Actually a little simpler than beta sheets, but getting close to the idea...however, there is still a lot of amorphous content in these ultra-drawn fibers or they wouldn't have any use as textiles. Juast to give you an example, very good HDPE is 65% crystalline, with the rest being amorphous. I'd bet the crystallinity in the ultra-drawn fibers is still beneath 80%. The mixture of crystalline and amorphous sections is what gives both polyethylene and polypropylene their stength & flexibility. In polymer chemistry, "crystalline" is a very relative term...usually meaning that the polymer has SOME crystallinity, but it is more or less understood that it isn't 100% crystalline. In polyetheylene % crystallinity is usually determined via DSC with 100% crystallinity assumed to be equivalent to 66 cal/g (area under the Tm curve). Showing my age, I know, it's not in joules...
We just got approval today (FEMA & Bush Clinton monies) to replace our DSC at McNeese which was damaged in Hurricane Rita, so maybe by early next year, I'll be back doing this type of research. Perkin Elmer really wanted to sell us this model, they knocked $18,000 off the price. Mark Delaney Henk Verhaar <[EMAIL PROTECTED]> wrote: On 15 Nov 2006, at 22:22, Pierre Bombardier wrote: Actually the crystallin segments aren't totally linear, but contain folded back and forth linear sections, the folds being amorphous and the links between linear sections being amorphous...sort of like crystals on a spit... and the crystalline portions alighned with the fiber...it would be easier to drawe it, but can't figure out how to do it with the limeit on VFB posts... Sort of like beta sheets in protein? Didn't realize that the linearization was that local... Henk ==========================Heisenberg was right!======================== | Dr. Henk J.M. Verhaar | | | Environmental Fate and Ecotoxicology Specialist | | Fly Tier | web: www.xs4all.nl/~flyrod | | Stichts End 17 | e-mail: [EMAIL PROTECTED] | | NL-1244 PK Ankeveen | phone: +31 35 656 2128 | | the Netherlands | ICQ: 15727113 | ==========================Uncertainty happens!========================= --------------------------------- Sponsored Link Mortgage rates near 39yr lows. $510,000 Mortgage for $1,698/mo - Calculate new house payment
