[Vakoss]

Hello, I have a situation that I want to tapering the filament to the brushes and I need help to thoroughly understand the process and what exactly to do. It is exactly a filament of PBT(Polybutylene terephthalate) fibers. the information I found about the liquid that can be used to do this looks like this.

an organic solvent and an inorganic solvent, and as the organic solvent, heated m-cresol, trifluoroacetic acid, o-chlorophenol, Trichlorophenol (phenol), phenol (phenol), tetrachloroethane (Tetrachloroethane) and any one selected from a mixture of phenol may be used.

As the inorganic solvent, strong alkali and strong acid may be used, and as the strong alkali, any one selected from sodium hydroxide and potassium hydroxide may be used, and as the strong acid, Sulfuric acid may be used.

And I have a few questions, which of these organic solvent or inorganic solvent will be the best for this job? In terms of ease of use, dangers (yes, I know they are all dangerous, which is the least dangerous). Unless someone has an alternative to this.

The question about the process itself, because when I read the instructions, they all say about immersion in a solvent, does it mean that I should pour the chosen solvent into the beaker, put the fibers in it? Anything else I need to add to this solvent? for example, I found this note when sodium hydroxide solution was used:

As described above, may be used by diluting the stock solution with an appropriate ratio of water, and heating to an appropriate temperature (100 to 150 ° C.), so that the chemical reaction in the dissolution process may be performed more quickly and stably.

One end of the PBT monofilament was immersed in 40 to 50% sodium hydroxide solution for about 5 mm, treated at 40 to 90 ° C. for 60 minutes, and then neutralized and washed with water. 

So if I understand correctly, I have to use e.g. a sand bath oven to heat and then immerse the fibers ? . I understand that the heating itself is to accelerate the procedure, anyone aware of how long it would take if it wasn't for the heating?