close

Вход

Забыли?

вход по аккаунту

?

Kinetic Study on the thermal degradation of anisolic resins.

код для вставкиСкачать
Die Angewandte Makromolekulare Chemie 33 (1973) 177-190 ( N r . 448)
From the P. G. Department of Chemistry, Sardar Patel University,
Vallabh Vidyanagar, Dist. Kaira, Gujarat State, India
Kinetic Study on the Thermal Degradation
of Anisolic Resins
By K. G. SHAH,D. H. DESAI,and B. N. MANKAD
(Received on 8. November 1972)
SUMMARY:
Thermal behaviour of anisolic resinsis studied and an order of thermal stability
of the investigated resins is observed. Thermal stability is found t o be dependent
upon the nature of the substituent present in the para position to the methoxy
POUP.
Kinetic parameters of the decomposition reactions are determined by CHATTERJEE and REICH
methods of analysis applied to the TG and DTA data.
ZUSAMMENFASSUNG:
Das thermische Verhalten von Anisolharzen wird untersucht ; die Harze lassen
sich nach ihrer thermischen Stabilitiit in eine bestimmte Reihenfolge einordnen.
Danach hiingt die thermische Stabilitiit von der Art des in p-Stellung zur MethoxyGruppe befindlichen Substituenten ab.
Nach den Methoden von CHATTERJEEund von REICHwurden die kinetischen
Parameter der Zersetzungsreaktionen aus TG- und DTA-Daten ermittelt .
Introduction
With the need for more heat resistant materials, studies of the rate of decomposition and products of decomposition have been intensified in recent
years. Thermogravimetric analysis and differential thermal analysis techniques,
long used with inorganic molecules, have been applied by a number of workers
t o phenolic resinsl-19.
However, no systematic work on the thermal degradation behaviour of
phenolic ether resins has been reported so far. The present investigation, therefore, aims a t characterizing the thermal decomposition of the anisolic resins
which may throw some light on their thermal stability and also on the mode
of thermal degradation.
Experimental
Two of the thermoanalytical techniques, TG and DTA, have been used to study
the kinetics of decomposition of the resins in the present investigation. The Linseis
thermobalance was used for TG experiments and a micro DTA cell20 constructed in
177
K. G . SHAH,D. H. DESAI,and B. N. MANKAD
our laboratories was used for DTA experiments. Cromel-alumel thermocouple
elements were employed to measure temperatures in both the techniques. Polystyrene and calcium oxalate monohydrate were used to calibrate the thermobalance,
while analar ammonium nitrate for DTA apparatus. Analyses of all the samples
were carried out in nitrogen atmosphere.
Anisole, p-methoxy-, p-methyl-, p-chloro-,p-nitro, and p-acetoxymercuryanisole
were used for condensation with formaldehyde *. The optimum conditions for the
preparation of the resins used in the present study are given in Tablel.
Table 1.
Conditions for preparation of the resins. Anisole 5 g, paraformaldehyde
2 g, acetic acid 15 ml, catalyst: 1 ml sulphuric acid.
No.
Name of the resin
1
2
Anisole-formaldehyderesin
p -Methoxyanisole-formaldehyde
resin
p-Methylanisole-formaldehyde
resin
p-Chloroanisole-formaldehyde
resin
p-Nitroanisole-formaldehyde
resin
p-Acetoxymercuryanisoleformaldehyde resin
3
4
5
6
Concentration Reaction
of the catalyst temperature
(Yo)
("C)
Time
(h)
100
80
2.5
20
60
2.5
100
80
2.5
100
120
225
100
120
24
100
80
2.5
40-100 mg of sample were used for TG experiments and 3 mg of the sample
mixed with alumina were used in DTA studies.
Results and Discussion
The TG and DTA thermograms of anisolic resins are shown in Figs. 1 t o 6.
Fig. 1 shows the TG and DTA thermogram of anisole-formaldehyde resin.
It can be seen from TG thermogram that decomposition starts a t 400°C and
ends a t 620°C. Two different steps of decomposition are observed from TG
thermogram, while in DTA thermogram an exothermic peak is observed a t
about 575°C which indicates the decomposition of the material. The nature of
this exothermic peak also indicates that two decomposition steps overlap with
each other. No physical transformation is observed which is indicative that
the polymer decomposes without melting.
*
K. G . SHAHand B. N. MANKAD,Angew. Makromol. Chem. 32 (1973) 1.
178
Degradation of Anisolic Resins
500
300
J
'
I
700
1
1
DTA
Scale
1
4C
300
400
500
600
TG Scale
Temp.'C.
Fig. 1. TG and DTA thermogram of sample No. 1, anisole-formaldehyderesin,
40 mg, R. H. 10°C/min for DTA and 3'C/min for TGA in Nz.
90
80
70
60
0
L;;
t
u)
3
50
2l
.
I
-
r
F
30
20
10
s
Fig. 2.
f
40
LYL
1
300
400
Temp.
I
U
0
W
500
; Scale
OC
TG and DTA thermogram of ample Nr. 2, p-methoxyanisole-formaldehyde resin, 40 mg, R. H. 10"C/minfor DTA and 3OC/min for TGA in Nz.
179
K.G.SHAH, D.H.DESAI,and B. N. M A N ~ A D
Fig. 2 represents the TG and DTA curves for the p-methoxyanisole-formaldehyde resin. It is obvious from the TG thermogram that decomposition starts
at 302 "Cand ends at about 560°C. A break at 436°C indicates that the degradation occurs via two steps. Two exotherms a t 440°C and 552"C, obtained in
DTA, suggest that degradation occurs through two stages.
200
400
600
800
DTA Scale
0
i
I-
I
0
f
200
300
400
500
Scale
Tern $C .
Fig. 3. TG and DTA thermogram of sample No. 3, p-methylmisole-formaldehyde
resin, 40 mg, R. H.10°C/minfor DTA and 3"C/min for TGA in N2.
TG and DTA thermograms of p-methylanisole-formaldehyderesin are shown
in Fig. 3. TG thermogram shows that decomposition starts at about 300 "C and
ends at 560°C. It also reveals that degradation occurs through two distinct
stages. A sharp exotherm at 4OO0C followed by a hump a t 480°C is obtained.
This clearly indicates that the decomposition takes place via two steps. It also
does not show any physical transformation before depolymerization.
Fig. 4 shows TG and DTA thermograms of p-chloroanisole-formaldehyde
resin. TG curve reveals that degradation is initiated a t 320 "Cand ends a t about
620 "C. Two distinct steps in decomposition are observed from TG thermogram
In DTA a hump a t 340°C and an exotherm at 490°C are observed which indicate the possibility of two reactions. It does not show any physical changes before decomposition.
180
Degradation of Anisolic Resina
I0
500
700
DTA Scale
::
i
1;1
I
0
C
w
D
TG Scale
T e rnp'c.
Fig. 4. TG and DTA thermogram of sample No. 4, p-chloroanisole-formaldehyde
resin, 40 mg, R. H. 10°C/minfor DTA and 3"C/minfor TGA in N2.
1
400
600 DTA Scale
Temp:
Fig. 5.
c.
TG and DTA thermogram of sample No. 5, p-nitroanisole-formaldehyde
resin, 40 mg, R. H. 10 'C/min for DTA and 3 OC/min for TGA in N2.
181
K. G. SHAH,D. H. DESAI,and B. N. MANKAD
Fig. 5 represents the TG and DTA curves of p-nitroanisole-formaldehyde
resin. It can be seen from the TG thermogram that the decomposition occurs a t
260°C and ends a t about 635°C. Two distinct steps in degradation are clearly
observed. A broad exotherm a t 496°C is obtained in DTA. The broadening of
the exothermic peak indicates that degradation is not simple but is a complex
one, and two or more than two reactions occur simultaneously. No physical
transformations are observed.
0
riC4
600
I
.
MASule
Fig. 6. TG and DTA thermogram of sample No. 6, p-acetoxymercuryanisoleformaldehyde resin, 40 mg, R. H. lO"C/min for DTA and 3OC/min for
TGA in Nz.
Fig. 6 shows the TG and DTA thermograms of p-acetoxymercuryanisoleformaldehyde resin. Decomposition begins a t 220°C and ends a t 660°C which
clearly suggests that the rate of decomposition is very slow. A break in the
region of 400430 "C also indicates the degradation t o occur via two steps. Two
exotherms, a t 416°C and 552°C respectively, are obtained. I n the temperature
range 280-62O0C, the TG thermogram shows appreciable weight loss which indicates that none of the exotherms belongs t o physical changes. DTA thermogram
also reveals that degradation occurs through two stages.
Initially a slow rate of weight loss is observed followed by a rapid rate during
the thermal decomposition of each sample. I n the final stage, rate of weight loss
182
Degradation of Aniaolic Resins
drops and levels off resulting into a sigmoidal thermogram. All the polymers
in the present study show similar type of nature. It is evident that almost all
phenolic and epoxy type of resins have a tendency to form char residue. It is
interesting to note, in the present study, that no such char formation is observed. Almost 100% weight loss is observed in each of the samples.
An examination of the data reveals that the thermal stability of anisolic
resins is dependent upon the nature of the substituent in the position para to
the methoxy group.
Anisole-formaldehyde resin is found to be the most stable resin amongst all
the resins studied in the present investigation. Stability of p-chloroanisole-formaldehyde resin is second to that of anisole-formaldehyde resin. This may be
attributed to the presence of electronegative chloro group. It is known that the
presence of fluorine in the polymer tends to increase the thermal stability due
to t,he electronegativityzl. Stability of p-methoxyanisole-formaldehydeand pmethylanisole-formaldehyde resins is almost equal. Stability of p-acetoxymercuryanisole-formaldehyderesin is the least and degrades a t about 220 "C. This
may be ascribed to the presence of bulky CHsCOOHg-groupsin the p-position.
Rate of degradation is also found to be dependent on the nature of the different substituent groups. Decomposition rate of anisole-formaldehyde and
p-chloroanisole-formaldehyderesins is higher than that of the remaining resins
in the present investigation. Both the resins decompose in the temperature
range of 400-620°C and 320-560°C respectively. The rate of degradation of
p-methoxyanisole-formaldehyderesin and p-methylanisole-formaldehyderesin
is almost the same and is lower than that of the above mentioned resins. This
may be due t o the existence of steric effect of methoxy and methyl groups.
These groups retard the degradation rate to some extent. The rate of decomposition of p-acetoxymercuryanisole-formaldehyderesin is lower than that of
other resins used in the present study. Degradation rate in this case may be
retarded by the presence of bulky CHsCOOHg-groups.
DTA thermograms reveal that the polymer decomposition is characterized
by exothermic peaks in all the cases. These exothermic peaks are not so sharp
and well d e h e d due to consecutive and competitive decomposition reactions
occurring in the course of pyrolysis. This is a well-known fact so far as the polymer pyrolysis is concerned22. No physical transitions are detected from the
DTA thermograms.
Generally, the exothermic peak temperature of the major decomposition
(c. f. DTA) is expected to coincide with the temperature giving maximum rate
of weight loss (c. f. TG). However, the exothermic peak temperature is higher
by 10-15 "C than that corresponding to maximum rate of weight loss. This can
be explained as follows. I n order to obtain good results, high heating rate in
183
p-Methylanisoleformaldehyde
resin (3)
p-Methoxyanisoleformaldehyde
resin (2)
Anisole-formaldehyde resin (1)
22.5
51.25
454-5 17
5 17-6 19
23.5
20.0
55.5
306-372
372-477
477-569
300-360
360-417
417-554
80
40
12.5
30
57.5
300-345
345-445
445-568
40
12.5
32.5
55
26.25
398-454
80
33
17.5
47.5
(%I
Weight loss
400-467
467-532
532-620
Temperature
range ("C)
40
Amount
(mg)
13.8
14.2
22.0
9.2
9.2
12.0
9.2
9.2
11.5
17.4
18.4
17.0
17.2
17.25
18.4
Energy of
activation, E
(kcal/mole)
0.71
2.2
0.65
0.66
0.90
0.43
0.66
0.90
0.43
1.45
0.42
0.66
0.66
1.45
0.42
Order of
rehction, n
Kinetic parameters for the decomposition of the resins obtained from CHATTERJEE method.
Polymer
Table 2.
2.476
0.766
3.195
4.475
1.525
4.937
6.033
1.954
4.4
2.972
2.217
1.493
1.442
2.949
1.481
102
101
102
*
. 103
. 101
. 105
. 101
*
. 101
. 101
. 102
. 104
*
'
p
p
?
I
x
. 104
&
p
102
F
?
. 104
*
. 104
Frequency
factor, A
(min-1)
p-Acetoxymercury anisole-formaldehyde resin (6)
p -Nitroanisole.
formaldehyde
resin ( 5 )
p-Chloroanisoleformaldehyde
resin (4)
,
2.
. 101
. 101
. 102
0.83
1.59
0.33
6.67
7.36
13.11
1.018
0.63
1.5
15.0
23.33
60.66
220-300
300-431
431-660
60
. 101
. lo1
. 102
0.83
1.59
0.33
6.9
6.9
12.9
1.546
0.055
2.12
15.0
25.0
60.0
220-290
290-400
400-660
. 101
. lo1
. 103
6.02
1.84
6.99
1.22
1.68
0.33
11.5
13.8
15.525
24.0
22.38
53.62
277-378
37 8-47 2
472-630
80
40
. 101
. 101
. 103
6.2
1.81
8.156
1.22
1.68
0.33
2
$
2,
i$
$.
$
5
&
8,
102
. 105
b
d
. lo5
. lo5
. lo2
. 105
. 103
. lo1
. 105
11.5
13.8
15.9
4.983
5.78.
1.95
0.39
1.48
2.43
4.918
5.96
2.102
1.58
0.543
2.89
23.15
25.8
50.7
17.25
16.84
31.28
21.25
18.25
60.5
0.39
1.48
2.43
0.71
2.2
0.65
279-380
380-473
473-632
328-380
38a-443
443-576
80
18.4
17.25
30.636
13.8
13.9
23.0
26.5
16.25
57.25
26.6
16.7
55.0
60
320-369
369-434
434-564
302-387
387-447
447-560
40
60
K. G. SHAH,D. H. DESAI,and B. N. MANKAD
DTA and low heating rate in TG are preferred. Any transition, physical or
chemical, is shifted to higher temperature when high heating rate is employed.
Thus, characteristic transition temperatures in DTA are always higher than
that obtained from TG ; of course, the other instrumental parameters should
not be overlooked.
Kinetic Parameters and Degradation Mechanism
I n order to understand the decomposition mechanism, the kinetic parameters,
e. g., activation energy, E, the reaction order, n, and the ARRHENIUS
frequency
factor, A, for the process have been evaluated from TG and DTA data employing CHATTERJEE~~
and R E I C H methods,
~~
respectively.
According to CHATTERJEEZ3 the reaction order is calculated from the rate of
weight loss, dW/dt, observed a t one temperature in a t least two TG thermograms differing only in their initial weights W :
AlOg (-dW/dt)
n =
.
alog w
(T=constant),
while activation energy is obtained from the data of one thermogram only,
following the relation
Alog (-dW/dt) =
E
-A (1/T)(W = constant),
2.303 R
The frequency factor A may be obtained from the ARRHENIUS
equation substituting the values of n and E. The competitive decomposition reactions may
also be detected by the CHATTERJEEmethod. The kinetic parameters thus obtained for the decomposition of the resins under investigation are tabulated in
Table 2.
R E I C Hhas
~ ~ reported an excellent method of evaluating kinetic parameters
from DTA data as follows:
log A T = log C - EV/4.6
V
=
[1/T - ~ ( l / T ) l ~ g
I'"""
A ( ~ / T )= i / ~ -, r
-a = A ' - y j T . d T
TO
slog
I= log(a/a')
where A represents the total area under the DTA curve, A T denotes the
height of the curve from its base line a t two temperatures T and T', prior to
and after DTA peak, respectively, C is a constant under the given experimental
conditions, and To is the initial temperature of the curve.
186
Degradation of Anisolic Resilw
The activation energy is obtained from the plot of log A T versus V, and n is
calculated from the following relation :
n
=
(E/2.303R) A(l/T)/Alog
a
The kinetic parameters, thus, obtained are represented in Table 3.
Table 3. Kinetic parameters for the decomposition of the resins obtained from
REICHmethod.
Polymer
1
Energy
Of
activation, E
(kcal/mole)
Anisole-formaldehyderesin (1)
11.4
p-Methoxyanisole-formaldehyderesin (2)
p-Methylanisole-formaldehyderesin (3)
p-Chloroanisole-formaldehyderesin (4)
p-Nitroanisole-formaldehyderesin (5)
p-Acetoxymercuryanisole-formaldehyde
resin (6)
13.6
20.7
28.8
33.7
28.8
1
Order of
reaction, n
0.95
0.98
0.99
1.14
1.47
1.25
The decomposition of a polymer involves a very complex phenomenon in
which variety of reactions occur, viz. chain breaking, rearrangement of chain
segments, decomposition of chain segments etc. The analysis of TG data of the
present polymers reveals that the decomposition can be approximated as
occurring through three consecutive reactions.
I n the case of anisole-formaldehyde resin, the initial reaction corresponds to
about 26% of the weight loss, the second about 1Sy0 while the third about 50%.
The order of reaction of the first two reactions is different but the activation
energy is the same. Though the last reaction is a major decomposition reaction,
its activation energy is comparable with that of the previous two reactions.
p-Methoxyanisole-formaldehyderesin decomposes through three reactions.
The two initial steps correspond to low activation energy ( w 9 kcal/mole) and
the last step corresponds to little higher energy of activation ( w 12 kcal/mole).
I n case of p-methylanisole-formaldehyderesin, the initial two reactions
correspond to almost the same activation energy ( w 14 kcal/mole). I n the last
decomposition reaction, higher activation energy is observed and a t the same
time maximum weight loss has been found. This is indicative for the fact that
the last reaction is the major decomposition reaction.
p-Chloroanisole-formaldehyderesin also decomposes through three consecutive and competitive reactions. The first two reactions give low activation
energy and show minimum weight loss. The last degradation step is associated
with maximum weight loss (60%) and higher activation energy (31 kcal/mole).
187
K. G. SHAH,D. H. DESAI,and B. N. MANKAD
I n case of p-nitroanisole-formaldehyde resin, maximum percentage weight
loss (53%) is observed in the region 470-630°C. The activation energy and
order of reaction are found to be 16 kcal/mole and 0.33 respectively. The weight
loss in the first two decomposition reactions is considerably lower than that in
the third major reaction. The activation energy in the first two reactions is
lower and order of reaction is higher while in the third reaction it is reverse.
p-Acetoxymercuryanisole-formaldehyde
resin also degrades via three decomposition reactions. The initial two reactions correspond to about 15% and 25%
of the weight loss while the third to about 60% is the major decomposition
reaction. The first two reactions are associated with lower activation energy
( w 7 kcal/mole) and the third reaction is associated with higher energy of activation (13 kcal/mole). Order of reaction is found to be different for all the
three degradation reactions.
Kinetic analysis revealed that the last step of degradation is the major decomposition reaction for each of the anisolic resins. Activation energy of all
samples for the major decomposition reaction is found to be different which
indicates that the substituents in the para position to the methoxy group play
a significant role in the course of degradation. The activation energies for the
first two reactions of all the samples are approximately the same which indicates that the two decomposition reactions may possibly overlap with each
other resulting into a single TG curve.
The kinetic data calculated according to REICHmethod from DTA show that
the order of reaction of the degradation of all the anisolic resins, in the present
investigation, is almost the same ( w 1). Only in the case of p-nitroanisole-formaldehyde resin, the order of reaction is found to be higher than unity ( w 1.5).
Activation energies from DTA studies are found to be higher (except anisoleformaldehyde resin) than those obtained from TG studies. This can be explained as follows. The decomposition of the polymer in a narrow cavity (DTA cell)
is retarded to some extent compared to that in a shallow boat (TG cell). This
ultimately results in a high activation energy in DTA studies. However,
high reaction order remains unexplained. The magnitude of energy for all the
samples is also found to be dependent upon the nature of the substituent present.
The major decomposition reaction is difficult to explain with the present
data. The detail analysis of the volatile products and the residues collected a t
various temperatures can explain the mechanism of the major decomposition.
However, free radical mechanism on the basis of phenolic resins14 may be proposed for anisolic resins.
It can be seen that the degradation of anisolic resins also occurs through
methylene linkages. Phenol resins are known to crosslink easily though the
188
Degradation of Anisolic Resins
phenolic chains are short and stiff.This suggests the occurrence of postcuring
in phenolic resins. In the present study as the para position is blocked postcuring may be absent. Moreover, in anisolic resins inter and intramolecular hydrogen bonding as in the case of phenolic resins is not possible. For this reason anisolic resins are found to be less stable than the corresponding phenolic resins. The absence of hydrogen bonding may also be the reason for higher
degradation rate of anisolic resins.
The results of this investigation can be summarized as follows :
1. Thermal stability observed for the present resins is in the following order :
anisole-formaldehyde > p-chloroanisole-formaldehyde> p-methoxyanisoleformaldehyde > p-methylanisole-formaldehyde> p-nitroanisole-formaldehyde > p-acetoxymercuryanisole-formaldehyde.
2. Thermal stability is found to be dependent upon the nature of the substituent present in the para position to the methoxy group.
3. No physical transformations are observed. Exothermic peak corresponding
to the decomposition of the material is observed for each of the samples which
indicates that the resins decompose without melting.
4. Examination of the kinetic data reveals that the decomposition occurs
through three possible steps.
5. The resins in the present study do not show any char formation.
6. The kinetic parameters such as order of reaction and energy of activation
are found to be independent of concentration of the resin which clearly indicates that the properties are extensive.
Thanks are due to Prof. R. D. PATEL,
Head of the Department of Chemistry, Sardar Pate1 University, for continous encouragement and providing all
the research facilities and also to Dr. K. C. PATEL,
Dr. C. K. PATEL,
and Shri
H. S. VEKARIA
for their help during the experimental work. One of the authors
(K. G. S.) is grateful to the C. S. I. R. for giving Junior Research Fellowship.
1
2
3
4
6
W. HERZOG,
Z. Angew. Chem. 34 (1921) 97
I. ALLEN,V. E. MEHARG,
and J. H. SCHMIDT,
Ind. Eng. Chem. 26 (1934) 663
N. J. L. MEGSON, “Phenomena of Polymerization and Condensation”, Faraday
Society (London) 1935
M. G. BARCLAY,
A. BURAWAY,
and C. H. THOMSON,
J. Chem. SOC.1944, 400
H. I. WATERMAN
and A. R.VELDMAN,
Brit. Plastics 8 (1936) 125, 182
R.T. CONLEY,Amer. Chem. SOC.Div. Org. Coatings PlQst.Chem. Pap. 26 No. 1
(1966) 138
7
8
9
J. J. MILLANE,
Plastics 28 (1963) 101; 29 (1964) 81
L. V. PEVZNER,
V. Z. KOLODYAZHNYI,
K. N. KARAKINA,
and G. B. REICH,
Soviet Plastics 8 (1966) 17
V. A. POPOV,
I. S. DRYAN,
and B. G. VARSHAL,
Plast. Massy 5 (1964) 15
189
K. G. SHAH,D. H. DESAI,and B. N. MANKAD
10
11
12
l3
14
15
16
l7
18
19
20
21
22
23
24
H.H.NAKAMURA
and L. M. ATLAS,Proc. Fourth Conf. Carbon, Pergamon Press,
Belfast (1960) p. 625
R. T.CONLEY,I. F. BIERON,and P. PERCH,
Amer. Chem. SOC.Div. Org. Coatings
Plast. Prepr. 20 (2) (1960) 244
R. T. CONLEYand J. F. BIERON,J. Appl. Polym. Sci. 7 (1963) 103
R. T. CONLEYand J. F. BIERON,J. Appl. Polym. Sci. 7 (1963) 171
W. M. JACKSON
and R. T. CONLEY,J. Appl. Polym. Sci. 8 (1964) 2163
G. P. SHULMAN
and H. W. LOCHTE,
J. Appl. Polym. Sci. 1 0 (1966) 619
G. S. LEARMONTH
and D. P. SEARLE,
J. Appl. Polym. Sci. 1 3 (1969) 437
I. AUERBACH,
J. Appl. Polym. Sci. 14 (1970) 747
V. F. SIMONOV
and V. G. KASHIRSKII,
Zh. Prikl. Khim. (Leningrad) 44 1 (1971)
228
V. I. KURACHENKOV
and L. A. IGONIN,
J. Polym. Sci. A-1 9 (1971) 2283
D. H. DESAI, C. K. PATEL,
K. C. PATEL,
and R. D. PATEL,
Stiirke 24 (1972)
42
R. B. HODGDON,
Jr., J. Polym. Sci. A-1 6 (1968) 171
J. K. GILLHAM
and R. F. SHWENKER,
Appl. Polym. Symp. 2 (1966) 59
P. K. CHATTERJEE,J. Polym. Sci. A 3 (1965) 4253
L. REICH,Makromol. Chem. 123 (1969) 42
190
Документ
Категория
Без категории
Просмотров
0
Размер файла
554 Кб
Теги
thermal, degradation, stud, resins, anisolic, kinetics
1/--страниц
Пожаловаться на содержимое документа