I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
356
and 35 to 50% b e t t e r scorch r e si s t a n c e than cyclohex ylbenz ot h i a zy luulf e n amide. Physical p r o p e r t i e s were equivalent to the c yclo hexylbenzo30: ’ 2 ’ 4 ’ 6 ’ ’ IO ‘ ! L t h i a zglsulfenamide control. This accelerator can be ueed in I E I conjunction with a secondary accelerator, resulting in lower accelerator costs with so 2 4 6 8 IO 12 essentially no HOURS AT 212 F. change in physFigure 7. Storage stability of ical or processing comDounded stocks properties. 0 0 . 7 part MeitBuSD per 100 In natural 0 0.8 part MeitBuSD per 100 0 1.0 part CHBTS per 100 r u bber, good A 1 . 2 5 parts CHBTS per 100 physical prope r t i e s a n d excellent scorch are obtained. When a stabilized urea complex is used as a secondary accelerator, excellent aging resistance is attained. Fully compounded stocks possess good storage stability, suggesting the desirability of N,N-dirnethyl-te~t-butylsulfenyl dithiocarbamate in camelback. Tire test data indicate that tread compounds accelerated with N,N-dimethyl-led-butylsulfenyl dithiocarbamate and cyclohexylbenzothiazylsulfenamide give essentially equivalent road wear performance.
--
Q
Table V.
Vol. 47, No. 2
Comparisoii of Tread Wear Ratings
MeltBuSD DPG CHBTS Abrasion index
98
100
97
100
ACKNOWLEDGMENT
The authors wish to thank their associates in the Research Compounding Laboratory for help provided in developing the data; C. 0. Himel and L. 0. Edmonds who conducted early work in this field, J. E. hlahan who supervised the synthesis of ? h e compounds, and W. B. Reynolds and P. G Carpenter €or their helpful suggestions in preparing this paper. LITERATURE CITED
Mliger, G., and Harrison, S. R., I n d i a Rubbey W o r l d , 123, 181
(1950). Chalmers, D., I b i d . , 121, 51 (1949). Holbrook, F. L., and Hunter, B. A., Ibid., 119, 208 (1948). Hunt, Madison (to E. I. du Pant de Nemours & Co.), U. 5 . Patent 2,390,713(Dec. 11, 1945). Schulze, W. A., Short, G. H., and Crouch, W. W.,IXD. ESG. CHEY.,42, 916 (1950). Shearer, R., Juve, A. E., and IIusch, J. H., India Rubbe? W o ~ l d117, , 216 (1947). Sperberg, L. R., Bliss, L. A., Svetlik, J. F., and Tschirley, N. K., “Compression Set as a Relative Xeasure of State of Cure,’’ Division of Rubber Chemistry, 110th Aleeting, AM. CHEM. S O C . , Chicago, Ill., 1946. Throdahl, M. C., and Harman, AI. W., IND.ENG.CHEM.,43, 421 (1951). Wolf, G. hI., Deger, T. E., Cremer, H. I., and deHilster, C. C., I b i d . , 38, 1157 (1946). Wolf, G. ill., and deHilster, C. C., Rubber Aye, 67, 193 (1950). RECEIVED for review ilpril 21, 1954. ACCEPTED September 17, 1954. Presented before the Division of Rubber Chemistry, AMERICAN CHEMICAL SOCIETY, Louisville, Ky., April 14 t o 16, 1954.
CORRESPONDENCE Thermal Conductivity of Granulated Beds SIR: Dr. Strickler’s ( 4 ) communication regarding a thermal conductivity equation for granulated beds pointed out the scarcity of data with which to check his relations. I n discussing that communication, Dr. Schneider ( 3 )suggested that certain experimental difficulties would be avoided if liquids were employed in place of gases as previously used. Having made a few measurements with liquids (or rather gels), I would like to show that these indicated agreement with the general equation.
Table I. Compariso,nof Experimental and Calculated Thermal Conductivities weight System Gel alone Gel with copper powder Copper powder Copper powder Copper powder Graphite powder Graphite powder Glass spheres Glass spheres
F‘rrtntinn .-. ...-
Solids
o.io6
0.500 0,638 0.733
::%} 0.112 0.382
System Conductivity. powder B.t.u./Hr., Sq.Ft.S(O F./Ft.) Xhdian ExDeriCaloulaDiameter, p , m&t tion
3:i 3.3 3.3 3.3 9S.570 pass a 200-mesh
screen 35
35
0.429 0.429 0.638 0.693 0,902 0.501 0.890 0.436 0,449
0:435 0.554 0.694
0.842 0.504 0 .Si5 0.437 0.465
The apparatus, technique and complete data concerning these measurements are presented elsewhere (1, 2). I n these teEts the ’ agar solid material was dispersed in water to which 2 weight % was added. The resulting gel prevented sedimentation, convection currents, and the necessity for contact among particles. Therefore, the conductivity of a two-phase system instead of a granulated bed was measured and Fz of Strickler’s development would be expected to be nearly zero. If Strickler’s F1is assumed to be 1, the measured conductivities may be compared with those calculated by Strickler’s Equation 1. Such a comparison is prel and confirm sented in Table I. The results indicate F1 t o be e the adequacy of the basic relation for simple systems. LITERATURE CITED
(1) Orr, C., Jr., Ph.D. thesis, Georgia Institute of Technology, 1962. (2) Orr, C., Jr., and DallaValle, J. M., Chem. Eng. Progr. Symposium
Ser., No. 9 (1954). (3) Schneidcr, W. G., IND. ENG.Cmmr., 46, 828 (1954). (4) Strickler, H. S., I b i d . SCHOOL O F CHEXICAL ENQINEERINQ OF TECHNOLOQY GEOBQIAINSTITUTE ATLANTA, GA.
CLYDEORR, JR.
