TECHNICAL REPORT* 72-35-CE

FEASIBILITY STUDY TO UETERMINE THE FLUORINECONTENT IN QUARPEL7TREATEO FABRICS BY ANALYSIS

WITH A 14 MeV NEUTRON ACTIVATION SOURCE

b~y

Forrest C. Burns

U. S. Army Materiais

Mechanics Research CenterWafertown, Mass.

andIHubertmna D. Hogan

8J I M, landGil M. DiasI

S .81 Army Notick Laboratories

Approved for public release; Natick, Mass.

distribution unlimited. March 1972

Clothing & Persona Life Sulport Equipment

SLabrtorya

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U. S. Army Natick Laboratories I UNCLASSIFIEDNatick, HA 01760 Zb" CROUP

REPOPT TITLE IFeasibility Study to Determine the Fluorine Content in Quarpel-Týeated Fabrics by

Analysis with a 14 MeV Neutron Activation Source

4 DESCRIPTIVE NOTES (2~p. ol tep t oa;d Inclusiv'e dates)

-•AUIN ORISI (FIirs nam.. mlddie In~tle.ll ast~ ncse)

Forrest C. BurnsHubertina D. IloganGil _. Dias

6 REPORT OATE 74. TOTAL NO 0PA 17b. No or s

March 1972 .IA 2 -*A. CONTRACT OR GRANT NO 9a. OIIIGINATOR° IMPORT NULATIER451

S. P-0JEC T NO. 72-35-CE(TS-181)

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U. S. Arm Natick Laboratories •4

Natick, HA 01760

A study was initiated on an Army-developed water-and oil-repellent fabric knownas "Quarpel" containing a fluorochemical component critical to the performance ofthe finished fabric. To analyze for fluorine content, Quarpel-treated fabrics weresubjected to neutron activdtion. This techpique of exposing a fabric to neutronsfrom a 14 MeV accelerator has not bee. previously reported. Fluorine content ofthe treated fabric thus can be measured before and after laundering or dry. cleaningand correlated with other physical tests to indicate the durability of the'fabric treatment.

Details8 Of 11hJ,qra1'o- ,this doci::nt .-i t T ina bz ,.!e

-ptueiod on microfiýhi

ths oC 3: .1 ,. .. . . .ttd

473. D P'OR0 147I'D I JAR 04. WHICH is

, I .147R uT- UNCLASSIFIEDS•curitv ClIaslifiation

UNCLASSIFIEDSe urity C:nssffication

KFY WCROS LINK A LINK a LINK CROL V WT ROLE WT ROLE WT

Feasibility Studies 8Measurement 8,9Fluorine 9 7Textile Finishes 9 9,1Quarpel 9 9,4

Neutron Activation Analysis 10Waterproofing 4Oil Resistance 4Protective Clothing 4 4Physical Tests 8Laundering

6Drycleaning 6

UNCLASSIFIEDScurit Classification

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TECHNICAL REPORT

72-35-CE

FEASIBILITY STUDY TO DETERMINE THE FLUORINE CONTENTIN QUARPEL-TREATED FABRICS BY ANALYSIS WITH A

14 MeV NEUTRON ACTIVATION SOURCE

by

Forrest C. BurnsU. S. Army Materials and Mechanics Research Center

Watertown, Mass.

and

Hubertina D. Hogan and Gil M. DiasU. S. Army Natick Laboratories

Series: TS-181

March 1972

Clothing and Personal Life Support Equipment LaboratoryU. S. ARMY NATICK LABORATORIES

Natick, Mass.

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FORVARD

This project is a joint effort conducted under the ProductionEnginering Program, *New Aplaications for Quarpel. Quarpel-treatedfabrics were prepared at the U. S. Army Natick iaboxatories prior towanyysis for fluorine content using a 14 NeV neutron acceleratcr atthe ArM Materials and Mechanics Research Center, Watertown, Msss.2he co-authors of this report, Mrs. Hubertina D. Rogan and Mr. GilDias of NLABS., performed the laboratory work with the guidance andassistance of Mr. Forrest PBrnsq the principal author and member ofWatertow's Materia~oa Science Division.

The authors witih to acknowledge the cooperation of Dr. RichardN. Macnair, Textile Research and •iieering Division, NLABS, in thepreparation of this report.

iii

,II

CONTENTS

Page

I,st of Tables V`

List of Figures

Abstract Vi

Introduction 1

Technique 2

Experimental 3

Apparatus 3

Procedure 5

Resuits 5

Evaluation of Untreated Fa!xi4 5

Determination of Positron E-itters in Quarpel-Treated Fabrics- 6

Evaluation of Treated, Laundered, Extracted,and Weathered Fabrics 7

Determination of the Hoogeniety of iluorine-Containing Polymer in Ca.ex-ciaiy Treated"Fabrics 8

Discussion 10

Conclusions 11

References 11

i

LIST OF TABLES

Table Page

I. Possible Nuclear Reactions induced in Quarpel-Treated Fabrics by 14 MeV Neutrons 2

II. Reproducibility of Fluorine Analysis 8

III. Percent Fluorine Content of Quarpel-TreatedFabric Samples Containing Two DifferentFluorochemica-s 8

IV. Fluorine Content of Fabric Treated with TwoConcentrations of Fluorochemical B 6

V. Fluorine Content of Fabric Treated with Fluore-chemical A, Initially and After Laundering andWeathering

Vi. Fluorine Content of Commercially Treated QuarpelFabrics9

LIST OF FIGURES

Figure

1. Nleutron Activation Accelerator with Sample -rra-diation Holders in Position

3. Sample Holders fo7L- Counting T7rradlated Sarples 5

4. Gamma Ray Spectra Show•ing the 0.511 NeV Pocsi-LonAnnihilation Peak 6

5. Exponential Decay Curve Showing Two DifferentPo-itron Emitters with Half-lives of i0 and 109Minutes 7

t4

3ý

r

ABSTRACT

I

A study was initiated on an Army-developed water-and oil-repellent fabric known as "Quarpel" containing a fluorochemicalcomponent critical to the performance of the finished fabric.To analyze for fluorine cnntent, Quarpel-treated fabrics weresubjected to neutron activation. This technique of exposing afabric to neutrlsns from a 14 MeV accelerator has not been pre-voac.•y reported. fleuorne content of the treated fabric thusc&u be musved before an( after Thundering or dt cleaning andcorra•, zo *b ot:r phsical tests to indicate the durabilityOf W,.cbJ treatgont.

.:J

Vis

_

INTRODUCTION

In 1960, personnel of the U. S. ArsW Natick Laboratories developed adurable water-and oil resistant treatmentU5 or textiles to provide betterenvironmental, protection for the soldier 1.. This treatment, calledQuarpel, is a combination of a quaternary pyridinium salt and a fLuorinecontaining polymer applied in a single bath system. Comparative datashowed the superior performance of textiles treated with Quarpel as com-pared with the standard water repellent finishes then in use. Severalvariants combining different quaternary compounds and fluorine-containingpolymers have since been explored and approved as Quarpel type systems

. meeting the essentia4 requirements established for the Quarpel label.

A series of tests were devised to evaluate the effectiveness of thesevarious Quaipel treatnents. These tests include spray rating, Sater Hydro-static, dynamic absorption' rai*lroom simulated rainfall at an inte+sityof 1 "/hour and oil contact a&gle ratings before and after laundering ofthe treated textile.

While these tests provide quite complete information on the durabilityand effectiveness of the Quarpel treatment, a need has been felt for asensitive analytical method that can reveal the fluorine and nitrogen con-centrations on fabrics that have undergone various degradative estso Anon-destructive test technique is preferred since it would permit nontinuedmonitorship of a given specimen through a whole sequence of p_•ocesses andstill allow other non-destructive analytical procedwres to be made aftereach process. Chemical analysis ana-physical test data could thus be con-pare4 effectively on the same specimen. This, of course. is no) po•ssblewith currently used wet chemical analysis techniques.

As a result of discussion with scientists at the U. S. Arui Materxialsand Mechanics Research Center, the use of neutron activation analysis wasselected since there are no obvious interfering nuclear reactians CTabie I)j,and a system especially designed to ana]; fze inh ageneous samples such as

rpel treated fabrics was available.V/ Fluorine analysis was set asthe&primary goal since a large amoint 'o nitrogen was already pre.sent insome of the fabrics to be analyzed. This was the basis for the ,-•erativeeffort, the resuits of which are reIorted herein.

o.I,

TABLE I

Possible Nuclear Reactions Induced in QuarpelYreated Fabrics by l4 MeV Neutrons

Najor Elements Natural l4 ReV NeutronPresent Isotope Reactions Half-Life

Nitrogen N-14 Nl 4(n,2n)N1 3 10 min.

Carbon C-12 none --

C-13 none --

Hydrogen H-i none --

H-2 none --

Fluorine F-19 F1 9 (n,2n)F1 8 109.5 min.F1 9 (n,p)O19 29 sec.

Oxygen 0-16 01 6 (n,p)N1 6 6.1 sec.

TECHNIQUE

The technique of performing an activation analysis is based on theequation:

XtA oa N(l-e )

where

A = number of counts produced by neutron bcobardsent

o = nuclear cross section of the reaction in barns

= neutron flux in neutrons/cm2 /sec.

N = number of atoms of the isotope involved in thenuclear reaction

(1 - e-•) = saturation factor based on the half-life of theisotope be!ig produced

A= product decay constant

t irradiation time (see)

Actually, by irradiating a standard of known elemental concentrationin conjunction with an unknown, o, * and (1 - e--t) can be cancelled out bysaying that the number of counts produced are directly proportional to themolar isotopic concentration of the sample as follows:

2

Ax VxA2 -2

where

- of atoms X S isotopic abundanceMolecular wt. x 6.023 x 1023 atoms

When this equation is modified to apply to this study it becomes:

%F of Standard X wt. of Standard %F of Smple X wt. of SampleCounts on Standard Counts on Sample

or:

%F of Sample = 2F of StandaWd X wt. of Standard Counts on SmpleCourts on Standard wt. of Sample

EXPERIMENTAL

Apparaltus.

The 14 MeV neutron source used in this work wa a Kaman NuclearA-700 Sealed tube unit with an output of approximately 6 . 10 IL neutrons/second. The complex irradiation system has been described in detailelsewhere2V, but the accelerator is shown in Figure 2., with the sampleirradiation holders in position. These holders are fabrica-.ed f.ompolyethylene and have a diameter of 0.35-inches and a length ol16-inches(Figure 2). Subsequent to irradiation the samples were taken -from heirradiation holders and placed in special counting holders (rigure 3),measuring 1-inch x 7/8-inch x 9!16-inch. The amount of activa-.ion wasdetermined by placing the held sample on a 3-inch X 3-inch Nai "l)well-crystal* with a Nuclear Data 130A Multichannel Analyzer.

• Thal~li-activated sodium iodide crystal.

3

"I

PI

Figure 1 - Neutron Activation Accelerator with SampleIrradiation Holders in Position

Reproduced frombest available copy. +0

Figure 2 - Sample Irradiation Holders

Figure 3 - Sample llo:lders for Counting Irradiated Samples

Procedure

Samples of the fabric and teflon tape were cut 1-inch x 7/8-inch sothat identical geometric shapes were obtained, placed collectively in theirradiation holders, and irradiated simultaneously for a total of 6 minutes.The fabric sample and the teflon standard were then placed in individualcounting holders and the amount of irradiation in each 0eteripined over aSminute period on the NaI(T1i) crystal. The fluorine in the sample wasthen calculated according to the modified equation given in the TechniqueSection. The theoretical fluorine content of the teflon tape was used asits actual fluorine content.

RESULTS

"Evaluation of Untreated Fabric

Initially untreated fabric samples were irradiated to determine ifthere were any interfering radioactive nuclides present. The spectra fromthese samples showed only a positron emitter of 10 minute half-life (Figure4), indicating the presence of nitrogen, an element known to be in fabricseither as a component thereof (nylon), or in applied treatments (dyestuffs,urea, quaternary nitrogen salts).

I

Positron Jkhi lation PIei

Determination of Positron Wutters in Tureated Fabfric

Samples of Quarpel treated fabric were then irradiated and theamma ray spectra obtained showed only a O.ýl 1 14eV peak on the Nr~lear

D~ata 130A ?Iiltichanmel Analyzer. This indicated only positron euittersto be present. Further studyr of the exponential decay curvb (Figure 5)yielded a composite of two ccnponentd hav~g haif-l-ifes of 10 minutes,and 109 minutes; nitrogen 13 and fluorIne, respectively, Since fluoriiewas the primary interest., -the nitrogen 13 was aflowed to. 41eca out; aperiod of 2 hours was found to be adequate.

I -3

!)

Poito A.iiainPa .. .

z ! :.De ~ tign f Positrn E•. er in rae ar~

Composite Curve

1.,,2. 0 main . : "

\ •

0 ;30~ 60 9D 120 150 ISO 210, Minutes

Figunre, 5 - E:onential D6cay Curve 'Sho-wing Two DifferentPositron Ebitters with Half-lives of 10 and 109 1Minutes

Evaluation. ofTreated, Laundered, ]ktracted and Weathered Fabrics

oye'ster/cotton" poplin, 5.7"oz/y*d2 , Cadet Grey 345 fabric was treatedin a finishing plant under controlled conditions with two'of the accepted fluo-ri•e-containing polymers (Product A and Product B). Samples of these fabricswere used to determine:

A. Eeproducibiliy of the fluorine analysis.The sample used for this vas treated with Product B and the

'results obtained are listed in Table II.

B. Comparison of the change in fluorine cbntent, of treated fabric contain-ing ProductsA and B, initially aqd after laUndering and chloro-.

form extraction, (Table III). ,

' The fluorine content of fabric: reated with 19.0% and 22.8%fluorochem5.cal B, (Table IV).

D. •The fluorine content of fabric treated "i-th fluorochemical A,initially and after laindering and weathering (Table V).

7 a

'.

a I* I

-. , * - - - -- _ _ _

"Determination of the HomogeneIty of Fluorin8-con2tain:ng Polyerin Commercialy3 Treated Fabrics.

Fouz different fabrics were drawn fram the Defense Personnel Supportcenter: (1) 9 oz/yd2 Nyco-sateen; (2) 5.5 cz/yd2 cotton oxford; (3) 5.5 oz/yd2

cotton warp-nylon fill oxford; and (4) 5.7 oz/yd? cotton/polyester poplin.These materials had been procured by the ArmW as Quar•pel treated fabrics butno further knowledge was received as to their history. The hoimogeneity wasstudied by following the fluorine concentration along the width (fill direc-tion) on the first two fabrics and along the length of the last two fabrics(warp direction). The results are shown in Table VI.

TABL II

Reproducibility of Fluorine Analyses

% Fluorine Variation

6o.64 +0.02 I0.59 -0.030.62 0.000.62 0.00

TABLE Mf

Percent Fluorine Content of Quarpel TreatedFabric Samples Containing Two Different

Fluorochemicals

Moica D~tlial, Lundered r Etracted

A 0.72 0.68 0.44

B 0.70 0.75 0.63

TABLE IV

Fluorine Content of Fabric Treated with

Two Concentrations of Fluoroche.ical B

19-0A Fluorochenical B 22.8g Fluorochemical B

o,6% 0.70%0.59% 0.73%-0.62;% 0&29%

Avg. 0.62% Avg. 0.71%

8-

. . ,

MIT .. .7 ...77,• • .•

TABIB V

Fluorine Content of Fabric Treated with Fluoro-chemical A, Initially and After Laundering and

WeatheriL,

Initial Laundered mosure (Dys)I18 4j2 60o.61% o.56% 0.63% 0.53% 0.65%

Fluorine Content * of Couaer.iall Treated Quapel

Fabrics

Fill Direction left Bad Center ight gnd

Nyco/sateen, 9 oz/yd o.01 0.55 0.42

Cotton-oxford, 5.5 oz/yd2 0.78 0.65 0.55

Warp Direction

Cotton Warp-Nylon Filloxford, 5.5 oz/yd 0.6? 0.5 02

Cotton/Polyester poplin5.7 oz/yd2 o.41o 0.56 0.58

• Measurements made at a minimum of 18 inches apart and atleast 3 inches frum the selvage.

9

DISCUSSION

Neutron activation analysis as applied to Quarpel treated fabrics isa new analytical tool. It is a fast, non-destructive method for deter-mining the fluorine content of such fabrics. Results obtained on theAMRC unique nuclear irradiation transfer apparatus are highly reproduc-ible (Table II). Two of the presently acceptea fluorine-con poly-mers were used in the Quarpel formulations and compared (Table III .Equal fluorine concentrations were found on both treated samples beforeand after laundering. However, the sample containing Product A showedgreater loss of fluorine when extracted with chloroform than did theProduct B sample. Interpretation of this phenomenon can not be made atthis time.

This new analytical tool can be used to determine the relative add-onof the polymers used in the Quarpel formulations (Table IV). A slgtincrease in the percent of Produ-ct B in the pad application bath (from19.0 to 22.8%) produced a 0.09% numerical increase in the percent fluo-rine content of the treated fabric.

Fluorocarbon loss in laundered and weathered fabrics can be determinedby the limited data in Table V. Thus, launderIng appears to reduce fiuo-rine content somewhat while weathering causes very little loss on an over-all basis.

The inconsistency in the weathering data (Table V) may have been dueto inhomogeneity in the sample treatment. Experience has taught thatcommercially prepared Quarpel treated fabrics had a non-homogeneous finish.However, in general, those fabrics procured under govermuent contracts wereable to meet the specification requiremaents for physical water and oil re-pellency tests because of the wide tolerance range indicated. Analysis offour stock fabrics drawn from the Defense Personnel Support Center substan-tiated this hard-earned experience (Table VI) indicating 3i ficant non-homogeneity. By effective use of nez-trn activation analysis these Labora-tories wnll be able to correlate maimu and minimum fluorine contents withrelative performance of Qmarpei treated fabrics i. th such correlationsmore exact specifications than now possible should be attainable for noni-toring procuremenats, thus assuring the best enviromment~l protection forthe soldier that is possible.

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ix

CONCLUSIONS

Neutron activation analysis is an effective means of determiningfluorine content of Quarpel treated textiles. It is non-destructiveand allows correlation of physical test evaluation data with quanti-tative fluorine data on identical samples. In addition, the decay

curve produced (Figure 5) could be resolved with the aid of a leastsquares computer program allowing the Army to monitor both the fluoro-chemical and the nit-ogen contents of Quarpel treated fabrics and com-pare them with performanee requirments.

RK MUCES

1. "Quarpel Water and Oil Resistant Treatment for Textiles,"Textile Series Report No. 111, Headquarter•s, QuartermasterResearch and Dineerig Command, Natick, Mass., 1960.

2. Priest, H. F., F. C. Burns, and G. L. Priest, "An IrradiationTransfer and Counting System, for Neutron Activatimn Analysis

of Short-lived Components in In-hmogeneous Samples,' TR 70-21,Army Yaterials and Yechanics Research Center, Watertown, Mass.,1970.

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