On the relation between the glass transition temperature of network epoxide polymers and their chemical structure

Glass transition temperature of network epoxide polymers

$73'

5. N. G. PAVERMAN, Kandidatskaya dissertatsiya (Candidate's Dissertation) D. I. Mendeleyev Chem. Technol. Inst. Moscow (MKhTI), 1975 6. A. CHIJSELS and H. MIERAS, J. Polymer Sci., Polymer Phys. Ed. 11: 1849, 1973 7. M. SAKAGUCHI and H. JAMAKAWA, J. Polymer Sci., Polymer Phys. Ed. 12: 193, 1974 8. H. ZAIDI, Kunststoffe 64: 171, 1974 9. V. Ye. GUL, Ye. G. LYUBESHKINA and D. V. KURILO, Vysokomol. soyed. A12: 1829, 1970 (Translated in Polymer Sci. U.S.S.R. 12: 8, 2074, 1970) 10. M. B. NEIMAN, Uspekhi khimii 33: 28, 1964 11. S. S. YUSHKYAVICHYUTE and Yu. A. SHLYAPNIKOV, Trans. AN Lit. SSR B58: 153, 1969 12. R, V. ALBARINO, Appl. Spectroscop. 27: 46, 1973 13. M. I. BULATOV and I. P. KALINKIN, Prakticheskoye rukovodstvo po fotokolorimetricheskim i spektrofotometricheskim metodam analiza (Practical Handbook on Photocolorimetric and Spectrophotometric Methods of Analysis) Izd. "Khimiya", 1976

Polymer Science U.S.S.R. Vol. 20, pp. 673-679. ( ~ Pergamon Press Ltd. 197~. Printed in Poland

0032-3950/78/0301-0673507.50/0

ON THE RELATION BETWEEN THE GLASS TRANSITION TEMPERATURE OF NETWORK E P O X I D E POLYMERS AND THEIR CHEMICAL STRUCTURE* T. I. POI~OMAREVA, V. I. IRZHAK a n d B. A. ROZEI~BERG Department of the Chemical Physics Institute, U.S.S.R. Academy of Sciences

(Received 27 May 1977) The glass transition temperature increments have been calculated for some network epoxide and amine chain fragments. I t has been found that the glass transition temperature is unambiguously predetermined by the chemical structure of the polymer. I~VESTIOATIO~rS u n d e r t a k e n w i t h t h e o b j e c t o f d e t e r m i n i n g r e l a t i o n s b e t w e e n t h e chemical s t r u c t u r e a n d m e c h a n i c a l p r o p e r t i e s of p o l y m e r s h a v e b r o u g h t a fresh i m p e t u s to t h e search for e q u a t i o n s r e l a t i n g i n d i v i d u a l p r o p e r t i e s w i t h p a r t i c u l a r details o f p o l y m e r s t r u c t u r e . I n p a r t i c u l a r , a v a r i e t y o f e q u a t i o n s h a v e b e e n p r e s e n t e d for calculation of t h e glass t r a n s i t i o n t e m p e r a t u r e (Tg) of linear p o l y m e r s . T h e s e e q u a t i o n s a r e b a s e d on t h e chemical s t r u c t u r e of t h e r e p e a t u n i t s a n d on t h e p r e s u m e d a d d i t i v i t y o f t h e i r c o n t r i b u t i o n to t h e v a l u e of Tg [1, 2]. * Vysokomol. soyed. A20: No. 3, 597-602, 1978.

~74

....

T . I . POrCOMAR~.VAeta/.

Using the additivity principle Becket [3] proposed the following formula for calculating Tg in the case of crosslinked polymers with a variety o f structures

~,atmT~+KP Tg~-- ~ a ~ n ~ '

(1)

.

~vhere T~ is the Tg increment for a given structural unit, and is proportional to t h e magnitude of the cohesion energy of the respective homopolymer; at, the :number of these structural units; m, the number of atoms ;that a given structural unit brings into the main chain of the polymer; P, the number of network points; K, a constant characterizing the contribution of the network point to Tg. For a ~hree functional network point K = 890°K irrespective of its chemical nature. TABLE 1.

C w A ~ & C T E R I S T I C S OF T H E I N I T I A L C O M P O U N D S

Name of compound I)iglyeidyl ether of hydroquinone (DGH) ,, resoreinol (DGR) ,, pyrocate.chin (DGP) phthalic acid (DGPA) •m-Phenylenediamine (PDA) :2,6-Diaminopyridine (DAP) 4,4'-Diaminodiphenylsulphone (4,4'-DADPS) :3,3'-Diaminodiphenylsulphone (3,3'-DADPS) 4,4 -Diaminodiphenylmethane (DADPM) Resoreinol Diglycidyl ether of diethylene glycol (DGDEG) 1,5-Pentadiamine (PDA) Phenylglyeidyl ether (PGE)

I Epoxide number 37.0 37.7 36.2 25.8

M.p., °C published experimental information 117-119 40-42 38-40

118-119 [4]

62-64

63-64 [5]

120 173-175 160-162 89-90 38.2

110 120"/0.15 tort 178" 135"/28 tort

90 [41 110.5 [41 135"/28 tort [6]

* B.p., °C.

The foregoing equation does not have any theoretical basis, and its validity has therefore to be verified experimentally. Our aim in the present work was to verify the validity of the Becker equation for calculation of Tg values of network ~poxide polymers having a variety of chemical structures, as well as calculation .of Tg increments for groups of atoms making up the repeat units of the polymers. In planning this investigation particular attention was paid to the purity characteristics of the initial monomer systems, and to the degree of completeness o f the hardening process, since the absence of any accurate information regarding the latter parameters means that no adequate basis exists for proper determination of the chemical structure of the hardened polymer, which is one of the main :factors giving rise to errors in determinations of Tg increments for polymers.

Glass transition temperature of network epoxide polymers

675

The initial monomers and hardening agents were purified by reeryst~lli-.ation or distillation. Table 1 gives the characteristics of the starting materials. The degree of completene~ of the hardening reaction, which was monitored by calorimetry and by chemical analysis, was 97-98%. The method of volume dilatometry was used to determine TI. The test specimens were cylinders measuring 4.5 mm, and the temperature was raised at the rate of 1 deg/min. In the calculations it was assumed that complete hardening amounts to 100%. Epoxide polymers are copolymeric systems, which means t h a t there is no w a y of finding the increments on the basis of homopolymers. To calculate the contribution of the structures to the value of Tg one m a y use isomeric Compounds, the increments of which ought, in line with formula (1), to be identical, but which differ in respect to the value of n. Thus as a result of comparing Tg values of polymers differing solely in r c s p ~ t to the main chain length we should be able to verify the feasibility of the Becker formula, and to find the appropriate increments. In this paper the method of interest is exemplified by calculation of Tg for polymers based on diglycidyl ethers of dioxybenzenes (hydroquinone, resorcinol and pyrocatechin) and 4,4'-diaminodiphenylsulphone. The structure of the repeat unit is represented as OH OH I I / CH~--CH---CH2--O--O--0--CH..,--CH-- CH~--

/

~

" ~

\CHz__CH__CH~__ 0__~x/-~-~#__0__CH~__CH__CII,,__ i \\-J i OH

OH

I n accordance with the common approach the increments of different epoxide units m a y be expressed in terms of one another, e.g. TDGH=TDGR+TB;

TDGp=TDGR--TB

,

where TB is the increment for a single bond of the benzene ring. In our case formula (1) has to be modified as follows:

T,=

aE [TDoR+ TB(nE--nDGR)]+aAT A+ 2K aE~E ~-aAWA

where TB and TA are increments for the epoxide and amine fragments; nE and hA, the number of atoms introduced into the main chain by the epoxide and amine fragments; nDGR, ditto for D G R , while aE and aA are concentrations of the epoxide and amine monomers. Expressing the amine increment in terms of group increments T A = 8TB-~-Tso, we obtain, after the appropriate transformations,

T g = TB-I- 2TDGR--~Tso--25TB-~-2K 2hE ~- 11

(2)

T, I. PO~O~2~VA et al.

676

.

]:"

~

Plots of experimental values of Tg vs:! 1/(2ni~+l D are' displayed in Fig. 1 for t h e systems examined. From t h e tan'gent of the angle of slope of the straight line, a n d taking Tso = 1 2 0 0 [3] we obtain: TDGR----3560; TA----g280; TTGH=4070; TABLE 2'

GLASS ~kNSITION ETHERS

TEMPE~TURES

OF E P O X I D E

OF ISOMERIC DIOXYBENZENE

P O L Y M E R S B A S E D ON D I G L Y C I D Y ~

AND AROMATIC DIAMINES

~g ~ OK

Epoxide monomer

4,4'-DADPS [

experimental

3,3'-DADPS -experi-

ealcula$ed ] mental

4,4'-DADPM

ealcu- experilated m e n t a l

m-PDA

DAP

expe-I c a l e u - r i m e n " ealcu. lated I tal lated

calcu- experilated mental i

DGR DGP

429 423 w

429 424

418 403

424 418

396 393

398 391

383 388

I

I~ 3 8 6 376

413 ] 411 393• 404

TT6r--~ 3050°K. The intercept on the ordinate axis, equal to: 510, is the incremenb for the benzene ring bond [3]. On the basis of the found increments we calculated the respective values of Tg, which appear in Table 2. TABLE 3.

COMPOSITIOI~ DEPENDENCE

OF THE GLASS TRAI~SITION TEMPERATURE

OF E P O X I D E

P O L Y M E R S B A S E D ON D I G L Y C I D Y L E T H E R S OF D I O X Y B E N Z E N E S a E AND D I E T H Y L E N E

GLYCOL aD

AND DIAMrINOPYRID1NE

aE 2.0 1.8 1"6 1.4 1.2 1.0 0-0

~

aD

"

DGH

Tg, °K

I)GR

:

experimental

calculated

experimental

calculated

418 403 392 373 363 353 277

418 404 388 374 360 345 277

408 398 383 363 343

411 397 382 367 353 340 277

0-0 0.2 0.4 0-6 0:8 1.0 2.0

338 277

Using formula (1) one may calculate Tg for complex systems consisting of several epoxide a n d amine components. Table 3 gives the experimental and calculated values of Tg. The calculations are done with the aid of the modified' formula (1) Tg----

aMTE + a A T A'I- aDTD + 2 K aEnE-{-ttAnA--~aDnD

,

(3)

where TD is the increment for the comonomer being introduced; a n , its concentration; nn, the number of atoms introduced into the main chain by the comonomcr. The concentrations are all referred to 1 mole of hardening agent.

Glass transition temperature of network epoxide polymers

67~

It was demonstrated in: [7] for the system epoxy compound-lactone-amine that the lactone polymerizing on amino-groups of the polymer enters the chain without reducing the number of functional groups of the reagents. Formula (3). is accordingly valid in this case (Table 4). ?~,°( 5

0

0

,eo 020 38D

0.01

O'O3

l

0.05 I 2n~÷ll

FzG. 1. Dependence of Tg of polymers on their structure on coordinates of equa-

tion (2).

The addition of chain lengthening agents such as resorcinol or aniline result 3 in a change in the glass transition temperature of the system. In this case formula (1) may be modified so as to allow for the modifier addition.

Tg•°K

TS,°K #00 360 320

l

K

l

0"5

I'0

1.5

I

2801

2"0 LFAniline],moles

FIG. 2 FzG. 2. Dependence

r

0"I

I

I

0"2

0"3

I

r

0.~ 0.5 [PGE],moles

FIG. 3

of T~ of the network

polymer

on content of aniline units: 1--system,

DGR-DAP-aniline; 2--system DGR-PDA-aniline; solid lines--calculated; points--experimental findings. FIG. 3. Dependence of Tg of system D G R - P G E - P D A on PGE content; solid line--calculated, points--experimental.

In the case of resorcinol, the components of the system (given an equimolar composition) satisfy the relation [E] = [R] + ~ [A], where [E], [R] and [A] are concentrations of the epoxide, resorcinol and amine: fragments in the system. Hence [E] / [R]-- x > 1

T . I . PONOMAREVA el~ al.

4~78

'The expressions for the resorcinol and epoxide concentrations are: [R] = x - - l '

[E]. = x-- 1

~Substituting the latter expressions into formula (1), we obtain 2

TEx-~ + TR

+TA+2K

Tg----

n.+2 nE , i +nR / ~vhere TR

is the increment for group 0 - - ~

1

0 ; nR, the number of atoms in-

TABLE 4. DEPENDENCE OF Tg OF THE SYSTEM D G R (aE)-~-£-CAPROLACTO~E ( a D ) + D A P oN THE LACTONE CONCENTRATION

I

Tg, ° K aL

experimental

calculated

0"00 0-26 0.44

413 393 392

414 400 392

°K

experimen. tal

calculated

0.83 1.25

388 383

377 364

T A B L E 5. C O M P O S I T I O N D E P E N D E N C E SYSTEM

Tz,

aL

OF T g FOR T H E

DGPA-RESORCINOL(aR)-DAP Tg ~ OK

aA

aR

1"00

0.00 0-5 1"0

0"75 0"50

TABLE 6. •C o m p o u n d DGH DGR DGP DGDEG DGPA Diglycidyl ether of diphenylpropane DAP •D A D P M

expe~memtal ,

calculated

393 378 358

408 390 373

I N C R E M E N T V A L U E S FOR T H E D I F F E R E N T GROUPS ni

T~ ~ ° S

12 11 10 13 11 17

4070 3560 3050 2300 3920 6340

5 11

2220 4255

Compound 4,4-Diaminodiphenylsulphide 4,4'-DADPS 3,3'-DADPS e-Caprolaetone PDA Aniline DPA PGE

11 11

4360 5280 4260 1515

875 680 1530 --530

Glass transition temperature of network epoxide polymers

679

troduced by the latter group into the main chain. Table 5 gives the data on T t for the system in question. I f aniline is used as the chain lengthening agent, formula (1) is written as Tg=

TAaA ~- TAN~t_SAN-I-TE (2aA-~-aAN)-~-2KaA 11 (2aA ~-aAs) ~- 5aA~aAN

The calculated and experimental data on Tg are displayed in Fig. 2 for the systems of interest. I t can be seen from Fig. 3 how Tg changes in the case of a system when the network density of the latter is regulated by a monofunctional monomer, i.e. b y phenylglycidyl ether. In this case Tg=

4T o( 1 --a~.) -5 2T~a~-{-- T AaA-[-2K aAnA--~2a~.nE

where Tg is the increment for the chain terminating agent. Table 6 gives the glass transition temperature increments for epoxide a n d amine chain fragments calculated from a s t u d y of the relation between T~ a n d composition for different systems. Thus it appears from a comparison of the calculated and experimental glass transition temperatures t h a t agreement to within 5% is obtained, and in general the error amounts to 0.5-1~/o. The results show t h a t in the case of epoxide polymers a parameter of the importance of the glass transition temperature is fixed unambiguously by the chemical structure of the polymers.

Translated by R. J. A. HENDRY REFERENCES

1. A. A. ASKADSKU~G. L. SLONIM~KII,Yu. I. MATVEYEVand V. Y. KORSHAK, Vysokomol. soyed. A18: 2067, 1976 (Translated in Polymer Sci. U.S.S.R. 18: 9, 2363, 1976) 2. L. V. van KREVELEN, Properties and Chemical Structure of Polymers, 1976 3. R. BECKER, Plaste und Kautschuk 20: 809, 1973; 790, 1975 4. A. M. PAKEN, Epoksidnye soyedineniya i epoksidnye smoly (Epoxy Compounds and Epoxy Resins) Izd. Goskhimizdat, 1962 5. Kratkii spravochnik khimii (Abridged Chemistry Handbook) Izd. "Goskhimizdat", 1955 6. BEILSTEIN, J. Organ. Chem. 1: 17, 50 7. G. A. ESTRINA, S. P. DAVTYAN and B. A. ROZENBERG, Materialy konf. po modifikatsii, strukture i svoistvam epoksidnykh soyedinenii (Trans. Conf. on the Modification, Structure, and Properties of Epoxy Compounds) Kazan, 1976