Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
417–423
EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION
RESISTANCE OF WOOD/PHENOLIC RESIN CARBON
COMPOSITES
VPLIV PARAMETROV IZDELAVE NA OKSIDACIJSKO
ODPORNOST OGLJIKOVIH KOMPOZITOV NA OSNOVI LESA IN
FENOLNE SMOLE
Yubo Tao, Peng Li
*
College of Material Science and Engineering, Northeast Forestry University, no. 26 Hexing Road, Xiangfang District, Harbin 150040,
Heilongjiang, China
Prejem rokopisa – received: 2018-10-05; sprejem za objavo – accepted for publication: 2018-12-20
doi: 10.17222/mit.2018.216
The oxidation resistance of wood/phenolic-resin carbon composites (woodceramics) in air was investigated from room tempe-
rature to 700 °C by the simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC) analysis. The
elementary analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were utilized to characterize
the woodceramics samples prepared with different weight ratios of wood powder to phenolic resin (PF) and carbonized under
800 °C, 1000 °C, and 1400 °C. The elementary analysis revealed that the higher carbonization temperature contributed to a
higher carbon content, whereas the higher ratio of PF led to a lower carbon content in the samples. The FTIR results showed
that the higher carbonization temperature was beneficial to a more regular carbon structure, which was further proven by XRD.
The TG-DSC analysis demonstrated that the oxidation resistance of woodceramics increased with the rise of carbonization
temperature, which was due to the development of graphitization of woodceramics under a higher carbonization temperature.
However, the increased ratio of PF did not bring apparent improvements to the oxidation resistance of the samples. The apparent
activation energy was high at the intial reaction stage, and then decreased with the development of thermal degradation, which
indicated that more energy was consumed for the completion of the oxidation reactions at the start stage. This study showed that
the developed woodceramics exhibited good oxidation resistance in air below 300 °C.
Keywords: woodceramics, oxidation resistance, TG, DSC
Avtorja opisujeta raziskavo oksidacijske odpornosti ogljikovih kompozitov na osnovi lesa in fenolne smole (angl.: wood-
ceramics) na zraku pri sobni in povi{anih temperaturah (do 700 °C). Pri tem sta uporabila simultano termogravimetrijo in
diferencialno vrsti~no kalorimetrijo (TG-DSC). Vzorce kompozitov sta pripravila z razli~nim masnim razmerjem lesnega prahu
in fenolne smole (PF). Karbonizacijo (pooglenitev) vzorcev sta izvedla pri 800 °C, 1000 °C in 1400 °C. Za karakterizacijo
vzorcev kompozitov sta uporabila elementno analizo, Furierjevo transformacijsko infrarde~o spektroskopijo (FTIR) in rent-
gensko difrakcijo (XRD). Elementna analiza je pokazala, da vi{ja temperatura karbonizacije prispeva k vi{ji vsebnosti ogljika,
medtem ko vi{ji dele` PF v kompozitu privede do manj{e vsebnosti ogljika v vzorcih. Rezultati FTIR spektroskopije so
nedvoumno pokazali, da vi{ja temperatura karbonizacije prispeva k bolj urejeni strukturi ogljika. To je bilo potrjeno tudi z XRD.
TG-DSC analiza je pokazala, da odpornost kompozita proti oksidaciji nara{~a z nara{~ajo~o temperaturo karbonizacije, kar je
posledica popolnej{ega razvoja grafitizacije kompozita pri vi{jih temperaturah karbonizacije. Po drugi strani pove~anje dele`a
PF v kompozitni me{anici ni prispevalo k izbolj{anju oksidacijske odpornosti vzorcev. Navidezna aktivacijska energija je bila
visoka v za~etnem stadiju reakcij in se je zmanj{evala z razvojem termi~ne degradacije. To nakazuje, da je ve~ energije porab-
ljene za dokon~anje reakcij oksidacije v za~etnem stadiju. [tudija je pokazala, da je razviti kompozit na osnovi lesa in PF dobro
obstojen proti oksidaciji do 300 °C.
Klju~ne besede: lesna keramika, odpornost proti oksidaciji, TG, DSC
1 INTRODUCTION
Biomass and resin hybrid carbon composites, i.e.,
woodceramics, are environmentally friendly, light
weight, and low cost. Woodceramics are usually ob-
tained through impregnating resin into wood or woody
materials, and then carbonizating in vacuum conditions
at high temperatures.
1–3
Woodceramics possess unique characteristics such as
high wear and friction resistance,
4
electromagnetic
shielding capacity,
5
and good mechanical properties.
6
Previous studies show that porous woodceramics have
potential applications for catalyst supports, gas filtration,
brake pads, etc. due to their hierarchical, biomorphic,
and porous structure.
7–14
The unique three-dimensional
natural microstructure of wooderamics cannot be artifi-
cially fabricated easily. Moreover, woodceramics have
hierarchical pores structures tunable in the micropore-
to-macropore range. Pan et al. proved that the sugarcane
bagasse woodceramics demonstrated a hierarchical
porous structure from the micrometer (0.6–21 μm) to the
nanometer scale (3.1–9.3 nm).
14
As reported by Yang et
al., these hierarchical pore structures were extremely
useful in terms of mass transfer and enhancing the
reaction pathways, and were anticipated to be effective
catalyst media.
12
Materiali in tehnologije / Materials and technology 53 (2019) 3, 417–423 417
UDK 620.168:546.26: 630*81:665.947.1:547.56:542.943 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 53(3)417(2019)
*Corresponding author e-mail:
lptyb@aliyun.com

However, as functional materials, the performances
of woodceramics are usually determined by the mate-
rials’ ability to resist heat. For example, catalytic reac-
tions involving oxidizing conditions above 250 °C
burned off carbon-supported catalysts and reduced its
lifespan.
15
Therefore, the thermal reactivity in air at high
temperatures is a crucial characteristic to evaluate wood-
ceramics’ proper utilization as catalyst supports for
durable applications. Ozao et al. analysed the thermal
properties of apple woodceramics and their results
showed that the higher carbonization temperature bene-
fited the oxidation resistance of woodceramics.
2
Oishi et
al. reported that the thermal degradation of woodcera-
mics was dependent on the oxygen concentration.
16
In this paper, to clarify the effects of the processing
parameters on the characteristics as well as the oxidation
resistance of woodceramics in air, the performances of
wood flour/PF woodceramics were investigated using
simultanous TG-DSC analysis from room temperature to
700 °C.
2 EXPERIMENTAL PART
2.1 Woodceramics preparation
The woodceramics were prepared using a labo-
ratory-made fir powder and laboratory-synthesized PF
resin. The fir powder used had a moisture content of 8 %
and a size passing through a 40-mesh sieve. The PF resin
had a solid content of 48–50 %, a viscosity of 30–40 s
(TU-4 viscometer), an alkali content of 2.0–2.7 %, bro-
mides of 16–24 %, and a storage period of at least 60 d
at 5–20 °C.
The composite preform was fabricated by impregnat-
ing PF resin into wood powder. The weight ratios of
wood powder to PF resin were 40:60, 50:50 and 30:70.
The procedures were conducted in three steps, i.e.,
drying, cold-pressing, and hot-pressing. Samples were
then carbonized at temperatures 800 °C, 1000 °C, and
1400 °C in a vacuum sintering furnace under the heating
rate of 2 °C/min.
2.2 Sample characterization
Before the thermal analysis, the samples were
analyzed to determine the properties that may affect the
thermal degradation abilities. The contents of C, H, and
N of the dried samples were investigated by the CHNS-O
Elemental Analyzer (Euro EA 3000-Eurovector Italy)
with a combustion temperature at 1020 °C. The FTIR
analysis was used to analyze the possible chemical
functional groups in the samples using a Nicolet Magna
560 at a resolution of 4 cm
–1
. The physical characteristics
of the prepared woodceramics were identified by the
X-ray diffraction (XRD) method on a Rigaku D/max-RB
12KW X-ray Diffractometer (Rigaku Corporation,
Japan) using the nickel-filtered Cu-K
 radiation in the
range of 2 (10°–90°), where the scanning speed was 2
degree/min.
2.3 TG-DSC analysis
The TG-DSC analysis of ca. 10 mg dried material
was performed under an air atmosphere in a TG-DSC
OLAP analyzer (Netzsch Sta 449c, Deutschland,
Germany) with the sensitivity of 0.1 μg and 0.1 °C. The
samples were heated from 25 °C to 700 °C in a Pt-Rh
crucible. The air flow rate was 30 mL/min throughout
the whole procedure. The test conditions are shown in
Table 1.
Table 1: Test conditions of woodceramic specimens
Sample
number
Weight ratios of
wood powder to
PF
Carbonization
temperature
(°C)
Heating rates
of TG/DSC
(°C/min)
S1 40 : 60 800 2
S2 40 : 60 800 5
S3 40 : 60 800 10
S4 40 : 60 800 20
S5 40 : 60 1000 10
S6 40 : 60 1400 10
S7 50 : 50 800 10
S8 30 : 70 800 10
2.4 Calculation of activation energy of thermal decom-
position reaction
Using the data of TG, the conversion rate of the
samples at any given time/temperature can be obtained
with Equation (1):
 =
−
−
()
()
mm
mm
01
0f
(1)
where,  : conversion rate; m
0
:initial sample weight; m
1
:
sample weight at any given time; m
f
: stable sample
weight at the end of reaction.
It is assumed that the woodceramics are reactive sub-
stances, and the Arrhennius equation could be used to
describe the reaction law of the thermal decomposition.
   == −
⎛ ⎝ ⎜ ⎞ ⎠ ⎟ −
d
dT
A
E
RT
n
exp ( ) 1 (2)
where,  heating rate, K s
–1
;  conversion rate; T tem-
perature of sample, K; A prefactor; E apparent activation
energy, J/mol; R gas constant, 8.314 J/mol·K; n reaction
order.
In order to analyze the kinetic parameters of wood-
ceramics, the apparent activation energy of woodcera-
mics is able to be calculated using four heating rates with
the Ozawa method.
17
The TG data curves obtained at heating rates of (2, 5,
10, and 20) °C/min and Equation (3) were used in calcul-
ation.
log .  !"#$+=
E
RT
Const (3)
Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
418 Materiali in tehnologije / Materials and technology 53 (2019) 3, 417–423

If the weight loss rate of formula (3) is a constant, the
heating rates  1
,  2
,  3
, and  4
correspond to the tempe-
rature T
1
,T
2
,T
3
and T
4
respectively. A straight line can
be drawn using the data of 1/T and log  . The apparent
activation energy E value can be obtained by calculating
the slope of the straight line.
3 RESULTS AND DISCUSSION
3.1 Element analysis of woodceramics
The contents of C, H, and N of woodceramics under
different carbonization temperatures as well as different
ratios of wood powder to PF were presented in Table 2.
As seen, the main component in all samples was carbon.
The hydrogen content was low because H
2
O, low mo-
lecular weight phenolic substances (LMP), and the low
molecular weight hydrocarbon (LMH, including CH
4
)
were produced during the carbonization process.
18
With
the increase of the PF ratio, the carbon content of
samples prepared under 800 °C declined slightly (S7, S3,
and S8) along with lower H and N contents. However,
under the same weight ratio of wood powder to PF (S3,
S5, and S6), the increased carbonization temperatures
contributed to higher carbon contents and lower amounts
of heteroatoms. The increase of the carbon content and
decrease of the oxygen content with the rise of carbo-
nization temperature revealed that more energy was
consumed to deprive the oxygen-containing functional
groups.
Table 2: C, H, and N contents of woodceramincs
Sample
number
Carboni-
zation tem-
perature
/°C
Weight ratio
of wood pow-
der to PF
C/% H/% N/%
O+
ash
/%
S7 800 50:50 91.6 0.7 1.5 6.2
S3 800 40:60 90.2 0.6 1.4 7.8
S8 800 30:70 88.3 0.6 1.2 9.9
S5 1 000 40:60 95.9 0.2 1.4 2.5
S6 1 400 40:60 99.5 0.0 0.0 0.5
Figure 1 shows the FTIR spectra of woodceramics
obtained at 800 °C, 1000 °C, and 1400 °C, respectively.
All the samples displayed a broad O-H stretching
vibration at around 3 430 cm
–1
. Meanwhile, the aromatic
and aliphatic C-H asymmetrical stretching vibrations
around 3000 cm
–1
exhibited a weak trend. C=O stretch-
ing vibrations between 1750 cm
–1
and 1700 cm
–1
dis-
appeared with the deprival of oxygen in the samples. A
symmetrical peak at 1629 cm
–1
was attributed to
aromatic C=C in-plane stretching vibration.
6
Strong ab-
sorptions at 1400 cm
–1
were the results of aromatic
stretching vibrations and -CH
3
stretching resulted in
peaks at 1384 cm
–1
.
18,19
Nevertheless, the vibration
strengths of the C=C and -CH
3
stretching were lowered
when the carbonization temperatures were increased.
This phenomenon was assocaited with the deprival of
low-molecular-weight substances and the diminished
carbon and hydrogen contents, as described in Table 2.
Figure 2 presents the XRD intensity curves for the
samples prepared under three carbonization tempera-
tures. Two main and a weak wide peaks were detected
over the scattering range. The peaks at around 22°, 43°,
and 80° correspond to the (002), (10), and (11) peaks,
which represented the graphite-like crystalline structure
in woodceramics.
6
The observed broad peaks illustrated
the weak regularity of carbon in woodceramics. Further-
more, the data indicated that the amorphous carbons
derived from wood powder and PF resin were hard to be
graphitized. However, as the carbonization temperature
increased, the (002) peak became sharper and moved to a
larger angle slightly. It was shown that the higher car-
bonization temperature contributed to higher levels of
graphitization and lower remaining content of the amor-
phous carbon.
20,21
Figure 3 shows the curves of woodceramics prepared
with different weight ratios of wood to PF. The contri-
bution of PF content to the graphitization of woodcera-
mics was not obvious. The research conducted by Qian
et al. obtained similar results.
6
Therefore, it can be con-
cluded that carbonization temperature is the vital factor
Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
Materiali in tehnologije / Materials and technology 53 (2019) 3, 417–423 419
Figure 2: XRD patterns of woodceramics carbonized under different
temperatures
Figure 1: FTIR spectra of woodceramics at different carbonization
temperatures (weight ratio of wood powder to PF is 40:60)

to improve the regularity and crystallite growth of wood-
ceramics.
3.2 Carbonization temperature vs. oxidation resistance
Figure 4 depicts the effects of carbonization tem-
peratures 800 °C, 1000 °C, and 1400 °C on the oxidation
resistance of woodceramics. The key data of TG from
Figure 4 were summarized and are listed in Table 3.
Table 3: Oxidation resistance of woodeceramics under different
carbonization temperatures
Sample
number
Temperature at
9 % weight
loss (°C)
Temperature at
a starting of
linear variation
(°C)
Residual
weight at
700 °C (%)
S3 (800 °C) 400 430 22.8
S5 (1000 °C) 565 600 60.9
S6 (1400 °C) 640 670 77.1
The results indicated that the higher carbonization
temperature was beneficial to the oxidation resistance of
the woodceramics. As shown in Table 3, when the
samples were burned in air till 700 °C, the residues left
increased greatly with the growth of carbonization tem-
perature. Moreover, at the first stage, samples carbonized
under 800 °C, 1000 °C, and 1400 °C exhibited a linear
relation with its9%w e ight loss, being reached at
400 °C, 565 °C, and 640 °C, respectively. After a short
period of accelerated weight loss, the remains of all
samples decreased linearly until the end of the test. An
exothermic peak and a small endothermic peak were
observed between 400 °C and 500 °C on the DSC curve
of woodceramics obtained under 800 °C, whereas these
peaks disappeared on the other curves.
The weight loss of woodceramics was due to the
reaction of carbon with O
2
. The TG-DSC results demon-
strated that the carbonization temperature was a vital
factor that affected the oxidation resistance of wood-
ceramics. With the growth of the carbonization tempera-
ture, the starting thermal degradation temperature of
woodceramics in air was extended into a higher tem-
perature zone and its oxidation resistance was enhanced.
It is well known that the oxidation resistance of wood-
ceramics depends on its reactivity with O
2
. Based on
previous studies involving the oxidation resistance of
carbon materials,
22,23
the oxidation deterioration of
woodceramics under high temperatures experiences at
least two steps: (1) oxygen diffusing through pores and
cracks in the woodceramics to form surface oxides on
the carbon surface; (2) reaction between carbon and
oxygen to form CO
2
, CO, and surface oxygen com-
plexes. Further, it can be assumed that the oxidation
resistance of woodceramics is affected by its micro-
structure, the portions of the surface which are active to
react with O
2
(also known as active sites), and the
reactivity of these active sites. The XRD results in this
study illustrated the graphite-like, crystalline amorphous
carbon structure of woodceramics, which was consistent
with the research conducted by Qian et al.
6
Nonetheless,
the higher carbonization temperature contributed higher
regularity of carbon.
20,21
Although woodceramics in-
herited the hierarchical porous structure of wood powder,
providing abundant oxygen pathways for carbon
contacts,
5
the higher carbonization temperature led to the
increase of carbon content and crystallinity, and reduced
the internal defects as well as heteroatoms of the
woodceramics. Additionally, the carbon crystallization or
crystallite growth would abate the reactivity of carbon
materials.
24
Therefore, the oxidation resistance of the
woodceramics was improved by increased carbonization
temperature.
3.3 Component ratio vs. oxidation resistance
Figure 5 shows that, with the increase of PF content,
the weight loss of woodceramics (carbonized under
Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
420 Materiali in tehnologije / Materials and technology 53 (2019) 3, 417–423
Figure 3: XRD patterns of woodceramics carbonized at 800 °C (with
different weight ratios of wood to PF)
Figure 4: Effect of carbonization temperature on oxidation resistance
of woodceramics (Weight ratio of wood to PF was 40:60; Heating rate
of TG was 10 °C/min; Carbonization temperatures were (800, 1000,
and 1400) °C; Gas environment of TG was Air)

800 °C) increased slightly. For all samples, the tempera-
ture inflection point of weight loss was in the range from
400 °C to 420 °C. At the temperature inflection point,
the sample prepared with the highest weight ratio of
wood powder to PF resin exhibited the fastest weight
loss among all the samples. At 700 °C, the remaining
sample weights were 25.8 % (50:50), 22.8 % (40:60),
and 7.6 % (30:70). The results showed that, with the
increase of PF resin ratio, the oxidation resistance of
woodceramics decreased slightly due to the uneven
carbonization of PF in woodceramics under 800 °C. As
shown in Table 2, the higher the ratio of PF resin in
samples, the lower the carbon content and higher the
amounts of heteroatoms were obtained. Therefore, the
unstable structure of samples contributed more weight
losses when they were heated in air at high temperatures.
The results showed that the increase of PF resin ratio
was unable to enhance the oxidation resistance of wood-
ceramics when they were fabricated under 800 °C.
The DSC curves in Figure 5 show that a distinct
exothermic reaction was exhibited between 370 °C and
450 °C. With the increase of PF resin ratio, the curve
peaks shifted to the higher temperature range and
covered a larger area. This phenomenon showed that the
increase of heat release with the rise of PF resin ratio.
After that, a small endothermic peak was observed, then
the woodceramics continued to have an exothermic reac-
tion. Theoretically, the reaction of carbon and oxygen in
air is an exothermic reaction. DSC curves proved that the
exothermic reaction was the most important reaction in
the thermal decomposition of woodceramics.
3.4 Heating rate vs. oxidation resistance
As shown in Figure 6, the heating rate has a signi-
ficant effect on the thermal decomposition of wood-
ceramics. Before the rapid degradation, all the samples at
four heating rates had low weight losses. With the
heating rates of (2, 5, 10, and 20) °C/min, the starting
temperatures of the rapid thermal decompositions were
at (350, 380, 410, and 450) °C, respectively. With the
rise of heating rate, the starting temperature of rapid
thermal decomposition moved to a higher temperature
zone. When the heating rates were at 2 °C/min and
5 °C/min, the thermal decomposition temperatures were
terminated at 490 °C and 570 °C. However, when the
woodceramics were treated under heating rates of
10 °C/min and 20 °C/min, their remaining weights were
22.8 % and 50.4 % at 700 °C, respectively, indicating
that the thermal decomposition was uncompleted.
The DSC curves in Figure 6 show that the four heat-
ing rates of all woodceramics appeared in exothermic,
endothermic, and exothermic reaction sequence. It was
revealed that there were some active groups in the wood-
ceramics incompletely degraded when they were pre-
pared under 800 °C.
The results showed that the speed of weight loss of
woodceramics was reduced with the increase of heating
rate. The performances of woodceramic products were
Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
Materiali in tehnologije / Materials and technology 53 (2019) 3, 417–423 421
Figure 6: Effect of heating rate on oxidation resistance of wood-
ceramics (weight ratio of wood to PF is 40:60; Heating rates of TG are
(2, 5, 10 and 20) °C/min; Carbonization temperature is 800 °C; Gas
environment of TG is Air)
Figure 5: Effect of component ratio on oxidation resistance of
woodceramics (Weight ratios of wood to PF are 40:60, 50:50 and
30:70; Heating rate of TG is 10 °C/min, carbonization temperature is
800 °C; Gas environment of TG is Air)
Figure 7: Conversion ratio of woodceramics using different heating
rates of TG

stable under 300 °C. Therefore, the woodceramics (car-
bonized under 800 °C, weight ratio of 40:60) are able to
be used in air below 300 °C for a long period of time or
be used under an instantaneous high-temperature en-
vironment.
3.5 Apparent activation energy of the thermal decom-
position reaction
The activation energy of a chemical reaction can be
used to characterize its reaction rate and analyze the
reaction mechanism. Using Equation (1), the conversion
ratios of samples (the weight ratio of wood to PF resin
was 40:60, the carbonization temperature was 800 °C,
and heating rates of TG was (2, 5, 10, and 20) °C/min
respectively) at any given time/temperature are shown in
Figure 7.
Figure 7 illustrates that at 700 °C, the final
conversion ratios of woodceramics were 81.2 % (heating
rate of 10 °C/min) and 52.2 % (heating rate of 20
°C/min). However, when the heating rates were 2 °C/min
and 5 °C/min, the conversions ended at around 500 °C
and 590 °C.
With the increase of the heating rate, the starting tem-
perature of rapid thermal decomposition moved slightly
toward higher-temperature zones. Meanwhile, the ending
temperature of thermal decomposition increased. Fur-
thermore, through the Equation (2) and (3), the apparent
activation energy E value can be obtained by calculating
the slope of straight lines as shown in Figure 7. The cal-
culated apparent activation energy are shown in Table 4.
Table 4: Apparent activation energies of thermal oxidation of wood-
ceramics using the Ozawa method
17
Weight loss (%)
Apparent activation
energy, E (kJ/mol)
R
2
20 55 0.98909
30 47 0.98889
40 43.5 0.99614
50 40.7 0.99624
60 40.1 0.98417
70 38.4 0.98056
From Table 4 and Figure 7, it was found that the
apparent activation energy decreased with the increase of
the weight loss of woodceramics. The activation energy
was relatively high at the initial phase of the reaction. As
the reaction proceeded, the activation energy declined.
The higher activation energy at the initial stage
denoted that it was difficult for some carbon molecules
to overcome the activation energy barrier to complete
oxidation reactions. In another word, more energy were
consumed to complete the oxidazation reaction at first,
which was consistent with the TG-DSC results.
It is noteworthy that once some carbon molecules can
overcome the activation-energy barrier and complete the
reaction, they would release energy. The released energy
supported other carbon molecules to surpass the energy
barrier and lead to a chain reaction.
25
Consequently, this
phenomenon contributed the higher oxidation rate of
woodceramics during the second stage. In theory, the
heat released from the thermal decomposition reaction
can promote the degradation process of woodceramics.
Furthermore, with the development of thermal degra-
dation and carbonic oxides emission, the volume of in-
accessible pores would diminish, making it easier for
oxygen to reach the interior surface of carbon and
accelerate the oxidation of woodceramics.
26,27
4 CONCLUSIONS
Woodceramics demonstrated good antioxidant pro-
perties in this research. Taking the sample prepared
under 800 °C as an example, due to eliminating moisture
and small molecule substance, the thermal weight loss in
air at 350 °C was merely 9 %.
The carbonization temperature was an important
factor that affected the oxidation resistance of wood-
ceramics. Proliferating the carbonization temperature
made it possible to improve the oxidation resistance of
the woodceramics. The results highlighted the potential
of woodceramics being used as catalyst supports.
The effect of PF resin content on the oxidation re-
sistance was not as apparent as the carbonization tem-
perature. With the increase of PF resin ratio, the thermal
weight loss of woodceramics increased, oxidation resist-
ance decreased, and heat release of thermal decompo-
sition increased. Therefore, an optimal ratio of PF resin
should be considered if it is desired that the wood-
ceramics can provide sufficient mechanical properties
when being used as catalyst supports.
With the growth of TG heating rates, the starting
temperature of rapid thermal decomposition increased
and slightly shifted to higher temperature zones. Mean-
while, the ending temperatures of oxidation degradation
increased.
As the oxidation mass loss increased, the apparent
activation energy of woodceramics declined. At the
initial stage of reaction, the apparent activation energy of
thermo-oxidative decomposition was relatively high. As
the reaction progressed, the heat released by decom-
position processes played an important role in helping
the continuous reaction.
Acknowledgment
We acknowledge the support from the Fundamental
Research Funds for the Central Universities (Grant no.
DL12CB07), the Fok Ying-Tong Education Foundation
for Young Teachers in the Higher Education Institutions
of China (Grant no. 122044).
Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
422 Materiali in tehnologije / Materials and technology 53 (2019) 3, 417–423

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Y. TAO, P. LI: EFFECTS OF FABRICATION PARAMETERS ON THE OXIDATION RESISTANCE OF WOOD/PHENOLIC ...
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