The effects of low level concentrations of several short chain processing additives on the properties of the 4,4'-bis(3,4-dicarboxyphenoxy) diphenylsulfide dianhydride (BDSDA)/4,4'-diaminodiphenyl ether (ODA)/1,3'-diaminobenzene (m-phenylene diamine) (MPA) (422) copolyimide were investigated. It was noted that 5 percent MPD/phthalic anhydride (PA) is more effective than 5 percent ODA/PA and BDSDA/aniline (AN) in strengthening the host material. However, the introduction of 10 percent BDSDA/AN produces disproportionately high effects on free volume and free electron density in the host copolyimide

Pratt, J. R.

Singh, J. J.

Stclair, T. L.

English

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4 
NASA Technical Memorandum 89023 
INASB-TM-89QZ3)  I N V E S I I G A S I C E  Cf THE N87- 126 14 
EEFEC'ES C F  SHCET CHAIN PEiGCESSINC A D D I T I V E S  
O N  POLYBERS ( E A S A )  10 F CSCL 110 
Unclas 
G3/24 44718 
INVESTIGATION OF THE EFFECTS OF SHORT CHAIN PROCESSING 
ADDITIVES ON POLYMERS 
JAG J, SINGH, TERRY L ,  ST, CLAIR, AND J, RICHARD PRATT 
NOVEMBER 1986 
National Aeronautlcs and 
Space Administration 
Langley Research Center 
Hampton, Virginia 23665 
https://ntrs.nasa.gov/search.jsp?R=19870003181 2020-03-20T13:38:30+00:00Z
ABSTRACT 
The effects of low level concentrations of several short chain processing 
additives on the properties of the BDSDA/ODA/MPD [422] copolyimide have been 
investigated. 
5 percent ODA/PA and BDSDA/AN in strengthening the host material. However, the 
introduction of 10 percent BDSDA/AN produces disproportionately high effects on 
free volume and free electron density in the host copolyimide. 
It has been noted that 5 percent MPD/PA is more effective than 
INTRODUCTION 
Physical properties of copolyimides synthesized from linear BDSDA/ODA and 
BDSDA/MPD homopolymers had been investigated previously, using Positron Annihilation 
Spectrosocopy (PAS) (l) . These studies had indicated that the copolyimides have 
a unique transition molecular structure characterized by higher electron density 
and stronger bonds, i.e., greater chain-chain interactions. The transition 
structure permits both physical as well as chemical entry of water molecules in it. 
Following these discoveries, it was decided to study the effects of several short 
chain processing additives on the properties of the optimal BDSDA/ODA/MPD [422] 
copolyimide. The results of these studies are described in the following sections. 
LIST OF SYMBOLS 
BDSDA 4,4' - bis(3,4 - dicarboxyphenoxy) diphenylsulfide dianhydride 
ODA 4,4' - diaminodiphenyl ether 
MPD 1 , 3 '  - diaminobenzene (m-phenylene diamine) 
PA Phthalic anhydride 
AN An i 1 ine 
BD S DA / AN BDSDA end-capped with aniline 
GDA/ PA SDA end-capped with phthalic anhydride 
MPD/PA MPD end-capped with phthalic anhydride 
BDSDA/ODA/MPD Copolyimide containing equal mole fractions o €  BDSDA/ODA and 
BDSDA/MPD homopolymers [424 
w/o Weight percent 
1 T Lifetime of short lifetime component in the positron spectrum 
'2 Lifetime of long lifetime component in the positron spectrum 
Intensity of the long lifetime component in the positron 
annihilation spectrum 
Sodium-22 (positron emitting isotope of sodium) 
I 2  
22 Na 
VC Microcurie - a unit of radioactivity equalling 3.7 x 10 4 
disintegrators/sec 
EXPERIMENTAL PROCEDURE AND RESULTS 
(a) Preparation of the 422 Copoly(amic acid) Powder"). Sublimed 4,4'- 
oxydianiline (ODA) (49.08 g, 0.2451 mol) was dissolved under nitrogen in 
2-methoxyethyl ether (diglyme) in a flamed 2 L reaction kettle equipped with a 
mechanical stirrer and lid. 4,4'-bis(3,4-dicarboxyphenoxy) diphenylsulfide 
dianhydride (BDSDA) (250.0 g, 0.492 mol) was added in one charge, washing traces 
of the remaining dianhydride into the kettle with the remaining diglyme and 
requiring a total of 1305 g of this solvent. Stirring was maintained at 300 rpm. 
After 25 min m-phenylenediamine (MPD) (26.47 g, 0.2448 mol) was added, resulting 
in the formation of  a slurry of stringy solid in a tan solution. The stirring 
was continued for 18 hours, during which time these suspended particles dissolved 
and the solution became black and viscous. Phthalic anhydride (PA) (0.7260 g, 
0.0049 mol) dissolved in 1.70 g of diglyme was then added and the stirring was 
increased to 700 rpm for 1 hour. The resulting poly(amic acid) solution at 
20 percent solids had an inherent viscosity of 0.61 when run in N,N-dimethylaceta- 
mide (DMAC) at 0.5 percent solids solution and 35OC. 
Precipitation of this resin was conducted in a large household blender by 
pouring a slow stream of the base resin solution into the stirred blender two-thirds 
full of distilled water. The precipitated off-white solid was filtered through 
cheese cloth, reslurried in distilled water in the blender, refiltered and dried 
at ambient temperature for 2 days. 
vacuum at ambient temperature. The yield of poly(amic acid) powder was 364.5 g 
(theoretical yield, 326.3 g), indicating that this polymer contained a residual 
amount of solvent and (or) water. Figure 1 shows molecular structure of the 
422 copolyimide. 
This solid was further dried for 1 week under 
(b) Preparation __ ~ of the Di(amic acid) Additives and the 422 Copolyimide 
Mixtures and Their Conversion to Target Moldings for PAS. As shown in Table I 
the three di(amic acid) additives were prepared at ambznt temperature by reacting 
~ _ _ _ - _ _ ~ - _ _ ~  __ 
the anhydride with the amine in the ratios-shown in an equivolume mixture of 
diglyme and 1-methyl-2-pyrrolidinone (NMP). Thus, BDSDA and aniline (An) were 
reacted in a 1:2 molar ratio; similarly, phthalic anhydride and ODA (2:l) were 
converted to the di(amic acid). Phthalic anhydride and MPD (2:l) were also reacted. 
The resulting amic acid solutions were precipitated with water, and the powders 
were air dried. 
2 
TABLE I. Experimental Summary of Di(amic acid) Additive Synthesis 
I 
Anhydride Amine Molar Ratio M.P. (DTA Onset,OC) 
BDSDA AN 1:2 100 
PA ODA 2:l 105 
I PA 1 MPD I 2:l 1 147 
C 68.96 
H 4.05 
N 4.02 
C 67.74 
H 4.06 
N 5.64 
C 65.34 
H 3.99 
N 6.93 
Analysis (%> 
Calculated Experimental I 
68.52 
4.43 
5.34 
70.92 
4.04 
6.44 
64.43 
4.96 
6.03 
 
The 20% solids 422 copoly(amic acid) solution was mixed with the calculated 
amount of each additive and stirred overnight at ambient temperature. The mixture 
was then precipitated with water in a blender, air dried, and imidized for 1 hour 
each at lOOOc and 220°c. 
moldings(3) for PAS measurements. 
similarly imidized for comparison. 
The resulting powders were then converted to unfilled 
The unmodified 422 copoly(amic acid) powder was 
(c) Measurement of Saturation Moisture Contents. It is expected that the 
physical properties of a polymer are intimately related to the volume occupied by 
the microvoids in it. In oder to infer free volume in various test samples, it 
was decided to measure their saturation moisture contents since the latter are 
directly related to the accessible free volume. The procedure for measuring the 
saturation moisture contents of the test samples was as follows: The samples 
were first saturated with water by immersing them in distilled water at 90°C €or 
several days until their weights became constant. They were then desiccated in a 
vacuum oven at 100°C for several days until there was no further reduction in their 
weights. The saturation moisture contents were then determined by comparing the 
corresponding saturated and desiccated weights for each sample. The results are 
summarized in Table 11. 
3 
TABLE 11. Summary of Saturation Moisture Contents of the Test Samples With 
Various Additives 
No. 
1 
2 
3 
4 
5 
Specimen 
BDSDA/ODA/MPD 422 Copolyimide (REF) 
422 + 5% BDSDA/AN 
422 + 5% ODA/PA 
422 + 5% MPD/PA 
422 + 10% BDSDA/AN 
(*I I Saturation Moisture Content 
1 1.52-tO.01 % - 
1.45-t0.03 % - 
1.41+0.01 - % 
1.36+0.02 - % 
1.27-tO.02  % 
I 1 1 I 
(*)These values represent average of saturation moisture contents of two 
samples of each material prepared under identical conditions. 
(d) Measurement of Positron Annihilation Characteristics. Positron lifetime 
spectra were measured using a standard fast-slow coincidence system(4). 
tion of the system, as measured with a Co60 gamma ray source, was approximately 
400 picoseconds. 
discs. A 10 pc Na22 source was sandwiched between the two sample discs and the 
entire source-sample assembly was placed between two scintillation detectors. 
Figure 2 shows a schematic diagram of the experimental system. 
The resolu- 
The test samples were fabricated in the form of 1" dia x 0.1" thick 
Detailed lifetime measurements were made in the reference targets and the 
targets containing short-chain additives. The largest impact on positron annihila- 
tion characteristics was noted for the samples containing 10 percent BDSDA/AN. 
Typical lifetime spectra required about 24 hours to obtain the statistics necessary 
for accurate deconvolution. 
the lifetimes and relative intensities of various components after subtracting a 
flat background from the raw spectrum. 
lifetime components were present in each spectrum, all the spectra were fitted with 
only two components since such analyses are expected(6) to reflect the main changes 
in the annihilation characteristics with the changing test sample molecular 
structure. The positron lifetime results are summarized in Table 111. 
The spectra were anal zed for constituent lifetime 
components using the RESOLUTION computer program( 5 7  which automatically calculated 
Instead of trying to decide how many 
4 
TABLE III. Summary of Positron Lifetime Characteristics in the Test Samples 
. 
No. Spec imen 
BDSDA/ODA/MPD 14221 
Copolyimide (REFERENCE) 
[425]+ 10% BDSDA/AN 
Additive Copolyimide 
Positron Lifetime Characteristics (*I 
379+2 - 
382+2 - 
17 15+60 - 
1604+60 
4.9a.5 - 
5.7+0.5 - 
(*)Only lifetime characteristics in copolyimide sample containing 10% BDSDA/m 
are shown here. The data in other samples containing lower concentrations of 
short-chain additives were correspondingly less impacted. 
DISCUSSION 
An examination of the saturation moisture contents summarized in Table I1 
shows that the free volume in the [422] copolyimide decrease systemetrically as 
we add 5% BDSDAIAN, ODA/PA, and MPD/PA, respectively. It thus appears that MPD/PA 
is the most effective short-chain additive for making the [422] copolyimide more 
compact, and consequently, denser. 
appears to have a disproportionately large effect on free volume in the base poly- 
mer. The positron annihilation data in the modified specimen, summarized in 
Table 111, is also consistent with this large reduction in free volume. A concommi- 
tant increase in the long lifetime component intensity suggests that most of the 
free electrons have been engaged in strengthening the electronic bonds between 
various segments of the molecular chains. 
But doubling the concentration of BDSDA/AN 
CONCLUDING REMARKS 
The effects of several short-chain processing additives on the physical 
It properties of  the BDSDA/ODA/MPD [422] copolyimide have been investigated. 
appears that a 10 percent addition of BDSDA/AN produces the most desirable effect 
of strengthening the copolyimide chain interactions and making it environmentally 
stable. 
reducing the free volume in the host material. 
It obstensibly does so by increasing the chain packing density and 
5 
REFERENCES 
1. J. J. Singh, Terry L. St. Clair, William H. Holt, and W. Mock, Jr.: "An 
Investigation of Molecular Structure of Copolymers Using Positron Annihilation 
Spectroscopy," NASA Technical Memorandum 86431 (May 1985). 
2 .  H. D. Burks, T. L. St. Clair, and J. Progar: "Synthesis and Characterization 
of Copolyimides With Varying Flexibilizing Groups," NASA Technical 
Memorandum 86416 (1985). 
3. H. D. Burks and T. L. St. Clair: "Synthesis and Characterization of a 
Polyethersulfoneimide, "NASA Technical Memorandum 84621 (1983). 
4. W. H. Holt and W. Mock, Jr.: "Positron Lifetime Technique for Nondestructive 
Evaluation of Materials," NSWC/DL-TR-3573 (1976). Available from DTIC as 
AD A038-305. 
5. J. J. Singh, W. H. Holt, and W. Mock, Jr.: "Effects of Metal Ions on 
Positronium Formation in Polymeric Systems," Bull. Am. Phys. SOC., - 30, 42, 
1985. 
6. H. E. Hamielec, M. Eldrup, 0 .  Morgensen, and P. Jansen: In "Reviews of Macro- 
molecular Chemistry," Vol. 10, edited by G. B. Butler, K. F. O'Driscoll, 
and M. Shen (Marcel Dekker, New York, 1973) pp. 305-337. 
6 
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Standard Bibliographic Page 
19. Security Classif.(of this report) 20. Security Classif.(of this page) 21. No. of Pages 
Unclassified Unc la s si f ie d 9 
. Report No. 2. Government Acceasion No. 
NASA TM-89023 
22. Price 
A02 
. Title and Subtitle 
Investigation of the Effects of Short Chain 
Processing Additives on Polymers 
'. Author(s) 
Jag J. Singh, Terry L. S t .  Clair and 
J. Richard Pratt 
Langley Research Center 
Hampton, VA 23665-5225 
I. Performing Organization Name and Address 
2. Sponsoring Agency Name and Address 
National Aeronautics and Space Administration 
Washington, DC 20546-0001 
3. Recipient's Cataiog No. 
5. Report Date 
November 1986 
6. Performing Organization Code 
505-63-91-01 
8. Performing Organization Report No. 
10. Work Unit No. 
11. Contract or Grant No. 
13. Type of Report and Period Covered 
Technical Memorandum 
14. Sponsoring Agency Code 
5. Supplementary Notes 
6. Abstract 
The effects of low level concentrations of several short chain process- 
It has been noted that 5 percent MPD/PA is more effective 
ing additives on the properties of the BDSDA/ODA/MPD [422] copolyimide have 
been investigated. 
than 5 percent ODA/PA and BDSDA/AN in strengthening the host material. 
the introduction of 10 percent BDSDA/AN produces disproportionately high 
effects on free volume and free electron density in the host copolyimide. 
However, 
17. Key Words (Suggested by Authors(s)) 
Copolyimides, Transition Molecular 
Structure, Short-Chain Proccesing 
Additives, Free Volume, Positron 
Annihilation Spectroscopy 
18. Distribution Statement 
Unclassified - Unlimited 
Subject Category 24 
For sale by the National Technical Information Service, Springfield, Virginia 22161 
N A S A  Langley Form 63 (June  1985) 


Investigation of the effects of short chain processing additives on polymers

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