315
Ind. Eng. Chem. Prod. Res. Dev. 1904, 23,315-317
Conclusion
TIME TO RUPTURE ,E
E
i
I
I
I
E
a
imh 2 22
h ‘
I
I
I
i
EPT-10 IN HYDRAZINE
b.7
-g
2 2
,E
m&
0.3-
i 0.2 p: 4 =; 0.1-
Acknowledgment
0-
-0.2
-
-0.3
-
-0.1
This program has demonstrated that the typical elastomer tensile property surface does exist for the EPT-10 and AF-E-332 materials in hydrazine and a method for defining these characteristics has been outlined. Additional experimental work is required to refine the failure curves for long operating times at low-strain levels and to establish the relationship between folding failures and the experimental tensile strain failure limits.
I -
I 4
I -
2
I
I
I
I
0
2
log I$,),
min
I
I 4
6
Figure 6. Tensile strain vs. time to rupture in hydrazine as a function of temperature for EPT-10 elastomer.
in hydrazine. The results of this present program would indicate that failures of EPT-10 could be produced in a few weeks if the tests were conducted at temperatures above 343 K. In this paper, no attempt has been made to specifically compare the performance of EPT-10 with AF-E-332 because the purpose here was to develop and evaluate a test method. Any performance differences which are apparent from these data should be confirmed by additional specific tests that have a more direct relationship to the intended use of the material.
We wish to thank John T. Schell of the Materials Division of NASA, George C. Marshall Space Flight Center (MSFC) Astronautics Laboratory for permission to publish this account. This program was performed by the Propulsion Division of the Jet Propulsion Laboratory under NASA Contract No. NAS 7-100. Registry No. Hydrazine, 302-01-2.
Literature Cited Boyd, W. K., et ai. “CompatlbliHy of Materiais with Rocket Propellants and OxMizers”. DMIC Memorandum 201, Defense Metals Information Center, Batteile Memorial Institute, Columbus, OH, 1965. Couibert, C. D.; Yankura, G. “Survey of Materials for Hydrazine Propulsion Systems in Multicycle Extended Life Applications”, Technical Memorandum 33-561, Jet Propulsion Laboratory, Pasadena, CA, 1972. Landei, R. F.; Fedors, R. F. “Fracture Processes In Polymeric Solids”, B. Rosen, Ed., Interscience: New York, 1964; Chapter 111 B, pp 361-485. Martin J. W.; Jones, J. F.; Meyers, R. A. “Elastomers for Llquid Rocket Propellant Contalnment”, Technical Report AFML-TR-71-59, Part I, Air Force Materials Laboratory, Dayton, OH, 1971.
Received for review August 12, 1983 Accepted October 20, 1983
COMMUNICATIONS Silicon Phosphates as a New Hardener for Alkali Silicate Solutions Silicon phosphates, 3Si02-2PO5 and Si02.P,05, were prepared by calcination of silica gel impregnated with H,PO, at temperatures up to 1000 C and tested as a hardener for an alkali silicate binder. The kind and properties of the products were found to vary with the preparation conditions, and a well-crystallized 3Si02*2P,05 exhibited a high adhesive strength with sodium silicate binder. The most important feature was that the hardened silicate materials obtained in such a system showed sufficient water resistance.
a
Introduction Alkali silicate solutions generally referred to as water glass are extensively utilized as a binder in adhesives (Vail, 1952; Falcone, 1982), and commonly used together with hardeners and fillers. A number of substances such as mineral acids, metal powders, oxides, hydroxides, fluorides, borates, phosphates, etc. are now being employed as a hardener for silicate binders, and the adhesive properties of the hardened silicate materials are found to be predominantly dependent on the kind of hardeners used (Kimura and Motegi, 1976,1982). In general the silicate adhesives have the advantages of being heat-stable, incombustible, and solvent-resistant. However, the water solubility of the silicate adhesives limits their further utilization. Therefore, special attention has been recently devoted to the development of a new hardener or additive which can provide the water insensitivity to the silicate
adhesives (Boberski et al., 1982; Campbell, 1975; Doi et al., 1972; Mclaughlin and Ramos, 1969; Nakajima et al., 1976). One of the present authors has previously shown that silicon phosphates, which were prepared by calcination of silica gel impregnated with a small amount of phosphoric acid at high temperatures, can be used as a hardener, and the hardened silicate materials obtained in such systems show water resistance (Sugawara et al., 1977). Since silicon phosphates were first synthesized by Hautefeille et al. in 1883, some informations about the preparation methods, crystal form, and chemical composition of the products have been reported by earlier workers (Boulle and Jary, 1953; Jary, 1957; Lelong, 1964; Liebau et al., 1968; Makart, 1967). However, no information is at present available on the preparation method based on the calcination process and the chemical properties of the products. In this study, we investigated the relationship 0 1984 American Chemical Soclety
ai6
~nd.Eng. chem. ~ o d RW. . DW.. VOI. 23. NO. 2, 1984
Table I. Adhesive Strength in Shear of the Sodium Silicate Binder Hardened by Use of the Typical Products as a Hardener adhesive strennth ~~~~~~~~
preparation no.
temp, "C
1 2
600
3 4
1000
5
850 850 850
additive
rate of induction hydrolysis, period of mL/min gelation, min
none none none
5% AIF, 5% Na,SiF,
0.29 0.10 0.29
29 46
0.16
~~~~~~
0~~~
after immersion not treated in water kglcm'
R
0.50 . ~.
~
kg/cm'
n
25 -.
0
103
32
30 93 91
46
110
100
0
between the characteristics of the silicon phosphate products prepared by the calcination method and their properties as hardener for the silicate binder. Experimental Section Preparation of Silicon Phosphates. All chemicals used were of reagent grade quality, commercially available. Silicon phosphates were prepared by impregnating H,PO, (PzO,: 63%) into silica gel (200-300 mesh) at a Si02/P,05 molar ratio of 0.5-2.0 and then calcinating the mixture for 1 h at 200 "C and for 0.5 h a t a temperature of 600-1000 OC. Characterization of the product was made by X-ray diffractometry (Rigaku Denki Geigerflex 2013 with Ni filtered Cu Ka radiation, with 30 kV and 10 mA) and scanning electron microscopy (Hitachi-Akashi MSM 4C102). For each set of measurements, the -200 mesh fraction of the pulverized product was used. Hydrolysis Rate of Silicon Phosphates. The hydrolysis rate of silicon phosphates in the silicate binder essentially relates to the induction period of gelation and to the adhesive strength of the hardened silicate material. However, the observation of the product hydrolysis hehavior in the silicate binder was quite difficult. In this experiment the measurement of hydrolysis rate was carried out in a model aqueous solution as follows: 15 mL of distilled water was transferred to an acrylic resin cylindrical reactor and maintained a t 25 "C under nitrogen atmosphere. Subsequently, 0.5 g of the product was added to the reador with vigorous agitation and then 0.05 mol/L NaOH was added continuously to the suspension to maintain the pH a t 10.5. The hydrolysis rate was estimated from the amount of NaOH solution added. Properties of Silicon Phosphates as Hardeners. Three parts by weight of product were mixed intoten parts by weight of a soluble sodium silicate (JIS No. 3; SiOz/ Na,O molar ratio 3.2, SiO, 29 wt %, specific gravity, 1.40) without any fillers, and the induction period of gelation was measured a t 40 O C under a stirring speed of 300 rpm. The adhesive strength measurement was also carried out for the hardened silicate materials obtained after standing a t rmm temperature for 24 h and also after additional immersion in water at room temperature for 24 h following the JIS method, i.e., the testing method for adhesive strength in shear by tension loading. The contacted area between iron and asbestos pieces was 25 mm X 30 mm. Result and Discussion Characterization of Silicon Phosphate Products. Figure 1 shows the X-ray diffraction patterns of the products obtained a t various SiOz/P,05 molar ratios at loo0 "C. It was found that 3SiO.$P,O, (hexagonal,ASTM card 22-1380) was produced at a molar ratio of 2.0, whereas two kinds of Si02.P206(hexagonal, ASTM card 22-1318 and tetragonal, ASTM card 22-1320) were produced together with 3SiOz.2Pz0, a t a molar ratio of 1.0. At a molar ratio of 0.5, the mixture consisting of SiOz.PzO, (hexagonal) and Si02.P205(monoclinic, ASTM card 25-755) was produced. The electron micrographs of the products obtained
S10~1P205:o 5
IO
20
10
20 ldrprrrl
'0
50
cum
Figure 1. X-ray diffraction patterns of the products obtained at loo0 'C.
- 10pm
S i 0 2 / P 2 0 5 = 2.0
5Pm
Si02/P205=0.5
Figure 2. Scanning electron micrographs of the products obtained at 1 w o "C.
at molar ratios of 2.0 and 0.5 are shown in Figure 2 (A) and (B), respectively. The shape and size of the phosphate particles were quite different. On the other hand, no effect of calcination temperature on the crystal form of the product was apparently observed over the temperature range of 600-1000 O C . In the Si0,-P,O, system, it was quite difficult to determine the reaction degree by X-ray diffractometry or chemical analysis. Therefore, the reaction degree was estimated from the hydrolysis behavior in an alkaline aqueous solution given as Figure 3. The ordinate of Figure 3 is the amount of 0.05 mol/L of NaOH added to the suspension to maintain the pH at 10.5. As the addition speed of NaOH solution increases with increasing hydrolysis rate, this measurement was quite convenient to presume the properties as a hardener. It was found that the hydrolysis rate decreased with increasing calcination temperature, whereas those of the products obtained at 1000 "C also decreased with decreasing SiOz/P,05 molar ratio. Adhesive Properties. From the viewpoint of industrial production, the highest possible Si02/Pz05molar ratio is
Ind. Eng. Chem. Prod. Res. Dev. 1904,
-
60
-
50
-
E n
g
40-
0010 2 0
#
I
%
30A 05
J
E
20
0 m
10
'0
20
40
60
80
100
120
Time(min)
Figure 3. Hydrolysis behavior of the products in aqueous solution of pH 10.5 at 25 OC.
preferable. The induction period of gelation and the adhesive strength of the hardened silicate material measured by use of typical products obtained at a molar ratio of 2.0 are summarized in Table I. It was found that the gelation occurred slowly and the adhesive strength increased with increasing calcination temperature. However, the hardened silicate materials obtained in runs 1 and 2 did not show the water insensitivity and were completely decayed during immersion in water. On the other hand, the hardened silicate material in run 3 showed sufficiently high adhesive strength not only in the air-dried state but also after immersion in water. Comparison tests of 3Si02.2P205with conventional phosphate hardeners, such as aluminum phosphate?magnesium phosphate, and zinc phosphate, prepared by the same method as that adopted here, were performed. As a result, the adhesive strength was found to be in the range of 33-46 kg/cm2, but the hardeners used never exhibited the water insensitivity with the hardened silicate materials. Five percent of A1F3 and Na2SiF6were used as an accelerator at 850 "C in runs 4 and 5, respectively. The product was found to consist only of 3Si02-2P205in both runs. The adhesive strength of the hardened silicate material in run 4 was increased remarkably, but no improvement in water resistance was observed. On the other hand, the product obtained in the presence of Na2SiF6 showed the same result as that shown in run 3. Since the fluoride ion produced by the decomposition of these additives attacks the surface of silica gel, the reaction of silica gel with phosphoric acid seems to be accelerated at a lower temperature. It is industrially valuable that 3Si02.2P205 having the same properties such as adhesive strength and water resistance can be prepared at lower temperature by
23,317-320
317
the addition of a small amount of Na2SiF6. Alkali silicate is generally known to produce silica gel during hydrolysis. The potential of providing more water-resistant adhesives by use of 3Si02.2P205as the hardener seems to be due to the hydrolysis behavior in which silicon phosphates produce the same composition, i.e., silica gel together with phosphate ions. As can be seen in runs 3,4, and 5 , the presence of other kinds of cation such as aluminum ion in hardened silicate materials loses the water resistance because of the acceleration of water permeation. Therefore?the realization of a more homogeneous state of the hardened silicate material in the structure and chemical composition is thought to be one of the reasons for the high adhesive strength and the excellent water insensitivity observed here. A detailed study concerning the mechanism of water insensitivity enhancement is currently under way. Acknowledgment The authors wish to thank Professor T. Okabe of Tohoku University for his helpful discussion and Professor K. N. Han of South Dakota School of Mines and Technology for his valuable comments. Registry No. 3Si02.2Pz05,12037-47-7;SiOz-Pz05,56646-32-3; water glass, 1344-09-8. Literature Cited Boberski, W. G.; Seiner, J. A.; Blasko, J. E. Ind. Eng. Chem. Prod. Res. Dev. 1082, 2 1 , 528. Boulle, A.; Jary, R. Compt. Rend. 1053, 237, 328. Campbell, L. U S . Patent 2 715 224, 1975. Dol, K.; Nakajima, J.; Takahashi, H.; Tomokawa, H. US. Patent 3669669, 1972. Falcone, J. S., Jr.. Ed. "Soluble Silicates", ACS Symposium Series No. 194, Amerlcan Chemical Society: Washington, DC, 1982. Hautefeuille, P.; Margottet, J. Compt. Rend. 1883, 9 6 , 1052. Jary, R. Ann. Chim. (Paris) 1057, 2 , 58. Kimura, K.; Motegi, A. Nippon Setchaku KyokaishilO76, 12, 394. Kimura, K.; Motegi, A. Nippon Setchaku Kyokaishi 1882, 18, 116. Lelong, B. Ann. Chi" (Paris) 1964, 9 , 229. Liebau. F.; Bissert, 0.; K6ppen, N. Z. Anorg. A/@. Chem. 1988, 3 5 9 , 113. Makart, H. Helv. Chim. Acta 1067, 5 0 , 399. McLaughlln, H. C.; Ramos, J. US. Patent 3435 899, 1969. Nakalima, J.: Iwai, H.; Momovama, I.; Fukushima, T.; Takeda, R. U.S. Patent 3 930 876, 1976. Sugawara, Y.; Noshi, Y.; Nalto, H.; Maruya, T. US. Patent 4018616, 1977. Vall, J. G. "Soluble Silicates. Their Prooerties and Uses"; Reinhold Publlshing Corp.: New York, 1952.
Mizusawa Industrial Chemicals, Ltd. Chuo-ku, Tokyo 103, Japan
Kazuhiro Sango Shigemi Sat0 Hiroyuki Naito Tomoji Saeki Tsuyoshi Matsushita Eiichi Narita*
Department of Applied Chemistry Faculty of Engineering Tohoku University Aramaki, Sendai 980, Japan Received for review August 1, 1983 Accepted November 21, 1983
A Simple Apparatus for Measurement of Liquid Permeabilities through Polymeric Films A concise description of the evolutionary design of a simple apparatus for measurement of the steady-state permeability of polymer films to penetrating liquids is presented. The cell eliminates inherently leaky polymeric seals (O-rings or gaskets) by using opposing metal O-rings whlch produce uniform deformation and seal of the experimental polymer film by the metal O-rings which are opposing and in perfect register. The permeability cell weighs approximately 125 g, is constructed entirely from off-the-shelf components, and permits gravimetric characterization of steady-state permeabilities by using a conventional analytical balance and a forced-air, constant-temperature convection oven.
Background and Introduction The estimation of permeation rates of liquids through polymeric films is a problem often encountered by pack0196-4321/84/1223-0317$01.50/0
aging engineers. Relatively few data exist to guide the practicing engineer in this regard for typical polymer/ penetrant systems due to the difficulty of performing such 0 1984 Amerlcan Chemical Society
