AD NUMBER CLASSIFICATION CHANGES · CLASSIFICATION CHANGES TO: unclassified FROM: confidential LIMITATION CHANGES TO: Approved for public release, distribution …

UNCLASSIFIED

AD NUMBERAD517602

CLASSIFICATION CHANGES

TO: unclassified

FROM: confidential

LIMITATION CHANGES

TO:Approved for public release, distributionunlimited

FROM:

Distribution authorized to U.S. Gov't.agencies only; test and evaluation; 28 Jun71. Other requests shall be referred toNaval Weapons Center, China Lake, CA93555.

AUTHORITYOCA; Sep 83 IAW Gp-4 document markings;USNWC notice dtd 4 Jan 84

THIS PAGE IS UNCLASSIFIED

FN IFIDENTIAL NWC TP 6187S. COPYI

• o•3-yeew intervals;=isd s6ta 12 years.

Fast-Burning Rate/High SlopePropellant Technology Program

Final Report [U]by

R. L. Lou

and

..j A. Katzakian

Aerojet Solid Propulsion Company (ASPC)Ir for the D D CCu") Propulsion Development Departr,.ent

OCT 18 1971I

Naval Weapons CenterCHINA LAKE CALIFORNIA A SEPTEMIU•Ti e ,DISTRIBUTION LIMITED TO U.S. GOVERNMENT AGENCIES ONLY; TEST AND EVALUATION; 28 JUNE 1971. OIHER

REQUESTS FOR THIS DOCUMENT MUST BE REFERRED TO THE NAVAL WEAMIMMENTER.

$PQNFIDENTIAL•No w

UNCI-ASS1FIED*

ABS TRACT

(U) TWo candidate propellant formtulations, ANB-3394 and ANBi-395-10 were developed that satisfied all the technical goals.

Additionally, these propellants were successfully test fired insmall scale motors verifying propellant ba.ilistic properties, excel-lent liner propellant bonds, and propellant processability adequatefor good grains.

NWC Technical Publication 5187

Published by. .. .............. Propulsion Development DepartmentC6llation . . . ...Cover, 31 leaves, DD Form 1473, abstract cardsFirst printing. .. .. ....................... 240Onumbered copiesSecurity classification . ......................................... NFIDENTIAL

Abstract alone. .......... .................... UNCIASSIFIEDTitle alone . .... .. .................... ..... UNCLASSIFIRD

SECURITY STATEMENT

THIS DOCUMENT CONTAINS INFORMATION AFFECTING THE NATIONAL DEFENSE OF THEUNITED STATES WITHIN THE MEANING OF THE ESPIONAGE LAWS, TITLE 18, U.S.C., SECTIONS793 AND 794. THE TRANSMISSION OR THE REVELATION OF ITS CONTENTS IN ANY MANNER'TO AN UNAUTHORIZED PERSON IS PROHIBITED BY LAW.

REPRODUCTION OF THIS DOCUMENT IN ANY FORM BY OTHER THAN NAVAL ACTIVITIES IS.NOT AUTHORIZED EXCEPT BY SPECIAL APPROVAL OF THIS CENTER.

UNCLASSIFIED

II

UNCLASSIFIEDCOfPJlA

Naval Weapons CenterAN ACTIVITY OF THE NAVAL MATERIAL COMMANDVW . J. Nln irar , R A D M , tjU',, .. .. ..... ........... . ... ... .. ... . Corn r Trn derH . j. . . . . . . . . . . . . .. . . . . . i !( h l( a l D e , to i

FOREWORD

This final report describes work conducted by Aerojet SolidPropulsion Company, Sacramento, California for the Naval WeaponsCenter, China Lake, California during the period 1 May 1970 through22 April 1971 under Navy contract N00123-70-C-1457. This workwas supported by the Naval Air Systems Command under AfrTaskWF 19. 332.302.

M. F. Pickett of NWC was technical coordinator for this programand has reviewed this report for technical accuracy.

Released by Under authority ofRAY MILLER, Head G. W. LEONARD, HeadPropU.Sion ','ys tc(.m ivision Propul.sion Dv., Zopment Department1 September 1971

This miaterial contains informration affect'ingr .- "

tlte national defense of~ the United States -iwithin the rnefn;rg of thme srionage Laws OCT(Title 18, TJS& .'0~on ~3 a'nd 794),the transrai,-:-:r r r,!: .- , of which in _1__.y .. ', ..... , .. d person is

r~~" ,'hvk- " 3.

....... .- -

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UNCLASSIFIED(This page is unclsats;;j)

UNCLASSIFIEDNWC TP 5187

CONT ENTS

Introduction....................... . ....... . . .... .. .. .. .......

Summary.......................... .. ....... . . ..... .. .. .. .......

Technical Discussion. .............................................. 3

Processing and Mechanical Property Studies.............6

Ballistic Studies .. ........................................... 20

Liner/Propellant Bond Studies .. ............................... 31

Hazard Testing of Propellants "A"t and "B".............33

SelecKion of Candidate Formulations .. ......................... 34

Propellant Scale-Up and Grain Preparations. ................... 38

Strain Measurements on Candidate Propellants. ................. 44

Small Motor Test Firings. ..................................... 44

Summary of Properties and Aging Results forANB-3394 and ANB-3395-1. ................................. 50

Recommendations for Future Work. ................................... 50

Glossary of Terms and Abbreviations. ............................... 59

ivi

iv UNCLASSIFIED


IINTRODUCTION

(U) The objective of this 11-month program was to advance thestate-of-the-art with regard to formulation of practical fast-burningand high-pressure-exponent propellants by expanding available technology.

(U) The specific goals were the formulation of two propellants,hereinafter referred to as "A" and "B", with respective burning ratesof 3.5 and 7.0 in/sec. at 2000 psia and a pressure exponent of about0.70. Both propellants were to be formulated to deliver a specificimpulse (j1000) of at least 240 lbf-sec/Ibm with a density of 0.063-0.065lbs/in. 3 . The study also included the development of adequate mechanicalproperties to withstand the temperature range of -40 to 160'F. Otherconsiderations were adequate processing, potlife (4 hrs. @ 135'F), thermaland aging stability and safety characteristics. Only composite propel-lants were to be considered, with porous AP (PAP) and non-volatile ferro-cene derivatives limited to the high burning rate prope)lant "B".

(U) As a final part of the program ten grains measuring 2 in.dia. x 6.25 in. length and four grains measuring 4.8 in. dia. x 15 in.length of each candidate formulation as well as representative samplesof these propellants were forwarded to NWC, China Lake, for furthertesting.

S UMARY

(U) Two candidate propellant formulations, ANB-3394 and ANB-3395-1,were developed on this program that satisfied all the technical. goals.Additionally, those propellants have been successfully test fired in smallscale motors verifying propellant ballistic properties, excellent linerpropellant bonds, and propellant processabilitv adequate for good grains.All required grains have been delivered to NWC, China Lake.

(U) Two propellant formulations, ANB-3361 and ANB-3364, from theprevious high burning rate/high slope program on Contract No. NO0123-69-C-0401 were chosen as baseline formulations. Both baseline formulations,-were processed at the beginning of this program and were found to bedeficient in processing, mechanical, and ballistic pr(Qerties.

UNCLASSIFIED


(U) Improvement in processing properties (viscosity, potlife)was considered to be the key to a successful program because it is anecessity for the processing of large batches for delivery grains andthat: excess processability may be traded for a higher burning rate. Theproblem of short potlife was solved by using a modified form of the pre-polymer R-45M. This modification consisted in blocking excess hydroxylgroups with a monoisocyanate which resulted in a three fold increase inpotlife for ANB-3394. However, ANB-3395-1, the Catocene containing formu-lation, did not show improvement in potlife using modified R-45M untilacetylacetone (HAA) was also added to the formulation. The Feq 4- contam-ination in the Catocene was catalyzing the isocyanate-hydroxyl reactionand the HAA served to suppress this catalytic effect through chelation.

(U) Improvements in propellant mixing and mechanical propertieswere achieved with the incorporation of the functional wetting agent DEOand the bonding agent TEA. These ingredients also made the incorporationof finer oxidizer and burning rate catalysts easier, while maintaining orimproving mechanical properties.

(U) Significant increases in burning rate were achieved by(1) increasing the propellant mix cycle, (2) replacing the 100 N'14C104with 5p NH4 CIO4 and, (3) in the case of ANB-3394, replacing the standardFe 2 0 3 with a finely ground, crystalline Fe20 3 . For ANB-3395-1, thedesired burning rat- was achieved by increasing the Catocene to 4% from3%, and using a more active porous ammonium perchlorate (PAP).

(U) Hazard characteristics of the final formulations were deter-mined in both the uncured and cured states. No unusual processing orhandling characteristics were indicated. One batch of ANB-3395-1, however,having a high Shore reading (74), exhibited high friction sensitivity,but all subsequent batches with shore hardnesses of less than 60 showedmuch greater stability to friction. Both candidate propellants wereclassified as Class "B" explosives by ICC tests.

(U) Two 175 lb batches, one each of ANB-3394 and ANB-3395-1,were processed from which six - 5 x 19 in. phenolic sleeves were castfrom each batch using an improved casting setup; all grains cast werevoid-free by radiographic inspection. Also, void-free gallon cartor.sand DPT specimens were cast from each batch to measure mechanical, bal-listic and bonding properties. This demonstrated that both candidateformulations have adequate processing characteristics.

(U) Reproducibility in mechanical properties and burning rateswere good from batch to batch for each candidate formulation. Afterone month aging at 135°F each formulation showed increases in tensilestrength with small decreases in elongation; burning rates as measuredin solid strands appeared unchanged and liner/propellant bonds remainedexcellent.

UNCLASSIFIED

CONFIDENTIALNWC TP 5187

(U) Several small grains were test fired to substantiate solidstrand burning rates, propellant/liner bond and grain integrity. Initialfirings resulted in erratic pressure--time traces due to aluminum deposi-tion on the nozzles. The following changes were effected to minimizesuch deposition: (1) Increase L* by shortening grain to 3 in., (2) casta 0.25 in. layer of non-aluminized propellant on the main grain to serveas a nozzle warmer, (3) use a contoured boron nitride nozzle, and,(4) change from H-95 to H-60 aluminum. After these changes had beenmade, good motor firings were obtained which verified the correspondingsolid strand burning rates.

TECHNICAL DISCUSSION

(U) The candidate formulations from the previous NWC contractN00123-69-C-04011, ANB-3361 and ANB-3364 (Table 1), were selected asbaseline formulations, respectively, for propellant "A" (ANB-3394) andpropellant "B" (ANB-3395-1). The processing and mechanical propertiesof the baseline formulations were marginal., and since the target burningrates for propellants "A" and "B" for this program were about 20% higherthan the rates for the baseline formulations (Figure 1) we decided tomake improvements in processing and mechanical properties first, andthen trade them off as needed to make the necessary ballistic improve-ments. Also, the work centered largely on meeting propellant "A" goalssince such progress could be readily used to achieve the correspondinggoals for propellant "B".

(U) Since poor propellant/liner bonding was the suspected causeof motor failures in the previous program, early demonstration of goodliner bonds and motor firings was planned and demonstrated.

I(U) Aerojet General Corporation. Fast-Burning Rate/High SlopePropellant Technology Program Final Report 15 March 1969--15 January1971. Sacramento, California.

CONFIDENTIAL 3


(C) TABLE 1. Composition of Candidate FormulationsDeveloped for NWC Contract N00123-69-C-0401

Composition, %

Ingredients ANB-3361 ANB-3364

NH4 Cl4 (0.51)a 50.00 35.00

NH4CI04 (7-100) 19.00 25.00

Porous NH 4CIO4 (18O0) ... 10.00

Aluminum (H-60) 15.00 15.00

Fe203 0.50

BRA-101 0.50 ..

HYCAT-6 .. 3.00

Plastinox #711 0.30 0.10

Agerite White 0.20 0.20

Sulfur ... 0.30

Oronite 6 4.50

R-45M 9.28 1.00

HT-Telagen ... 9.76

TEA 0.04

C-1 . 0.05

IPDI 0.68 0.59

100.00 100.00

aBDB coated, 0.5%.

CONFIDENTIAL

4-

IUNCLASSIFIED

NWC TP 5187

9.08.0 -7.0 - ANB-33646.0

5ANB-3361 S5.0• ... n 0 090

,• 4.0 -

4 . 3.0 -

S2.0

1.0 n

200 500 1000 2000 3000Pressure, psia

(U) FIG. I. Plot of Solid Strand Burning Rates vs. Pressure forCandidate Batches from Previous NWC Contract N00123-69-C-0401.

UNCLASSIFIED 5

.~ . .. .. .

. .


PROCESSING AND MECHAN JAL PROPERTY STUDIES

(U) The problems of poor processing and mechanical propertieswere solved by a combination of approaches involving the use of afunctional wetting agent, that also serves as a bonding agent, incombination with a functionally modified prepolymer and second bondingagent. For the Catocene containing propellant the inclusion of achelating agent greatly increased the potlife. Various otherapproaches to improving processing and mechanical properties wereexplored, some moderately successful and others unsuccessful. Allthe approaches are presented and discussed in the followingsections.

Evaluation of Wetting and Bonding Agents

(U) The addition of diethanololeamide (DEO) into the ANB-3361formulation resulted in greater ease of mixing, a smoother, lesspasty appearance to the propellant, noticeably better castability andmechanical properties, but little or no improvement in potlife. TheDEO approach was evaluated further in conjunction with TEA. The resultsof these studies are summarized in Table 2. Inspection of the tablereveals some interesting trends. For example, when TEA was eliminatedfrom the formulation a loss in elongation was noted although mixing andcasting properties were unchanged. When TEA and DEO were both removedmixing, casting and mechanical properties were all impaired. Havingestablished the need for TEA and DEO, we determined those levels ofeach that yielded optimum processing and mechanical properties.Referring to Table 2 again, a significant upward trend in mechanicalproperties was observed with the stepwise increase of DEP at theexpense of R-45, holding TEA and IPDI constant. Both tensile strengthand elongation increased implying that the DEO was also functioningas a bonding agent. Unfortunately, at the high DEO level the potlifewas extremely short resuJting in poor castability and a poroussample that prevented the measurement of mechanical properties.The data suggest, however, that an optimum level of DEO is about0.2% of the formulation corresponding to in equivalence level between10 and 15. The optimum TEA level is indicated at .02% of theformulation which corresponds to about 5 equivalents. A lowerIPDI level is also indicated since a lower modulus and higherelongation is desired.

(U) The addition of TEA after IPD1 addition in the mixcycle resulted in a slight increase in elongation with a drop intensile strength and modulus (Table 2). This technique has shownincreases in both1 tensile strength and elongation in otherpropellants, but appears here to have simply reduced the effectiveIPDI level by reaction with ammonia released from TEA-N 4CIO 4interaction, since similar results would be expected.

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(U) Although this formulation has responded favorably tobonding agents, the effects were not as large as was expected,We suspected, therefore, that the BDB ccatinp on UFAP may either beinterfering with the bonding agent, or functLon as a bonding agentitself. This hypothesis was tested by comparing 0.9ýi UFAP coatedwith 0.5% Victoria Blue R (a rosanilin dye) against 0.9i- UFAP coatedwith 0.5% BDB. The dye coated UFAP mixed and cast with moredifficulty and gave a lower burning rate at 2000 psia than the BDBcoated UFAP, probably due to differences in deagglomeration rates.

0.9p UFAP 0.9ýi UFAP(0.5% BDB) (0.5% Dye)

rb, in/sec@ 2000 psia 2.92 2.73

(U) Although mechanical properties were not measured, it wasclearly evident that the BDB coated UFAP produced a propellant withsuperior mechanical properties.

(U) An unsuccessful attempt to further enhance the beneficialproperties of DEO was made by adding a non-functional co-wetting agentsuch as lecithin to the formulation. This wetting agent adverselyaffected both the mixing and casting characteristics of thepropellant. No further work with co-wetting agents was conducted.

Evaluation of Alternate Prepolymer and Curing Systems

(U) Because of the short potlife exhibited by the R-45M/IPDIbinder, alternative prepolymer and curing agents were evaluated inthe "A" formulation. However, no significant improvements in processing,potlife or mechanical properties were produced by these systems.

(U) Carboxyl-Terminated Polybutadiene/Epoxide System. The useof HC-434 carboxyl-terminated polybutadiene with epoxide curing agentssuch as ERL-4221 or ERL-4205 did not improve the potlife of the "A"formulation.

(U) R-45M/Imine System. Utilization of the diimine, BISA, as acuring agent for R-45M in the "A" formulation afforded negligiblepotlife and resulted in a hard, brittle propellant mass.

(U) R-45M/Epoxide Systems. The application of ERL-4206 epoxideas a curing agent for R-45M provided a 4 hour potlife at 135 0 F for the"A" formulation. However, a satisfactory elastomeric cure was notachieved. Replacement of ERL-4206 with ERL-4221 in the "A" formulationresulted in a negligible potlife and a brittle propellant.

(U) R-45M/Epoxide/IPDI Systems. The use of various epoxidesin combination with IPDI were evaluated with the goals of extendingpotlife and providing propellant with adequate mechanical properties.With the IPDI held at 35 eq. the following diepoxides were formulatedat the 65 eq. level in the "A" formulation:

8 CONFIDENTIAL


Epoxide Batch No.

None AK-7591-24CResorcinoldiglycidyl ether (CIBA AK-7591-24D

ERE 1359)

Vinylcyclohexene dioxide (Union AK-759]-24ECarbide ERL-4206)

(U) The data from these experiments are summarized in Table 3and show that no significant improvements in potlife or mechanicalproperties were gained from the epoxide/IPDI curing systems.

(U) Cure Retarders. Experience at ASPC in other propellants hasshown that trioctylphosphine oxide (TOPO), phenol and trioctylphosphate(TOF) can be used to extend the potlife of polyurethane propellants.The use of TOPO (0.3%), phenol (0.2%), or TOF (4.5%, as a replacementfor the Oronite 6 plasticizer), however, did not increase the potlifeof the "A" formulation.

(U) Blocked Isocyanate. Blocked isocyanates have been used todelay polyurethane cure reactions. In order to obtain a blockedisocyanate, TDI was combined with the blocking agent, acetylacetone,for 48 hours prior to use in the propellant. However, no increase inthe potlife of the "B" propellant was observed when the blocked TDIwas used in place of IPDI.

(U) Dimerized Isocyanate. TDI dimer was obtained via 4the following reaction.

CH- 0OCN NCO

S. . .. .. >N M2 (C41 9 ) 3 PO (:1{ -(N CH3

NCO Toluene 0

Thp dimer ý,,as formed by blending I mole of TDI In 500 ml toluene with5 drops of tri-n-butylphosphine as the catalyst. The mixture wasstirred overnight and the resulting solid was collected by filtrationand washed well with hexane, The vacuum dried material had a m.p. of154-156'C, identical to the literature value. The I.R. spectrum wasalso in accord with the expected imerized structure, giving a strongisocyanate absorption at 2280 cm- and a strong urea-like carbonyl J

absorption at 1772 cm- 1 . The propellants made with this material gavereasonable potlifes, but cured rapidly to a hard, brittle materialwith poor mechanical properties. (Table 3, #AK7591-17, -24A, -24B)Since no advantage in potlife was demonstrated (Figure 2, #AK7591-24A),and ,ince the resultant mechanical. properties were poor, no furtherwork was done wLth this material.

CONFIDENTIAL 9


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Effect of Plasticizer Type and Level

(U) Because of the much lower viscosity of IDP relative toOronite 6, it was of interest to determine whether or not IDP wouldimprove processing and mechanical properties. Consequently, a batchof propellant "A" was prepared wherein all the Oronite 6 was replacedwith IDP. Although this change resulted in a more processable propel-lant, no improvement was observed in mechanical properties and theburning rate of the cured propellant was adversely affected (Table 4,#AK7591-ll). The decrease in tensile strength was not explainableand may not be a result of using IDP. The depressing effect onburning rate was attributed to the ester group in IDP since suchgroups do tend to give lower burning rates at high pressures(1000 - 2000 psi). Since losses in burning rate could not be tolerated,IDP was not considered further.

(U) Increasing the Oronite 6 plasticizer from 4.8 to 8.6%did not significantly increase the potlife of the "A" formulation(Table 4, #AK7591-52). Moreover, the burning rate and mechanicalproperties were adversely affected by the additional plasticizer.Efforts in this direction were discontinued.

(U) Due to the processing improvements that have been made inpropellant "A" (TEA-DEO system), lower plasticizer levels were evaluatedto see if mechanicai properties could be improved while maintainingadequate processability (Table 4, AK7591-79, -81, -83, -85).Unfortunately, only increases in tensile strength were achieved,elongation remaining constant. Moreover, the propellant viscosityincreased significantly at the lower plasticizer levels as shown inFigure 3. A comparison of viscosity buildup vs. time under a shearstress of 10,000 dynes/cm2 at 120'F is piesented in Figure 3 for threeplasticizer levels. The potlife, measured as time to 50,000 poise,falls off rapidly as plasticizer decreases. Primarily, this is a resultof higher initial viscosities, since the rates of viscosity buildupare similar. Going to higher cast temperatures lowers these initialviscosities, but due to rapid buildup rates, the useful potlife isshortened (Figure 4).

Effect of Aluminum Particle Size, Ballistic Solids And IPDI Level

(U) An enhancement of the mixing operation was realized whenthe coarser 11-95 aluminum was used to replace the H-60 aluminum. Thecastability was also somewhat better, but the short potlife tended toobscure improvements in this area. No significantly adverse effectswere observed on the burning rate.

rb, in/see

PressureAl-H60 Al-H95

500 psia 1.04 1.032,000 psia 2.92 2.86

NOTE: Slope of both propellants 0.74.

12 UNCLASSIFIED


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CONFIDENTIAL


A

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* Oronite 6 (3.5%)

10 * Oronite 6 (4.5%)

0 12 3 4Hours after IPDI Addition

(U) FIG. 3. Effect of Oronite 6 Level on Propellant "A" Viscosityvs. Time at 10,000 dynes/cm2 Shear Stress and 120*F.

1.4 CONFIDENTIAL

_ _ _ - -- * - -- - - ~ - ---- - - - - -~ - - -


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50 0.5 1 .0 1.5 2.0 2.5

flours after TPD1 Addition

(U) FIG. 4. Viscosity Buildup of Candida ~es "A" (110-F, 120 0 F, and

1350 F) and "B" (1.200 F), at 10,000 dynes/cm~ Shear Stress.

UNCLASSIFIED 1


H-95 Al was used until near the end of the program when nozzle depositionwas shown to be a problem in small motor testing. The final formulationsused the finer H-60 Al.

(U) Because of the long interim mix cycle and the coarse aluminumused in these propellants, it was desirable to know whether or not thealuminum was producing any side effects as a result of abrasion. Onebatch was therefore prepared in which the H-95 Al was added after theinterim mix cycle. The daa (Table 5, #AK7591-26) indicate a slightlowering of the burning rate and a somewhat harder cure than is normallyseen. The lower burning rate could be due to less efficient breakup ofthe UFAP particles and the harder cure may be attributed to less reactionof the fresh aluminum surface with the hydroxyl groups thereby allowingmore complete reaction with the isocyanate curing agent. The effect issmall enough, though, to be considered as a normal variation for thispropellant.

(U) Iwo batches were made in which the ballistic solids werelowered by one and two percent, respectively (Table 5, #AK5691-42 and-28). Significant improvements in processing and mechanical propertieswere seen, especially for the 83% solids formulation. The sacrifice inburning rate, however, was too great to give serious consideration tothis appro. "h to improving processing and mechanical properties.

(U) Observation that residual R-45M on the outside of thecontainer eventually formed a polymer led to the speculation thatoxidative crosslinking may be slowly causing a viscosity increasein the R-45M being used. An unopened can of the same lot of R-45Mwas evaluated to see if any differences in processing were apparent(Table 5, #AK7591-56). Although the end of mix viscosity data showno significant differences, due to rapid cure, there was a noticeableimprovement in the mix viscosity indicating that the exposed containerof R-45M had undergone a small amount of oxidative crosslinking.

(U) Since previous work had shown that 70 equivalencs of lPDlstill produced too hard a propellant (Table 5, #AK7365-71) and currentwork (Table 5, #AK7591--24C) showed a significant increase• in potlife

by lowering IPDI, a series of three batches were prepared (Table 5,#AK7591-30, -32, -34) varying the IPDL from 45-65 equivalents.Rotovisco data (Figurc 5) were taken on these batches to determ.;nethe viscosity buildup at each 1I1D1 level. The data indicated that anIPDI level of 55-60 equivalents would be desirable from the standpointof processing and mechanical properties.

Impnroved Potlife With Modified R-45M and Acety lacetoine (I•AA)

(U) No significant increase in the potlife of propellant ''A': wasrealized until modified R-45M was used in place of R-45M. This amodification was accomplished by blocking a portion of the hydroxylgroups on R-45M with a mono isocyanate" , hence, the designation R-45M-25means 25% of the hydroxyl groups are blocked, R-45M-31i mvaos 35% areblocked, etc. Using R-45M-25 resulted in an increase in potlife(Table 6, #AK7591-.76, -70) two and one half times that ebtained with

16 UNCLASSIFIED

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CONFIDENTIAL 19


unmodified R-45M). A graphic illustration of this potlife effect is

shown in Figure 6, where viscosity buildup for the two batches is

measured with time at two different shear stresses.

(U) The desired level of blo,ýking was chosen at 35% (R-45M-35)as a reasonable compromise to achieve reasonable potlife, with adequatecure and mechanical properties. These experiments are summarized inTable 6. Although propellant "A' responded to modified R-45M with asignificant potlife increase, such was not the case for propellant "B".

Assuming that the catalytic effect of Fe-++ contamination in theCatocene was overriding the potlife effect of the modified R-45M,acetylacetone (HAA) was added to the formulation to deactivate thiscatalytic species by chelation. This resulted in a potlife (Table 6,#IOGP-2457) comparable to that achieved for propellant "A" withmodified R-45M. The small drop in mechanical properties noted for the

HAA containing batch was attributed to incomplete cure, since lateraging results have yielded almost identical properties to the "B"formulation without hAA (lable 6, #10(;P-2248). The conclusion was thatILAA has no significant effect other than increasing potlife.

BALLISTIC STUDIES

(U) Because of the previously described processirg improvements,finer oxidizer blends as well as very fine iron oxide were able to beprocessea into propellant 'A", which in combination with a long mixcycle yielded the desired burning rate of 3.5 in./sec at 2000 psia.Likewise the goal of 7.0 in./sec for propellant "B" was very nearlyrealized. In this case attainment of the desired burning rate was madesomewhat less difficult because porous ,.immonium perchlorate (PAP) andCatocene were allowed in the formulation.

Importance of Amount and Particle Size of Ammonium Perchlorate

(U) As in the processing and mechanical properties study, wefelt that any progress made on propellant "A" could be applied towardachieving the burning rate goal for propellant "B". Conventional methodswere used to accomplish this goal, such as increasing ballistic solids

and/or fine oxidizer content. The burning rate data are summarizedin Table 7. As can be seen from the table, the major increase inburning rate was realized whern the 8pi AP (MA) was replaced with uncoated3.1p UFAP. A result that was initially puzzling was derived from the86 and 87% solids propellants wherein the solids increase was due to7-10 All (MA). Neither exceeded the burning rate of the 85% solidscontrol formulation even though they showed an internally consistentrate increase. This was explainable, however, in light of later data(Table 7, #AK7365-71.) acquired on an identical 86% ballistic solidsbatch. The mix cycle of this batch was increased by one hour over theformer 86% solids batch, resulting in a '"7% increase in the burningrate. Apparently the increased mixing time further deagglomerates theUFAP which increases the burning rate.

20 CONFIDENTIAL

CONFIDENTIALNWC TP 51.87

100r2000 = 3.40 ips

90 40 UFAP (0.50i)

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Regular R-4'M (AK7591-70) andl (2)3 Modified R-45M (AK7591-76). I

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22 CONFIDENTIAL


(U) Increasing the UFAP content at the expense of the 7 -li0i AP(MA) also failed to show any increase in burning rate. Again this wasunderstandable, in light of tile effect of mix time on burning rate.Replacing the 8j. AP (MA) of this batch with 1801A AP (unground (Ung)) resulted,however, in a 5-6' lowering of the burning rate. This result coupledwith the rate increasing effect of tile 3.1pi UFAP underscores the impor-tance of the coarser oxidizer fraction in influencing the burning rate.Strangely enough, though, little effect on burning rate was noted ingoing from 0. 4 i to 0.9p UFAP. This either reflects the insensitivityof burning rate to UFAP particle sizes less than 1.0n or indicates thedifficulty in breaking up fine UFAP agglomerates in the sub-micron range.This latter explanation is consistent with the observed effect of process-ing time on burning rate, and significant burning rate increases werelater realized with the finer UFAP and long mix cycles. There doesappear to be a practical limit to increasing the burning rate bydecreasing the particle size of the All since a burning rate of 3.5in./sec at 2000 psia was also demonstrated using a 0.55p UFAP. Evidentlysufficient deagglomeration of the LIFAP does not take place in thissystem to distinguish between 0.40 and 0.55p UFAP.

(U) Using the binder system and some of the ballistic knowledgedeveloped for propellanL "A", a batch of propellant "B' was preparedthat nearly achieved the 7.0 in./sec target burning rate (Figure 7).The ballistic modifications consisted of increasing the O.5w UFAP by 5%,incorporating a more active PAP and replacing ilycat 6 with catocenewhich is believed to be more effective (Table 7, #AK7365-87). Theattempt here was to achieve the desired burning rate without drasticallyincreasing the propellant sensitivity with higher levels of PAP and(atocene than were used in ANB-3364. By increasing the processing timeand making minor ballistic modifications the target burning rate for "B" ,was achieved as shown in the next section. This illustrates howprogress made on propellant "A" was adapted to meeting propellant "B"requirements.

Evaluation and Conparison of Burniný, Rate Catalysts

(U) A significant increase in the burning rate of propellant"A" was achieved (Table 8, #AK7591-93, -75) by replacing the pigmentgrade iron oxide ordinarily used (C. K. Williams, Lot #RY2196) with ared crystalline iron oxide (F. C. Davis Company), a sample of which wasprovided by the Naval Weapons Center. No other effects, adverse orotherwise, were observed with this new iron oxide; therefore, it wasused in all subsequent propellant "A" formulations. This increasebrought to three the number of independently achieved burning rateincreases to date, the other two being achieved by (1) replacing the 81, 4

MA AP with 3 1, UFAP and (2) increasing the length of the mix cycle (seethe previous section). All three factors were combined into onepropellant to yield a solid strand burning rate of 3.62 in./sec at 2000psia (Table 8, #AK7591-1) which exceeded the minimum program goal forpropellant "A". An identical batch prepared to confirm this burningrate (Table 8, #AK7591-19), yielded a burning rate of 3.4 in./sec at2000 psia. Tile reason for the lower rate is uncertain, but may be a

CONFIDENTIAL 23

V CONFIDENTIALNWC TP 5187

Ingredients wt. %

UFAP (0.39m) (0.5% BDB) 40.00AP (MA) 20.00PAP (UNG) 10.00AI-H95 15.00

Agerite White 0.10Plast inox 0.1I0Catocene 3.00Oronlte 6 1.80

R-45M (75 eq) 8.90DEO (20 eq) 0.39TEA (5 eq) 0.02IPDI (70 eq) 0.69

100.00

7.0

• 6.0S5.0 ,

J4.0

n•0.87

=o3.0

2.0

500 1000 2000Pressure, psia

(C) FIG. 7. (Upper) Propellant "B" Formulation (Batch No. AK-7365-87)with (lower) Corresponding Plot of Solid Strand Burning Rate vs. Press.

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result of different testing methods used. In the former batch, thestrands used were exactly 1 inch long and were fired in a closed bomb.The latter batch was tested in regular fashion with standard 5 inch strands.

(U) It was of interest at this time to learn if the sameburning rate achieved with the 50/50 mixture of Silon S and the redcrystalline iron oxide could be achieved or surpassed by using this newiron oxide as the sole burning rate catalyst at the same total percent.The rate achieved (Table 8, #AK7591-5A) did not equal the rate (Table 8,#AK7365-93) achieved by the 50/50 combination of Silon S and the samecrystalline iron oxide. A synergistic effect is indicated by this anddata from another program regarding the effect of Silon S concentration.

(U) To determine just how much the catalyst was contributing tothe burning rate, a batch was prepared in which the 0.41 UFAP wasincreased by 1%, replacing the catalyst (Table 8, #AK7365-81). Thedata indicate that the catalyst system contributes approximately 25%to the burning rate at 2000 psia. However, due to a higher slope, 0.82versus 0.77 for the catalyzed propellant, the contribution increases withdecreasing pressure.

(U) As a possible replacement for Fe 2 0 3 , a solid ferrocene-formaldehyde polymer was evaluated with Silon S (Table 8, #AK7365-51).A lower burning rate and pressure exponent (n) resulted. It appearsthis ferrocene polymer does not dissolve to any appreciable extentin the binder, solution being important if ferrocene compounds are tobe effective burning rate catalysts. To offset this lack of solubilitythe ferrocene polymer was ground to a very fine powder and evaluated atthe 2% level (Table 8, #AK7591-50) to see if it would now approximatethe behavior of soluble ferrocene derivatives, i.e., show a nearlylinear increase with level. Not only did it not significantly increaseburning rate, but it severely curtailed processability and promoted avery rapid cure. A possible explanation for its poor behavior as aburning rate catalyst is its high polymeric nature which reduces itsability to interact with the N 4 Ci10 4 , contrary to the low molecularweight liquid and solid ferrocene derivatives, such as catocene andn-butyl ferrocene.

(U) Having settled on .he red crystalline Fe 2 0 3 as the type ofFe 2 0 3 to be used in propellant "A", a comparison of activity of thesample of crystalline Fe 2 0 3 (Lot 15) from NWC was made with a 10 lb lotof crystalline Fe 2 03 purchased from Frank C. Davis Company to see iflot-to-lot variations existed. No differences in burning rate wereobserved (Table 9, #AK7591-48, -58), but the batch containing the (Lot15) Fe 2 0 3 did process somewhat better. A significant increase inburning rate (Table 9, #AK7591-60) was achieved, though by grinding aportion of the crystalline Fe203 from the 10 lb lot for two hours inFreon using A12 0 3 1/4 inch cylinders for grinding, and a mechanical paintshaker to provide agitation. The resulting powder was much finer thanthe unground material and was redder in appearance; the average particlesize was not determined. The finer Fe 2 0 3 also appeared to function asa better cure catalyst since the data show a shorter potlife for thisbatch.

26 CONFIDENTIAL


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-- CONFIDENTIAL 27


(U) Since the ground Fe 2 0 3 gave a faster burning rate than as-received, an evaluation was made to determine if the concentration of 0.55pUFAP could be reduced and still meet the 3.5 in./sec, burning rate goalat 2000 psia. The data (Table 9, #AK7591-68, -70) indicate that adrop of 5 wt% in this fine oxidizer very nearly meets the desired burningrate. Also, the processability improves very rapidly as the level of0.55P UFAP is lowered. The binder was altered for these batches toprovide a softer propellant, which explains the lower tensile and higherelongation values.

(U) Utilizing the information gained in developing propellant"A", a batch of propellant "B" was prepared (Table 10, #AK7591-54) thatexceeded the 7.0 in./sec burning rate goal at 2000 psia using fourpercent Catocene. Additionally, better mechanical properties wererealized than before, but the Shore "A" hardness was too high and thepotlife was not as long as desired. It was expected that the potlifewould be significantly extended by the use of modified R-45M, but asstated earlier, no improvement in potlife was realized until 2,4-pentanedione was incorporated in the formulation.

(C) Although the burning rate goal at 2000 psia for propellant"B" was exceeded using 4% Catocene and 8% unground PAP, a series ofbatches were prepared in which various combinations of oxidizer blendand Catocene level were evaluated to determine how low in Catocene andUFAP level the desired burning rate could be achieved (Table 10). Thiswas desirable from the standpoint of improving the processing and safetycharacteristics of this propellant. The study revealed that thecatalyst level was significantly more effective than the 0.55p UFAPlevel in raising the burning rate. Also, to improve processing thecoarse NH4 C104 fraction was changed from 5p to l0p average particlesize with a small loss in burning rate. The final choice in Catocenelevel was 4% since hazard tuits showed little change in safety charac-teristics in going from the 3 to 4% level, thus allowing improvedprocessability.

Evaluation of Alternate Metal Fuels, Oxidizer and FluorocarbonPlasticizer

(U) A number of ballistic modifications were evaluated that hadshown ballistic improvements in other propellant systems at Aerojet

Solid Propulsion Co. It was hoped that they might do so with thepropellant "A" formulation, but no advantages were observed and in onecase processing was severely degraded. These modifications are discussedin the following paragraphs.

[ (U) Magnesium and Magnesium/Aluminum Alloy Powders. The replace-ment of aluminum with magnesium powder and a powder consisting of a65/35 magnesium/aluminum alloy showed no improvement in burning rate(Table 11, #AK7591-5B, 5C, 5D). The failure, however, of magnesium toelevate the burning rate was not too surprising, since burning rateincreases observed with this metal powder were in propellants containingvarying amounts of fluorocarbons. The magnesium powder did not adverselyaffect processing, cure or mechanical properties.

28 CONFIDENTIAL

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CONFIDENTIAL 29

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(U) Methylamine Perchlorate (MAP). A portion of the 0.4p UFAPwas replaced with a like amount of unground MAP to see if a significantincrease in burning rate could be achieved. The burning rate achieved(Table 11, #AK7365-89), however, was not quite as good as that for thecontrol (Table 11, #AK7365-93).

(U) Fluorocarbon Plasticizer. An attempt was made to incorporatea fluorocarbon ester into propellant "A" and evaluate its effect onburning rate. This ester was prepared by condensing 216 gms (0.5 mole)of l,l,9-trihydrohexadecafluoro-l-nonanol with 144 gins (1.0 mole) of2-ethylhexanoic acid catalyzed with one gm of conc. H2 S0 4 all in 250ml of toluene. The solution was refluxed for 6 hrs in which time nineml of water were azeotroped oft by the toluene signifying completion ofthe reaction. The toluene solution was washed twice with distilledwater dried over anhydrous MgSO 4 and filtered to remove drying agent.The toluene was removed under vacuum on a rotary film evaporator andthe resultant oil was distilled under vacuum to yield U200 gms of thedesired ester boiling at 107-109'C/3mm 11g. Only half of the Oronite 6was replaced with this material, but it made the propellant difficultto process resulting in a brittle propellant which could not be testedfor burning rate. Since it appeared that significant amounts offluorine could not be incorporated into this propellant system withoutseverely degrading processing and mechanical properties, no furthereffort in this direction was planned.

LINER/PROPLLLANT BOND STUDIES

(U) One of the problem areas identified in the 1969 program wasthe poor bonding between the propellant and the liner which wassuspected to be the cause of motor failures. Therefore, motor testswere conducted early in the current program to demonstrate thatsuccessful tests could be made. In preparation for an early motordemonstration test, promising liners developed on another program wereevaluated with representative propellants of this program.

(U) To measure liner propellant bond, 434-4 liner, both partiallycured and completely cured prior to casting, as well as SD-898 wereevaluated (Table 12). It is noteworthy that the excellent propellant-liner bond was achieved with the 434-4 liner in light of the fact thatgood bonding to I'TPB propellant has been, heretofore, difficult toachieve, especially --ith UFAP containing propellants.

(U) DPT molds were prepared with each candidate propellant usinga modified 434-4 liner. Previous tests had shown 434-4 liner to givegood bonds to these propellants. The modified 434-4 liner also gavegood bonds to these propellants as shown on page 33.

UNCLASSIFIED 31

L. , •.,,W•• ,••- .., .,,.a. JL., •.k .. ,L...... ' .- .±S . . .. •. .,,:... .. ,C ... A s :• . S•.•7..

Vv UNCLASSIFIEDNWC TP 5187

(U) TABLE 12. DPT Line,: Evaluation Using 86% Solidsa

10-lb Batch of Propellant "A".

Liner Cure state Tensile, psi Type of

failure

SD-898 Cured 50.8 Adhesive

434-4 Cured 52.5 Adhesive

434-4 Partially 92.8 Cohesivec u r e db. ..

Liner Formulations

SD-898Ingredients (wt.%)

Sb 0 9.50

2,3

P-33 9.50

Refracil 6.00

Agerite White 2.00

Plastinox 711 1.00

Thixcin E 1.00

ZrAA 1.00

Cr Oleate 0.50

HC-434 63.52

DER-332 5.98

100.00

aBatch No. AK-7365-73.

bCured 4 hrs. @ 135°F.

32 UNCLASSIFIED

I UNCLASSIFIEDNWC TP 5187

DPT Values for Candidate Propellants UsingModified 434-4 Liner at 74.6 0 F

ANB-3394 ANB-3395(lOGP-2213) (10GP-2248)

Tensile, psi 68.9 94.9Type of Failure In Propellant In Propellant

Liner modification consisted simply in reducing the filler concentra-tions to improve the viscosity and flow properties of the 434-4 liner.No changes were made in the polymer composition.

(U) Since this modified liner appeared to be satisfactory, itwas used as the liner for the propellant grains that were prepared and

delivered to Naval Weapons Center as per contractual requirements.

HAZARD TESTING OF PROPELLANTS "A" AND "B"'

(U) Safety data acquired on the propellant "B" formulationcontaining four percent Catocene indicated this propellant had highfriction sensitivity. At three percent Catocene the friction sensitivitywas quite low indicating a less hazardous propellant. Unfortunately,the more sensitive propellant also had a high Shore hardness while theless sensitive one had a low hardness reading, and since frictionsensitivity tends to go up with propellant hardness it was not knownwhether high catocene, high Shore hardness or both were responsible forthe increased friction sensitivity. Since subsequent batches at fourpercent Catocene and lower Shore "A" hardness values did not show highfriction sensitivity it was concluded that hardness level wasresponsible.

Ha-ards Test Data

Propellant "B"

Batch No. AK7591-54 AK7591-74(See Table 10) (See Table 10)

Bureau of Mines Impact

50% Fire Point 1.1 cm/2 kgm

Friction (Rotaryj

Gins load/RPM 400/3000 2000/3000

DTA

Onset of Exotherm 328 0 F ... 49Exothermic Peak 3800 FAutoignition 423 0 F

(U) In selecting the final composition for propellant "B",consideration was given to the hazard characteristics of the two .composi tions from which the candidate formulation was selected. Thedesired composition from the standpoint of processing, AK7591-89,contained 40% 0.5p UFAP and 4% Catocencand it was feared that the

UNCLASSIFIED 33

P ~ 4 ktjif


higher Catocene level of the former would give a less safe propellant.The data shown below, however, indicated little or no differencesbetween the two, allowing the desired choice to be made based onprocessability. In addition, hazard tests were run on the uncuredpropellants to see if any special proceosing or handling techniqueswere required. The data indicated both uncured propellants-were quitesafe to handle in ordinary fashion.

Hazard Tests on Propellant "B"Uncured and Cured

Batch AK7591-87 Batch AK7591-89(See Table 10) (See Table 10)Cured Uncured Cured Uncured


50% Fire Point, 10.0 18.7 11.4 19.2cm/2kg

Friction,Rotary2300 3000 2200 3100

Gms load/RPM 3000 5200 3000 4700

DTA

Onset of Exotherm 329Exothermic Peak, 'F 395 ... 309

Ignition, *F 444 ... 432 ...

(U) Both candidate formulations from 10-lb batches were againchecked for impact and friction sensitivity in the uncured state todetermine possible differences in hazard properties due to scale-up.None were evident from the data.

Safety Tests on Both UncuredCandidate Propellants

ANB-3394 ANB-3395(lOGP-2194) (lOGP-2220)


50% Fire Point 26 cm/2kg 14.4

Rotary Friction

gm load/3000 RPM 2420 3200

(U) I.C.C. hazard classification tests were run on ANB-3394 and-3395 as outlined in TB-700-2. The results (Table 13) show bothpropellants to be Class 'B" explosives.

SELECTION OF CANDIDATE FORMULATIONS

(U) In selecting the candidate formulations for this programthe following criteria were used in decreasing order of importance:(1) burning rate, (2) processing characteristics, (3) mechanical

properties and (4) hazard characteristics.

34 UNCLASSIFIED


(U) TABLE 13. Safety Data, NWC Candidate Propellants

Candidates

A (ANB-3394) B (ANB-3395)

1. Bureau of Mines Impact50% pt., cm/2 Kg. wt. 17.0 13.5

2. DTA Results

Onset of Exotherm, OF 335 328Exotherm Peaks, OF 435 385Ignition, OF 451 428

3. Copper Block

Autoignition, OF 433 368

4. Thermal Stability at75%C for 48 hr. No change No change

5. Detonability with No. 8 Burned in Burned inBlasting Cap 8 sec. 4 sec.

6. Unconfined Burningfor 2 in. cube 9 sec. 4 sec.

7. Friction Rotary, 1750 gin. load 1700 gin.50% point 3000 rpm load,

3000 rpm

8. Spark Gap Test, 50% pt. 3.30 oules 2.70 ioules

CONFIDENTIAL 35


Candidate "A" (ANB-3394)

(U) The final formulation selected for candidate "A" (ANB-3394)is shown in Table 14. The extent to which this formulation satisfiedthe selection criteria is summarized below:

(U) Burning Rate. The desired goal was 3.5-4.0 in./sec at 2000psia. This formulation achieves the low end of this range. Althoughrates higher than 3.5 in./sec have been achieved, too great a sacrificein processing properties was required to make those compositionsfeasible.

(U) Processing Characteristics. A potlife of at least threehours at 120'F was required to successfully scale-up this formulationand cast motor grains. With the use of modified R-45M this minimumpotlife was realized. This formulation had virtually no static flowcharacteristics, but under suitable vibration flow was adequate to castvoid-free grains.

(U) Mechanical Properties. Tensile strengths of 100-150 psi andelongations of 30% were desired. This formulation was low on bothproperties; hcwever, it represented an adequate compromise between formu-lations that achieved the desired tensile strengths but were very low onelongation, and vice versa.

(U) Hazard Characteristics. A formulation was desired thatwould qualify as a Class "B" explosive. This formulation was classifiedas such by I.C.C. tests.

Candic~ate "B" (ANIB-3395-1)

(U) The final formulation selected for candidate "B" (ANB-3395-1"is shown in Table 14. The extent to which this formulation alsosatisfied the selection criteria is summarizcd below:

(C) Burning Rate. A burning rate of 7.0 in./sec or higher at2000 psia was sought for this formulation. The rate achieved, however,is about 4-5% low for this candidate formulation. Rates greater than7.0 in./sec were achieved in other compositions, but again, as inANB-3394, the sacrifices in processing characteristics were too greatto make these compositions feasible. Also, the overall pressureexponents were too high in some cases.

(U) Processing Characteristics. As in ANB-3394, a potlife ofat least three hours at 120'F was required to successfully scale-upthis formulation and cast motor grains. This minimum potlife wasachieved with the use of modified R-45M and HAA. This formulation alsoexhibited static flow and under vibration was more than adequate tocast void-free grains. 4

: (U) Mechanical Properties. Mechanical property requirements

were the same as for ANB-3394. This formulation also fell short of theminimum desired properties, but more nearly achieved them than didANB-3394.

36 CONFIDENTIAL


"(C) TABLE 14. Candidate Formulations, Propellants "A" and "B".

Designation A(ANB-3394) B(ANB-3395-1)

Ingredients wt. % wt. %

NH ClO (0.5p) 45.00 42.00 W.4 4

NH ClO (5p) 24.00 --

NH CO (1011) -- 20.004 4

NH ClO (Porous, 180p) -- 8.004 4

Al-H60 15.00 15.00

Catocene -- 4.00

Fe 0 (crystalline) 0.50 --

Silon S 0.50 --

Agerite White 0.20 0.20

Plastinox #711 0.30 0.30 J1

HAA -- 0.20Oronite 6 4.50 0.30

R-45M-35 (78 eq.) 9.08 9.08

DEO (15 eq.) 0.21 0.21

TEA (7 eq.) 0.02 0.02

IPDI (100 eq.) 0.69 0.69

100.00 100.00

i'i

CONFIDENTIAL37

J

CONFIDENTIALNWAC TP $187

(U) Hazard Characteristics, This formulation was expected toqualify as a Class "B" explosive. I.C.C. tests confirmed thisclassification.

PROPELLANT SCALE-UP AND GRAIN PREPARATIONS

(U) Early in this program an 86% solids version of propellant

"1I"Cwas scaled up to a 10-lb batch si:: (Table in) to determine scale-

upproblems, if any, and to obtain viscosity buildup, liner bonding andgrain casting data. The batch nmixed well, using a mix cycle one hourlogrthan had been used in the 30 mbthstudies,anwsvaumcastable. However, the material flowed only with vibration and had a

veyshort ptfe(Figure 8).Baitianmehiclporydta,weemeasured on this formulation, showing it to have adequate

mechanical properties, but falling about 1%lwi civn hdesredburning rate (Table 16). Subsequent 10-lb batches were notprepreduntil the candidate formulations, ANB-3394 and ANi3-3395...

(ANB-3395-l was alater modification ivvngtheadionf .weeselected. Three 10-lb batches of each candidate formulation were •prepredto provide sufficient propellant to cast 28 phenolic sleeves, :•

2.00 in. dia x 7.00 in. long. These sleeves were lined with modified •434-4 liner that was precured for 1.5 hours at 75 0 C prior to castingV with propellant. Final cure of the liner took place with the propellantK cure after it was cast, which resulted in excellent liner/propellantbonds.

(U) Both candidate propellants were mixed without difficulty,however ANB-3394 had nof- 1ceably better potlife than ANB-3395. Viscositybuildup data (Figure 9) also indicated that ANB-3395 had far lesspotlife than ANB-3394, due to the catalytic effect of catocene acceler-ating the cure rate. This problem was later resolved with the addition ;

S~~of HAA (0.2%) to the formulation, thereby changing the designation to i.i ANB-3395-1. Mechanical properties were measured on both candidate

formulations over the temperature range of 160 to -40 0 F (Table 17)showing good agreement within each three batch set as well as very little

:: variation in elongation over the entire temperature range. However,I ~nearly all the grains cast contained voids as revealed by X-radiography, :! requiring the preparation of additional 10-lb batches to prepare suffi-

cient good grains for delivery to NWC, China Lake. This time, however,casting procedures were modified to assure a higher yield of good grains, iThe modifications included: (1) overcast additional 1-inch, (2) lowfrequency - medium amplitude cast vibration and (3) small stream casting,These changes resulted in a much higher yield of void-free grains, suf-ficient in number to meet contractual requirements.

(U) The scale-up of ANB-3394 and ANB-3395-l to 175-lb batch sizeto cast the 5-in. dia x 15.-in. long grains, was accomplished essentiallywithout problem. All grains and cartons cast were shown to be voIld-~free

by X-radiography. This success was largely attributed to the availabilityand use of casting equipment that allowed all the units to be kept undervacuum throughout the whole casting operation and beyond, while beingsubjected to low frequency - medium amplitude vibration.

38 CONFIDENTIAL_____


(C) TABLE 15. 86% Solids -10-lb Scale-Up BatchOf Propellant lAtla

Ingredients Weight%

UFAP (0.39p)(0.5% BDB) 50.00

AP (MA) 20.00

Al-H95 15.00'1

Fe 0 0.502 3Silon S 0.50

Agerite White 0.10

Plastinox 711 0.10

Oronite 6 4.80

R-45 M (75 eq) 8.01

DEO (20 eq) 0.35

TEA (5 eq) 0.02

1PDI (70 eq) 0.62

100.00

aI

TeTEA was added after IPDI in the mix cycle.

."a

CONFIDENTIAL 3

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UNCLASSIFIED 43


Additionally, multiple small stream casting was used to enablesufficient deaeration to take place.

STRAIN MEASUREMENTS ON CANDIDATE PROPELLANTS

(U) Bore strain measurements were made on both ANB-3394 and-3395-1 candidate formulations. Two sets of four 2 x 3-in, steel straincylinders were lined wich modified 434-4 liner. Each set of fourcylinders was fitted with cores having the diameters 0.5, 0.6, 0.7 and0.8 inches and cast with a candidate propellant. Since 135*F was thecure temperature for both sets, this temperature was taken as the zerostrain temperature. All theýstrain cylinders were then lowered tcr-40'F in discreet temperature intervals for fixed time periods, and thechange in bore diameter was measured at each temperature. These data wereused to measure bore strains. If the propellants survived this cyclingdown to -40'F, they were returned to room temperature and then cycleddirectly down to -40'F. This cycle was repeated five more times oruntil propellant failure occurred, whichever came first. ANB-3395-1survived all the cycles at all the strain levels, but ANB-3394 failedduring the first cycle (Table 18). Inspection of the failure cracksalong the bore revealed that they propagated axially rather thanlongitudinally as is usually the case. They also were found to originatefrom subsurface voids generated during the casting of these cylinders,as a result of poor propellant flow characteristics coupled with

reduced casting volume due to the presence of the cores. It isexpected, but has not been demonstrated on this program that grainsof ANB-3394 would show greater strain capabilities if void free.

SMALL MOTOR TEST FIRINGS

(U) Initial test firings of ANB-3394 and ANB-3395 in 2-in.-diax 6.25-in.-long end burning grains resulted in erratic pressure-timetraces (Figures 10 and 11). Initial deposition of condensable materialon the nozzle was blamed for these results and subsequent firings(Figures 12 and 13) used contoured boron nitride nozzles. Boron nitridenozzles have shown more resistance to deposition than carbon nozzles andcontouring was expected to provide smoother gas flow.

(U) As can be seen from the pressure-time traces, going to con-toured boron nitride nozzles showed some improvement but did notadequately solve the deposition problem. It appears that the coarseH-95 aluminum is not completely burned in the initial phase of thefiring, which in combination with a low motor L* and an unfavorableaft-closure design, causes deposition of condensable species in the

exhaust. The shape of the pressure-time (p-t) trace and level of theequilibrium pressure of these firings, however, indicate that grainintegrity is not a contributing factor to the pressure irregularities.The problem of low L* and consequently low residence time is frequentlyencountered when high r propellant is test fired in motors designed forlow r propellants. The average pressures were calculated from thesepressure-time traces and the resulting burning rates were in good agreement

44 UNCLASSIFIED

I


fI

"(U) TABLE 18. Results of Strain Measurements

C 'V

ANB-3394

Strain Cylinder, no. 1 2 3

Bore Diameter, in. 0.50 0.60 0.70 0.80

Cycles Completed None None None NoneFailure Temp., OF 40 40 20 0

% Strain at Failure 7.2 8.9 8.3 7.1Cause of Failure Void Void Void Void

ANB-3395-1

Strain Cylinder, no. 1 2 3 4

Bore Diameter, in. 0.50 0.60 0.70 0.80Cycles completed 1 2 2 6Failure Temp., OF -40 -40 -40 ...a% Strain at Failure 18.7 15.6 ll. 9Cause of Failure ESC ESCb ESC

Did not fail.Exceeded strain capabilities.

UNCLASSIFIED 45

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with the solid strand rates from the same propellants (Figure 14).F,(U) Subsequent batches were prepared with H-60 aluminum replacingthe coarser H-95 aluminum. This was expected to improve the combustionefficiency of the aluminum and thereby reduce deposition. To increaseL*, firings were made using 3-in, grains. Also, 0.25 in. of a non-aluminized propellant was cast on top of these grains that served topreheat the nozzle prior to ignition of the candidate propellants.Preheating the nozzle was expected to further minimize deposition andignition of the main grain was signaled by a sharp rise in pressure.All these grains (Figures 15-17) exhibited successful motor firings.Some of the grains exhibited progressive pressure-time traces whichcould have been a result of uneven ignition of the main grain by theprewarming grain. Interestingly, one motor fired successfully withoutthe benefit of the prewarming grain (Figure 18), but postfiringinspection of the motors disclosed slag on the nozzle that was notpresent when the prewarming, grain was used. This was interpreted as apositive contribution by these grains towards minimizing deposition.

SUMMhARY OF PROPERTIES AND AGING RESULTS FOR ANB-3394 AND ANB-3395-1

(U) The processing, mechanical, ballistic and liner/propellantbond properties are summarized for ANB-3394 and ANB-3395-1 in Tables19 and 20, respectively. In addition, the results of one month agingat 135*F on these properties are also presented in these tables. Themajor changes brought on by this short aging period were chiefly in the

A mechanical properties. Both formulations showed increased Shore "A"

hardness readings which were probably a result of incomplete cure atthe time of initial property measurements, progressing to final cureduring aging.

(U) The liner/propellant bond properties only showed improve-ment on aging with failure occurring in the propellant, and the ballisticproperties essentially remained unchanged. Solid strand and motorburning rates are presented in Figure 19 for both candidate formulationsand show excellent agreement with each other.

RECOMMENDATIONS FOR FUTURE WORK

(U) We recommend that additional work be initiated to improvethe potlife and mechanical properties of both propellants. Anapproach to improving potlife would be an evaluation of the cure

properties should greatly increase potlife. Further, mechanicalproperties could be improved by lowering or eliminating plasticizer

if sufficient increase in potlife is realized to allow processing athigher temperatures.

50 UNCLASSIFIED I


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3 4 5 6 78910 15 20 30-2

Pressure, psia x 10

(U) FIG.14. Solid Strand and Motor Burning Rate Curves for ANB-3394 (A)

and ANB-3395 (B) Propellant Formulations.

UNCLASSIFIED 51

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(U) TABLE 19. Summary of Initial and Aged Properties of ANB-3394

Processing and Cure Properties

Initial Aged 1 Month @ 135°F

Potlife, hrs. 3.0 ...Shore "A" Hardness 45 52Density, g/cm3 ... 1.719

Mechanical Properties

Initial Aged 1 Month @ 1.35F

160°F 77 0 F OOF -40nF 160°F 77 0 F O°F -40°F

a m psi 43.3 72.5 131 270 59.5 90.2 177 329M) % 18.5 20.8 18.3 14.8 13.2 14.4 14.7 13.0

Eo, psi 275 453 956 2836 477 704 1490 3606

Ballistic Properties


RB1 in/sec

500 psia 1.21 1.161000 psia 2.06 2.002000 psia 3.42 3.30

n (500-2000) 0.77 0.77

Liner/Propellant Bond Properties

Initial Aged I Month 0 135°F

DPT, psi J 69.5 (P 2 break) 92.4 (P break)

2 2!

56 UNCLASSIFIED

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(U) TABLE 20. Summary of Initial and Aged Properties of ANB-3395-1

Processing and Cure Properties

Initial Aged 1 Month @ 135'F

Potlife, hrs. 3.0Shore "A" Hardness 43 47Density, gm ... 1.729

Mechanical Properties


160°F 770 F 0°F -40°F 160°F 77 0 F OOF -40°F

Um, psi 48.5 73.7 151. 367 62.9 88.1. 192 46924.7 25.5 22.8 16.5 23.7 22.8 19.8 14.0

Em, psi 257 383 967 3650 337 528 1435 5123

Ballistic Properties


RB, in/secAi

500 psia 2.18 2.13 V.

1000 psia 3.55 3.492000 psia 6.80 6.81" (500-1000) 0.71 0.72 I"n (1000-2000) 0.92 0.94

Liner/Propellant Bond Properties


DPT, psi 85.3 106.7(P 2 break) (P 2 break)

I..

UNCLASSIFIED 57

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30

25 ANB-3394

0 Motor Firings20

* Solid Strands

15 ANB-3395-1

o Motor Firings

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09

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5

3 P A 3n 0 .7 8

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,, I , , I I I I I I I I I i I , l I I15 20 30 40 50 60 80 100

Pressure, psia x 10-2

(U) FIG. 19. Burning Rate Curves from Solid Strand and Motor RateData for ANB-3394 and ANB-3395.

58 UNCLASSIFIED


Glossary of Terms and Abbreviations

Agerite White Antioxidant

AO-2246 Antioxidant

AP Ammonium Perchlorate

BDB Aerojet proprietary coating agent

BRA-99 Aerojet proprietary combustion catalyst

BRA-1OI Aerojet proprietary combustion catalyst

CTPB Carboxy terminated polybutadiene

DEO Hydroxy functional wetting agent

DOA Dioctyladipate

EDB Aerojet proprietary fuel component

ERL-4205 Bis(2-3-epoxycyclopentyl)ether

ERL-4221 3,4-Epoxycyclohexylmethyl-(3,4-epoxy) cyclohexanecarboxylate

FC-155 Aerojet proprietary fuel component

Freon-113 1,1,2 Trifluoro-l,2,2 Trifluoro-l,2,2 Trichloroethane

HC-434 Carboxy-terminated polybutadiene (Thiokol Chemical Co.)

HDI Hexamethylene diisocyanate

HTPB Hydroxy terminated polybutadiene

Hycat-6 A non-volatile liquid ferrocene derivative

IDP Isodecyl pelargonate plasticizer

IPDI Isophorone diisocyanate

Isonol Phosphorous containing polyol IMA Mikro-atomizer ground ammonium perchlorate

MSA Mine Safety Appliances Co., particle size measuringapparatus, a liquid sedimentation technique

nBF n-Butylferrocene

P-33 Thermal carbon black

PAP Porous Ammonium Perchlorate

Plastinox 711 Antioxidant

R-45M Free radical initiated IITPB

Refrasil Silica Fiber

SS-AP Slow-speed mikro-pulverized ground ammonium Iperchlorate

UNCLASSIFIED 59

UNCLASSIFIEDNWI TP 5187

Glossary of Terms and Abbreviations (Cont'd)

SURFAC OS Carboxy functional wetting agent

TEA Triethanol amine

TEHOS 2-Ethylhexylorthosilicate

Thixcin E Modified 1-hydroxy stearin

UFAP Ultra-fine ammonium perchlorate (<5p)

VEM Vibro-energy mill

60 UNCLASSIFIED

41

UNCLASSIFIEDsc ll%'o1I

DOCUMENT CONTROL DATA R & D

1 1 16 1,1 I t N I_ 4C IV ,fCi Ur. .I tl,, I'' .

SolidPropusionCompay ~ONFI DENT IALAerojet Soi rplinCmay-

/4Final ~ei Ds't- 1 May 07,0 rsa 22 p 71

R.L./Lou 40A.jKatzakian/

Ry .7/

is54 Eý4N 0.-7--15 "*'.--YNWC TP -5187

AirT Wf '9 32.40'2N '4~OTII'LR RE P OR1 0(S) (An iW~f~

'ASPCý ~ r6 -26F7'

10 DISTRIr3UTION STATEMENT

Distribution limited to U.S. Government agencies only; test and evaluation,28 June 19 71. Other requests for this document must be referred to theNaval. Weapons Center.

11 5UPPL viMIN 'A',' NOILI1. 12. PONSORING MILl 1 AIV AC TI VITY

Naval Weapons CenterChina Lake, California 93555

11 AB3STRACT

(U) Two candidate propellant formulations, ANB-3394 and ANB-3395-1,were developed that satisfied all the technical goals. Additionally, thesepropellants were successfully test fired in smallscale motors verifyingpropellant ballistic properties, excellent liner propellant bonds, andpropellant processability adequate for good grains.

DD IIO617

UNCLASSIFIED5/1 010I 807-6801 Secui'tvt ClasifSitatiI)n

_IINCT.A•qTTTSecurity Classification

' 4. LINK A LINK B LINK C!¢,-•KEY WORDS

ROLE WT ROLE WT ROLE WT

PropellantHigh Burn RateFerroceneUltra Fine Ammonium PerchloratePorous Ammonium PerchlorateHTPB

7

'!

DD ,o.,14 73 (B UNCLASSIFIED(PAGE 2) Security Classification

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