Final Report to Manufacturing Development General Motors Technical Center, Warren, Michigan 48090 ENVIRONMENTAL AGING OF SMC COMPOSITES Submitted by George S. Springer Department of Mechanical Engineering The University of Michigan, Ann Arbor, Michigan 48109 November 1979

ENVIRONMENTAL AGING OF SMC COMPOSITES ABSTRACT The effects of environment on glass fiber reinforced polyester and vinylester composites immersed in liquids and in humid air were investigated. Tests were performed at temperatures 23 C and 93 C with the materials exposed to humid air at 50 and 100 percent relative humidities, and to five different liquids: saturated salt water, No. 2 diesel fuel, lubricating oil, antifreeze, and indolene. Changes in weight, ultimate tensile strength, tensile modulus, short beam shear strength, and shear modulus were measured over a six month period, and the effects of the environment on these parameters were assessed.

2 I. INTRODUCTION The major objectives of this investigation were to determine the absorption characteristics of glass fiber reinforced polyester and vinylester composites immersed in different fluids, and to evaluate the changes in material strength due to the absorbed moisture. Three different types of materials were tested, these being designated as SMC-R25, SMC-R50, and VE SMC-R25. Brief descriptions of these materials are given in Tables 1 and 2. The following parameters were measured during the tests: a) weight change, b) ultimate tensile strength, c) tensile modulus, d) short beam shear strength, and e) shear (flexural) modulus. The measurements were performed over a six month period with the materials immersed in humid air at 50 and 100 percent relative humidities, saturated salt water, No. 2 diesel fuel, lubricating oil, antifreeze, and gasoline (Indolene HO 0). The experimental procedures are discussed in the next section. II. EXPERIMENTAL The weight changes of the materials during immersion were obtained as follows. Before placing the test specimens (Table 3) into the moist environment (liquid or humid air) the specimens were dried in an oven at 66 C until their weight loss became stabilized and no more weight loss was observed. The specimens thus dried were then placed in the appropriate environmental chambers and their weights were measured by weighing them periodically on a Mettler Analytical Balance. The temperatures of the environmental chambers were controlled by heaters and were kept within ~ 1 C. Hundred percent relative humidity was maintained

3 by keeping water in a closed,half-filled container. The temperatures of the water and the air above the water (where the specimens were located) were regulated by separate heaters. At 50 percent relative humidity and 23 C the specimens were kept in an air-conditioned, temperature controlled room. At 50 percent relative humidity and 93 C the specimens were mounted above the surface of a water-ethylene glycol mixture. The temperatures of both this liquid mixture and the air above it were regulated by heaters. In all the tests the relative humidity of the air was measured with Abbeon Hygrometers. The data are presented in terms of percent weight change which is defined as M = weight of specimen - weight of dry specimen x 100 (1) weight of dry specimen The tensile and shear properties of the materials were determined in the following manner. The specimens, described in Table 3, were immersed in the appropriate environment for a predetermined length of time. The strength and the modulus were then measured at room temperature using an Instron. The cross head speed was 5 mm/min for the tensile tests and 1 mm/min for the shear tests. The tensile modulus was estimated from the load-deflection curve. The shear strength and the shear (flexure) modulus were measured by the three point short beam method. The arrangement described in the ANSI/ARTM-D2344-76 standard was used in these tests (Fig. 1). The apparent shear strength and the shear modulus were calculated from the expressions [4, 5] 0.5) (P) 2) T - (2) (b) (h) - (P) (S)3 (3 s 4(d) (b) (h)3

4 where T is the shear strength, E is the shear (flexure) modulus, P is the s breaking load, b and h are the width and thickness of the specimen, respectively, d is the deflection at the center point, and S is the span between the supports. III. RESULTS Tests were performed with specimens immersed in humid air and in five different liquids at 23 C and 93 C. The test conditions are summarized in Table 4. The weight changes, as well as changes in tensile and shear properties, are presented as functions of time and temperature in Figs. 2 to 22. Each point in these figures is the average of five data points. For weight change all five data points were generally within ~ 15 percent. The spreads in the mechanical properties data are indicated by error bars. a) Weight Change At every test condition the weights of the specimens increased at first and then leveled off for some length of time. The data indicate that both the initial rate of weight increase and the value at which the weights leveled off depend on (a) the material, (b) the temperature, and (c) the environment (relative humidity of air or the type of liquid used). The data also show that in some instances the weight did not always remain constant after it reached a level value, but kept either increasing or decreasing. This suggests that under some conditions the moisture transport was by a "non Fickian" process. To assess the conditions under which the absorption was governed by Fick's law, weight changes were calculated by the expression developed for

5 "Fickian" diffusion [6] M = - 8 exp[-2J + 1)2 (Dt/h2)] (Mm - M) + (4) 7T2 j=' 0 (2j + 1)2 ( i+ 1 In the present tests the initial moisture content M. was zero. The apparent maximum moisture content (Mm) was taken from Figs. 2 to 22 as the value at which the weight change first seemingly leveled off. The apparent diffusivity was calculated by assuming that the moisture absorption process followed Fick's law. Hence, the apparent diffusivity was calculated from the expression [6] h 2 M2 - M 2 h \-2 D l= + + (5) 2 1 where h, Q, and n are the thickness, the length, and the width of the specimens, respectively. M1 and M2 are the moisture contents at times t1 and t2, these lj2 times being sufficiently low so that the weight change can still be taken to 1/2 vary linearly with (time). The Mm and D values are listed in Table 5. The calculated weight changes are shown as solid lines in Figs. 2 to 21. In most cases the calculated values and the data agree reasonably well until the apparent maximum weight change is reached. Beyond this point the data often deviate from the calculated values, the differences between the measured and the calculated values being more pronounced at the higher temperature. Once the data deviated from the calculated values the absorption process was "non-Fickian." One reason for this may be that moisture transfer through the resins did not proceed according to Fick's law. Such "non-Fickian" behavior has been observed in the past with rubbers and polymers [7]. Another

6 plausible explanation of the observed non-Fickian absorption process is as follows. Owing to the moist, high temperature environment, microcracks developed on the surface and inside the material. Moisture rapidly entered the material, causing the increase in weight. As the cracks developed, material, most likely in the form of resin particles, was actually lost. In fact, such material loss was frequently observed after a few hours of exposure to the moist environment. As long as the moisture gain was greater than the material loss, the weight of the specimen increased. Once the weight of the lost material exceeded the weight of the absorbed moisture, the weight of the specimen decreased. Of course, when material was lost, the measured weight change no longer corresponded to the moisture content of the material. Non-Fickian absorption similar to that observed here was observed with graphite epoxy composites immersed in saturated steam at 150 C. The microcracks formed during these tests were readily apparent on photo-micrographs taken of the specimens [8]. Weight changes of SMC-R25 have been measured previously [9]. The present data agree reasonably well with the earlier measurements, with the exceptions: 100% relative humidity air at 23 C, No. 2 diesel fuel at 23 C and lubricating oil at 23 C. For these conditions the previous data show a one to two percent larger weight change than the present measurements. To ascertain the validity of the present data the weight change measurements were repeated at the above three conditions. The data thus obtained agreed with the present first set of measurements which are given in Figs. 3, 5, 6. A completely satisfactory explanation for the above noted discrepancies could not be found. Some likely causes for the differences between the

7 present and the previous results can be offered. In the tests with humid air the temperatures in the previous (32 C) and the present (23 C) tests were different. Impurities in the fluids or differences in material composition may also have contributed to the differences in the weight change. b) Strength and Modulus The ultimate tensile strengths, the shear strengths, and the tensile and shear moduli were determined at room temperature immediately after the materials were received (i.e. without the test specimens having been placed in the environmental chambers). The results of these measurements (designated as "baseline" data and identified by the subscript o) are listed in Table 6. All data presented in Figs. 2 to 22 were normalized with respect to the values given in Table 6. As a check on the "baseline" data, a set of the received specimens were dried at 66 C and their properties were then determined. The properties of the "baseline" (as received) specimens (Table 6) and the "dried" specimens did not differ appreciably. In order to evaluate the effect of specimen size on the short beam shear strength and on the shear modulus, "baseline" data were obtained with two different size specimens (see Table 3). The specimen size did not significantly affect either the short beam shear strength or the shear modulus. It is noted that for SMC-R25 and SMC-R50, the values given in Table 6 are of the same order of magnitude as reported previously [1] - [3]. The results in Figs. 2 to 22 show that exposure to a moist environment affects both the strength and the modulus of the materials. The change in strength and in modulus depends upon a) the material, b) the temperature, and c) the environment (relative humidity of air, or type of liquid used). The most

8 important of these three factors seems to be the environment. Although there is a loss in the properties after exposure to most fluids, antifreeze and indolene have the most pronounced effects. All three materials exposed to these liquids at 93 C suffered a significant loss in strength and modulus. The weight changes were also largest at these conditions, suggesting —as expected —that the amount of moisture absorbed and the material properties are related. However, there does not seem to be a clear correlation between the losses in strength and modulus and the weight change. Thus, a unique relationship between the weight change and the change in properties cannot be established readily. It is of interest to determine whether or not the changes in strength and modulus are permanent. To answer this question the strengths and moduli were measured of specimens which were immersed for six months in the test environment and then were dried at 66 C for three weeks. These data are represented by solid circles in Figs. 2 to 22. As can be seen, by drying the material, some, but not all, of the loss in strength and modulus is recovered. It appears, therefore, that changes in the material properties are nearly permanent. Drying out the material does not restore either the strength or the modulus to their original values. c) Scanning Electron Microscope Examinations Selected tensile specimens were examined by a scanning electron microscope (Table 7). Photographs were taken of the failure surfaces using 57x and 570x magnifications. Unlike metals (which usually fail along a surface normal to the load), the SMC materials tested here failed along a slanted surface as illustrated in Fig. 23. Thus, the failure mechanism could not

9 be discerned on the photographs. Typical SEM photographs are shown in Figures 24 and 25. Prints of all the photographs have been delivered to General Motors.

10 REFERENCES 1 B.A. Sanders and R.A. Heimbuch, "Engineering Properties of Automotive Fiber Reinforced Plastics," General Motors Corporation, Manufacturing and Development Report No. MD77-020, General Motors Technical Center, Warren, Michigan, 1977, and presented to the Conference on Environmental Degradation of Engineering Materials, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, October 10, 1977, and to the Society for Experimental Stress Analysis, 1977, Fall Meeting, Philadelphia, October 11, 1977. 2 D.A. Riegner and B.A. Sanders, "A Characterization Study of Automotive Continuous and Random Glass Fiber Composites," General Motors Corporation, Manufacturing Development Report No. MD79-023, General Motors Technical Center, Warren, Michigan, 1979, and presented to the Society of Plastics Engineers, 1979 National Technical Conference, Detroit, Michigan, November 1979. 3 D.L. Denton, "Mechanical Properties Characterization of an SMC-R50 Composite," SAE Paper No. 790671 (1979). 4 Standard Test Method for Apparent Horizontal Shear Strength of Reinforced Plastics by Short Beam Shear Method. ANSI/ASTM Standard D 2344-76 (1976). 5 J.M. Whitney and G.E. Hussman, "Use of Flexure Test for Determining Environmental Behavior of Fibrous Composites," Experimental Mechanics, Vol. 18, (1978), p. 185. 6 C.H. Shen and G.S. Springer, "Moisture Absorption and Desorption of Composite Materials," Journal of Composite Materials, Vol. 10, 1976, pp. 1-20. 7 J. Crank, Diffusion in Solids, Oxford Press, Chapter (1976). 8 A.C. Loos and G.S. Springer, "Effects of Thermal Spiking on GraphiteEpoxy Composites," Journal of Composite Materials, 13, 1979, p. 17. 9 A.C. Loos, G.S. Springer, B.A. Sanders, and R.W. Tung," Moisture Absorption of Polyester-E Glass Composites," Journal of Composite Materials, (in print).

11 Table 1 Descriptions of the Polyester E glass Composites used in this investigation [1,2,3] SMC - R25 Ingredient Type Weight % Resin Polyester (OCF E-920-1) 29.4 Filler Calcium carbonate 41.8 Internal Release Zinc Stearate 1.1 Catalyst Tertiary Butyl Perbenzoate 0.3 Thickener Magnesium Hydroxide 1.5 Pigment Mapico Black 0.8 2.54 cm Chopped E-glass (OCF 951 AB) 25.0 SMC - R50 Ingredient Type Weight % Resin OCF-E-980 Polyester 32.3 Filler Calcium Carbonate 16.1 Mold Release Zinc Stearate 0.8 Thickener Magnesium Oxide 0.5 Catalyst TBP 0.3 Inhibitor Benzoquinone Trace 2.54 Chopped Class OCF 433 AB 50.0

12 Table 2 VE-SMC-R50 paste formulation Component Parts A-SIDE XD-9013.03 10 TBPB 1 Camelwite 92 Zinc Stearate 3 B-SIDE Derakane 470-45 100 Maglite D 50 Camelwite 100 Pump 10-14/1 by weight A/B Max viscosity = 6000 cps (90F, RVT, #4 Spindle, 20 rpm) Registered Trademark of Dow Chemical Company

Table 3 Nominal dimensions of specimens used in the tests. All units in mm. SMC-R25 SMC-R50 VE SMC-R25 Type of Test Thickness Width Length Thickness Width Length Thickness Width Length weight change 2.41 12.7 50.8 2.41 12.7 50.8 3.30 12.7 50.8 tensilea 2.41 12.7 80.0 2.41 12.7 80.0 3.30 12.7 80.0 short beam shearb 2.41 6.35 15.2 2.41 6.35 15.2 3.30 6.35 15.2 a- "Dogbone" specimens. Dimensions given are for gauge section. Total specimen length: 180 mm. Width of grips: 25 mm. b- With SMC-R50 "baseline" data were also obtained with 8.5 mm thick, 8.5 mm wide, and 50.0 mm long specimens.

14 Table 4 Summary of test conditions Temperature Duration of Test Substance 23 C 93 C humid air 50% rel. hum. x x 6 months humid air 100% rel. hum. x x 6 months saturated Nacl-water solutions x x 6 months No. 2 diesel fuel x x 6 months Sunoco 10-W-40 lubricating oil x x 6 months antifreeze (ethylene glycolwater mixture, 50%-50% by x x 6 months volume) indolene HO 0 x x 6 months

Table 5. The apparent maximum moisture content Mm and the apparent diffusivity D. Subs e Tmperaure SMC-R25 VE SMC-R50 SMC-R50 Substance Temperature 5 5 Mm Dx 10 Mm Dx 105 Mm Dx5 C~ % mm /sec % mm2/sec % mm /sec Humid air, 50% 23 0.17 10.0 0.13 10.0 0.10 30.0 93 0.10 50.0 0.10 50.0 0.22 30.0 Humid air, 100% 23 1.00 10.0 0.63 5.0 1.35 7.0 93 0.30 50.0 0.40 50.0 0.56 50.0 Salt water 23 0.85 10.0 0.50 5.0 1.25 10.0 93 2.90 5.0 0.75 30.0 1.20 80.0 No. 2 diesel 23 0.29 6.0 0.19 5.0 0.45 5.0 93 2.80 6.0 0.45 10.0 1.00 5.0 Lubricating oil 23 0.25 10.0 0.20 10.0 0.30 10.0 93 0.60 10.0 0.10 10.0 0.25 10.0 Antifreeze 23 0.45 50.0 0.30 30.0 0.65 10.0 93 4.25 5.0 3.50 1.5 2.25 7.0 Indolene 23 3.50 1.0 0.25 10.0 0.60 10.0 93 4.50 20.0 5.00 2.0 4.25 1.5

16 Table 6 Initial strengths and initial moduli of the materials at 23 C ("baseline" data). Average of five measurements. SMC-R25 SMC-R50 VE SMC-R50 ultimate tensile strength (MPa) 84 180 165 tensile modulus (GPa) 5.0 8.0 7.0 short beam shear strength (MPa) 18 29 35 shear modulus (GPa) 5.0 7.0 4.0

17 Table 7 Summary of tensile specimens which were examined by a scanning electron microscope. Two magnifications were used for each photograph (57x and 570x). SMC-R25 SMC-R50 VE SMC-R50 Baseline, as received x x x Antifreeze 93 C, 18 days immersion x Antifreeze 93 C, 6 months immersion x x x No. 2 diesel 93 C, 6 months immersion xx x indolene HO 0 93 C, 6 months immersion x x x Saturated salt water 93 C, x x x 6 months immersion

Load: P II 1/4 in radius Specimen 1/8in. radius' d - 1/8rdius g 1Spanr s Fig. 1. Schematic of apparatus used in the short beam shear tests.

1.0 1.0 — o0.5 10.50 ~1 I I 0- 1 1 1 1 0 iki 1.0 — — f —- - 1.0 -------- t )05 0.5 (0.5- 0o D -TENSION I ^ |SMC-R251 z 3 -HUMID AIR 50% RH 3 93C 5 2I: 1 1<OI0000 0 | 0 Jl 05 01 1 0 50 100 200 01 10 50 100 200 TIME, doys TIME, doys Fig. 2. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. - Fick's law solution. - Fick' s law solution.

C/) Un 1.0 1.0 -- - 0.5 0.5- Lz -TENSION - -1 I I9 I i.o0 —- 1.0- - - t? ~ -1 —T9 O O z _ 0.5 0.5t: < SHEAR M I? (,Q I i I ~o O O' 0 _ 1.0 50.~. 0:o2 -. - 5- Li- t - 20.5-TENSION i -1- b I s t - Fick'Is law solution SHEAR "'r ~0 4 ~~~4 LU SMC-R25 z 3- HUMIDAIR, 100%RH 3- 93C < 23C o2- 2 --- o: 0 10 50 100 200 0 1 10 ~:boo000 200 TIME, days TIME, days 0 o o 0 Fig. 3. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

0,_______________________ 0.5 0.5 0 - TENSION oL oL I SHEAR _ 3 0 O-1-0-50-100-200 a 1- 050 10-0: 0QI OI M, LL 1.o - --- 0.5- 0.5 D TENSION 80'SHEAR o o 2.o 3C h 41.oo —.... U - 0.5 0.5 __< -TEARNIO 01 10 I LU1 SMC-R25 3 SATURATED SALT WATER 0 0 00 < 23C, C 23 21~- 1~-2 (9 o_ 0-~,, 0 I A II I I' ~ 001 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 4. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data, --- Fick's law solution.

/ -:.o ---- 1.0 T -, — b 0.5 10.5 z tTENSION, o _O4 0I I o co 2.0 —-' —Y-i- _____ n'l i__ Z 1.0 4' 1. O - o5 t 0.5 t0. Z W W QII - I.| 5:TENSION OE ~ t Z e 1 9 1.0 5- - -- - - - 0010- - - — 0L0.51 1 0.5 - -SHEAR: -: O-. 1 I I: I I O i t i! l I Ld 0 _ 0 o' Il 1 1 0 50 100 200 01 10 50 100 200 0.5- 0.5 o TIME, doys TIME,doys Fig. 5. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. - Fick's law solution. ~I O F-I I I I I I I 4 4 1.0 2.0 F3 - No. 2 DIESEL 20FUEL 3-93C 0 200 TIME, doys TIME, doys Fig. 5. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. "baseline" data. ~ specimens tested after 6 months --— Fi ck's law solut ion.

1.-0 - -— F- - T 1.0 — 0.5 0.5.o0 --- (:- 0 1- ----- w 1.o — 1.0 -0.5_ 0.5t 1 30.5 0 3 t0 —-------- - 4 4 —---- D TENSION 8o I I I C! I I I, I 0I 1[:.0 —-- - -1.o O! 0.5 0.5 — SHEAR lI I I I Ir 0 0 0.5 1 o 10000000: 01 10 50 100 200 01 10 50 100 200 TIME, doys TIME, days Fig. 6. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. 0 specimens tested after 6 months inmmersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

o) 1.0 1.0 0.5- 0.5- Q.5 TENSION 0.5 o i F ~ tl i I I I I Jo 0'' I I I 0.5- t 0.5...:SHEAR 1.0 — 4 —- o1.0__ — 0).51 0.5 8- 1.0 I I, I 1- I- LU, t (5 0.5 0.5 -TENSION.OR 4 4 1:4 005 1O 5 0 0 1 - < — SHEAR | - uJ SMC-R25 3- ANTIFREEZE 3-93C < 23 C 02.- 2- 2 LLI 01 ib % 01 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 7. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

i 1.0.5 -. - 0.5- 0.5 z TENSION M o I OI —-10l I I -— I z 1.0 — 7 —O —- + - 10t -- b —--—.05 1.0 1.0 0.5 o0.5 - gTENSIONLI - I < =-SHEAR: - | Oi-'' I I O0' 0 5.O- 1 —- -2 0- 1.0 — 5 10 1:0 ]0.5i 0.5s d -TENSION z.o - t 1.0 — _ — 0 25 C 0.5- -U L -I I II o0~~~4 0 a TIME, doys TIME., doys t 4' "aln' daa o iSMCm-R25 foo o3-INDOLENE dr^ 3 93 C < 23C o oi 1 01 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 8. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

0 - 0 (?) 1.0 00 —------ 1.0^ — ^ -— _1 o0.5- 0.5z tTENSION - 1 1 I I I I - J I I z i.o — j —o —-- 1.0' — O-4 —< -SHEAR _: | I Ol ----- OI I - I 0 0 U) 4: $ yi:? o ^ 1.0- 1.0 30.5 0.5 >:TENSION 1.0 1.0 0.5 0.5 05' SHEAR T OlII I I 0. A O O 0 4 4. 4 LUJ SMC-R50 z 3-HUMIDAIR 50% RH 3-93 C < 23 C 2- 20 0 00 00 01 0 0 00 00 01 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 9. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immnlersion time. - "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

cn -: I:, 0.51 0.5z tTENSION oI o-1 I I o l 0.5 0.5 < -SHEAR M 0oi1 I 1 I - I I - | t) OC; O 1.0 1.0 ~- — o9 30.5: 0.5 -TENSION 80 o'' —-- -I -I I —I I I I I o O --- 1 1.0-__ -0.5-, 0.5,:SHEAR c 44.4 Li SMC-R50 z 3-HUMIDAIR 100% RH 3-93C < 23C 5 2- 2I 1; 1 00 Io 0 01 10 50 100 200 01 10 O~~?00 200 TIME, days TIME, days 0 o O Fig. 10. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

en 1.0 _ —__ —-_- — _ 1.0_ —_- -----— _ — o0.5- 05t $0 z -TENSION I I~I II - I I | I I I ).o0 — 1.0 —----- o 0.5- 0.5- P L - SHEAR l 3:TENSION t 80'' I -1 I I LL 1.0_ - 1.0 -- -- ^0.5 0.5 0 -SHEAR | I I v h I-I-I I O 0g05, F~ 4 40 TMEdys TMEdys o o TIME, doys TIME., doys 0 Fig. 11. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. -- "baseline" data. specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

en 1.K — ~ —- -a- 1.0:^ —-a —- --— ^ 5 0.5 0.5 Z:TENSION ~0-'' I I o I I T -uu 0 1.0 +- -— 4H1.0 - ^0.51 0.5 L 05[,,, 0.5 W SHEAR c O- ll I:_I I i I D -TENSION 8 0'' I IG'I SMEAR 5_ L SMC-R 50 0 z 3 No.2DIESELFUEL 3 93 C < 23 C 2 2000 0 000 o - Ioco00 ~ ~ I |, ~ o o oI o I 3 0 1 0 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 12. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

() -T cn 1.0 ---- - 1.0 -- 0.5- 0.5 z:TENSION _ 0 -!''' I! 1.0o --- 10 —--- - 0.5 0.5 i -SHEAR |: O: I I I I I. _ I._.. I I. 0 1.0k- 1.0 0.5- 0.5 D:TENSION 8 0''lI! I' 0 I I, I o 0O L —L 0 41.0 1.0 o —-_ 0.5 - 0.5: < -SHEAR I I I... I 0I.. 4 —4 4 Uii SMC-R50 I 3- LUBRICATINGOIL 3 93 C <L 23 C..2- 2I: 11 (5, 0 0 0 1 5000 20 01 10 50 100 200 01 10 50 100 200 TIME, doys TIME, days Fig. 13. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

n 1.0 I) 0.5 0.5 Z TENSION t LU - 0 —--- 0:^ —---------- 0.5 10.5 - -SHEAR 0' O'L, —.... I o0-' —-----— _ 1.0I - I 05 0.5 D tTENSION o!t I I -I I O l I L <1 i.0 -Q 1.00'0.5T 0.5 - - -SHEAR: 61 Ol i I —---—. o-, I i -?I 4 4-... 4 LU SMC-R50 Z 3- ANTIFREEZE 3-93 C < 23 C (.. 2- 2-0 oo2) 00 0..000ooooooo o 0 0 0 0 1 00 01 10 50 100 200 01 1 50 100~ oI 0 10 50 100 200 01 10 50 100 TIME, days TIME, days Fig. 14. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. ~ specimens tested after 6 mQnths immersion followed by 3 weeks drying. Bars indicate spread in data. - Fick's law solution.

n 1.0O --- -T 4 1.0 ---------- <i Ii 0.5 0.5 Z t TENSION ^ 0'i —-- I I0'0.5 0.Q5 < -SHEAR r lii vO t i C I 0' I Li -.0 1.0.. 0.5 0.5- d:TENSION: ~ o"-1-4 —- — I — - I oI J- SHEAR 0o 40 4'I SMC-R50 5 3-INDOLENE 3-93C < 23 C o 2- 2- 3:: 1- )n noo ~~ ~ (. ~ 0 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 15. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

--------- 0.5 &0.5- 05z tTENSION Eo o —--- o —------— ^ z 1.0 —o - --- 1.0 — --- 0.5- 0.5 < -SHEAR | - 1.0 10 - ^ - - -,. 1.0o —-: —----- - I:SHEAR I I I 1 3-HUTENSION IlMo- 4' l -__ z 0.5- < 23 C 5 2u- 20 0 01 10 50 100 200 01 10 50 100 200 TIME, doys TIME, days Fig. 16. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

cn 1.0o —-- -— o 1.0. —- —...-. 5 0.5- 0.5- ~; z -TENSION W 0o I- 0-I I I ".0o —--- 1' t —---------- z _ 0-.5- 0.5 L z W < -SHEAR _ Q oi I I I O i I I? 0 LLJ 1.0 _ -— 1.0 —----- J0.5r 0.5 D t-TENSION 83 0 I _ I I I | o II I I I I I 0 0" I 1.0 9 1.0 -__ 0.5 o 0.5 -SHEAR c - r T r- I I I - II o I 4, 4, Lw VE SMC-R50 z 3-HUMID AIR 100% RH 3-93C < 23 C 502- 2-: 1: 1 (5 01 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 17. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. * specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

(.0 1.0 0.5- 0.5- Z:tTENSION ~ OZ' o z.o0 X-J —— l O1' —--— _ —--- wz O o0.5- 0.5 o W o ~ < -SHEAR. - jLI O I I 0 I- 0 l, I 1.0 — 1 1.0 ---- D -TENSION 3 0_ I 0 5 10 0 ^ 1.0> - - -^- - -? - - -^ - 1.0 ^ ---.- - -^ - - SH TIEAR -M, - tensile modulus, shear modulus, and weight as functions of immersion C 0 I E I I I 0 4 4 time. "baseline" data. * specimens tested after 6 months U -'VE SMC-R50 Z 3- SATURATED SALT WATER 3- 93 C < 23 C 5: 2- 2 0O o0 0 0 O 01 10 50 100 200 01 10 50 100 200 TIME, doys TIME, doys Fig. 18. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

10 1.0 —----- o 0.5- 0.5z:TENSION.0:1 — oo-.( — _ I.o --- s-1 --- --- i 0.5 R 0.5 SHEAR I I O-, OI 0 0 LU 1 1.0 -- ---.oF ---- 30.5 10.5 D ETENSION l. Oi j ---- -^ o^ _1.0 — — _ 0.5 0 0.5 < =SHEAR l:~ ~ 5 O^ —- ---— L o —--— L O 0 4 4 LJ VE SMC-R50 z 3-No. 2 DIESELFUEL 3-93C <::'23 C I 2- 2 I 1;_^0ooooO1 oo o o o o LcX o222 2I~9 o 5 01 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 19. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. --- Fick's law solution.

in 1.0 _-_ -- ---— t 1.0o -------— 4_ 30.5- 0.5 z 0 tTENSION I ZI 0= - I- 1 0- - 0- - yo05S 1 05S f I 0.5- 0.5 __: TENSION 10J L- I i I:- 1 I I- I I 0 1.O -------- 1.O4 —------ ]O.5 0.5 LiJ VE SMC-R50 D TENSION30-LUBRICATINGOIL - 9C 502- 2NO.5 0.5 < -SHEAR 0 QI I 5 -~1 10 500 0 200 01 10 50 100 200 O" 41 1 4 VE SMC-R50 z 3- LUBRICATING OIL 3 93C < 23 C 2 21- 1 2 P 001 10 50 100 200 01 10 50 100 200 TIME, days TIME, days Fig. 20. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. --- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

0 ____-_______ CO) -: (? 1.0^ -—, —-- -- }.0' —-- --.5 0.5 - t TENSION z~~ 0.5Qi~~~~~ I - I.I,, 0I I 1.0 -- 1.0 —-- 30.5 l 0.5 < t-SHEAR | 0E-' O I I I l I I 01. LU1.0- _1.0 Q0.5 0.5S_D:TENSION oO O 1.0 4-4 A 1.0 4 - o0.5 0.5 ) 2:: — SHEAR i 5 I 0-I —-I-0 "" 4 4 LU VE SMC-R50 o o I 3- ANTIFREEZE -93 C 3 < 23 C 502- 2 n: 1 OO LLI L__)0C C>C D000(~- oa O (5.9 0 Qooo0or~ B 01 10 50 100 200 01 10 50 100 200 TIME, doys TIME, doys Fig. 21. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. ---- "baseline" data. ~ specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. Fick's law solution.

0l) - I 1.0 o-To —- -— ^- io --------- to 0.5- 0.5-z TENSION Z o I I I I I 1.O —------- 10 ---- -- 0.5 0.5 - < -SHEAR I t I I I0 1 I I I 1 1 1 0o — 09-,-o 0 30.5 0.5 D -TENSION o O-I I I I I I I I o 0.:'0D —------- 1.0 -- 1.0-_ O I Io I I Co 0 I J <.- 0 Z 3 -INDOLENE 3-93C l < 23 C 25- - 9TIME, doys TIME, doys Fig. 22. Changes in ultimate tensile strength, short beam shear strength, tensile modulus, shear modulus, and weight as functions of immersion time. -- "baseline" data. 0 specimens tested after 6 months immersion followed by 3 weeks drying. Bars indicate spread in data. -- Fick'-s law solution. - Fick's Law soluut:on.

Fig, 23.* TYPical failure Surface in tensile tests.

Fig. 24. SEM photographs of "baseline" (as received) VE-SMC-R50 composites (top 57 X magnification, bottom 570 X magnification).

Fig. 25. SEM photographs of SMC-R25 composites immersed in 93C antifreeze for six months (top 57 X magnification, bottom 570 X magnification).