Polartec Alpha Direct in Polypropylene!

there’s something about the regular polyester fleece.  It does not absorb water from the outside.

For example, if I have a fleece hat on and the inside of my hood gets wet because the WPB fabric wets out and condensation accumulates, the hat doesn’t absorb water.

But woven polyester does absorb water.

Maybe on fleece, the outside face is the ends of polyester fibers.  There isn’t a lot of surface area to absorb.

So, there’s less need for polypropylene fleece

It’s good that manufactures are getting into polypropylene a little.  I would like to see woven polypropylene that’s stronger, like 2 ounce / yd2.  Or 4.  And for the outside face of WPB fabric.

Adsorb?

Hi Jerry,

I’m wondering the same, what’s the point?! But also happy to see brands investing in PP :)

This new product line includes several constituents that can be combined to meet the conditions. I purchased one of the jackets to examine.  It has Quantum Air on the outside, polypro mesh in the front, and hydrophilic fabric on the back.  I am hoping that the Quantum Air has air permeability over 40-50 and that the polypro might provide a more rigid mesh than Alpha Direct.  A garment like this could be excellent for cold-weather cycling and backcountry skinning.  If not, back it goes. I will post something after I have a chance to measure its performance.

Absorb – water is absorbed into the fibers

Adsorb – water is on the outside of the fibers, between the fibers that make up the fabric

Polyester absorbs maybe 0.5% of it’s weight in water, nylon 3%.  But water can cling to the outside of the fibers so the fabric can adsorb a much bigger percent of it’s weight in water.

Maybe you could say the fabric absorbs water

I think I have that right :)

Hi Jerry:  I think you can do a little better by distinguishing between hydrophilic and hydrophobic fibers.  Adsorption is easily observed in hydrophilic fibers due to bonding between water and fiber surfaces. This produces capillary forces that send the water into yarns. In hydrophobic fabrics, capillary forces usually resist water entry. Liquid water can still occupy voids, but typically only when external pressure, mechanical forcing, surfactants, contamination, or favorable pore geometry overcomes the capillary entry pressure.  You can read all about these forces in my next article, which is somewhere in the bowls of BPL.  I would say that adsorption is less a factor in hydrophobic fibers than hydrophilic fiber. Yet, water does get pushed in and out of hydrophobic fabrics, just by different mechanisms.  In the upcoming article, you can see how hydrophobic fabrics can actually be more effective at moving water from skin, through a base layer and into a receiving layer.

I’m looking forward to that article.  The whole subject is rather complicated and hard to understand in some ways.  Your articles have made it a lot more clear, thanks.

I’m making a pair of polypropylene pants to see if they would be better in the rain.  But the fabric is sort of plasticy feeling, and stiff.  I would like to see more polypropylene fabric choices.  Manufacturers can’t patent it though, so there’s no reason for them to develop it.

Awesome! Looking forward to read your results :)