The Aquadyne DVS are fully automated, gravimetric, one (Aquadyne DVS-1) or two (Aquadyne DVS-2) sample water vapor sorption analyzers. They measure adsorption and desorption isotherms of water vapor both accurately and sensitively, including sorption kinetics, with minimal operator involvement. The weight(s) of one or two sample(s) is/are constantly monitored and recorded as the relative humidity is automatically varied by the blending of dry carrier gas with a saturated gas stream. The dual balance design of the Aquadyne DVS-2 allows increased analysis throughput, side-by-side comparison with known or reference materials, or an extended mass range for a single sample. The independently temperature-controlled balance head environment ensures long term stability. The small sample chamber ensures rapid changes in sample atmosphere conditions when the relative humidity is altered during an analysis. Sample(s) can be pre-dried in situ at up to 85°C (DVS-2) in a flow of dry gas. The software supports multiple users with password-controlled access.
MEASUREMENT CAPABILITIES
Isotherms: Mass change as a function of changing relative humidity, increasing mass during adsorption (increasing RH%), decreasing mass during subsequent desorption (decreasing RH%).
Kinetics: time-dependent sorption studies give the rate of sorption.
Effect of Temperature: isotherms and kinetics change as a function of temperature. Can be used to yield sorption enthalpies.
APPLICATIONS/RESULTS
Deliquescence: certain salts exhibit the property of dissolving in self-adsorbed water.
Equilbrium moisture content: quantitatively the amount of water associated (adsorbed/absorbed) with the material under given atmospheric conditions of temperature and relative humidity. (Organic materials may be subject to molding according to atmospheric humidity, for example).
Hysteresis working range: adsorption and desorption usually differ by hysteresis - this gives a range of stability in which subsequent sorption cycles produce no change in equilibrium moisture content.
Hydrophobicity/philicity: the shape of the isotherm reveals relative strength of affinity between water and the surface, due to polar or other chemical interactions.
Micropore investigations: even hydrophobic materials can take up moisture if their pores are small enough.
Crystallization phenomena: certain amorphous materials will undergo crystallization as a function of water sorption due to, for example, shifts in glass transition points.
Sample form: sorption kinetics can be altered by the physical form of a material - powder, granule, pellet, tablet, monolith etc.
SPECIFICATIONS
Balance heads: |
|
2(DVS-2), 1(DVS-1) |
Balances, type: |
|
ultrasensitive electronic microbalances |
Balance capacity(each): |
|
5g |
Balance capacity(combined): |
|
10g (DVS-2 only) |
Dynamic weighing range(each): |
|
-500mg to +500mg, 0 to +1000mg |
Dynamic weighing range(combined): |
|
-1000mg to +1000mg, 0 to +2000mg (DVS-2 only) |
Weighing resolution: |
|
0.1µg |
RH range: |
|
<2% - 98% (depending on temperature) |
RH resolution: |
|
0.1% |
RH accuracy : |
|
± 0.8% RH at 25°C |
Sample chamber temperature range: |
|
<10 - 80°C (DVS-2), 15-60°C (DVS-1) |
Sample chamber temperature stability: |
|
± 0.1°C |
Balance head temperature : |
|
Up to 85°C (DVS-2) , 75°C (DVS-1) |
Gas flow rates: |
|
0 - 200 cm3/min (mass flow controllers) |
Viewing port / sample chamber door |
|
heated, triple-glazed |
Data acquisition rate: |
|
adjustable, up to 12 points per minute |
Sample pan material: |
|
silica |
Water reservoir capacity: |
|
46 ml |
|
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