Glass fibers actually are hydrophilic. The sizings and possibly adsorbed contaminants make them hydrophobic. If you want a glass fabric hydrophilic then clean it!

I while ago I wrote here:

Glass has a high surface free energy. Therefore, water spreads on a clean glass surfaces. But it also collects substances from the surrounding atmosphere like water and hydrocarbons. The latter reduce the hydrophilicity giving water contact angles in the range between 40° an 70° instead of < 10°.

The cleaning procedure depends on what kind of fibre you really have. In case there is a sizing you will have to invest more efforts than to remove the adsobates only. In laboratory, Priranha solution (sulfuric acid + hydrogen peroxide) is a simple and relatively cheap cleaning method. Plasma treatment was mentioned by Helga Thomas. If you have the equipment it is straight forward to do. If there is a sizing a precleaning before the plasma would be advisable. Ultrasonication with a non-ionic detergent solution is a good option. As an alternatgive for the plasma you can use a flame treatment as another option. The sizing will pyrolyse. But this might be tricky with delicate fibres.

In any case you have to be aware of the fact that the clean high energy surface will be re-coated by adsorbates again quite quickly. So don't store them before further processing.

In addition:

On glass fibric you can have a rather large amount of sizings. A thorough washing might be a good first step. Pyrolysis usually produces a lot of fume.

Andreas Holländer Thank you It was a very conclusive answer. Could you please also comment on textile fabrics like carbon and pararamid if we want to convert these fabrics to hydrophilic? Furthermore, Woven fabrics have interlacement. will interlacement effect the hydrophilic nature of complete fabric once we convert it to hydrophilic?

Carbon fibers and aramide fibers really are hydrophobic. And they usually have sizings, too. If you want to have a good adheseion of the fibers you have to remove the sizings first.

Making these fibers really hydrophilic (i.e. water spreading on the surface) is a difficult task since you have to dimage the surface molecular structure. In order to introduce functional groups which improve the adhesion to a matrix/ adhesive/ coating there are many options. For example, electrical discharge plasmas are a suitable tool.

Since this kind of process is rather delicate for your materials I suggest to collaborate with people who have experiece with that. Have a look to the Ecole Politechnique in Montreal or the University in London Ontario.