Reactive Oligomers - American Chemical Society

2 Synthesis of Bisphenol-Based Acetylene Terminated Thermosetting Resins 1

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Downloaded by UNIV OF CALIFORNIA SAN DIEGO on June 4, 2015 | http://pubs.acs.org Publication Date: July 9, 1985 | doi: 10.1021/bk-1985-0282.ch002

J. S. WALLACE , F. E. ARNOLD , and W. A. F E L D

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Air Force Wright Aeronautical Laboratories, A F W A L / M L B P , Wright-Patterson Air Force Base, OH 45433 Department of Chemistry, Wright State University, Dayton, OH 45435

A series of high molecular weight (750-950 amu range) bis-phenol based acetylene terminated (AT) resins were synthesized by reacting four moles of 4,4'-dihalodiphenylsulfone (chloro and fluoro) with one mole of a bis-phenol (4,4'-isopropylidinediphenol, 4,4'-thiodiphenol, p,p'-biphenol, and resorcinol were used), end-capping the resulting halo-terminated products with 4-(m-hydroxyphenyl)2-methyl-3-butyn-2-ol, and caustically cleaving the terminal acetone protecting groups to give free ethynyl functionalities. This synthesis produces a mixture of monomer and oligomer AT-products which were separated by column chromatography. Pure AT-monomers and the monomer/oligomer mixtures produced by the outlined stoichiometry were cured at 288°C (550°F) for 8 h in a i r . Glass transition temperatures (Tgs) of the cured (by thermomechanical analysis) and uncured (by differential scanning calorimetry) AT-systems were measured. Thermo-oxidative stability of the resins was evaluated by isothermal aging (ITA) in air at 315°C (600°F) for 200 h. In recent years acetylene terminated resins (AT-resins) have shown promise i n the area of high temperature applications and are possible replacements f o r state-of-the-art epoxy r e s i n systems where humidity exposure i s expected. Acetylene terminated resins have two important advantages over previously developed systems: 1) cured products have high thermal s t a b i l i t y and exhibit good mechanical properties a f t e r exposure to humidity, and 2) the resins are cured through an addition reaction so no v o l a t i l e by-products are evolved giving a voidless f i n a l matrix. (J^) These properties make AT-resins especially a t t r a c t i v e f o r advanced a i r c r a f t and aerospace vehicles where material weight i s a c r i t i c a l factor and high temperatures as w e l l as humidity are l i k e l y to be encountered. 0097-6156/85/0282-0017$06.00/0 © 1985 American Chemical Society

In Reactive Oligomers; Harris, F., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTIVE OLIGOMERS


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In an e f f o r t to optimize mechanical and processing properties, many d i f f e r e n t molecular systems have been inserted between terminal acetylene groups, with each system imparting i t s own unique properties to the f i n a l r e s i n . The f i r s t of these systems to demonstrate good mechanical properties were the quinoxalines. These systems, with t h e i r large f l e x i b l e molecular structures, d i d not however meet epoxy processing standards ( i . e . , melt p r o c e s s a b i l i t y and room temperature tack and drape)(2) because of a high i n i t i a l Tg.(3) Two approaches were taken to resolve t h i s problem. The f i r s t approach, which i s presently s t i l l under investigation, was to incorporate reactive p l a s t i c i z e r s into the quinoxaline resins. Preliminary data shows that t h i s has the e f f e c t of lowering the i n i t i a l Tg, but further study i s required before e f f e c t s on mechanical properties can be completely evaluated.(4) The second approach involves the substitution of aromatic d i o l and b i s - d i o l groups (resulting i n a group of compounds c a l l e d phenylene Rs) into the backbone. The f i r s t group t r i e d , the diphenyl sulfone linkage, l e d to resins (commonly known as ATS) with good processing properties but which were b r i t t l e i n nature. (_1) A factor which has been associated with r e s i n toughness i s c r o s s l i n k density of the matrix. This density can be controlled by increasing or decreasing the molecular weight of the monomer and oligomer molecules which make up the r e s i n . Reducing the c r o s s l i n k density i n a matrix has been shown to y i e l d improved toughness.(5) In an e f f o r t to improve the mechanical properties of AT resins, monomers and oligomers of higher molecular weight, with various phenylene R backbones, are being evaluated. This work i s centered at the Materials Laboratory of the A i r Force Wright Aeronautical Laboratories and i s the basis f o r the research presented here. The combination of a semiflexible backbone and lower c r o s s l i n k density should provide an AT-resin with superior mechanical properties. The objectives of this research therefore were: 1. The synthesis of higher molecular weight (750-950 amu range), semi-rigid AT-resins, with the general formula 1_ (Figure 1) with the potential of improved mechanical properties. The d i o l and b i s - d i o l s used i n these systems were chosen because of t h e i r low cost and ready a v a i l a b i l i t y . Meta- rather than para-AT end capped systems were synthesized because the former generally have lower uncured Tgs which are desirable f o r easy processing. 2. Development of a new acetylene terminating procedure to f a c i l i t a t e the synthesis of the aforementioned systems.

Experimental Synthesis of the End-Capping Agent 4-(m-Hydroxyphenyl)-2-methyl-3-butyn-2-ol I_ A three-necked 500mL round-bottom f l a s k was f i t t e d with a reflux condenser, magnetic s t i r bar, stopper, and gas i n l e t / o u t l e t adapters. Under dry nitrogen the f l a s k was charged with m-bromophenol (10.Og, 57.8 mmol), 2-methyl-3-butyn-2-ol (5.0g, 59.4 mmol) and 250 mL of d i s t i l l e d triethylamine r e s u l t i n g i n a pale yellow solution. The mixture was heated at reflux f o r 15 min while



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Acetylene-Terminated Resins

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a nitrogen atmosphere was maintained. After the reflux period the catalyst system consisting of dichlorobis(triphenylphosphine) palladium II (0.1g), triphenylphosphine (0.2g) and cuprous iodide (O.lg) was added. Addition of the catalyst system caused the reaction mixture color to deepen to yellow-orange. After heating at reflux for 25 h, light-colored s a l t s formed. Reaction progress was followed by gas chromatography (GC) using phenol as a standard. A f t e r cooling to 25°C, the reaction mixture was f i l t e r e d under nitrogen through a glass f r i t packed with c e l i t e . The remaining l i g h t gray p r e c i p i t a t e was rinsed with a d d i t i o n a l triethylamine and the f i l t r a t e s combined, concentrated (rotary evaporator) and the r e s u l t i n g yellow o i l dissolved i n 200 mL of toluene and then washed with 120 mL of 8% hydrochloric acid. The hydrochloric acid washing was extracted with three 50 mL portions of ethyl acetate which were combined, concentrated (rotary evaporator) and the r e s u l t i n g residue dissolved i n 25 mL of toluene. The toluene fractions were combined and dried (magnesium s u l f a t e ) . The dry toluene solution was treated with ethylene diamine (brown solution) and s t i r r e d with heating (50-60°C) under nitrogen f o r 15 min which resulted i n a blue p r e c i p i t a t e . After cooling to room temperature, the solution was f i l t e r e d to remove the p r e c i p i t a t e and the f i l t r a t e was extracted with 250 mL of d i s t i l l e d water and three 125 mL portions of 10% potassium carbonate. The base extract was s t i r r e d i n an ice/water bath and neutralized with 6N hydrochloric acid (addition was continued u n t i l the pH was s l i g h t l y a c i d i c ) . The aqueous solution was extracted with one 250 mL and three 125 mL portions of ethyl acetate which were combined, dried and evaporated. The r e s u l t i n g dark yellow-orange o i l was induced to c r y s t a l l i z e by dissolving i t i n methylene chloride, adding n-hexane u n t i l s l i g h t l y cloudy, seeding and cooling by r e f r i g e r a t i o n f o r 24 h. The r e s u l t i n g s o l i d was r e c r y s t a l l i z e d from n-hexane/methylene chloride (2/3) to y i e l d 4.lg (41%) of a white s o l i d : mp 94-95°C; IR (KBr) 3380, 3160 cm (0-H). 3000, 1575 cm (aromatic), 2930 cm ( a l i p h a t i c ) , 2210 cm (C C), 1215, 940 cm (C-OH). Anal. Calcd. f o r C H 0 : C, 74.91; H, 6.81. Founa: C, 74.52; H, 6.96. Cu and Pd Analysis: Cu, 3ppm; Pd, 3ppm. n

1 9

ii

Example Procedure f o r Preparation of Halo-Terminated Intermediate Monomer/Oligomer Mixtures 1

1,1 -(1-Methylethylidene)bis[4-[4-[(4-fluoropheny1)sulf onyl] phenoxy]benzene] II and -[4-[l-[4-[4-[(4-Fluoropheny1)sulf onyl]phenoxy]phenyl]-1-methy1ethy1]phenyl]- -[4-[(4-fluoropheny1)sulfonyl]phenoxy]poly[oxy-1, 4-phenylenesulfonyl-1,4-phenyleneoxy-l,4-phenylene(1-methyl ethylidene)-l,4-phenylene] I I I A three-necked 250 mL round-bottom f l a s k , was equipped with a magnetic s t i r bar, reflux condenser, Dean-Stark trap, and a gas i n l e t / o u t l e t adapter. The following mixture was added:


REACTIVE

20

OLIGOMERS


f

4,4 -isopropylidenediphenol (3g, 13.2 mmol), difluorodiphenyl suIfone (13.43g, 52.8 mmol), anhydrous potassium carbonate (1.91g, 13.8 mmol), 25 mL of freshly d i s t i l l e d N-methyl-2-pyrrolidone and 25 mL of benzene. The reaction mixture was heated at reflux (100°C) and s t i r r e d rapidly under dry nitrogen u n t i l a l l water (a reaction side product) was removed by azeotropic d i s t i l l a t i o n with benzene. The reaction (dark purple color) temperature was then raised and maintained at 135°C f o r 5h. The mixture darkened during t h i s period. A f t e r cooling to room temperature, the reaction mixture was d i l u t e d with 100 mL of methylene chloride and washed with three 200 mL portions of 10% hydrochloric acid, one 200 mL portion of d i s t i l l e d water, dried (magnesium sulfate) and f i l t e r e d . The f i l t r a t e was concentrated (rotary evaporator) and chromatographed on a quartz column f i l l e d with activated s i l i c a g e l (460g). Unreacted difluorodiphenyl sulfone was eluted with methylene chloride/petroleum ether (*s), monomer II was eluted with methylene chloride/petroleum ether (h) to y i e l d 6.61g of a white c r y s t a l l i n e s o l i d : mp 120-122°C; IR(KBr) 3070, 1575, 1480 cm" (aromatic), 1230 cm" (ArF), 1320, 1145 cm (SO ), 1095 cm" (ArOAr); Anal. Calcd. f o r C H F S 0,: C,67.23; H,4.34; S,9.20; F,5.45. Found: C,67.21; H,4.58; S,9.05; F,5.44. Oligomer I I I was eluted with methylene chloride to y i e l d 1.39g of a clear viscous o i l : IR (NaCl film) 3070, 1570, 1475 cm" (ArF), 1320, 1150 cm" ( S O J , 1100 cm" (ArOAr). Total y i e l d was 8.00g (87.3%, i f based on pure monomer t h e o r e t i c a l yield). 1

qQ

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1

Example Procedure f o r Preparation of Acetone Protected AT-Products Monomer Product 1

4,4 -[(1-Methylethylidene)bis(4,l-phenyleneoxy-4,1-phenylenesulfonyl-4,l-phenyleneoxy-3,1-phenylene)]bis[2-methyl-3-butyn-2-ol] IV To a 50 mL, three-necked, round-bottom f l a s k equipped with magnetic s t i r bar and nitrogen i n l e t / o u t l e t was added 40 mL of dry DMSO. While s t i r r i n g under nitrogen, 4-(m-hydroxyphenyl)2-methyl-3-butyn-2-ol I_ (1.67g, 9.48 mmol) and potassium methoxide (0.67g, 9.48 mmol) were added. The mixture was s t i r r e d at 40°C f o r 1 h to complete generation of the potassium s a l t . A 250 mL three-necked round-bottom f l a s k , equipped with a gas i n l e t / o u t l e t , addition funnel, and magnetic s t i r bar was charged with II (3.0g, 4.31 mmol) dissolved i n 40 mL of dry DMSO. Under nitrogen, the solution was heated to 90°C with s t i r r i n g . The potassium s a l t of 4-(m-hydroxyphenyl)-2-methyl-3-butyn-2-ol 1^ was transferred (under nitrogen) to the addition funnel and added to the solution of I I over a period of l h . After addition was complete, the reaction mixture was maintained at 90°C f o r an additional 3 h, cooled to room temperature and d i l u t e d with 150 mL of methylene chloride and was washed with three 200 mL portions of 10% hydrochloric acid and one 300 mL portion of d i s t i l l e d water. The methylene


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Acetylene-Terminated Resins

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chloride solution was dried (magnesium s u l f a t e ) , f i l t e r e d , and concentrated (rotary evaporator) to y i e l d a pale brown product. The crude product was chromatographed on a quartz column f i l l e d with activated s i l i c a gel (160g). The product was eluted with hexanes/ethyl acetate (3/1) t o . y i e l d 3.82g (87.9%) of white s o l i d : mp 179-181°C; IR(KBr) 3480.cm (COH), 3060, 1570, 1475 cm" (aromatic), 1380, 1360 cm (gem dimethyl), 1315, 1145 cm" ( S O J , 1100 cm" (ArOAr); Anal. Calcd. f o r C,.H-^O. : C, 72.70; H. 5.21; S, 6.35. ^Found: C, 72.14; H, 5.49; S. 6.01. n


b A

Example Procedure f o r Cleavage of AT-Product Acetone Protecting Groups Monomer Product 1,1'-(l-Methylethylidene)bis[4-[4-[[4-(3-ethynylphenoxy)phenyl] sulfonyl]phenoxy]benzene] V A solution of IV (2.0g, 2.0 mmol) i n 150 mL of dry toluene was formed with heating under nitrogen i n a three-necked, 250 mL, round-bottom f l a s k which was equipped with a Dean-Stark trap, r e f l u x condenser, magnetic s t i r bar and a gas i n l e t / o u t l e t adapter. Dry, powdered potassium hydroxide (2.0g) was added and the mixture was s t i r r e d and heated at reflux f o r 1 h. Acetone formed as the reaction progressed was removed by azeotropic d i s t i l l a t i o n with toluene. The toluene was replaced and the d i s t i l l a t i o n procedure repeated two more times. The progress of the reaction was followed by TLC on s i l i c a g e l (methylene c h l o r i d e ) . After 3 h the reaction mixture was cooled to room temperature, f i l t e r e d through c e l i t e and washed with three 200 mL portions of d i s t i l l e d water, dried (magnesium s u l f a t e ) , and f i l t e r e d . The f i l t r a t e was concentrated (rotary evaporator) and chromatographed on a quartz column f i l l e d with activated s i l i c a g e l (160g). The product was eluted with hexanes/methylene chloride (3/1) t o . y i e l d 1.56g (83%) of a white s o l i d : mp 80-82°C; IR(KBr) 3300 cm" (C CH), 3050, 1570, 1475 . (aromatic), 1380, 1360 (gem di-methyl), 1315, 1340 ( S O J , 1100 cm (ArOAr) H NMR 6.86-8.20 (m, aromatic, 32H), 3.15 (s, acetylene, 2H), 1.71 (s, methyl, 6H); Anal. Calcd. f o r C^JL.^S^O'. C, 74.00; H, 4.53; S. 7.18. Found: C, 74.36; H, 4.83; S, 7.02.

Results and Discussion End-Capping Agent _I

In previously employed end-capping schemes a palladium catalyst was used to d i r e c t l y connect a protected ethynyl group (2-methyl-3-butyn-2-ol) to a bulky intermediate. This procedure r e s u l t s i n the entrapment of catalyst metals which must be laboriously removed from the f i n a l AT-product. I f these metals are not removed, premature curing of the system occurs which narrows



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REACTIVE OLIGOMERS

the processing window. In extreme cases where large quantities (>100ppm) of palladium remain, curing i n the reaction vessel during the cleavage of the acetone protecting group has been observed.(6) The end-capping agent 4-(m-hydroxyphenyl)-2-methyl-3-butyn-2-ol 1^ eliminates t h i s problem. The synthesis of I i s accomplished by using a palladium catalyst to replace the bromine atom of m-bromophenol with 2-methyl-3-butyn-2-ol, a protected ethynyl group. This route r e s u l t s i n the preparation of a substituted phenolic acetylene which can be completely isolated from the catalyst metals by an ethylenediamine treatment (Figure 2). The u t i l i t y of a palladium catalyst i n the synthesis of substituted a r y l acetylenes i s well established.(7,8,9,10) The end-capping agent 1^ was produced by using a standard catalyst system, dichlorobis(triphenylphosphine)palladium (II)/copper (I) iodide/triphenylphosphine mixture, which has been employed i n previously developed ethynylation procedures.(10) The copper (I) iodide i s believed to act as a cocatalyst, reducing the palladium (II) complex to the active palladium (0) c a t a l y s t . The scheme i s shown i n Figure 3 (diethylamine i s the solvent).(11) Sonogashira has proposed a c a t a l y t i c cycle (Figure 4) which shows: 1) the reduction of the palladium complex, 2) coordination of the a r y l halide and acetylene with the palladium (0) complex and 3) the reductive elimination of the substituted a r y l acetylene and regeneration of the active catalyst.(10) The use of a basic solvent ( i n t h i s case diethylamine) i s important to s t a b i l i z e acetylenic anions.(9) The t h i r d c a t a l y s t system component, t r i p h e n y l phosphine, i s presumably added to help replace l o s t t r i p h e n y l phosphine ligands on the palladium complex and thus prevent metal agglomeration. Triethylamine, because of i t s basic properties was chosen as the solvent f o r the end-capper 1^ synthesis. Reactions were run at r e f l u x for times ranging from 2 to 30 hours. Reaction progress was followed by gas chromatography (GC) using phenol as a standard. A l l reactions were run under a dry nitrogen atmosphere. Yields rapidly increased with time up to 12 hours, slowly increased with time up to 24 hours, and showed a slow decline thereafter. The reaction never appears to go to completion regardless of reaction time, and there i s always r e s i d u a l m-bromophenol remaining (detected by GC and TLC). Dieck and Heck state that the major l i m i t a t i o n of substituted a r y l acetylene preparation i s that a r y l halides with strongly electron-donating substitutents have r e l a t i v e l y low r e a c t i v i t y toward oxidative addition.(9) The f a i l u r e of the end-capper reaction to go to completion i s most l i k e l y associated with the inductive electron-donating e f f e c t of the hydroxy group of m-bromophenol. This leads to the unproven hypothesis that the palladium c a t a l y s t i s involved with a competing deactivation reaction with a r e l a t i v e l y fast rate. Thus, a portion of the catalyst i s deactivated or destroyed before i t can react with m-bromophenol. The acetylenic s t a r t i n g material, 2-methyl-3-butyn-2-ol was used i n s l i g h t excess because i t was known that some would be l o s t to side reaction products.(9) Increasing the excess had no observable e f f e c t on reaction y i e l d (consistently 40%).


WALLACE ET AL.

Acetylene- Terminated Resins


. -0*0- . Figure 1 . General Structure of Synthesized High Molecular Weight AT-Resins.

OH

i

ISOLATE

REACT

csc

**°iÇr

WITH

3

niHALICE

Figure 2 .

C

-C-CH,

>

K

O

C

H

-

* PURIFY

OH

Synthesis of Endcapping Agent.

Cul

HNEt

2 m

( NEt )„CuI H

2

HC«CR HNEtj Pd-C • CR

Pd-X

(HNEtj)„CuC • CR + Et,NH* Γ

(HNEt,).CuX X - I, Br, OR Ci Figure 3 .

Proposed Role of Copper (I) Iodide.


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REACTIVE

OLIGOMERS

(03P) PdCl (II) ^-HCsCR a

2


Cul/Eta NH V*(E NH )*cr t2

2

R - ARYL, ALKYL, H Figure 4.

C a t a l y t i c Cycle Proposed by Sonogashira.


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WALLACE ET AL.

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AT-Monomer and AT-Monomer/Oligomer Systems The general approach used to synthesize the AT-monomer and AT-monomer/oligomer products consists of three synthetic steps: 1) synthesis of halo-terminated intermediates, 2) end-capping of the intermediates with end-capping agent 1, and 3) cleavage of the acetone protecting groups to produce the f i n a l AT-product. Production of both monomeric and oligomeric products i s an inherent part of t h i s synthetic route (Figure 5). P u r i f i c a t i o n by column chromatography i s required after each synthetic step. A procedure s i m i l a r to that developed by McGrath, e t . a l . , was used to produce halo-terminated products.(12) The use of both 4,4'-difluoro and 4,4 -dichlorodiphenyl sulfone (chosen f o r the s u l f o n e s a b i l i t y to activate the displacement of the terminal halo groups) to end-cap several bis-phenols were evaluated. In an e f f o r t to produce primarily monomer products, dihalodiphenyl sulfone was used i n a 4:1 molar excess with respect to the bis-phenols (the four d i f f e r e n t bis-phenols used were bisphenol-A; 4,4'-thiodiphenol; p,p -biphenol; and r e s o r c i n o l ) . The stoichiometry outlined above produced monomer/oligomer r a t i o s ranging from 100/0 to 60/40 depending on the bis-phenol reactant used. Yields of the products ranged between 75 and 90% with the fluoro-terminated products generally about 10% higher than chloro-terminated products (only two of the bis-phenols were reacted with 4,4 -dichlorodiphenyl sulfone). A l l reactions were run i n N-methyl-2-pyrrolidone (NMP) under nitrogen using potassium carbonate as a base. Typical reaction time was 4 hours with reaction progress followed by TLC. A higher reaction temperature was required f o r chloro displacement (150°C f o r chloro vs. 100°C for f l u o r o ) . Before end-capping, monomer was separated from oligomeric products by column chromatography. Monomer/oligomer r a t i o s were determined by weighing each component a f t e r separation. In the next step, acetylene end-capping i n DMSO, an unexpected problem was encountered with the chloro terminated intermediates. As i n the f i r s t step a high temperature (150°C) was required f o r chloro displacement. The combination of high temperature and basic conditions (potassium methoxide was used) produced i n t e r e s t i n g l y , the f i n a l unprotected AT-monomer and AT-monomer/oligomer systems i n low y i e l d (20-40%). Evaluation of the s t a b i l i t y of the potassium s a l t of 1^ (using sodium nitroprusside as an indicator f o r acetone) showed i t was losing i t s acetone protecting group at approximately 130°C i n DMSO. This loss occurred below the 150°C temperature required f o r chloro displacement. Weaker bases such as potassium carbonate were t r i e d , but gave s i m i l a r r e s u l t s . Reaction of the fluoro terminated systems with I_ went smoothly and gave good y i e l d s (70-80%) of the protected AT-systems. Displacement of the fluoro atoms was accomplished at 85-90°C and remained completely i n t a c t . Caustic cleavage of the protecting groups gave AT-monomer and AT-monomer/oligomer mixtures i n y i e l d s ranging from 80 to 85%. Overall synthetic y i e l d s f o r t h i s procedure ranged between 50 and 60% depending on the bis-phenol used. l

1

?

,


26


REACTIVE OLIGOMERS

X = F,

Cl

Figure 5 .

AT-Monomer/Oligomer Synthetic Route.


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WALLACE ET AL.


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AT-Resin Thermomechanical Properties After f i n a l chromatographic p u r i f i c a t i o n , samples of the AT-systems were cured i n a i r at 288°C (550°F) f o r eight hours. Samples chosen f o r curing included pure monomers, monomer/oligomer mixtures produced by the stoichiometry outlined i n the previous section, and i n one case (the bisphenol-A based resin) pure oligomer. This set of samples was selected to provide data showing the effect of oligomer concentration on thermomechanical properties. D i f f e r e n t i a l scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to measure the glass t r a n s i t i o n temperatures (Tgs) of the uncured and cured AT-resins respectively (Figure 6). For composite applications and a 350°F use temperature, cured resins must exhibit a minimum Tg of 220°C. A review of the cured Tg values shows that only the bisphenol-A based r e s i n does not meet t h i s c r i t e r i a . For easy processing, an i n i t i a l Tg of /- -4 /h

100/0

s

V—/

60

—

/40

1 0 0 / 0

--

1 8 0

100/0 70/30

70 —

a

Tpoly Onset(°C)

a

160 160 160 110

145

Tpoly Max (°C)

a

250 245 270

240

150

230

1 8 5

2 3 0

130 135

230 235

a) Determined by DSC (10°C/min).

Figure 7.

Onset and Peak of AT-Resin Polymerization.


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WALLACE ET AL.


new systems gave promising results and might provide a solution to t h i s problem. What e f f e c t the addition of t h i s diluent might have on the synthesized r e s i n s ' mechanical properties remains to be seen. Scale-up of the resins to the 50g l e v e l would provide material f o r mechanical properties characterization and determine i f these increased molecular weight systems have improved toughness.

Literature Cited


1. 2.

3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

C. Y-C. Lee, I. J. Goldfarb, T. E. Helminiak, F. E. Arnold, Soc. Adv. Matr. Proc. Eng. Ser., 28, 699 (1983). J. Gamble, "The Effects on Ridgidity as a Function of Para Ethynylphenoxy Linkages in an Acetylene Terminated Thermosetting System," (M.S. Dissertation), Wright State University, 1981. C. Y-C. Lee, I. J. Goldfarb, F. E. Arnold, T. E. Helminiak, Org. Coat. Appl'd Polym. Sci. Preprints, 48, (1983). S. Sikka and I. J. Goldfarb, Org. Coat. Plast. Preprints, 45, 138, (1981). T. E. Helminiak and W. B. Jones, Org. Coat. and Plast. Preprints, 48, 221, (1983). Ε. T. Sobourin, The Synthesis of Polymer Precursors and Exploratory Research Based on Acetylene Displacement Reaction, AFWAL-TR-80-4151 (1980). Ε. T. Sobourin, Preprints Div. Petr. Chem., 24, 233 (1979). L . Cassar, J. Organomet. Chem., 93, 253 (1975). H. A. Dieck and R. E. Heck, J. Organomet. Chem., 93, 259 (1975). K. Sonagashira, Y. Tohda, N. Hagihara, Tet. Letter, 4467 (1975). K. Sonagashira, T. Yatake, Y. Tohda, S. Takahashi, and N. Hagihara, J.C.S. Chem. Comm., 291 (1977). D. Mohanty, J. Hedrick, K. Gobetz, B. Johnson, K. Yilgor, E. Yilgore, R. Yang, and J. McGrath, Polym. Preprints, 23(1), 284 (1982).

RECEIVED February 26, 1985


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Reactive Oligomers - American Chemical Society

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