MIL-PRF-46197A
3.3
Roving .
3.3.1 Yield . The nominal roving yield shall be 250 yds/lb (504 m/kg) ± 8.5%.
Rovings with higher yield (750 or 1250 yds/lb) may not be substituted without
written approval from the acquisition activity. A semi-compatible sizing shall
be used.
3.3.2 Density . The roving shall have a package ball density of not less than
0.035 lb/in 3 nor greater than 0.065 lb/in 3.
3.3.3
Hardness . The roving shall have a shore "O" package ball durometer
hardness of not less than 50 nor greater than 90.
3.3.4 Catenary . The roving shall have a catenary requirement of not greater
than 1.0 in/50 ft. Unless otherwise specified, the catenary requirement
applies only to rovings having a yield of 700 or more yards per pound.
3.3.5 Tensile strength . The roving shall have a tensile strength of not less
than 400,000 psi.
3.3.6 Resistance to fusion . An ignited specimen shall be examined for fusion.
The specimen shall not fuse during the specified ignition.
3.3.7 Woven glass roving . The material shall conform to the requirements as
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specified by the procuring activity. Fabric weight shall be 24 oz/yd
± 3%
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(813 g/m ± 3%). Additional requirements include:
a. A colored tracer yarn shall run down the center of the material
to indicate the warp direction.
b. The material shall be free of all knots. Splices between rovings
shall allow adequate strength to withstand vertical tower prepregging.
Acceptable methods include overwrapping, air splicing, and adhesive splicing.
The adhesive used in the latter method shall be limited to the rovings being
spliced and shall not be spread to the surrounding fabric.
c.
The fabric shall be evenly woven, clean, free of creases,
wrinkles and other forms of permanent distortion. The finished fabric shall
conform to the quality of product established herein. Any sizings or other
fabric treatments shall be compatible with the resin system or shall be
formulated to ensure ease of removal during standard fabric cleaning
operations.
3.3.8
Resin . The resin shall be in a form (liquid or solid) suitable for
impregnating or furnished already impregnated on fabric (pre-impregnated). The
resin shall be free from foreign materials.
3.4
Prepreg physical properties .
3.4.1
Characteristics . The impregnated woven glass roving shall be a self-
tack material with good drape characteristics. Stiff boardlike material shall
not be acceptable. It shall release readily from the polyethylene separator
sheet without being deformed or losing resin from the surface.
3.4.2
Volatile content . Volatile content shall be not greater than 3%.
3.4.3
Resin content . Resin content shall be 34 ± 3% by weight.
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