1628
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
natural s:implcs.. 111 micrographs of flus-rcilciiid saniplw, I-Iyflo Super-Cel and J3I I, there ~ a ‘ no : eviclcnce of fine struetlit(~. The sample appewed sintered, as indicated by drop-sli:ipt*d portions arid smooth outlinw of all particles. Sonic larger p o r w ~ w r erroded :ind erilargrd until they merged with acljaceiit IIOIYT and all ~ n i u l lpores had disappeared. Speedflon- and 1’s fillcr ~ h o n - i ~more ! fiiie structure than the samplcs j List descrilrc.il, anti thcl degree of sintering and croiion TT:E less. Cnlciucstl ;.;implt: J l I I1 shc?\\-edslightly more structure th:in Speedflo\v o r PS fillvr. The surface :mas, fine structure of clcctron niiwographs, m d diffuscncss of x-ray diffraction p x t t r r n s :ire iii qua lit:^tivc :igrccment for these calcined saniplcs. Adsorption isotherms of naturnl kiesrlguhrs sho\vcd hysi t,rc>his ahovth ri-.l:itive pressures of 0.4, but the isotherm of Ilyflo Super(:el s h o i r c d litt IP, if any, hysteresis in this range. Since p o i w thle in these micrographs (100 h.)~ c r found c iri guhrs but not in the flus-calcined samples, i t may bc inferred that natural kieselguhrs also contain pows sniallc~than 100 .i. in diameter and flus-calcined mstct,i not. This agrees with the current be$f that the hj-atci associated with pores smaller than 100 A. in diametcr. I n many eases the avcrage pore diameters from the r:itio of porv volunie t o surface area (Tahle 111) were of thc s ~ m cortlcr of magnitude as those estimated from the larger pores of ttir micrographs, and for t,he high-area kieselguhrs tlie agrcenitnt n-as very good. This agreement is believed t o be fortuitou:: because: ( a ) the micropore volume was larger than the volumt, of the holes shown in the niicrograph because it, probnbly contained considerable volume between part ides for which t lie pore ‘diameters might be less than 5 microns, the liniit of mercury perletration, and ( b ) a sizable fraction of the area of thc nxtural kitwlpuhrs pr:bably came from very small porcs of diuneters, less than 200 A. as shown in Figure 10; hence the surfnce area vas larger than t h a t observed in t,he micrographs. I n most natural kicselguhrs these effects apparently cancel, :ind the caleulatcd pore diameters approsimat,ely equaled those ohservcd. K i t h highly sintered kieselguhrs the micropore volumes TTei’e not seriously changed, but the surface areas were decreased eonsidaerably o\ving t o remcval of the ultrafine structure. For these
s:~iiiph~s thc: calculated pore radii n v r tliose o t w s r v t d iii the micrographs.
Vol. 39, No. 12 era1 fold larger than
ACI(NOWLEDG>\IEST
,.I
l i t ’ :it11 !1~>1~5 gratefully scknoivletlge the a Sc,lviy ailti 1.’. 11. Gibson for the aiialytical fiir I I ~ I ’ r:iiry-rlcnsit>I tleterniinations, 1Ii-s. IT. C. Peehlcs for tiit, x-r:ty cliffriictinn patternq. a n d IIarlaii IIen-let8tfur prcparatiori ~1 saiuples. .icknowlctlgmcnt is given t o A. It. Bol1:tIii t OF t l i c 1)ic:ilite Company, 1%. L. King, J r . , of Johns-llsnvillt. fi)r lic~lpfuldiscussions, anti Herman E. Rics, Jr., for constru(ai ive criticism of tlie m:inuscript.
L I T E R A T L ~ R ECITED
SO(..for Tc,titig SIaterials. “Data Cards for ILleiitification o n Crysrailine hIatc=rids,” Philadelphia, Pa. ( 2 ) lii.unauer, Deming, Deming, and Teller, J . Am. Chem. SOC., 62, 1723 (1940); Brunauer, p. 150, “Adsorption of Cases and Vnlmrs,” Plinceton University Press, 1913. (3’1 Bi~unnuer,T n i n i e t t , and Teller, 6 .Am. Chem. SOC.,60, 309 (1935). i$ 1 Calvcl t. “Diatomaceous Earth,” X e w Tork, Chemical Catalog fl)
.\in.
co., 1930.
( 3 ) Ettirnett, “Xdrances in Colloid Science,” ed. by Krnemer,
Vol. I, pp. 1-36, Xew York, Interscience Publishers, 1942; Emmett, ISD. EXG.CHEK, 37, 639 (1945). (ii) I. In the more seiere soil burial test, cloth impregnated with ieroteu ga,e the best performance. Whereas the untreated cloth lost all of its tensile strength in less than 7 dajs, a n impregnated cloth containing 5.9% icroteu \I-3 retained all of its strength for the duration of the test of 1L days. ilthough the preliminary experiments presented do not si1 e any indications as to the effectiFeiiess of resin-inipregnation relati3e to other antimildewing treatments, they
. 5’..Irrrij Qtcartermuster
Corps., Philadelphia, P a .
sLigge3t another purpose to which the many Taried re-in
Iweparations can be directed.
P
LL~~LI~IIS.iltY histological investigations ori the pent!tr:ttion of cotton fibers by fungi and Ijaeteria. (3, 4)indicate th:tt tlie orgmisiiis artark fi.r)m the outer surface iii\varcis in a n : t I ) i ) : L w i i t ly highly localized iiianncr. .LccordingIy, it seeins li,yicul to a s u m e t h a t any inert physical barrier preventing the i’uiigi 31111bacteria from coming into intimate contact u i t h the c~~lluliw may protect the cotton fabric against t h e microbio11 altacli. It ~ ~ thought s s that such a microbiologically ant cimtiiig can be applied ill the form of a resin inipregThe prvseiit paper describes preliminary studies in the ii:ition. niildew resist ancc of resin-impregnated clot,hs.
December 1947
I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY MATERIALS AND 3lETHODS
x
I: I
__
+c
Bleached 3.3ounce cotton print cloth was impregnated with resin either with or without p r e v i o u s mercerization. 51erc e r i z a t i o n wis applied without tension. S a m ples 1 to 18 n-ere impre g n a t e d nith diffrrcnt percentages of RHonite and Reslooni resins. The resin solut i o n s were padded on the respective samples, dried, c u r e d for 10 minutes at 300" F., 'and finally n-aehed f o r 3 minute.. i r i t h watcr a t 120' F. For samples 19 t,o 26 he tlifferent, resin forniul a t i o n s were padded on t,he cloth n-ith a load of 8 . 6 t o n s , frame-dried a t 180" F., cured at 3 0 0 " F. f o r 6 minutes, rinsed t h o r o u g h l y in water, then finally dried. A mixture cont a i n i n g 16'; h e r o t e x 450, 0.28% Accelerator 1 8 7 , a n d 0.10% Decerosol O T 2 5 5 was used for samples 1 9 a n d 2 3 . The same c o n s t i t , uents in amount F of 32 $, 0.56C;-, a n d O . l O c c , respectively, mere used for samples 20 and 24. Saniples 21 and 25 were padded Iyith a mixture of 5.3% .kerotex 11-3, 0 . 1 6 5 % .Iccelerat,or 187, O . l O ~ o Decerosol OT 25%, and
1629
7.40% accelerator 190.4. Similarly a formulation containing 11.0% herotes Al-3, 0 . 3 3 5 accelerator 187, 0.10% Decerosol OT 25%, and 7.4% accelerator 190-4 was employed for samples 22 and 26. I n tests for the resistance of the cloth to microbiological attack the samples were ravelled along the direction of the warp to a width of 1 inch and cut t o 6-inch lengths. For pure culture tests the strips were autoclaved for 20 minutes at, 15 pounds pressure, placed one each on the surface of Greathouse formula .I mineral agar ( 2 ) in Petri dishes, and inocul:%tedw-ith a heavy spore suspension of the fungus. riftcr incubation at 8.5" F. aud 8 0 s relative humidity for the indicated number of days, the htrips m r e harvested, exposed overnight t o formaldehyde vapors to kill the fungus, washed ivith t a p water, air-dried, conditioricd at 73" F. and SOY0 relative humidity for 24 hours, and fi~lnlly broken on a Scott tensile strength tester. The decrease in t,cnsile strength of the inoculated strips n-as talcen as a convenient iiitlen of the drgree of microbiological degradation. The organisms used for pure culture tests n-ere Aspergillus $ai,ipes PQllD 24a and Jletarrhizium glutinosum USDA 1334.2. Inasmuch as there may be criticisms against relj-ing solely on pure culture mycological tests as a basis for determining the resistance of fabrics t o microorganisms, the various rcsin-impregnated samples were also subjected t o soil burial tests ( 1 ) . For the latter test the strips n-ere buried at a depth of 1.5 inches in rich garden soil n-ith moisture content adjusted to 32O1 in Pyrex trays. RESULTS
The summarized data on the resistance of the various resinimpregnated samples are presented in Tables I and 11. The data shox a high degree of resistance to microorganisms imparted t o the cloth by the resin impregnations. I n the pure culture tests, while the untreated cloth lost all of its tensile strength, cloths containing 6.4% Resloom, 5.5'z .4erotex, and 5.0% RHonite resins retained all of their strength. Inasmuch as these were the lowest concentrations tried, the figures do not represent the minimum threshold values. A photograph showing the gron-th of .Vetarrhizium glictinosuin on impregnated and nonimpregnated cloths is given in Figure 1. Khereas the nonimpregnated cloth is completely covered with growth, only scant grorvth which did not affect, the tensile strength of the ieloth is evident in the e h t h cmntaining 5C; resins. The large dark splotches on the strips are merely t,he result of wet contact between the cloth and the under support during the photographing. I n the more severe soil burial tests, however, a much higher percentage of resin content was required t o withstand the test. Khercas the untreated cloth lost all of its tensile strength in less than 7 days, cloth containing 6.4% Resloom KC-50 lost 3557, of its strength in 7 days. S o st,rength x a s lost by cloth containing 7 . 4 5 Resloom HP in the same test. For RHonite impregnations a content of 15,OC; resin was necessary before a negligible loss of tensile strength by the cloth was obtained during the 7-day soil burial. The best resistance t o the soil burial test was given by cloths impregnated n-ith Aerotex 11-3 melamine resin. In cloths containing only 5.9", .ierotex AI-3 withstood 1 completely for the duration of the 14-day test. From the data it is not possible t,o conclude whether the resistance of resin-impregnated cloth t o microorganisms m s brought about through a blocking of the cellulose by means of an inert physical barrier, or whether i t is due to the presence of antiseptic compounds in the resins. In the use of resins with a high formaldehyde content the latter cause may contribute t o the final resist,ance of the cloth. On the other hand, unpublished data show the greater susceptibility of depectinized cotton t o microorganisms than raw cotton; this suggests that t'he physical prevention of the organism from making contact with the cellulose may be a very important factor in rendering resin-impregnated
INDUSTRIAL AND ENGINEERING CHEMISTRY
1630
Vol. 39, No. 12
TLRLE11. RESISTAKCE OF CLOTH?IWI~EGSITED n I T I I RESIYSTO MICROBIOLOGIC~L ATTACK hlicrohiological T e s t s l'ninoc i i l a t p i l
Sample 1ier:eriNo. zation
Kesin Ai,plicd
cintrol cloths .iv. tensile strength, lh.
Resin on Clotli
Replications
6 4 6.5 17.8 18 0 7.7 7.4 16.8
9
I l r t n ~ r h i z i u mg l u t i n n s u m . 6 days A T . tensile Loss in strength, strength, Anit. visual growth Ib. %
Replirations
Buried 7 Days 9
Kesloonl YC-50" Resloom NC-50 Reslooin XC-50 Resloom SC-50 Resloom H P Resloom H P Reslooni H P l'rea formaldehydes Urea formaldehyde Urea formaldehyde Kone Sone
10 11 12
13 14 15
16 17 18 27 28
19 20
Ae1ote-r Aerotex Aerotex Aerotex herotex Aerotex Aerotex Aerotex
1;
23 24 25 26 a C
15.4
16.8 7.4 0
0
9 9 9
9 9 9 9 9 9 9 9
32.4 36.3 29.3 32.6 27.1 32.4 32.3 28.9
32.3 30.3 35.3 31.4
Y
9 9
9 9 9 9 9
9 9 9 9
31.2 35.2 31.1 33.7 27.2 31.9 31.7 29 6 29.7 31.1 0 4.0
0 0 0 0 0 0
4 3 0 0 0 2 2 0 8 0 100 87
0
0 0 0
+++-"
-!++!-
0
450c 480 31-3e hI-3 450 450 11.3 11-3
0 22
0 15 0 40 3
4
Buried 14 Days 15.9 50
+-+T ++
4 4
0
I
4
31.2
+A
4 4 3
4
31.7 5.8
32.2 10.4 31.7
0 83 10
64 0 100 0
1Ielaniine resin high in foriiialdehg-de prepared hy hlonsanto Chemical Company. Dimethyl01 urea resin. Urea and melamine resins, respectively, prepared h y the American Cyanamid Company.
iatant t o fungi. Further work is iiecessary, hoivever, befow this and other issues, such as, mildew resistance of resin-impregnated cloth.: can be eettled. in actual ~ i s ( h ,
SUaIMARY
>Iildc\v tests using J l c t a i r h i 2 i ~ i n giutirwsunt and Aspei,yillus vflar'ipes as n-ell aij soil burial tmts nerc conducted on cotton cloths impregnatt:d with urea-formaldehyde and melamine resins. In gonelal, a high degree of resistance t o mirrohiologicnl dqyadation was imparted t o the cloth through the application of resins. Coniplcte Iristaiico t o the pure culture mildew tests vas exhibited by cloths containing 6.4y0 Resloom, 5.5%) .%erotes, and 5.0y0 RHonite rcsins, respectively. I n the more severe soil burial test, impregnated n i t h Aerotex 11-3 cloth gave the gwatcst resistance to degradation. Although the untreated cloth lost all of its tensile strengt,h in less than 7 days, a sample containing 5.9yc Aerotes 11-3 retained all of its strength for the duration of the 14-day test. ACKNOWLEDGMEST
This iiivestigat,ion was conducted at, t,liit suggestion of Lt. Col. Frank Steadinan. The authors are also grateful t o Rohm & Hans Company, hlonsanto Chemical Company, and hmerican Cyanamid Company for supplying fabrics impregnated with IEHonit,e, Ilesloom, and Awetes, respectirrly. LITERATURE CITED
(1) Bertolet, E. C., din. Soc. Testing Materials
Symposium on Mildew Resistance, March 1941, p. 23. (2) Greathouse, G . A . , Klemme, D. E., and Barker, COURTESY
A-0 RESIN
Control
Inoculated
PHIL&DELPHIA QUARTERMASTER DEPOT A h D R O H M B H A A S C O M P A N Y
5 % RHONITE609
Control
Inoculated
5% RHOVITEQJ85 Control Inoculated
Figure 1. Effect of Resin Impregnation on TkIercerized (above) and Unmercerized ( b e l o w ) Bleached Cotton Sheeting to Metarrhiziccrn glutinosum
H. D . , ISD, F A G . CHEX.,dh-AI,.ED.,14,614 (1942).
(3) Marsh. P. B., and Butler, M. L., IXD. ENG. CHEM., 38,701 (1946). (4) White, W. L., and Sanderson, K., unpublished data (1945). RECEIVED September 26, 1946.
