D F Lively wrote: >>When I worked for AeroJet in Sacramento they were winding 2nd stage "Peace Keeper" motor cases with "Pre-preg Kevlar Filament Roving" The most importent reguirement was that it be conditioned in a 20% RH environment after being prepreged with Resin because moisture levels above that lead to delaminations in the wound cases..<<
The problem with Kevlar layups absorbing moisture is a Kevlar problem, not an epoxy problem. That kind of moisture absorbtion has caused delamination of Kevlar parts on airliners due to freezing, and hence, it's fall from grace in even non-structural parts in the aviation industry. Don't even get me started on Kevlar. Although it makes a dandy bulletproof vest, it has virtually no use on aircraft. I've been using some dark red Aeropoxy hardener for years now, and see no difference in the new amber stuff. If you can't get that stuff to harden in 98F degree weather, there's a real problem somewhere. I lay up glass or CF using Aeropoxy in the morning, leave it in the high humidity 110 degree hangar, and fly it and/or sand it later in the afternoon... Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net --------------------------------------------------------------
