Material Based on Cyanate ester/BMI/Epoxy
Figure 6.5 FT‐IR absorbance spectra for the reactions of LECY/BMI
6.4.5 Considerations of Kinetics
Figure 6.6 Difference spectra (At‐Ao, t in mins) the reaction of LECY/
BMI/ Epoxy at 140 o C for various time.
6.4.5 Considerations of Kinetics
Based on the above discussions, three systems all in equivalent ratio of (1) LECY/epoxy, (2) LECY/MBI, and (3) LECY/Epoxy/MBI were prepared and coated on each KBr plate and monted on FTIR sample holder at constant temperature (130, 140, 150 and 160 o C). Functional group changes during co‐curing reactions were monitored with FTIR with a resolution of 1 cm‐1.Data were collected at each 5 mins interval. The absorbance of a specific Functional group is directly proportional to the concentration of the group, according to Beer’s law. The conversion, α, is defined as
α =（A0‐At）/（A0‐A∞）
Where A0 is the initial absorbance of OCN, At is the absorbance at time t,
A
20- A
0A
40- A
0A
60- A
0A
80- A
02237
2271
1681
A
100- A
01367 914
147
A∞is the absorbance at infinite time, i.e., no further changes in absorbance. Difference spectra is obtained by subtracting absorbance at time t from that at time zero, using the absorbance of υSi‐O‐Si at 1060 as internal reference, which was adjusted to zero, according to the method developed by Koenig [16]. Non‐catalytic and autocatalytic reactions can be combined by
Where k1 and k2 are rate constants for non‐catalytic and autocatalytic reactions; m and n are reaction orders. This type of rate equation has been generally accepted and widely discussed in literature [17‐22].
Data treatment and the solution method has been successfully developed by Kenny graphic‐analytical technique [18]. Plot of conversion α versus t is giving in Figures 6.7,6.11 and 6.15 . The corresponding reaction rate, dα/dt, at time t can be obtained from slope
Rearranging equation (1),obtaining
1 2
Plot of ln 1 (1 )
versus ln α shows a straight line (Figures 6.8,6.12
148
and 6.16), and the values of m and ln k2 can be obtained from the slope and the intercept. The activation energy can be measured from the plot ln k versus 1/T, as given in Figures 6.9,6.13 and 6.17. Kinetic
parameters thus obtained are listed in Tables I, II and III.
(1) Kinetic analysis in LECY/Epoxy
Equivalent ratio of LECY and Epon 828 together with 10 ppm of Co2+complex (as catalyst, Based on LECY) were blended and was coated between two KBr plates, and mounted in IR holder. The conversion of cyano group, α, was then ploted against time t (Figure 6.7). Data were treated by Kenny graphic‐analytical technique [19] and results are listed in Table 6.I. The calculated kinetic parameters for the curing reactions of (1) LECY/EPOXY indicated E1 = 52.62 kJ/mole, E2=43.26 kJ/mole, with n
= 0.87 to 1.02 and m = 1.16 to 1.04
Figure 6.7 Plot of conversion,α, versus reaction time t for the LECY/Epoxy
System at 130 o C (o),140 o C (▲ ), 150 o C (▓ ), and 160 o C (x).
0.0 0.2 0.4 0.6 0.8 1.0
0 10 20 30 40 50 60 70 80 90 100
Curing Time ,min
Conversion , α
T = 403 K T = 413 K T = 423 K T = 433 K
149
Figure 6.8 Plot of dα/dt vs α for LECY/Epoxy system at 130 o C (o),140
o C (▲ ), 150 o C (▓ ), and 160 o C (x).
Figure 6.9 Plot of ln[(dα/dt)/(1‐α)n‐k1] vs ln α for LECY/Epoxy system
at 130 o C (o),140 o C (▲ ), 150 o C (▓ ), and 160 o C (x)
-5.5 -5 -4.5 -4 -3.5 -3 -2.5 -2
-2.5 -2 -1.5 -1 -0.5 0
ln α ln [(dα/dt)/(1-α)n -k1]
T = 403 K T = 413 K T = 423 K T = 433K
0.0000 0.0050 0.0100 0.0150 0.0200 0.0250
0 0.2 0.4 0.6 0.8 1
α
dα/dt
T = 405 K
T = 415 K
T = 425 K
T = 435 K
150
Figure 6.10 Plot of ln k vs 1/T for LECY/Epoxy system.
Table 6.1 Kinetic parameters for LECY/Epoxycuring system.
Temp, oK 403 413 423 433
k1*103( S‐1) 3.0 4.5 5.5 8.2
k2*102( S‐1) 4.2 6.2 6.6 8.6
N 0.87 0.91 0.94 1.02
M 1.16 1.13 1.09 1.04
n+m 2.03 2.04 2.03 2.06
E1(kJ/mole) 52.62
E2(kJ/mole) 43.26
-7 -6 -5 -4 -3 -2 -1 0
2.3 2.4 2.4 2.5 2.5
1 / T * 10 3
ln k
151 (2) Kinetic Analysis of LECY/BMI
LECY and MBI were blended in equivalent weight, together with 10 ppm of Co2+complex (as catalyst, Based on LECY). Similar treatment of data give the corresponding Figures6. 11,6.12,6.13 and 6.14, and the calculated kinetic parameters are listed in Table II. Itis found that for this system, The non‐catalytic reaction constant E1=57.78 kJ/mole, autocatalytic reaction con‐ stant E2=46.67 kJ/mole, with reaction orders n= 1.05 to 0.98 and m = 1.04 to 1.14.
.
Figure 11. Plot of conversion α vs reaction time t for curing LECY/BMI system at 130 o C (o),140 o C (▲ ), 150 o C (▓ ),and 160 o C (x).
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0 10 20 30 40 50 60 70 80 90 100
Curing time,min
Conversion , α
T = 403 K T = 413 K T = 423 K T = 433 K
152
Figure 6.12 Plot of dα/dt vs α for curing LECY/BMIsystem at 130 oC (o),140 o C (▲ ), 150 o C (▓ ), and 160 o C (x)
Figure 6.13 Plot of ln [(dα/dt)/(1‐α)n‐k1] vs ln α for curing LECY/BMI at 130 o C (o),140 o C (▲ ), 150 o C (▓ ), and 160 o C (x)
0.0000 0.0050 0.0100 0.0150 0.0200 0.0250
0 0.2 0.4 0.6 0.8 1
α
dα/dt
T = 403 K T = 413 K T = 423 K T = 433 K
-5.5 -5 -4.5 -4 -3.5 -3 -2.5 -2
-3 -2.5 -2 -1.5 -1 -0.5 0
ln α
ln [(dα/dt)/(1-α)n-k1]
T = 403 K T = 413 K T = 423 K T = 433 K
153
Figure 6.14 Plot of ln k vs 1/T for curing LECY/BMI system.
Table 6.2 Kinetic parameters for curing LECY/BMIsystem
Temp, oK 403 413 423 433
k1*103( S‐1) 2.5 3.5 5.0 7.5
k2*102( S‐1) 3.6 4.6 6.5 9.0
n 1.05 1.02 0.98 1
m 1.04 1.07 1.1 1.14
n+m 2.09 2.09 2.08 2.14
E1(kJ/mole) 57.78
E2(kJ/mole) 46.67
-7 -6 -5 -4 -3 -2 -1 0
2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.5 2.5
1/T * 10 3
ln k
154 (3) Kinetic Analysis of LECY/BMI/EPOXY
LECY、BMI and Epon 828 in equal equivalent weight were Blended with 10 ppm of Co2+complex as catalyst based on LECY), and coated between two KBr plates. Similarly, the absorbance of cyano group was monitored for kinetic analysis. Similar data
treatment and similar plots were given in Figures 6.15,6.16,6.17 and 6.18, and kinetic parameters given in Table 6.3. Kinetic parameters found are activation energy for non‐catalytic reaction E1 = 66.64 KJ/mole, that for catalytic reaction E2 = 45.75 KJ/mole, with the corresponding reaction orders of n = 0.98 to 1.03, m = 1.02 to 1.21.
All the above three systems reveal a fact that energies of
non‐catalytic reactions are generally higher than those of autocatalytic reactions; while the reaction constants of non‐catalytic reactions are almost 10 times lower than those of autocatalytic reactions. Reaction orders m and n are close to 1, with a total reaction order near 2. This result appears seasonable for a bimolecular curing reaction.
155
Figure 6.15 Plot of conversion α vs. reaction time for curing LECY/BMI/
Epoxythree components system at 130 o C (o),140 o C (▲ ), 150 o C (▓ ), and 160 o C (x)
Figure 6.16 Plot of dα/dt vs α for curing LECY/BMI/Epoxy system at 130
o C (o),140 o C (▲ ), 150 o C (▓ ), and 160 o C(x)
Conversion , α
Curing time , min
T = 405 K
156
Figure 6.17 Plot of ln [(dα/dt)/(1‐α)n‐k1] vs lnα for curing LECY / BMI system at 130 o C (o),140 o C (▲ ), 150 o C (▓ ),and 160 o C (x).
Figure 6.18 Plot of ln k vs 1/T for curing LECY/BMI/Epoxy .
-6 -5 -4 -3 -2 -1 0
-3 -2.5 -2 -1.5 -1 -0.5 0
ln α ln [(dα/dt)/(1-α)n -k1]
T = 403 K T = 413 K T = 423 K T = 433 K
-7 -6 -5 -4 -3 -2 -1 0
2.3 2.3 2.4 2.4 2.5 2.5
1/T * 10 3
ln k
157
Table 6.3 Kinetic parameters for curing LECY/BMI/Epoxy system.
Temp, oK 403 413 423 433
k1*103( S‐1) 2.0 2.5 4.0 7.5
k2*102( S‐1) 4.4 5.4 7.1 8.9
n 1.03 1.02 1.01 0.98
m 1.02 1.05 1.14 1.21
n+m 2.05 2.07 2.14 2.17
E1(kJ/mole) 66.64
E2(kJ/mole) 45.75
6.5 Conclusions
Investigation of co‐curing reactions for LECY/Epoxy/MBI material by monitoring IR absorbances of cyanate group conformed Martin, Shimp and Bauer’s former findings that cyanate ester trimerized to form aryl cyanurate, followed by insertion reaction of epoxy to yield
oxazolidinone. In the three components LECY/Epoxy/MBI co‐curing system, there is no additional chemical bonding found between the two net works (1) LECY/Epoxy and (2) LECY/MBI. In a co‐cured material of LECY/Epoxy/MBI, It is believed that the two networks formed
independently and simultaneously, and there are only physical
entanglement between the two networks, which means a formation of interpenetration polymer networks (IPNs).
158
Kinetic data were treated with Kenny graphic‐analytical technique to solve the generally recognized rate equation:
m n
T
k dt k
dα =( 1+ 2α )(1−α)
⎥⎦⎤
⎢⎣⎡
.
Both reaction orders m and n are very close to 1, and the total reaction is near second order. Furthermore, activation
energies of non‐catalytic reactions are generally higher than those of autocatalytic reactions; while the reaction constants of non‐catalytic reactions are almost 10 times lower than those of autocatalytic
reactions.
This result appears reasonable for a bimolecular curing reaction, which formed an IPN material.
6.6 REFERENCES
1. Xiao Hu, Jing Fan, Chee Yoon Yue, J. Appl. Polym. Sci., 80, 2437‐2445 (2001).
2. C. Wang, H. Hwang, J. Appl. Polym. Sci., 60, 857‐863 (1996) 3. J. Roger, E. Morgan, E.Shin, B. Rosenberg, A. jurek, Polymer, 38,639‐646 (1997).
4. C. M. Go’mez, H. B. Recalde, I.Mondragon, European Polym.
J,41, 2734 (2005).
5. H. B. recalde, D. Recalde, R. Garc, C.M. Go’mez, European Polym.J,41, 2635 (2005).
6. P. Bartolomeo, J. F. Nicolais, Polym. Comp., 13, 191 (1992).
159
7. M. Bauer, J. Bauer and G. Kuhn, Acta Polym., 37, 715 (1986).
8. M. Bauer and J, Bauer, Act. Polym., 38, 16 (1987).
9. S. L. Simon and J.K. Gillham, J. Appl. Polym. Sci., 47, 461 (1993).
10. C. A. Fyfe, J. Niu, S. J. Rattig and N. E. Burlinson, Macrol, 25, 6289 (1992).
11. L. J. Kasehagen and C. W. Macosko, Polym. Intl., 44, 237 (1997).
12. E. grigat Angew. Chem. Int. Ed. Engl., 11,949 (1972).
13. V. Mirco, f. mechin and J.P. Pascault, ACS Div. Polym.
Mater. Sci.Eng., 71, 688 (1994).
14. M. Bauer, Academy of Sci. of the GDR, Berlin, (1980).
15. S. C. Lin and E. M. Pearce,edited,”High Performance Thermosets, Hanser Publishers, New York, 1994, p. 102.
16. J. L. Koenig, Appl. Spectrosc., 29, 293 (1975).
17. I. mondragon, L. sollara, I. B. Recalde, C. M. Gomeza, Thermochimica Acta., 19, 417 (2004).
18. C. H. Lin, Polymer, 45, 7911 (2004).
19. J. M. Kenny and L. Nicolais, Polym. Comp., 13, 191 (1992).
20. M. S. Lin, R. J. Chang, T. Yang and Y. F. Shih, J. Appl.
Polym. Sci. 55, 1607‐1617 (1995).
21. O.A. Moroni, J. Mijovic, E. M. Pearce, and C. C. Foun, J.
Appl. Polym. Sci., 32, 3761‐3773 (1986).
22. C. C. Riccardi, H. E. Adabbo, and J. J. William, J. Appl.
Appl. Polym. Sci.,30, 2481‐2492 (1984).
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Chapter VII CONCLUSIONS
Chapter I dealed with the curing behavior and properties of
siloxane‐ and imide‐ containing tetrfunctional epoxy. Improved physical properties of this material with decreased dielectric constant were
observed, mainly because lots of polar OH groups formed during epoxy curing. In chapter II, effort was made to enhance the dielectric
constant by incorporating POSS molecule into epoxy, the dielectric constant was able to reach below 3, while some of physical properties degraded. In chapter III and IV, new structure of cyanate ester
containing siloxane, imide and allyl groups was designed and was
blended with commercial BMI to prepare a new type of BT resin. This BT resin further blended with commercial epoxy to form new types of co‐cured materials. Both physical properties and dielectric property are improved except for coefficient of thermal expansion.
Further efforts were made in chapter V to design novel type of epoxy and novel type of BT resin. Both not only contain siloxane and imide groups, but also contain an allyl group. This novel BT resin first blended with commercial epoxy to form new resin called part A. Part A and the novel epoxy were co‐cured in various equivalent ratios. This new co‐cured material was able to possess enhanced material performances, such as resin curing, thermal stability, dimensional stability, mechanical toughness, …,etc.. In addition, both dielectric constant (near 3) and dissipation factor were improved. It appears that this co‐cured material
161
is a permissible material suitable for microelectronics application.
For optimal processing, an accurate knowledge of the kinetics of curing and polymer conversion as functions of curing temperature is vital. The behavior of resin curing was performed with dynamic DSC in each chapter. And the kinetic study was done in chapter VI. In
kinetic studies of the three components cyanate ester/ BMI/epoxy system, the functional group changes basically were the combination of those of cyanate ester/epoxy and cyanate ester/BMI. There was no new chemical bonding found between the two net works of cyanate ester/epoxy and cyanate ester/BMI. Kinetic parameters found
indicated very similar to one another among the three different systems, namely, the rate constants of catalytic reaction (k2) was found to be approximately 10 times higher than that of non‐catalytic reaction (k1), and increased activation energies for both catalyzed (E2) and
non‐catalyzed (E1)reactions, when compared with those of single component reaction. This result probably explains why co‐cured materials usually showed lower gel fractions as found in each chapter of this study.