I knew the difference between the two materials, though I wasn't sure what material the HD vest used or how it was being used until I heard it described here. The polyacrylate fabric vests I've seen don't use pouches/packs at all because the vest material itself is what absorbs the water. The whole reason I got turned on to them was a friend who had been using one for several years and loved it. When I heard about the exploding HD vests I searched and found other vests that use polyacrylamide crystals but the HD description says "polyacrylite" when it now appears they use packets of polyacrylamide.

Here is what wikipedia has on the two different materials:

polyacrylate - also known as waterlock, is a polymer with the chemical formula [-CH2-CH(COONa)-]n widely used in consumer products. It has the ability to absorb as much as 200 to 300 times its mass in water. Acrylate polymers generally are considered to possess an anionic charge. While sodium neutralized polyacrylates are the most common form used in industry, there are also other salts available including potassium, lithium and ammonium.These cross-linked acrylic polymers are referred to as "Super Absorbents" and "Water Crystals", and are used in baby diapers.[1] Copolymer versions are used in agriculture and other specialty absorbent applications.The origins of super absorbent polymer chemistry trace back to the early 1960s when the U.S. Department of Agriculture developed the first super absorbent polymer materials.[2] This chemical is featured in the Maximum Absorbency Garment used by NASA.

polyacrylamide - (IUPAC poly(2-propenamide) or poly(1-carbamoylethylene)) is a polymer (-CH2CHCONH2-) formed from acrylamide subunits that can also be readily cross-linked. Acrylamide needs to be handled using best laboratory practice (such as wearing appropriate gloves, lab coat etc. and having safe systems of work) to avoid poisonous exposure since it is a neurotoxin. Polyacrylamide is not toxic, but unpolymerized acrylamide can be present in the polymerized acrylamide.[1] Therefore it is recommended to handle it with caution. In the cross-linked form, it is highly water-absorbent, forming a soft gel used in such applications as polyacrylamide gel electrophoresis and in manufacturing soft contact lenses. In the straight-chain form, it is also used as a thickener and suspending agent. More recently, it has been used as a subdermal filler for aesthetic facial surgery. Concerns have been raised that polyacrylamide used in agriculture may contaminate food with the nerve toxin acrylamide. While polyacrylamide itself is relatively non-toxic, it is known that commercially available polyacrylamide contains residual amounts of acrylamide remaining from its production, usually less than 0.05%

The only reason I posted was because of the reactions I got from multiple HD dealers here in Japan. The HD product is no longer sold in Japan because of these exploding packs. Sorry you want to conspiracy theory up this thread but I am not selling outside Japan so posting here for sales is pointless. Either way, since you think this thread about cooling vests I posted while it's snowing here is motivated by trying to make some sales, I'll gladly remove the brand name I'm distributing from my original post. All I was interested in is getting the facts about the HD vest (be them good or bad) not promoting any other product or making sales here.

 

Basically, I would like say "it's all good", but the wild imaginational hysteria of tactics such as "conspiracy theory up this thread" and and basically irrelevant dodges of "since you think this thread about cooling vests I posted while it's snowing here" just add more suspicion to your motivation. I'm glad you haven't screamed "I know you want to poison everyone's neurons but I'm just trying to help innocent victims on the other side of the world" yet, make me hesitant to wish you good luck and to thank you for what actually could be valuable information if not for the fact that I'm compelled to consider the validity of your wikipedia info in the face of the fact that some common diversionary debate tacticss may be in play now that cause highlight to possible motivation and irrationality that direct my attention to the degree of validity resulting in the delay of recognition of acknowledgement of your claims.

But, yeah, I was a little put off by the proprietary nature of the required cooling pouches and I have used plain cloth soaked in water in lieu of the cooling pouches, if having wet clothes when I take off the jacket isn't a concern, even if it doesn't work well. I have two sets of the pouches and they are far from the end of their usable lifecycle. They DO work really well, although the jacket design seems to limit maximum benefit. I'm a little less likely to use them than I was, now.

I hate the heat, but I hate to let it keep me off of the bike and in my A/C'd cars.

I really need to look at the structure of the compounds you mrntioned, though..

 

I'll buy two of them Studebakers'