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Electron Microscopy Sciences

Technical Data Sheets

EMS Poly III Embedding Programs

EMS Catalog #4444

Description

There is a choice of 3 embedding programs in the EMS Poly III catering for 3 different solvents. They have been pre-programmed for general use but the user can change the programs to fit specific specimens.

Program 1: for removal of ethanol
Program 2: for removal of acetone
Program 3: for removal of propylene oxide

The programs each have up to 5 steps that bring the specimens from the resin/solvent mix through removal of the solvent into pure resin.

The individual steps, using Program 1 as an example:

The Program starts at a temperature of 25°C.
The vapor pressure of ethanol at that temperature is ~8kPa.

Note: Steps 4 and 5 are mandatory steps when working with low vapor pressure solvents such as ethanol. More volatile solvents can usually be removed in a shorter procedure only using Step 3, or using Step 3 and 4.

Step 1 serves the gentle removal of air bubbles that may have been introduced.

Step 2 aims at the bulk removal of ethanol, using a pressure of 15kPa at 25°, which is slightly above the max vapor pressure. Ethanol will evaporate from the surface of the resin/solvent mixture. The pressure will increase as a result.

Evaporated ethanol is diluted with air that is admitted into the recipient and then pumped away. These events are controlled by the setting of global variables:

∆P1, which relates to the pressure increase resulting from evaporation and

∆P2, which determines how much air is admitted to dilute the evaporated solvent.

The technical manual provides information on how to set the parameter values for these variables.

When, as a result of evaporation, the pressure has increased by preset threshold level ∆P1, the air admission valve opens. The time that passes before this happens is in the order of minutes and depends on the number of specimens, more accurately on the total evaporating area in the recipient, the pressure in the recipient and on the volatility of the solvent.

Example: Let us assume ∆P1 was set to 1kPa and ∆P2 to 25kPa, which are recommended settings.

When the pressure in the recipient has gone up by 1kPa to 16-17kPa (error margins ± 1kPa) the air admission valve opens. The pressure in the recipient increases as a result and when it has gone up by 25kPa the air admission valve is closed again. The pump is activated and diluted ethanol vapor is removed until the set pressure of 15kPa has been reached again and the pump switches off. As long as ethanol keeps evaporating this process will be repeating itself, initially with short time intervals, later with gradually increasing intervals. When the interval time has increased to >30 min, indicating that the bulk of the ethanol has been removed, the instrument automatically switches to Step 3, regardless of whether the set time (in the default set up this is 5 hrs) has not yet been completed.

Step 3 starts with raising the temperature and lowering the pressure. Residual ethanol is more easily removed under these conditions and the process described for Step 2 continues until the interval time between pump cycles has increased to >30 min. Then a flush/pump cycle is started: the air valve is opened and the pump switched on so the pump works under gas ballast conditions, improving evaporated solvent removal. This flush/pump cycle is repeated twice within a few minutes, after which the system is pumped down to the set vacuum level. After 30 min the process is repeated. After a total number of twelve of these cycles the system goes to Step 4.

Step 4 starts with raising the temperature after which the same process as described for Step 3 is activated.

Step 5 as Step 4.

The program ends after Step 5 has been completed.

The Technical Manual describes programming steps as well as deleting steps.

Polymerization Programs

There is a choice of 2 programs for polymerization in the EMS Poly III. They have been pre-programmed for general use but the user can change the programs to fit specific specimens.

Program 4: for 24 hr polymerization (temperature curing)

Program 5: for 48 hr polymerization (temperature curing)

The programs each have up to 5 steps.

The individual steps are explained using Program 4 as an example. Note: each step switches to the next one based on the programmed time, unlike the steps in Programs 1, 2 and 3.

When embedding has been completed, specimens need to be polymerized. The programs use a minimum of 2 steps.

Step 1 raises the temperature over a period of approximately 30-40 minutes to the 60°C whereas the vacuum is set at 10kPa. Under these conditions the viscosity of epoxy resin is much reduced and the specimens yield the last traces of solvent.

Step 2 starts with releasing the vacuum and slightly raising the temperature. The start of step 2 is the preferred moment for the BEEM vials to be topped off with pure resin. After the polymerization time has passed the polymerized specimens are removed from the recipient.

Factory Preset Programs 1-3 and Steps

Program 1 2 3
Solvent Resin Ethanol Acetone Propylene Oxide
Step 1
Duration 00:05:00 00:05:00 00:30:00
Temperature 25°C 25°C 15°C
Pressure 65kPa 65kPa 100kPa
Step 2
Duration 05:00:00 05:00:00 00:05:00
Temperature 25°C 25°C 15°C
Pressure 15kPa 30kPa 65kPa
Step 3
Duration 02:00:00 02:00:00 05:00:00
Temperature 30°C 30°C 20°C
Pressure 20kPa 20kPa 60kPa
  6 hr. flush 6 hr. flush 6 hr. flush
Step 4
Duration 02:00:00 02:00:00 02:00:00
Temperature 30°C 30°C 25°C
Pressure 10kPa 10kPa 40kPa
  6 hr. flush 6 hr. flush 6 hr. flush
Step 5
Duration 02:00:00 02:00:00 05:00:00
Temperature 45°C 45°C 45°C
Pressure 10kPa 10kPa 20kPa
  6 hr. flush 6 hr. flush 6 hr. flush

Factory Preset Programs 4-5 and Steps

Program 4 5
Polymerization Resin Short
Epoxy Methacrylate
Long
Epoxy Methacrylate
Step 1
Duration 02:00:00 02:00:00
Temperature 60°C 60°C
Pressure 10kPa 10kPa
Step 2
Duration 22:00:00 46:00:00
Temperature 65°C 60°C
Pressure 100kPa 100kPa
Step 3, 4, 5
Duration Unused Unused
Temperature    
Pressure    

Product Information

EMS Poly III Evaporation-Controlled Automated Embedding and Polymerization