Sam,

Many thanks for your reply.
Actually I am trying to check if glass fiber (which is stored for a long-time) could be used for FRP pressure pipe or not?

Reza

: Reza,

: If we assume good storage conditions, the potential shelf life
: affects are with respect to the finish (sizing). So, one would
: want to select a test for which the results are dominated by the
: finished fiber to matrix bond strength. The most direct way to
: do that is with a single fiber pull-out test. Off-axis tensile
: or short beam bending may also work. Of course, testing to
: demonstrate that material is "still good" requires
: acceptance/rejection criteria. There is some discussion of this
: topic at:
: http://www.compositesworld.com/articles/fiber-matrix-interfacial-bond-test-methods
: .

: Controlled quantitative testing is expensive, so it would likely
: only be used in a manufacturing quality control program that
: affects critical applications and or large volumes of material.
: The DIY enthusiast would not benefit from it, unless the main
: objective was to learn more about testing than about a roll of
: leftover glass in the garage. Typically, DIY kayak builders
: aren't adversely impacted by using materials with a wide range
: of properties, even properties that have degraded over time.
: This works fine in most cases. Just like eating old food from
: the fridge - some individuals may prefer to pickup a carton of
: fresh milk rather than drink the old stuff.

: Sam