ASTM D3918-96(2003)
(Terminology)Standard Terminology Relating to Reinforced Plastic Pultruded Products
Standard Terminology Relating to Reinforced Plastic Pultruded Products
SCOPE
1.1 These definitions cover terms used in the reinforced plastics pultrusion industry. In some cases the terms may be identical to those employed in other standards or by other standards bodies.
Note—There is no similar or equivalent ISO standard.
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Designation:D3918–96 (Reapproved 2003)
Standard Terminology Relating to
Reinforced Plastic Pultruded Products
This standard is issued under the fixed designation D3918; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope chips—minor damage to the pultruded surface that removes
material but does not cause a crack or craze.
1.1 These definitions cover terms used in the reinforced
concave surface—a local concave curvature in the flat sur-
plastics pultrusion industry. In some cases the terms may be
faces of pultruded plastic parts as measured transversely to
identical to those employed in other standards or by other
their length.
standards bodies.
convex surface—a local convex curvature in the flat surfaces
NOTE 1—There is no similar or equivalent ISO standard.
of pultruded plastic parts as measured transversely to their
length.
2. Terminology Definitions
crack—a visual separation that occurs internally or penetrates
black marking—black smudges on the surface of the pul-
down from the pultruded surface to the equivalent of one full
truded product that cannot be removed by cleaning or
ply or more of reinforcement.
scrubbing or wiping with solvent.
crater—a small, shallow pultrusion surface imperfection.
craze—multiple fine cracks at or under the pultruded surface.
NOTE 2—Black marking results from excessive pressures in the die
craze, hairline—multiple fine pultrusion surface separation
when the pultrusion is rubbing against soft or unchromed die surfaces.
cracks that exceed ⁄4 in. (6.4 mm) in length and do not
blister—a rounded elevation of the pultruded surface with
penetrate in depth to the equivalent of full ply of reinforce-
boundaries that may be more or less sharply defined.
ment.
craze, resin—multiple fine separation cracks at the pultruded
NOTE 3—The rounded elevation somewhat resembles in shape a blister
on the surface of human skin. Blisters may exist within the pultrusion as
surface not penetrating into the reinforcement.
a hollow delaminated area (usually gas-filled) under a raised portion of the
NOTE 6—This condition is usually due to resin shrinkage during cure in
surface.
resin-rich areas.
blooming, fiber—a pultrusion surface condition exhibiting a
craze, star—multiple fine pultrusion surface separation cracks
fiber prominence or fiber show that usually has a white or
exceeding ⁄4 in. (6.4 mm) in length but not penetrating in
bleached color and a sparkling appearance.
depth to the equivalent of a full ply of reinforcement, that
NOTE 4—Thesurfacegenerallyfeelsroughwhentouchedbythefingers
appear to emanate from a central point.
and is of superficial thickness easily removed by buffing or light sanding.
NOTE 7—This condition is often caused by impact damage.
blooming, undercure—a dull and bleached surface color that
delamination—the separation of two or more layers or plies of
is evident in pultruded material not exposed to the weather.
reinforcing material within a pultrusion.
NOTE 5—Thisconditionisusuallytheresultofinsufficientsurfacecure.
die-parting line—a lengthwise flash or depression on the
surface of a pultruded plastic part.
bow—a condition of longitudinal curvature in pultruded parts.
burn—a discoloration, distortion, or destruction of the pul-
NOTE 8—The die-parting line is associated with the area where separate
truded surface as a result of thermal decomposition.
pieces of the die join together to form the cavity.
discoloration—a streak or other pattern on the surface that
causes a noticeable change of color from the rest of the
These definitions are under the jurisdiction of ASTM Committee D20 on
Plastics and are the direct responsibility of Subcommittee D20.18 on Reinforced
pultruded surface.
Thermosetting Plastics.
dry fiber—a condition in which fibers are not fully encapsu-
Current edition approved November 1, 2003. Published December 2003.
lated by resin during pultrusion.
Originally approved in 1980. Last previous edition approved in 1996 as D3918 - 96.
DOI: 10.1520/D3918-96R03. dullness—a lack of normal pultruded surface gloss or shine.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3918–96 (2003)
NOTE 9—This condition can be caused by insufficient cure locally or in
inclusion—any foreign matter or particles that are either
largeareas,resultinginthedullbandcreatedonapultrudedpartwithinthe
encapsulated or imbedded in the pultrusion.
die when the pultrusion process is interrupted briefly (see stop mark).
insufficient cure—a pultrusion abnormality created by lack of,
or incomplete, cross-linking of the resin.
dwarf width—a condition in which the crosswise (of the
direction of pultrusion) dimension of a flat surface of the part
NOTE 18—This condition can usually be detected by dull surface
is less than that the die normally would yield for a particular
appearance, low Barcol hardness, and low physical properties. Thick
composite.
sections, cured from the outside in, can reveal insufficient cure in the
center of the section even though completely cured on the surface. This
NOTE 10—This condition is usually caused by a partial blockage of the
condition can be caused by insufficient die temperature, improper catalyst,
pultrusion die cavity caused by “build-up” or particles of the composite
or pulling too fast for the die temperature.
adhering to the cavity surface. This condition is commonly called a “lost
edge” when the flat surface has a free edge that is altered by the build-up.
intermittent disfigurement—disfigurement of the shape of
the pultrusion for a limited length.
exposed underlayer—the underlying layer of mat or roving
not covered by surface mat in a pultrusion.
NOTE 19—This condition usually results from die fouling or from
folded or crowded reinforcing material and is corrected after a short
NOTE 11—This condition can be caused by reinforcement shifting, too
distance.
narrow surface mat, too wide underlying mat, uneven slitting of surface
mat, or necking down of surface mat or excessive tension in pulling it off
internal shrinkage cracks—longitudinal cracks in the pultru-
the spindle.
sion that are found within sections of roving reinforcement.
fiber bridging—reinforcing fiber material that is found bridg-
NOTE 20—This condition is caused by shrinkage strains during cure
ing across on an inside radius of a pultruded product.
that show up in the roving portion of the pultrusion where transverse
NOTE 12—This condition is caused by shrinkage stresses around such a strength is low.
radius during cure.
lack of resin fillout—a pultrusion condition where an area
fiber prominence—a visible and measurable pattern of the
contains reinforcement not wetted with sufficient quantity of
reinforcing material on the surface of a pultru
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