As part of an effort to develop high performance structural resins for aerospace applications, work has continued on block copolymers containing imide and arylene ether segments. The arylene ether block used in this study contains a bulky fluorene group in the polymer backbone while the imide block contains an arylene ketone segment similar to that in the arylene ether block and has been named LaRC-ITPI. A series of imide/arylene ether block and segmented copolymers were prepared and characterized. Films were prepared from these copolymers and mechanical properties were measured

Jensen, Brian J.

Working, Dennis C.

English

NASA Technical Reports Server

NASA Technical Memorandum 104099
_,!:k>?LY_, :: "t:" L_<_,_A) 12 r_ t. SCL ]].C
-;_Ic7
. i
)i _-"
!
+*'7 [-L '_ 7 !
LaRC-ITPI/Arylene
Copolymers
Ether
Brian J. Jensen
Dennis C. Working
May 1991
NASA
National Aeronautics and
Space Administration
Langley Research Center
Hampton, Virginia 23665-5225
https://ntrs.nasa.gov/search.jsp?R=19910017064 2020-03-19T16:48:32+00:00Z

LaRC-ITPI/Arylene Ether Copolymers
by
B. J. Jensen
NASA Langley Research Center
Hampton, VA 23665-5225
and
D. C. Working
Analytical Services and Materials, Inc.
Hampton, VA 23666
Introduction
As part of an effort to develop high performance structural resins for
aerospace applications, work has continued on block copolymers containing imide
and arylene ether segments. The copolymers reported herein represent an
extension of previous work 1-3 on imide/arylene ether copolymers. The arylene ether
block used in this study contains a bulky fluorene group in the polymer backbone
while the imide block contains an arylene ketone segment similar to that in the
arylene ether block and has been named LaRC-ITPI 4. A few copolymers containing
an imide block and some other block have been reported. Most notably, the
copolymers containing imide and siloxane blocks have received considerable
attention 5-8 and more recently, polyimide-polyformal block copolymers 9 and triblock
copolymers containing imide-aryl ether phenylquinoxaline blocks 10 have been
reported. The preparation of amine-terminated sulfones by a method similiar to that
used herein has been reported.11
E.z,D.e.da E  
Monomers - 9,9-Bis(4-hydroxyphenyl)fluorene (BPF) was synthesized as previously
reported 12 and recrystallized from toluene to yield an off-white solid (m.p. 222-
223.5°C). 1,3-Bis(4-fluorobenzoyl)benzene (FBB) was synthesized as previously
reported 12 and recrystallized from toluene to yield a white crystalline solid (m.p.
178-179°C). 4-Aminophenol was obtained commercially and vacuum sublimed to
yield an off-white solid (m.p. 188-190°C). 4,4'-Isophthaloyldiphthalic anhydride
(IDPA) (m.p. 215-217°C) was obtained from AIIco Chemical and used as received.
m-Phenylenediamine (m-PDA) was obtained commercially and vacuum
sublimed to yield a white crystalline solid (m.p. 64-66°C). 3,3',4,4'-
Benzophenonetetracarboxylic dianhydride (BTDA) was obtained commercially
and vacuum sublimed to yield a white crystalline solid (m.p. 224-226°C).
Oligomers - The amine-terminated poly(arylene ethers) (ATPAE) were synthesized
as shown in Eq. 1 by aromatic nucleophilic substitution of FBB with BPF and 4-
aminophenol in N,N-dimethylacetamide (DMAc) using potassium carbonate. The
oligomers were prepared at two different calculated molecular weights (Mn) by
adjusting the monomer ratio (BPF/FBB) to 0.816 and 0.908 to provide Mn of 3110
and 6545 g/mole, respectively. The anhydride-terminated poly(amic acids) were
prepared in DMAc at two Mns as shown in Eq. 2 by adjusting the monomer ratio (m-
PDA/IDPA) to 0.842 and 0.923 to provide Mn of 3110 and 6545 g/mole, respectively.
D_.g.D.gJ.E]3.._- The copolymers were prepared by adding a DMAc solution of the
ATPAE to the anhydride terminated m-PDA/IDPA reaction mixture. For example, to
2
prepare ATPAE 3110/ITPI 3110, IDPA (2.1317 g, 5.0 mmol) was added to a solution
of m-PDA (0.4552 g, 4.21 mmol) and DMAc (14.7 g). The mixture was stirred for 3 h
to form a clear solution. A solution of ATPAE 3110 (2.5867 g, 0.8318 mmol) in
DMAc (14.7 g) was added to the poly(amic acid) solution prepared above to form a
clear, viscous solution. On occasion, some reactions became very viscous and
gelled within .-10 min, but additional stirring (normally overnight but sometimes for
several days) or warming to ~70°C provided a clear viscous solution. These
solutions were used to cast films which were thermally imidized.
Characterization - Inherent viscosities (T]inh) were obtained on 0.5% solutions in
CHCI3 at 25°C for FBB/BPF and in DMAc at 25°C for the other polymers and
copolymers. Differential scanning calorimetry (DSC) was performed at a heating
rate of 20°C/min with the apparent Tg taken at the inflection point of the AT versus
temperature curve. Torsional braid analysis (TBA) was performed at a heating rate
of 3°C/min with the Tg taken at the peak of the damping curve.
Films - DMAc solutions (15% solids) of the polymers were centrifuged, the decantate
doctored onto plate glass and dried at room temperature to a tack-free form in a dust
proof chamber. The films on glass were dried 1 h each at 100, 200 and 300°C.
Mechanical tests were performed according to ASTM D882 on at least four
specimens per test condition.
Results and Discussion
ATPAEs with calculated MnS of 3110 and 6545 g/mole were prepared by
offsetting monomer stoichiometry. These oligomers had 11inhSof 0.18 and 0.30 dL/g
and Tgs of 193 and 207°C, respectively, as shown in Table I. When the oligomers
were reacted with a stoichiometric amount of BTDA, the TlinhS and Tgs increased as
3
expected. The high 1]inhSobtained indicated that the calculated Mns were
essentially correct. Table I also shows data for the homopolymers and a 1:1
physical blend of the homopolymers prepared by mixing DMAc solutions of each.
This blend phase separated in solution as well as in the cured film. A DSC sample
containing both phases displayed the two Tgs of the homopolymers.
Four different block copolymers were prepared as shown in Table II from the
ATPAE and ITPI oligomers. The copolymers were prepared by reacting a
stoichiometric ratio of oligomers (using calculated Mns) producing poly(amic acids)
with 13inhSranging from 0.63 to 0.91 dL/g in DMAc. The cured polyimide films were
characterized by DSC and results are shown in Table I1. Tgs range from 224 to
257°C with the ATPAE 6545/ITPI 6545 block copolymer displaying two Tgs, slightly
above and below the Tgs of the FBB/BPF and ITPI, respectively. Block copolymers
with shorter imide blocks display a DSC Tg slightly above the Tg of the FBB/BPF
homopolymer while the block copolymer with the shorter arylene ether block and the
longer imide block displays only the Tg slightly below that of the ITPI homopolymer
(253°C). Apparent TgSby TBA are also shown in Table II and range from 246 to
254°C after curing the braids 1 h each at 100, 200 and 300°C. Copolymer with
longer imide blocks display higher transition temperatures than those with shorter
imide blocks as expected.
Two segmented copolymers, ATPAE 3110/ITPI 3110 (segmented) and
ATPAE 6545/ITPI 6545 (segmented) were prepared by dissolving the ATPAE and
m-PDA in DMAc and then adding the appropriate amount of IDPA to the solution.
The m-PDA/IDPA ratios were adjusted to give a Mn of either 3110 or 6545 g/mole,
the same Mn as the ATPAE block. As shown in Table II, very high 1]inhSwere
obtained from these reactions. When characterized by DSC, cured films of the
ATPAE 3110/ITPI 3110 (segmented) copolymer had a Tg = 230°C while cured films
4
of the ATPAE 6545/ITPI 6545 (segmented) copolymer had Tgs at both 230 and
255°C, similar to that of the ATPAE 6545/ITPI 6545 block copolymer.
Tensile properties of the clear yellow-orange films of the copolymers and
homopolymers are shown in Table II1. The polyimide has higher strength and
modulus than the arylene ether as expected. The tensile strength and modulus of
the copolymers varied widely. The ATPAE 6545/ITPI 6545 block copolymer
produced a phase-separated textured film with very poor properties while the
ATPAE 6545/ITPI 3110 displayed excellent retention of strength at 177°C and very
high modulus at RT and 177°C. The other films displayed properties intermediate to
those of FBB/BPF and ITPI homopolymers.
Conclusions
A series of imide/arylene ether block and segmented copolymers were
prepared using an arylene ether block with a relatively high Tg and an imide block
with high mechanical properties. A 1:1 blend of high molecular weight
homopolymers was incompatible in DMAc solution and in the solid state. One block
copolymer displayed higher film properties than either homopolymer while the
remaining copolymers displayed properties which were intermediate to those of the
homopolymer.
5
REFERENCES
1. B.J. Jensen, P. M. Hergenrother and R. G. Bass, Proc. Polvm. Matl. Sci. and
_Q.g., 60,294 (1989).
2. B.J. Jensen, P. M. Hergenrother and R. G. Bass, _, 30(2), 132
(1989).
3. B.J. Jensen, P. M. Hergenrother and R. G. Bass, Ibid., 31(1) 618 (1990).
4. J.R. Pratt and T. L. St. Clair, SAMPE Journal, 26(6), 29(1990).
5. F.F. Holub, U. S. Patent 3,325,450 (1967) (To General Electric).
6. W.A. Fessler, U. S. Patent 3,736,290 (1973) (To General Electric).
7. J.T. Hoback and F. F. Holub, U. S. Patent 3,740,305 (1973) (To General
Electric).
8. I. Yilgor, E. Yilgor, B. C. Johnson, J. Eberle, G. L. Wilkes and
J. E. McGrath, _ 24(2), 78(1983).
9. M.M. Grade and J. W. Verbicky, Jr., J, pQIvm. Sci., Polyrn. Chem. Ed., 27,
1467 (1989).
10. J.L. Hedrick and J. W. Labadie, High Performance Pol,vmers, 2(1), 3 (1990).
11. J.H. Kawakami, G. T. Kwiatkowski, G. L. Brode and
A. W. Debroin, J, Polym, Sci.. Pol,vm. Chem. Ed., 12,565 (1974).
12. P.M. Hergenrother, B. J. Jensen and S. J. Havens, Polymer, 29, 358(1988).
6
a?
>,
o
o_
o
0
0
W
d
0¢_ _
I.l.l
0
8
cxl
d d c/ c5
- -i F-
c_
10
Report Documentation Page
1, Report No.
NASA TM-10409g
4. Title and Subtitle
2. Government Accession No.
LaRC-ITPl/Arylene Ether Copolymers
3, Recipient's Catalog No.
5. Report Date
7, Author(s)
Brian J. Jensen and Dennis C. Working
9. Performing Organization Name and Address
NASA Langley Research Center
Hampton, VA 23665-5225
12. Sponsoring Agency Name and Address
National Aeronautics and Space
Washington, DC 20546-0001
Administration
May 1991
6. Performing Organization Code
8. Performing Organization Report No.
10. Work Unit No.
505-63-50-01
11, Contract or Grant No.
13, Type of Report and Period Covered
Technical Memorandum
14. Sponsoring/_gency Co(le
15. Supplementary Notes
Use of trade names or names of manufacturers does not constitute an official endorsement of
such products or manufacturers, either expressed or implied, by the National Aeronautics and
Space Administration
Brian J. Jensen: NASA Langley Research Center, Hampton, Virginia
Dennis C. Working: Analytical Services and Materials, Hampton, Virginia
16. Abstract
As part of an effort to develop high performance structural resins for aerospace applications,
work has continued on block copolymers containing imide and arylene ether segments. The
arylene ether block used in this study contains a bulky fluorene group in the polymer backbone
while the imide block contains an arylene ketone segment similar to that in the arylene ether
block and has been named LaRC-ITPI. A series of imide/arylene ether block and segmented
copolymers were prepared and characterized. Films were prepared from these copolymers and
mechanical properties were measured.
17. Key Words (Suggested by Authoris))
Polyimides, Poly(arylene ethers),
Copolymers, and Block Copolymers
19. Security Classif. (of this report)
18. Distribution Statement
Unclassified - Unlimited
Subject Catagory - 27
20. Security Ciassif. iof this page) 21 No. of pages
11Unclassified Unclassi fied
NASA FORM 1626 OCT 86
:99 Price
A03



LaRC-ITPI/arylene ether copolymers

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server