I double checked and I had corresponded with sommone from a different company that offers the same product line under a different brand name here is a link to that company's website:
I also cut and pasted this from their FAQ page;
How does the boat material P.V.C., compare to hypalon?
Hypalon came into the industry, when a boat manufacture used a low grade P.V.C. for manufacturing their inflatable boats. The low grade P.V.C. had no UV protection and it turned nasty colors of brown. The company stood behind the product but not without tremendous loss! This miss adventure also hurt the P.V.C. industry.
This opened the door for a new fabric called Hypalon. The fabric competitor was quick to attack the P.V.C. market with statements of fact, based on a low quality P.V.C. The truth is there are several grades of P.V.C.. Inflatable Marine Products Inc. use only the finest protected materials available. We rate the material a level 10! We also stand behind the material for 5 years.
More Fabric facts. All though Hypalon is claimed to be the better material recent tests performed by third party groups, have determined that both P.V.C. and Hypalon have there ups and downs. All fabrics need to be cared for regardless of what it is. If you want it to last, take care of it!
I find this a little misleading in that even the 'finest' PVC fabrics will not have close to the life expectancy that hypalon will. I know a zodiac dealer who very readily admits that the PVC zodiacs (using the brand name 'strongan') don't last nearly as long as the older hypalon ones did.