Reddish, W., Trans. Faraday Soc. 4 6 , 459 (1950). Simril, V. L., Curry, B. .4.,M o d . Plastics 36, 121 (1959). Warfield, R. W.? Petree, M. C., SPE Trans. 1, 80 (1961). IYhitehead, S.,“Ditlectric Breakdown of Solids,” Oxford Clarendon Press, 1951.
literature Cited
(1) Amborski, L. E., Burton, R. L., Elec. Mfg. 53, 124 (1954). (2) Birks, J. B., “Modern Dielectric Materials,” Academic Press, Inc., N. Y . , 1960. (3) Du Pont de Nemours, E. I., & Co., Teflon FEP Fluorocarbon Film Tech. Rept., 1961. (4) Jackson, W., “The Insulation of Electrical Equipment,” Chapman & Hall Ltd., 1954. (5) Javits, A. E., Elec. M f g . 65, 60 (1960). (6) Mathes, K. N., Electro-Technol. 66, 149 (1960).
RECEIVED for review June 3, 1963 ACCEPTEDJuly 10: 1963 Division of Polymer Chemistry, 144th Meeting, .4CS, Los Angelrs, Calif., April 1963.
EFFECT OF MOLECULAR STRUCTURE ON PROPERTIES OF HIGHLY CROSS-LINKED URETHANE POLYMERS W . C. D A R R , P. G . G E M E I N H A R D T , A N D J.
H. SAUNDERS
M o b a y Chemical Co., Pittsburgh, P a .
Physical properties of highly cross-linked urethanes were evaluated by examining Vicat softening data of solid polymers prepared from a variety of polyol and polyisocyanate reactants. The complete curves of Vicat penetration vs. temperature were plotted and interpreted as the modulus-temperature relationship of the polymers, thus indicating the property behavior of the polymers over a wide temperature range. Interesting relationships with molecular structures of the reactants are shown. for rapidly screening the many urethane reactants available for rigid foam.
HE tremendous growth of the urethane chemical industry Tduring the past few years has been tied very closely to the flexible foam market and the use of di- and trifunctional reactants. Because of several recent economical improvements, including lower cost polyether resins and less costly. improved isocyanates. interest has been increased in the production of more highly cross-linked polymers, especially in the form of rigid foam. Many widely variant raw materials are now available for study. These materials, both polyols and polyisocyanates. differ widely in chemical composition, functionality. and molecular configuration. These variations and the resulting effects on physical properties of the polymers are being investigated in this work. The pol yether polyols used had branched aliphatic. heterocyclic, or aromatic nuclei. The polyols also varied in functionality from three to eight. Aromatic isocyanates were used primarily in this study, and a n aliphatic diisocyanate was included for theoretical interest. The effects of structure of the
The study offers promise
reactants on certain of the final properties of the polvmers \\‘ere much greater than expected. In addition. techniques used in this work offered a new procedure for screening the many possible polymer combinations which may be of interest for rigid foams. Experimental
This work was primarily concerned \\it11 stud>ing the different types of polyols and polyisocvanates now commercially available. No attempt was made to compare the many similar products of each type. The raw materials and their analytical data are shown in Tables I and 11. Polyols are given a code designation showing the nature of the initiator to which propylene oxide \vas added, the functionalitv. and the equivalent weight.
Polyols. ALIPHATIC.3(150), polyether triol. equivalent weight about 150, Pluracol T P 440. based on trimethylolpropane (Wyandotte Chemicals Corp.).
Typical Chemical Properties of Various Polyether Polyols .4liphatic Heterocyclic 4( 725) 4( 750) 6( 72.5) 6( 750) 4( 725) ?( 750) 8(125)
Table 1. 3( 750)
Hydroxyl No.
400
450
P . 0 ner hrancha
1 6 7.0 c .03
1 6
r--
xiid
NO.^ Viscosity, c.P.s., 25’ C.
Cyclic, weight
70
615 0
6.6
0.027
1550 0
375 2 0 6.9
0.018
1150 0
490 1 4 5 2 0.15 10,000 0
380 2 0 5.1
460 1 2 7 1
0.16
0.17
3000
>100,000
0
16.4
430 1 4
R( 750)
370 1 8 7.5 0 16 22,500
-somewhat sharper than by Clash-Berg. For this reason. and for convenience of operation, the Vicat procedure was chosen for property measurements on all the solid polymers. VOL. 2
NO. 3
SEPTEMBER 1963
195
Table 111. 3(750) .MDITDI 2.5
Foam System Density, lb./cu. ft.
Comp. str., p.s.i. to yield Closed cells, 70 K factor Dimens. stability, 7c vol. change 7 0 " C., 100% R.H. 100' C., amb. R. H. Softening point, C.
2.4 29
a
904-
Properties of Polyether-Urethane Foams
Aliphatic 41 125) .MUITDI 2 5 2.0 2.1
19
29
85+ 92f 0 . 1 5 0.12
b
24 Hour5
Heterocyclic 41 725 i 81 125) MDIMDITDI 2 5 TDI 2 5
Aromatic 31 750)LZfDITDI 2 5
2.1 27
61 125)
TDI
2.0 22
.tlDI2 5 1.6 19
80+ 89+ 0.17 0 . 1 5
1.7 20
91+ 88+ 0.16 0.14
29
1.9
1.6 9
2.1 30
2.0 32
86+ 0.13
4 0.20
0 16
95
SO+ 0.15
4 Weeks 2 Wfeks 4 Weeks 2 11 14 0 >50 20 10 4 9 8 4 0 >50 20 160 120 150 160 154 >200 85 95 >200 90 120 'Vat measured because of primary shrinkage durnng jirst f e w hours as foam cools. ,lrot measured because f o a m &as not dzmensionally stable at room temperature. 4 Hours
> 50 > 50
>20 >20 95
24 Hours
