strictly in accordance with the method for the determination of the softening point of ointments 2102 in 2020. This method is used for the determination of the temperature when the plaster is softened by heat under specified conditions, that is, the temperature when the plaster falls to 25mm due to heat according to the following method.
It can be used to detect the aging degree of the plaster and indirectly reflect the viscosity of the plaster.
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