| Summary: | 碩士 === 國立臺灣大學 === 森林學系 === 85 === Summary
This research evaluates the effect of fire-retardant treatment
time on the physical and mechanical properties and
combustibility of plywood by comparing the properties of a
customized 3-layer plywood, which was glued from single plates
by high-temperature-harden PF, untreated with any fire-retardant
chemical with the properties of one with spraying treatment then
pressed to 5.5mm thick, and the properties of one with dipping
treatment of two fire-retardant chemicals（AF21 and立安302）then
pressed to 10.5mm ick. All plywood were high temperature treated
for 80 days(77℃, 50%RH). In our work, we also study the
accommodation effect on temperature and humidity of the fire-
retardant plywood we developed while they were used as in-door
decoration materials. The effect of fire-retardant chemicals on
the combustibility using heat analysis technique is studied as
well.
The result shows that the physical and mechanical properties of
the fire-retardant treated plywood present declined trends. MOE
values, MOR values, and shearing strength of glue-coupling of
flame-retardant and fire-retardant plywood are lower than those
of untreated plywood vary with composition of chemicals. Both
properties are proportional to the amount of chemicals absorbed.
In addition, as strength of static bending is concerned, after
80 days of high temperature heating treatment tests, MOE and MOR
values of all kinds of plywood are inverse proportional to the
heating time, 6.5%∼47.3%. The heating treatment affects
chemical treated plywood more than the one without chemical
treatment. Especially, the plywood treated with 立安302 shows a
clear declining tendency. In the aspect of shearing strength of
glue-coupling, after 80 days of high temperature heating
treatment testing, l plywood, no matter treated with chemical or
not, shows declined tendencies (15.0%∼42.3%) on glue-coupling
shearing strength of normal type and boiling-water-durable type
as high heating time grows. Also, heating treatment affects
fire-retardant treated plywood more. With the same heating time,
it shows following glue-coupling shearing strength tendencies：
UST > AST > LST, USTW > ASTW > LSTW, UDT > ADT > LDT, and DTW >
ADTW > LDTW. When the fire-retardant chemicals are concerned, no
matter what kind of gl is used, 立安302 treated plywood seems
will be affected more.
All wooden material can became in-door decoration material with
excellent capability of accommodation humility, however, their
properties vary with fire retardant. The hygroscopic-
conditioning index (b values) of flame-retardant plywood and
fire-retardant plywood, both treated with AF21, are 0.0224 and
0.0250, all belong to Type 1, respectively. These two values are
greater than 0.0181 and 0.0183（belong to Type 2）, the value of
their counterparts of plywood which haven't treated with
chemical and have samthickness. The values also greater than
0.0195 and 0.0197(belong to Type 2 ), the values of their
counterparts of plywood after 80 days heating treatment. The
result shows that the chemical treatment can play a important
role on accommodating humidity of wooden materials.
When concerning burning properties, after 80 days of high
temperature treatment, the burning properties of plywood
treatment with AF 21 or 立安302 all are affected. Especially ,
the one treated with 立安302 shows a more notable effect. Within
it, AST and ADT pass flame-retardant tests specified in CNS 8736
standard and 3rd level fire-retardant tests specified in CNS
8737. However, the LST after 20 days and 30 days heating
treatment didn't pass the flame-retardant tests specified in CNS
8736. This may be dueo influence of composition of chemicals and
equilibrium moisture content（EMC）. In addition, using TGA and
DSC testing curves of heat analysis knowing the heat
decomposition activities under high temperature environment, we
find that fire-retardant chemical performs its effect making
pyrolysis temperature declined and accelerating the generation
of carbon residues.
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