Cyclododecane (CCD)
Cyclododecane is a saturated, alicyclical hydrocarbon.
Chemical Characteristics
It is one of the most stable representatives of this family, and its capability of chemical reaction inertia is comparable with the saturated open chained hydrocarbons.
Physical Characteristics Melting point 58-61°C Boiling point von 243°C Flash point bei 98°C Fire point 265°C Vapor pressure (20°C) ca. 0,1hPa Specific gravity at 65°C 0,830g/ccm Viscosity at 65°C 2,2 mPa s
Solubility
Non-polar solvents very high solubility
(saturated, aromatic and halogenated hydrocarbons)Pentane (boiling point 36°C)
Hexar (boiling point 68°C)
iso octane (boiling point 99°C)
Octane (boiling point 126°C)
Naphta
Dichloromethane (Caution poisonous)
Polar solvents almost insoluble
Water
Ethanol
Isopropanol
AcetoneSolvents of medium polarity only have a very poor solubility.
The insolubility in polar solvents like water is of central importance for any application in the field of restoring. It is only due to this characteristic that a volatile sealing, or adding of hydrophobic features as a protection against water or other polar solvents, becomes possible. This protection is not reached because of the insolubility of cyclododecane in polar systems alone. The formation of the film and its characteristics are the most critical factors for the production of the film.
Formation of the film and its characteristics
The way CCD forms a film is best compared with a crystallization. Basically it does not form an absolutely homogeneous film, neither when solidifying from the melt nor when precipitating from a solvent. It forms needle-like crystals, positioned more or less close to each other. As the density of the films very often determines whether or not the procedure will be successful, the conditions during the crystallization are very important.
Crystallization from a melt
Key rule for crystallization from a melt:
The slower the temperature sinks from above the melting point to a temperature below it, the more distinctive the felt formed by the crystals will be. A quick cooling down on the other hand will result in significantly more homogeneous and denser films.
In practice this slow cooling down and forming of a crystal felt from a pure melt only takes place when casting big pieces. Films of less than 3mm will cool of that fast at room temperature, that forming large crystals is impossible.
Mechanical Characteristics:
Very resistant against pressure, very good elasticity, nearly abrasion-proof.
Density of the film:
A very thick film offers a very good protection against water as well as against ethanol, isopropanol or acetone.
Reversibility:
It takes a long time, laborious procedure to remove a film by using a hot-air gun or solvents. A rather long period of time should be taken into account for the sublimation!
WARNING
Using a brush to apply the pure, unthinned melt should be absolutely avoided. The high melting point and the fast cooling down of the material very often leads to unsatisfying results.
Tips and Tricks
We have had no problems when using a hot-spraying machine. For this job we used a machine produced by Fa. Wilhelm Wagner (WiWa). The machine was modified to a fully heatable system by Fa Eltherm. The following parts are heatable, the temperature is adjustable up to about 120°C: Boiler, pump, tube, spray gun. The temperature at the nozzle should be at least 80°C. Consumption: At least 400g/m².
Films from a melt with added solvent need to be regarded separately.
On an absolutely non-absorbent surface you will get a felt of crystals at first.
On an absorbing surface you will have a decisively denser film.
As an explanation the following should do:
When reaching the consolidating temperature two processes are taking place.
The fluid CCD, being homogeneous at a higher temperature, disintegrates into two phases. A relatively temperature-independent fluid phase consisting of a saturated solution of cyclododecane in the solvent and a temperature-dependent phase of pure melted cyclododecane. The presence of the fluid phase on a non-absorbent surface enables the pure cyclododecane to form crystal needles during solidification.
This is quite different on an absorbing surface. As soon as the separation into two phases starts with sinking temperature, the fluid phase is being absorbed by the surface and separated from the solidifying cyclododecane. The forming of the film is similar to the pure melt. A very dense film is being formed. (This phenomenon is being researched more thoroughly at the moment)
Mechanical Characteristics:
The mechanical characteristics are a less good compared to the pure melt. Resistant against pressure, very good elasticity, good resistance against abrasion.
Density of the film:
Thick film offers a very good protection against water as well as against ethanol, isopropanol or acetone.
Reversibility:
It takes a long time, laborious procedure to remove the film by using a hot air gun or solvents. A rather long period of time should be taken into account for the sublimation!
Tips and Tricks
It is not possible in any practical way to apply a melt by using a brush - unlessadding a certain amount of solvent. Thus lowering the melting point and at the same time avoiding before time solidification. From my own experience I can say that the hotter the mixture is being applied, the better the characteristics of the film will be. Solvents with a low boiling range will give you better results.
The following recipes proved themselves to be very successful:
On well absorbing surfaces adding up to 10% iso octane with its boiling point at 99°C to the CCD-melt.
On poorly absorbing surfaces adding up to 10% pentane 36°C to the CCD-melt.
Films from a solution
Meanwhile we have established, that a film from a solution always produces a less thick film than from a melt. For non absorbing surfaces the key rule for the crystallization also applies:
The slower the temperature sinks from above the melting point to a temperature below it, the more distinctive the felt formed by the crystal needles will be. A fast transition on the other hand leads to rather more homogeneous and denser films.This leads to select a solvent that is highly volatile and has a low melting point in order to end up with films as dense as possible.
Mechanical characteristics:
The mechanical characteristics show much lower values compared to the pure melt.
Sufficiently resistant against pressure, sufficient elasticity, sufficient resistance against abrasion.Density of the Film:
Highly porous film, offers a very good protection against pure water, but not sufficient against water with a wetting agent, ethanol, isopropanol or acetone!
Reversibility:
Method to remove by using a hot air blower or a melt. Because of the high porousness of the film, the solvent is very effective.
WARNING
It is not practical to try to get a protective cover on a porous surface by using a saturated sollution. A large amount of the material will penetrate into the surface, thus only building a cover after repetitive application. It means you will have to wait for the solvent to evaporate after each application before a film can build up. This method will cause unnessarily high expenses because of the large amount of solvent used and the much higher time effort.
Tips and Tricks
The solidification of porous and sucking surfaces is achieved by using solvents. Although this application will give you very good results you must keep in mind, that a lower boiling point of the solvent also means that the solvent penetrates less deep.
Solutions of CCD in pentane (boiling point at 36°C has) and in iso octane (boiling point at 99°C) have been tested successfully.
Film from a spray can
The application from aerosol-spray cans proved to be very useful to make water-proof, protective covers. Here the propellant (methane-butane mixture) works as the solvent.
The quickly subliming solvents build an amorphous precipitation, developing into a film building up by time. This film is absolutely water-proof, it also offers mechanical protection.
The usage of cyclododecane as a spray represents the third form of application after melt and solution.
Inside the spray can cyclododecane is present in a solved form. In this case the propellant is the only solvent. Additional solvents are not present.
The propellant, being extremely volatile, also determines the major characteristics of the cyclododecane film.
The spray film is impermeable for water and therefore and excellent protection against water and dirt.
While the melted film offers perfect protection against all highly polar solvents, any sprayed film can be penetrated by polar solvents without being loosened itself.
Mechanical Characteristics:
The characteristics are different from those of a melt. You have a rather amorphous film, highly porous. The mechanical solidity depends on the distance of spraying, but does not reach neither density nor solidity of the melt. From the moment of applying it the density increases.
Sufficiently resistant against pressure, sufficient elasticity, sufficient resistance against abrasion
Density of the Film
Highly porous film, offers a very good protection against water, but not sufficient against water with added wetting agent, ethanol, isopropanol or acetone!
ReversibilityThe characteristics of the sprayed CCD-film also determines the rate of evaporation. A melt with a 1mm film needs about 30 days to evaporate completely, whereas a sprayed film evaporates distinctively faster. A 1mm film will disappear completely in 2 to 3 days at 20°C. On façades without direct sun the same film may disappear within a day. If the film needs to stay on only for a very short period of time, it is easy to be removed with a hot-air gun or solvents.
Instant removal of the CCD-film
In some situations you would like to be able to remove the film without having to wait until it evaporated. Spraying or brushing naphta makes this possible without a problem. On sensitive surfaces you should use a solvent without aromatic additives such as iso octane. Because the film is highly porous, the solvent penetrates easily and therefore the takes effect quickly.
WARNING
A saturated solution penetrates rather deep into a porous surface, whereas a sprayed film hardly penetrates at all. Therefore the film does not have any consolidating effect. If you need the consolidation effect I recommend using a solution as a preliminary treatment.
Tips and Tricks
Spraying distance: Important!
Because the propellant dissolves rather fast from the fluid into the gaseous state, the cyclododecane , dissolved at first, precipitates in a solid state. That part of the gas that is still fluid in the sprayed fog when exiting the spray can gets less and less with growing distance to the nozzle until only the pure cyclododecane dust is left over. To create a film that is as dense as possible, the distance between nozzle and object should be as short as possible.To get a film that does not rub off a distance of 3 to 4 cm is recommended.
You will get a soft but very even film with a distance between 6 and 10cm.
Larger distances will lead to films that come off easily. They also lead to high loss.