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o Fiber bundles and impact-fragment ends cause punc
ture wounds.
o Composite dust cause allergic reactions.
· Fire damage:
o Resin combustion immediately releasing toxic prod
ucts into the plume.
o Fibers either melt, oxidize and/or decompose.
TO 00-105E-9
3-27
o Fibers that melt do not remain airborne.
o Severely impact and fire damaged carbon fiber will
release fibers that linger.
o Filament wound, woven fabrics inhibit release of
particulate into the air.
o Advanced composites can smolder without any visible
sign.
c. DISPOSAL OF COMPOSITES Routine decisions
made for industrial waste is not routine when determining
how to dispose of mishap-composites. Characterizing
mishap-composite debris for regulatory compliance
requires knowledge of the materials within the system
and mishap conditions. The knowledge is needed to adapt
sampling plans for composite material. The knowledge
is needed when reviewing regulatory lists and when interpreting
analytical results. This paragraph reviews the
material specific aspects for environmental concerns of
mishap-composites.
(1) WASTE CHARACTERIZATION. Waste characterization
begins with an understanding of what the materials
are within the system. A composite part is made
by layering-of-material1 . A basic system will use the same
material for each layer, a polymeric resin and a synthetic
fiber. A hybrid system contains different material layers.
For instance, the design may incorporate a metal-coated
fiber layer, a metal mesh layer or the resin may contain
metal particulate. If the debris was not involved in a fire,
the composite will have coatings. Waste characterization
also considers what could have contaminated the
composite during the mishap.
(a) Physical Damage. The chemical and physical
properties of the composite used for environmental assessment
has not changed when a composite fractures.
The solid matrix surrounds the fiber protecting it from environmental
exposure and is still considered chemically
non-reactive in the bulk form.
(b) Fire Damage. Chemical and physical changes do
occur when a composite is thermally damaged. Fibers
melt, oxidize or decompose. The resin melts, decomposes,
volatilizes and forms a char2 layer. Post-fire material
is in a solid form. The decomposition products of
the materials will vary widely and may be a potential environmental
hazard if present in detectable concentrations.
The decomposition products for JP8 fuel will also
be present.
(c) Mishap-Site Contamination. Was the debris JP8
soaked, AFFF soaked or hydraulic fuel soaked? Is the
hold-down solution environmentally friendly?
(2) SAMPLING.
(a) Amount. Most of the composites in an aircraft will
take the form of a solid laminate or sandwich laminate.
Each form will be considerably less dense than soil or
sludge of the same volume. The four-ounce soil jar used
for organic sampling may not hold the minimum amount
of sample required for TLCP1 analysis.
(b) Collection and handling method. Zero headspace
will be hard to achieve because the form may not allow
for compaction within the sampling jar. Cutting composites
out in the field to fit into a sampling jar will require
special tools and personal protection equipment. Avoid
cutting in the field if at all possible.
(c) Selection of sampling location. Because composites
are made with layers sample selection could mistakenly
leave out the layer that could be of concern. Composite1
sampling should be used. However, results obtained
from composite sampling of a mishap-composite
is considered representative of only one specific site and
sample type.
(d) To minimize worker exposure when sampling and
handling burnt carbon fiber composites, glass bottle is
preferred over plastic.
(3) SAMPLE PREPARATION. The sample preparation
step for a volatile analysis is performed with or without
heat depending on the sample type. If a fire-damaged
sample is going to be analyzed (and not it’s leachrate),
handle it just like it was a soil. The carbonaceous nature
of the char and soot material will require heat to desorb
any combustion products.
(4) ANALYSIS. To determine what constituents to test
for, and what concentrations to expect a better understanding
of the material in relationship to the analytical
methods is needed. The three major components of the
system to consider for environmental disposal are the
fiber/matrix and core layer, the coatings layer and the
hybrid layer. Generally speaking, an organic constituent
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