oldguy Posted February 2, 2011 Posted February 2, 2011 Not a question, just tossing this out here. Just tinkering with differing waterproof materials for a few experimental ground flare tubes, I rolled a few tubes out of some Tyvek I have a roll of.Tyvek is a flashspun high-density polyethylene synthetic fiber paper like material manufactured by DuPont. Its lightweight, waterproof, durable and inert to most chemicals, acid and sulfide free. Come to find out testing the Tyvek tubes with slow, medium & fast ground flare comps, it deflagrates at the same rate the differing speed comps did & did not create any chimney effect. I have no inkling of how it would work in other pyro applications, or aloft. Since it will melt/deflagrate under heat. But on the ground it fit the ticket I was looking for & about any adhesive will work with it. It can also be impulse, or heat roller sealed together.Its cost is higher than paper, but it has several attributes that paper doesn’t. Gluing TYVEK From http://www.materialconcepts.com/sewglufab.shtml A number of adhesives can be used to glue TYVEK, either to itself or to other substrates. In general, water-based adhesives that provide quick tack and fast drying are preferred. However, the first step in choosing an adhesive is to determine how it will react with TYVEK. Testing a small TYVEK sample is the best way to make this determination. Natural-product adhesives based on starch, dextrin, casein or animal byproducts are preferred to synthetic-based adhesives. Hot animal glue is an excellent adhesive for adhering TYVEK to paperboard. Water-based synthetic lattices also bond TYVEK to itself and a variety of substrates. Ethylene/vinyl acetate adhesives are especially useful, as are the acrylic pressure-sensitive adhesives. Synthetic adhesives often contain low-molecular-weight materials that can act as solvents at elevated temperatures, causing swelling and wrinkling. Solvent-based single-component polyurethane adhesives provide optimum adhesion (lap and shear), flexibility and water-resistance for adhering TYVEK to itself and a variety of substrates.
Bonny Posted February 3, 2011 Posted February 3, 2011 Tyvek is not actually waterproof. It is water resistant. Considering it's common use as a building wrap, the material is (and needs to be) breathable to prevent rot and mold growth. IIRC, it was discovered when a lab tech wanted to try and find a use for the scrap "angel hairs" produced by conveying plastic resin... hence its makeup of fine fibers or strands.A solid waterproof sheet would simply be extruded.
oldguy Posted February 3, 2011 Author Posted February 3, 2011 (edited) You are correct, I should have said, "relatively" waterproof, e.g. a moisture barrier. Tyvek will not absorb or "wick" moisture or water, as paper will. I have used certain types of thicker tyvek as an 0.02 micron ambient gas exchange filter for years in other applications. You could make a bag out of tyvek & carry water in it. Not so with ordinary paper. You can also steam autoclave tyvek @ 250F, to sterilize it. Do that with ordinary paper & you would end up with paper pulp. You can also run tyvek through a washing cycle in a washing machine like a cotton sheet. Not so with ordinary paper. Tyvek will cut just like paper, but tearing it by hand is like trying to tear a phone book in half. I soaked a tyvek bound fusee in a bucket of water overnight.It was dry & ignited perfectly the next day.Do that with untreated kraft paper wrapping & it would not ignite at all. Edited February 4, 2011 by oldguy
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