Prepreg tack standard test?
Prepreg tack standard test?
(OP)
Traditionally where I am, tack is assessed subjectively, e.g. bend the material through 180 degrees and see how "well" it sticks to itself (basically if stays stuck on or quickly peels off).
Does anyone use (or know of) a more numerate test?
Does anyone use (or know of) a more numerate test?





RE: Prepreg tack standard test?
- clean a steel plate using a solvent (M.E.K.) and dry it.
-cut the specimens of prepreg 2" by 2", apply the specimen to the plate using light hand pressure, remove the backing film, apply a second specimen on top of first one, remove the backing film and apply a third specimen using hand prssure (firm for last one).
- the steel plate with the three attached prepreg specimens shall maintain in a vertical position for 30 min at 72F+-5F (23C+-3C). the prepreg material shall adhere for this period of time
- a minimum of 3 determination shall be made, the failure of one specimen will indicate a rejection.
RE: Prepreg tack standard test?
Another possible test would be to place e.g. a PTFE block on the prepreg sheet and tilt the sheet until the block slides off. This is a measurement of friction. It can be quantified using a digital spirit level available from hardware stores (around $50 from Sears, I have two of them). You record the angle at which the block begins to slide.
Good luck.
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RE: Prepreg tack standard test?
RE: Prepreg tack standard test?
Tack actually involves all of these issues:
Resin visco-elasticity
Speed of surface wetting.
Contact area
Resin cohesive strength
Resin adhesive strength
Contact surface texture
Contact time and pressure
Almost all of these are strongly influenced by temperature and humidity.
RE: Prepreg tack standard test?
At the moment we're most interested in the separation of automatic tape layer prepreg material from its paper backer and its adhesion to the tool and material already deposited.
We can see several ways to invent a test that might work; we were interested in any methods out there that might have track record.
The issue of material remaining outlife vs. ambient temperature and himdity is a tricky one, and we we're hoping to do a series of tests which might give us some idea of the trade off between them.
RE: Prepreg tack standard test?
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