JAD-A119 608 DEFENCE RESEARCH ESTABLISHMENT OTTAWA (ONTARIO) F/B 11/5THE EFFECT OF LOW TEMPERATURES ON COATED AND UNCOATED FABRICS,ItJ)

I MAR 82 R M CROW, M M DEWAR

UNCLASSIFIED DR E ORR-858 L

RESEARCH AND DEVELOPMENT BRANCHDEPARTMENT OF NATIONAL DEFENCE

CANADA

DEFENCE RESEARCHESTABLISHMENT OTTAWA

DREO REPORT NO. 858DREO R 858

THE EFFECT OF LOW TEMPERATURES ONCOATED AND UNCOATED FABRICS

by

R.M. Crow aid M.M. Dewar

DTlCCELECTEuat

SEP?7 1982,

MARCH 1982OTTAWA

Ai.)p.zv' dc fur p.J'J T,- (~~It-Of) .Distnibtition U~iii

RESEARCH AND DEVELOPMENT BRANCH

DEPARTMENT OF NATIONAL DEFENCE

CANADA

DEFENCE RESEARCH ESTABLISHMENT OTTAWA

REPORT NO. 858

THE EFFECT OF LOW TEMPERATURES ONCOATED AND UNCOATED FABRICS

by

R.M. Crow and M.M. Dewar

Environmental Protection SectionProtective Sciences Division

Accession For

NTIS PA .&IDTIC TAP FUann ownc c *d -JUStification

By.

Distribution/ _

Availability CodesAvail and/or

Dist Speciala

MARCH 1982

OTTAWA

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ABSTRACT

The effect of low temperatures on the shape of the load-elongationcurve, the initial modulus, breaking load, percent elongation and work torupture of 13 coated and uncoated fabrics was examined. It was found thatthe 'cotton/synthetic blends were least sensitive to low temperatures, thenylon fabrics, be they coated with polyurethane or neoprene, or uncoated,were more sensitive. The PVC-coated nylon scrims were the most sensitiveand, for all practical purposes, completely inappropriate for use at temper-atures below 0*C.

R&SVTh

L'effet des basses tempfratures sur la forme de la courbe decharge-allongement, le module initial, la charge de rupture, le pourcentaged'allongement et le travail a la rupture de treize tissus enduits et nonenduits a fif 6tudig. Ii ressort qua les raglanges coton-matiires synthfitiquessont momns sensibles aux basses tempfiratures alors qua lea tissus de nylon,enduits de polyurigthane ou de nf~oprA-ne ou non enduits, sont plus sensibles.Les canevas de nylon enduits de chlorure de polyvinyle sont les plussensibles et, 9 toutes fins utiles, complatement inutilisables 1 destemgratures inf~rieures 1 00 C.

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TABLE OF CONTENTS

Page

ABSTRACT/RE-SUME .............. .......................... iii

TABLE OF CONTENTS ......... ........................... v

INTRODUCTION ............... ............................ 1

METHOD ................ ............................... 2

FABRICS USED ............. ......................... 2

EXPERIMENTAL METHOD. .......................... 5

METHOD OF ANALYSIS .................................. 5

RESULTS ............................................ 11

COTTON BLENDS ......... ......................... .i.i.. 11

NYLON FABRICS ......... ......................... .... 15

PVC-COATED NYLON SCRIMS ...... .................... ... 16

MAGNITUDE OF CHANGES ....... ..................... ... 19

GENERAL SUMMARY AND DISCUSSION ...... ................... .... 23

CONCLUSION. ......... ............................ 25

REFERENCES .............................................. 26

APPENDIX A ..................................... 27

V

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INTRODUCTION

The purpose of this study is to determine the effect of low temper-atures on the pertinent physical properties of a variety of coated and uncoatedfabrics. This was undertaken because some fabrics, especially coated ones,are known to become hard and brittle at low winter temperatures. Their use-fulness at low temperatures will be determined by their ability to retaintheir room-temperature properties at these temperatures.

The effect of low temperatures on fabrics can be characterized bychanges in the basic shape of their load-elongation curves, and in othermechanical properties such as initial modulus, breaking strength, percentelongation at break, and work of rupture. Considerable previous work haGbeen done to determine the load-elongation curves of fibres, especially attemperatures at and above room temperature, since most textile processingtakes place at elevated temperatures. Occasionally low temperatures wereincluded. Graphs reproduced by Morton and Hearle (1) show the effect of-57*C on the load-elongation curves of fibres. The low temperature made themstiffer, with a higher initial modulus, and stronger and less elastic atbreak.

Coplan and Singer (2) studied the effect of temperature on nylonyarns and fabrics at 177, 99, 21 and -57*C. They found an increase in break-ing load and a decrease in extension as the temperature decreased. They gavestress-strain curves for a nylon yarn at +21 and -57*C. The curve at +21*Chad no yield point, but a secondary yield point. At -57*C, the opposite wastrue, the yarn now had a yield point, but no secondary yield point, and theydescribed this as "brittleness" of the yarn.

Two small studies carried out by Russian workers (3,4) looked atthe effect of low temperature on the physical properties of fabrics. In thefirst of two studies, Bozov and Nikitin (3) compared the effect of lowtemperatures on the strength, elongation, stiffness, crease resistance andcomponents of total deformation of a 70% wool, 30% staple rayon suitingfabric, a 66% wool and 34% polyester suiting fabric and a 100% cotton water-proofed tenting material. For the strength and elongation tests, the spec-imens were cold-soaked for 2 hours before they were broken. No actual dataare given in the report, but they write that the reduction in temperature to-40*C increased the strength of the wool blends significantly (9 to 30%) andreduced that of the cotton fabric (up to 10%). They found that the breakingelongations varied in both the warp and weft direction, particularly for thecotton fabric. In discussing the effect of low temperatures on the variousphysical properties which they measured, they say that increased moisture

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content and subsequent formation of ice crystals in the fibre causeirreversible changes in the fibre structure and properties. They also comentthat at low temperatures, there is a reduced mobility of the macromolecularchains in the structure of the fibres, resulting in a loss of elasticity.

In the second study (4), Nikitin, Bozov and Somova chose a 'plasticcoated' 100% polyamide, a waterproofed 67% polyester, 33% viscose rayon and a"waterproof fabric with water-repellent impregnation" 65% polyester, 35%cotton. They measured the breaking strength and extension at +20, -20, -40and -500C. These specimens were cold soaked for 15 minutes before testing.Their results are given in Figure 1. They point out that there is a markedchange in strength and extension of the blends at -20°C. They comment thatfabrics have increased breaking strength at low temperatures and that viscoserayon or cotton in the blends lessen the effect of cold on the properties offabrics.

Therefore, because of the lack of a comprehensive study of theseeffects, the present study was undertaken. A range of thirteen coated anduncoated fabrics were broken at four temperatures, 20, 0, -20 and -406C, andchanges in yield point, secondary yield point, initial modulus, breaking load,percent elongation at break and work to rupture were determined and compared.

METHOD

FABRICS USED

Descriptions of the fabrics used are given in Table 1. The fabricswere selected from existing or experimental Canadian Forces stock to includea range of coated and uncoated fabrics. Fabrics PE/C, N/C-G and N/C-F areuncoated, plain-weave fabrics, PE/C being a polyester and cotton blend, andN/C-G and N/C-F a nylon and cotton blend, N/C-F being the finished and dyedversion of N/C-G. Fabrics N-R and N-R-PU are similar ripatop nylons, N-Rwith water-repellent finish and N-R-PU with one side coated with polyurethan.For this study, N-R is considered to be nominally uncoated. Similarly, N andN-PU are nominally the same fabric, N-PU being polyurethane coated, N not.Fabric N-PU-L is a lighter weight version of N-PU. Fabric N-NE was chosenbecause of its neoprene finish. Fabrics N-PVC-L, N-PVC-H, N-PVC-HT and N-PVCare all lxl nylon scrims laminated with polyvinylchloride (PVC), but ofvarying counts (about 6x6 or 9x9) and varying weights. They are constructedsuch that the yarns are imbedded in the PVC.

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1. Warp "Plastic-coated"100% polyamide

2. Weft "Plast.ic-coated"100% polyamide

3. Warp 67% polyester33% viscose

4. Weft 67% polyester

3.5 33% viscose

140- 5. Warp Waterproof fabric65% polyester

32 35% cotton

16. Weft Waterproof fabric

o 6 65% polyester35% cotton

40-

20

20 -20 0 -6TEMPERATURE (-C)

20 2

~2.4

2 0 _40 -4 t6TEMPERTURE (-C)

Figure 1: changes in Breaking Load and Extension of Fabrics atLow Temperatures (Adapted from original (4)).

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EXPERIMENTAL METHOD

The tests were carried out in an environmental chamber fitted ontoan Instron, Model 1102. The chamber was cooled with solid carbon dioxideplaced in the bottom of the chamber. Since Buzov and Nikitin (3) point outspecifically that moisture in the specimens can affect their breakingcharacteristics, an attempt was made to prevent moisture from penetrating intothe fabrics, despite the fact that the tests had to be carried out in aconditioning room, set at 200C ± 10C, 65% R.H. ± 5%. The specimens wereplaced in a desiccator containing Drierite for 24 hours prior to testing. Thespecimens were removed from the desiccator, one at a time, and fitted intothe jaws of the Instron inside the environmental chamber. At 20*C, thespecimens were broken immediately. For the other temperature, the specimenswere cold-soaked for 15 minutes before they were broken. At 0*C, it took2 minutes of the 15-minute period for the chamber to come back down to thistemperature after the opening and closing of the chamber door, 3 minutes at-200C and 5 minutes at -40*C. The tests were carried out in accordance toCAN 2-4.2 M77, Method 9.1, Breaking Strength of Fabrics - Strip Method(Constant-Time-to-Break Principle), with, obviously, a modification to theconditioning procedure. In order to prevent the specimens from slipping, thejaws were lined with emery paper.

METHOD OF ANALYSIS

Figure 2 is an idealized load-elongation curve for a woven fabric.The "secondary yield point" has been added to the parameters which con-ventionally describe this curve because, for many of the fabrics, its presenceor absence was temperature-dependent. Rennell (5) calls the secondary yieldpoint "a 'hardening' point". However, we think that "secondary yield point"defines this point more accurately, as hardening occurs before this pointand yielding after. (It may be that, for fabrics, gross changes in fabricand yarn structures contribute to the first yield point, and changes inpolymer-chain configuration cause the secondary yield point.) In this study,the yield point is defined as occurring at a low load and low elongation andthe secondary yield point at a high load and high elongation. For clarity,the yield point is occasionally called the conventional yield point. Themethod used to measure all the secondary yield points and most of the yieldpoints was that proposed by Meredith (as reported by Morton and Hearle inPhysical Properties of Textile Fibres (1)) for determining yield points,i.e., the yield and secondary yield points are the successive points at whichthe tangent to the curve is parallel to the line joining the origin to thebreaking point as illustrated in Figure 3a. For a few curves whose yieldpoints could not be found in this way, a modification of Coplan's construction(as reported by Morton and Hearle in Physical Properties of Textile Fibres (1))

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ftI

LOAD II "

Work to Rupture(Ares .n~ Iuv

ELONGATION

Figure 2: Idealized Load-Elongation Curve for a Woven Fabric.

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-I

Fg : eonanpoint

ELONGATION

Figure 3a: Determination of Yield Point and Secondary YieldPoint by Meridith's Method.

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LOAD

horiZontal line through

Figure 3b Determination% f Yinonty h oiie o a

method. For this idealized curve, our yield pointcoincides with the one obtained by Meridith's method.

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was used as illustrated in Figure 3b. By using the bisector of the tangentsto obtain the yield point rather than using the horizontal line drawn throughthe intersection of the two tangents, one gets a yield point which is closerto the yield point as found by Meredith's method.

Examination of the results showed that there can be considerable

variation in the behaviour between the warp and weft of the same fabric andamong materials of nominally the same fibre content and coating. Therefore,the general characteristics of the load-elongation curves as shown by thepresence or absence of yield and secondary yield points will be discussedqu itatively, the coordinates of these points being given in tables forcompleteness.

As stated earlier, considerable work has been done on the stress-strain characteristics of fibres, and to a lesser extent on yarns. Althoughthere are variations in the shape of the curve for any one polymer, there ismore or less a characteristic shape for a particular polymer. Figure 4 showstypical specific stress-strain curves for polyester, nylon and cotton fibres(6). The curve for polyester fibre can terminate at any point along thecurve, depending on the type of polyester and its history, i.e., it can havea yield and a secondary yield point as shown here, or just the conventionalyield point. Hearle et al (7) give load-elongation curves for polyester yarnswhich are similar to the curve for the polyester fibre, with only the con-ventional yield point. The load-elongation curves of nylon yarns as given byHearle et al, have shapes similar to the curve given here for the polyesteryarns.

Unlike the fibres, there is not really a 'standard' curve for thecoatings, polyurethane, PVC and neoprene, because of the great variation inplasticizers, formulation, heat treatment, etc. of these materials.

The shape of the load-elongation curve of each fabric at 200 C willbe compared to the shapes of the fibre or yarn curves.

The actual measurements of initial modulus, breaking load, percentelongation at break and work to rupture was quite straightforward. However,arriving at a method to compare the results was more difficult. Inengineering, the breaking load, for instance, is normalized in order to com-pare materials of different shapes and composition. To do this, the breakingload is divided by the area of cross-section of the material to give specificstress. However, for textiles, the area of cross-section of fibres and yarnsis not well defined and a more convenient quantity based on the mass of thespecimen is conventionally used, i.e. the specific stress is the load dividedby the mass per unit length. If the concept of using mass per unit lengthis applied to fabrics, the mass per unit area would be the normalizing factor.However, variables such as the type of weave, thread count, yarn twist andinteryarn friction are ignored in this simplistic treatment. In this study,some fabrics had the added variable of a coated continuous film on one orboth sides of the fabric, which, while adding substantially to the total massof the specimen, may not have contributed proportionally to the strength.Thus it was concluded that normalization of this set of specimens based onmass per unit area is not appropriate.

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LUC I

0~isb Ilb~

Nolon fibr

ELONGATION

Fig'ure 4: Characteristic Specific Stress-Eiongation of Fibresand Yarns.

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Therefore, the results of the effect of temperature on the initialmodulus, breaking load, percent elongation and work to rupture for each fabricare only compared statistically here. This was done by using a paired t-testto compare the parameters at 20 and 0, 0 and -20, and -20 and -40*C. Themaximum increase and minimum decrease in each of the four parameters, cal-culated as a percent of the 20*C value, are also given.

As mentioned earlier, the results show that there can be considerablevariation in behaviour between the warp and weft of the same fabric. Further,the change in breaking load and the change in percent elongation with temper-ature were not always consistent. This resulted in changes in work to rupture,which, for the most part, reflected the product of changes in breaking loadand in elongation. Therefore, because of the cumulative variability of thework-to-rupture results, these results are presented, but not discussed.

It is noted that some of the curves, especially for the uncoatedfabrics at the higher temperatures, have a small 'run-in' which probably isthe crimp being removed from the yarns as stress is applied to them. This'run in' was included in the calculation of percent elongation and work torupture because it tended to disappear as the fabrics were broken at thelower temperatures, and thus is a real part of the curve for the presentcomparisons.

RESULTS

Typical load-elongation curves for each fabric at the four temper-atures are given in Appendix A. Also given in Appendix A are the mean valuesand coefficient of variation of the initial modulus, breaking load, percentelongation and work to rupture for each fabric at the four temperatures, andthe related statistical analysis. The presence or absence of yield andsecondary yield points is noted; if either is present, the mean of itscoordinates for that temperature is recorded.

In Tables 2 to 4, the pertinent information from Appendix A issummarized.

COTTON BLENDS

The load-elongation curves of the 50% nylon-50% cotton blends,N/C-C and N/C-F, at 20*C are concave, similar to the cotton-fibre curve orthe first part of the nylon fibre curve. As the temperature is lowered,

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TABLE 2

Summary of Parameters for Cotton Blends

Temperature/ .. ... FabricTemperature N/C-G N/C-F PE/C

Change Warp Weft Wa Weft Warp Weft

Yield Point 20*C x x00C .. . . . x x

-200C . . . vvsl x x-40°C .. . vvsl vvsl x x

Secondary Yield 20C -- vvsl .. .. .. ..Point 00C - vvsl .. .. .. .

-200C vvsl x -- vvsl .. ..-40"C vvsl x x vsl .. ..

Initial Modulus 20 to 0°C .. .. .. .. 0 -0Breaking Load + + + + + +Percent Elongation + + + + + 0Work to Rupture + + + + + 0

Initial Modulus 0 to -200C -- -- -- -- + +Breaking Load 0 0 0 + 0 0Percent Elongation - 0 0 0 - 0Work to Rupture + 0 0 + 0 +

Initial Modulus -20 to -40C -- -- -- -- + +Breaking Load 0 0 0 0 0 0Percent Elongation 0 0 0 0 - 0Work to Rupture 0 0 0 0 - 0

x - presence-- absencevsl - very slight

vvsl - very very slight+ - statistically significant increase- - statistically significant decrease0 - no significant change

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TABLE 4

Summary of Parameters for PVC-coated Nylon Scrims

Temp./ FabricTemp. N-PVC-L N-PVC-H N-PVC-HT N-PVCChange Warp Weft Warp I Weft Warp Weft Warp Weft

Yield Point 200 C x x x x x x x --O°' X X x x x X X X-

00 C x x x x x x x x-200 C x x x x x x x x-400 C x x x x x x x x

Secondary Yield 200C x x x x x breaks x --

Point 00C x x x x x x val --

-200 C breaks breaks breaks x x x val --

-40*C breaks breaks breaks breaks vvsl breaks breaks --

Initial Modulus 20 to + + + + + a. 0 --

Breaking Load 00C + + + + + + + +% Elongation + + 0 + 0 0 0 0Work to Rupture + + + + + + 0 +

Initial Modulus 0 to + + + + 0 a. + +Breaking Load -200C - 0 0 + + + 0 0% Elongation - - - 0 0 0 -

Work to Rupture - - 0 0 0 - 0 0

Initial Modulus -20 to + + 0 + + a. + +Breaking Load -400C 0 0 0 - 0 0 - 0% Elongation 0 0 0 - 0 0 - 0Work to Rupture 0 0 0 - 0 0 - 0

a. Has measurable Initial Modulus at +20 and -40*C.

Has 2 slopes at 0 and -200 C.

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N/C-F developed a slight yield point and a secondary yield point. FabricN/C-G did not develop a yield point as the temperature was decreased, but diddevelop a slight secondary yield point in the warp direction and a distinctone in the weft direction. Fabric N/C-F has been finished under tension, soits yarns are in an extended state. Therefore, it would seem that any stiff-ening of this fabric due to the lower temperatures is sufficient to causeyield and secondary yield points to appear. Fabric N/C-G is the greige goodsof N/C-F, and has yarns which are still in a relatively relaxed state in thefabric. Although N/C-G did stiffen at the lower temperatures as indicated byits secondary yield points, it was still sufficiently relaxed that the low

temperatures did not affect its ability to extend easily at low loads asshown by its lack of conventional yield point. Although N/C-F developedslight conventional yield points, it did not have measurable initial modulus.The breaking load and percent elongation increased significantly from 20 to0°C for both fabrics and then remained more or less the same for furtherdecrements in temperature.

The load-elongation curve of the 65% polyester, 35% cotton blend,PE/C, has a truncated polyester-fibre curve at 20*C. At all four temperatures,the curves have yield points, but not secondary yield points. However, as thetemperature was decreased from 0 to -20 and from -20 to -40*C, there was asignificant increase in the initial modulus of this fabric. The warpdirection of this fabric behaved similarly to the nylon/cotton blends N/C-Gand N/C-F with a significant increase in breaking load and percent elongationfrom 20 to 00 C. The breaking load remained the same and the percentelongation decreased as the temperature was lowered to -400C. In the weftdirection, the percent elongation remained incrementally unchanged as thetemperature was decreased. The breaking load increased from 20 to 0°C andthen it too remained unchanged through to -40*C.

NYLON FABRICS

As mentioned earlier, two pairs of polyurethane-coated and uncoatedfabrics were selected. Fabric N is the uncoated version of N-PU, and N-R thenominally uncoated ripstop nylon version of N-R-PU. The other two fabrics inthis series are N-PU-L, another polyurethane-coated nylon and N-NE, aneoprene-coated nylon.

At 20*C, the load elongation curves of N-R-PU warp, N-R warp,N-PU-L warp and N-NE warp and weft have yield and secondary yield pointssimilar to the nylon-yarn curves. The weft directions of N-R, N-R-PU andN-PU-L have only secondary yield points, making them similar to the nylon-fibre curves.

The fabrics which had conventional yield points retained themthrough to -40*C, with the exception of N-R warp which lost its yield pointonly at 0*C. Fabric N-R-PU weft and N-PU-L weft acquired yield points at-20 and N-R weft did not stiffen enough to acquire one.

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Fabric N-R-PU warp and weft, N-R weft, N-NE warp and N-PU-L warp andweft all stiffened sufficiently at -40*C to break before measurable secondaryyield points were reached. N-R warp and N-NE weft retained their secondaryyield points throughout.

Some of the load-elongation curves of the plain nylon, N, and itscoated version, N-PU, were difficult to analyze. Apparent yield and secondaryyield points, and initial moduli, were generally visible, but it was a matterof conjecture whether or not some of them were measurable or even whether ornot they existed. Therefore, no conclusive comments will be made on thesecurves. Fabric N-PU weft did have two distinct yield points at -40*C. Thismay indicate that the polyurethane coating and the nylon fabric were yieldingat different loads at this temperature.

When a comparison of initial modulus could be made, there was nochange from 20 to 00 C for N, N-PU, N-R-PU and N-PU-L and a decrease for N-NE;as the temperature was lowered to -400 C, there was an increase in initialmoduli for all fabrics except N which had no change from -20 to -40*C.

The behaviour of the breaking load and percent elongation withtemperature decrease is identical for the two uncoated nylons, N and N-R.Their breaking load increased continually through to -20*C, then stayed thesame to -400 C. Their percent elongation increased to 00 C and then decreasedto -400 C. With the exception of the occasional difference between the warpand weft, the polyurethane-coated nylon, N-PU-L, followed the same patternfor breaking load and percent elongation, the polyurethane coated nylon,N-PU, for just the breaking load, and N-NE, the neoprene-coated nylon, justfor the percent elongation. The change in percent elongation of N-PU differedfor its warp and weft, but the trend was for an increase in percent elongationfrom 20 to 00C and then a decrease to -40*C, as N and N-R. The breaking loadof N-NE increased to 0°C and stayed the same to -20*C, then tended to increaseto -400 C. The behaviour of this neoprene-coated fabric does not distinguishit from the other nylons discussed above.

Fabric N-R-PU's behaviour was dissimilar to the other five nylons.Its breaking load and percent elongation did not change from 20 to 00 C.Between 0 and -20*C, its breaking load increased and its percent elongationtended to decrease. From -20 to -40*C, both its breaking load and percentelongation decreased. Thus, it would appear that it is the polyurethanecoating of N-R-PU which is more resistant to changes in temperature than theother polyurethane-coated fabrics, its properties not being affected until-20*C is reached.

PVC-COATED NYLON SCRIMS

The PVC-coated nylon scrims, N-PVC-L and N-PVC-H, had similar PVCcoatings, with N-PVC-L being the lighter weight, more closely-woven scrim ofthe two. At 200C, both had load-elongation curves similar to the nylon-yarncurve, i.e. they both had yield and secondary yield points. They bothretained their conventional yield points as the temperature was decreased.

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At the lower temperatures, the PVC coatings became brittle, shattered andflew off in all directions, coating the inside of the environmental chamber.The irregular breaks in their load-elongation curves show the sudden failuresin the coating (Figure 5).

For N-PVC-1. the initial modulus, breaking load and percent elongationincreased significantly from 20 to OC with the initial modulus continuing toincrease significantly through to -40*C. From 0 to -20*C, there was a decreasein breaking load and percent elongation, and then once the ccatings started toshatter, there was no change in either parameter, indicating that N-PVC-L hadreached its maximum brittleness at -20*C for the range of temperatures con-sidered here.

Fabric N-PVC-H followed much the same pattern as N-PVC-L, withN-PVC-H weft reaching its maximum brittleness at -40*C rather than -200C.

Fabric N-PVC-HT was the heaviest and thickest of the four PVC-coatednylon scrims. It had a PVC coating which appeared to have more plasticizer init than the others. At 20'C, N-PVC-HT had load-elongation curves similar toN-PVC-L and N-PVC-H, the nylon-yarn curve. In the weft direction, it hadirregular breaks at 200C due to the fact that the nylon yarns in the middleof the specimen broke first, then the coating covering these yarns broke. Theouter nylon yarns were then pulled back through the coating, at which pointthe coating covering these yarns broke. This type of break always occurredat the upper jaw and may have been avoided if larger jaws had been used.However, w:der jaws did not fit into the environmental chamber which was re-quired for the lower temperatures. The same type of break was observed,although to a lesser extent, on the chart trace for some of the specimens at0 to -20°C, and was more distinct at -400C. Actual observation was impossiblebecause of frosting of the environmental chamber window.

When the curves of N-PVC-HT weft were analyzed, conventional yieldpoints were present at all four temperatures. At 20 and -40*C, there was adistinct and measurable initial modulus, but at 0 and -200 C, there were twoslopes in this yield region. Since the coating and scrim were acting in-dependently at break, it is probable that the two were yielding independentlyof each other due to differences in hardening at the lower temeratures.At -40*C, both were either equally hard and yield together, or one of the twohad become so stiff that its yielding masked that of the other, resulting inone distinct initial modulus.

The breaking load of N-PVC-HT warp and weft increa3ed from 20 to-20*C, then remained unchanged. The percent elongation rema.ned unchanged

throughout.

The last PVC-coated nylon, N-PVC, was tactilely the most rigid ofthe series. At 200C, it had a nylon-yarn type curve in the warp direction anda concave nylon-fibre type curve in the weft. T, the warp direction, it re-tained its conventional yield characteristics throughout. At 0 and -200C,its secondary yield point became slight, indicating that it was breakingbefore its secondary yield point was reached. At -40*C, a jagged trace wasproduced before the main break by shattering of the coating. However, thisoccurred with less violence than was the case with N-PVC-L and N-PVC-H.

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00

0 5 10 15 20% ELONGATION

Figure 5: Load-Elongation Curve of N-PVC-L Weft at -40 "C.

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In the weft direction, it stiffened sufficiently for a yield pointto appear at O°C and remain through -20 and -40°C, but it did not acquire asecondary yield point as the temperature decreased. It is a matter of con-jecture whether the weft was so hard that it broke before the secondary yieldpoint was reached, or whether it just extended easily at high loads. Becauseof this distinct behaviour, N-PVC was examined carefully and it was found thatit was relatively easy to delaminate the PVC manually from the scrim in theweft direction only; it was impossible to delaminate the PVC film manuallyfrom the other PVC-coated nylons, in either direction. Therefore, it ispossible that the PVC film was delaminating from the nylon scrim of N-PVCweft under severe tension as experienced at the upper limit of the load-elongation curve and that this curve was, in fact, the resultant of the load-elongation curve of the PVC film and the nylon scrim. The fact that the PVCfilm did not break in the weft direction as it did in the warp directionsupports this view. Since the PVC film was not in intimate contact with thenylon scrim in the weft direction, the two materials were able to breaksmoothly on their own. The load-elongation curve of N-PVC weft at -40*C isshown in Figure 6 because of its distinctive yield point. This curve is nottypical of conventional textile materials, but rather similar to the onesgiven for plastics by Billmeyer (8) who describes such a curve as beingcharacteristic of a "hard and tough" polymeric material.

Examining its measured properties, we found a significant increase

in initial modulus as the temperature was decreased. Its breaking loadincreased from 20 to 00C and then remained the same or decreased. The percentelongation either stayed the same or decreased with temperatre.

MAGNITUDE OF CHANGES

The foregoing dealt, in part, with the statistically significantdifferences of initial modulus, breaking load and percent elongation forincremental decreases in temperature. Of equal interest are the gross changesin these three parameters from their initial values at 200C. Tables 5 and 6give the maximum increase and minimum decrease expressed as a percent of their200C value and the temperature at which these occur for the initial modulus,breaking load, percent elongation, and for completeness, work to rupture.Since we are looking at differences between any temperature and 20°C, thestatistical patterns described previously do not necessarily apply here.

For the fabrics which had initial modulus at 20*C, there was nevera decrease in this parameter, and the maximum increase always occurred at-40*C. The coated fabrics, polyurethane, neoprene and PVC, had increases ininitial modulus of over 100%, the uncoated fabrics less than 75%, indicatingthat the coated fabrics are stiffening more than the uncoated ones at lowloads.

Turning to the breaking load, we found that all fabrics had anincrease in this parameter from their 200 C value, the temperature at whichthis occurred varying with the fabric, as it was statistically shown

UNCLASSIFIED

20 UNCLASSIFIED

3,000 I

2,50-

2,000-a

1,000-S1500-

I - - I -I I I I I I0 5 10 15 20 25 30

% ELONGATION

Figure 6: Load-Elongation Curve of N-PVC Weft at -40°C.

UNCLASSIFIED_________ -- -- ------ -.--~-- -

UNCLASSIFIED 21

TABLZ 5

Maximum Increase of Cited Properties, £xpressed as aPercent of the +20*C Value

Pabric Initial Temp Breaking Temp 2 TeW Work to To"Modulus (OC) Load (OC) Elongation (*C) Ripturs (OC)

N/C-G warp - - 29 -40 12 0 62 -40weft - - 34 -40 13 0,-40 96 -40

K/C-F warp - - 26 -40 12 0 65 -40weft - - 39 -20 13 0,-20 66 -20

PE/C warp 40 -40 27 0,-20 16 0 42 0weft 36 -40 19 -40 - - 23 -40

N warp 47 -40 39 -40 26 0 102 -40weft 74 -40 29 -20,-40 12 0 27 -20

N-PU warp 117 -40 51 -20 41 0 105 0weft 23,119 -40 31 -40 - - 5 0

N-R-PU warp 133 -40 16 -20 - - 0 -weft none t +20 24 -20 - 18 -20

N-R warp 64 -40 34 -20 52 0 100 0weft none 23 -20,-40 28 0 47 0

N-PU-L warp 142 -40 28 -40 11 0 28 0weft none at +20 30 -20 24 0 58 0

N-NE warp 360 -40 30 -40 17 0 34 0weft 510 -40 36 -40 - - 12 -40

N-PVC-L warp 800 -40 38 0 22 0 108 0weft 671 -40 24 0 7 0 46 0

N-PVC-H warp 204 -40 30 -20 4 0 27 0weft 690 -40 36 -20 19 0 57 -20

N-PVC-HT warp 102 -40 31 -40 - - 25 -20weft 270 -40 64 -40 - - 60 0

N-PVC warp 175 -40 20 -20 0 0 27 -20weft none at +20 17 -40 3 0 3 -40

UNCLASSIFIED

- -.- ~--,- - - .--

22 UNCLASSIFIED

TABLE 6

Minimum Decrease of Cited Properties, Expressed as aPercent of the +20"C Value

Fabric Initial Temp Breaking Temp % Temp Work to TempModulus (OC) Load (*C) Elongation (OC) Rupture (OC)

NIC-G warp ......... .weft ........ .

N/C-F warp ....... .weft .. .. ..- -.

PE/C warp - 14 -40 - -weft - 7 -40 - -

N warp . ..- - -weft . .- 10 -40 - -

N-PU warp .. .. . . 16 -40 - -weft .- -- 71 -40 160 -40

N-R-PU warp .. .. 1 -40 120 -40 133 -40weft ..- -- 52 -40 28 -40

N-R warp . .. . . 10 -40 - -weft .. . .. 21 -40 9 -40

N-PU-L warp . . . .. 13 -20,-40 - -weft .. .. .. .. 50 -40 30 -40

N-NE warp . .. . .. 16 -40 - -weft . . . .. 26 -20 14 -40

N-PVC-L warp .. . . .. 92 -40 14 -40weft .. .. . .. 59 -40 13 -20

N-PVC-H warp . .. . .. 37 -40 - -weft .. .. .. .. 16 -40 -

N-PVC-HT warp .. . . .. 21 -40 - -weft ..- -- 8 -40 - -

N-PVC warp - -- 1 -40 22 -40 1 -40waft -- -- 21 -40 - -

UNCLASSIFIED

UNCLASSIFIED 23

previously. Within experimental error, none of the fabrics decreased inbreaking load from that at 200C.

The magnitude of the maximum increase in breaking load for all thefabrics was about the same, a mean increase of 29% for the cotton blends, 31%for the uncoated nylons, 30% for the polyurethane coated nylons, 33% for theneoprene coated fabric and for the PVC coated nylons.

The maximum increase in percent elongation for the majority of thefabrics occurred at 00 C. It was expected that since the breaking load of thefabrics was increasing from 20*C to O°C, some stiffening of the fabrics wasoccurring, and so logically the percent elongation of the fabrics shoulddecrease. Since this was not the case, samples of the fabrics were driedover a desiccant and the change in weigh't after 15 minutes exposure toapproximately 200 C, 30-40% humidity (the equivalent saturation vapour pressureat OC) was measured. The 15-minute period was chosen as this was the lengthof time the specimens were cold-soaked at OC before being broken. All thesamples picked up some moisture in that time, the PVC's the least (approx-imately 0.05%) and the cotton/nylon blends the most (approximately 1.5%).Because of the Russian studies of Buzov and Nikitin, the method for break-ing the specimens was chosen to eliminate as much moisture from the specimensas possible. However, it appears that at O0 C there was sufficient moisturepickup by the specimens in the 15-minute cold-soak period to make the yarnsand fibres slide easily over each other, although the majority of the fabricswere getting stiff in the cold. This would account for the increase in boththe breaking load and percent elongation at this temperature, and the loss ofyield point of N-R warp.

The minimum decrease in percent elongation occurred for the majorityof the fibres at -40*C, with the exception of the cotton/nylon blends whosepercent elongations did not decrease below their original value at +20°C.The variation in the percent elongation was much greater than that for thebreaking load for fabrics within a group. The decrease for uncoated nylonsranged from 10 to 21%, polyurethane-coated nylons from 10 to 71%, theneoprene-coated nylon, 16 to 26%, and the PVC-coated nylon scrims from 8 to92%.

GENERAL SUMMARY AND DISCUSSION

The load elongation curves of the fabrics at 200C are typical oftextile fibres or yarns, whether coated or not, indicating that either theload-elongation curves of the polyurethane, neoprene or PVC are similar tothose of textile materials, or that the textile base structure determines theshape of the load-elongation curve. The second alternative is more likely asthe coated nylon-based fabrics had curves similar to either the nylon fibre ornylon yarn curves.

UNCLASSIFIED

24 UNCLASSIFIED

The cotton blends have curves resembling the first part of thesynthetic fibre-curves with which they were blended. The truncation of thesecurves shows the influence of the low extensibility and relatively lowerbreaking strength of the cotton on their general shape.

As the temperature decreased from 20 to -40*C, the basic shape ofthe load-elongation curve as defined by the presence or absence of yield andsecondary yield points changed for all fabrics but the polyester/cotton blend,PE/C, whose curve remained basically the same. The first indication that afabric was stiffening due to the low temperatures was the appearance of ayield or secondary yield point, if one did not exist at the higher temper-atures. A further indication of stiffening was the disappearance of thesecondary yield point, with the fabric hardening and breaking before thesecondary yield point was reached. This behaviour is similar to that reportedby Coplan and Singer for nylon yarns.

The most spectacular stiffening occurred with the PVC-coated nylon

scrims, with breaks in their coatings and/or unsynchronized yielding orbreaking of the coating and the scrim.

If the sensitivity of these fabrics to cold temperatures is judgedsolely on the change in the basic shape of the load-elongation curve, thenthe cotton/polyester blend, PE/C, would be considered insensitive, the cotton/nylon blends, slightly sensitive, and the set of coated and uncoated nylons,with the PVC-coated nylon scrims the most sensitive. As we have seen in theprevious section, this last statement is not entirely true, as the measuredparameters of the polyester/cotton do change significantly with decreasingtemperature. However, the order of sensitivity, i.e. the cotton blends, thenthe nylons and finally the most sensitive PVC coated fabrics, is still validand observations of change in the shape of the load-elongation curve, asoutlined here, would be a quick and easy way of qualitatively determining thesensitivity of a fabric to temperature change.

The variability in the behaviour of the warp and weft of some of thefabrics was somewhat unexpected. It was considered that since the warp andweft were the same fibre(s), and for the coated fabrics, covered with thesame polymeric film, they would react similarly to low temperatures and havesimilar -hanges in their load-elongation curves and similar increases ordecreases in the measured parameters. Obviously, the difference in suchthings as yarn coustruction and number of threads per centimetre between thetwo directions were sufficient to override the effects of low temperatures ontheir physical properties.

The statistically analyzed parameters confirm the change in theload-elongation curves, i.e. all the fabrics were affected by a decrease intemperature. The increase in initial modulus from 20 to -400C was common toall fabrics. This is the only parameter which really distinguishes thepolyurethane-coated nylons from the uncoated ones, the former having changesin initial modulus greater than 100% from 20 to -40*C, the latter, less than75%.

The breaking loads of all fabrics increased from the 20*C value,the maximum percent change being much the same for all fabrics, about 30%.

UNCLASSIFIED

UNCLASSIFIED 25

The temperature at which this maximum occurred varied from fabric to fabricand often from warp to weft.

The changes in percent elongation occurred independently of thebreaking load, with the majority of the fabrics having their maximum increaseat 00 C, and minimum decrease at -40*C. It has been hypothesized that theincrease at 00C was due to moisture in the specimens, which made them moreplastic and extensible at large loads. The magnitude of the percent changeswere not as consistent as were the ones for the breaking loads, the variationin warp and weft again reappearing.

The changes in breaking load and percent elongation confirmed workby others, namely, that the breaking load increased with a decrease in temp-erature, be it for fibres, yarns or fabrics, and the percent elongationvaried in both the warp and weft directions. However, for this set of fabrics,there was not the marked change in breaking load and extension at -20*C,except for N-R-PU, the polyurethane-coated nylon, as found by Nikitin et al (4).However, this study does confirm their finding that the inclusion of cotton ina fabric makes this fabric blend less sensitive to low temperatures.

CONCLUSION

The purpose of this study was to determine the effect of low temper-atures on the pertinent physical properties of coated and uncoated fabrics.It was found that all fabrics tested were affected at low temperatures,becoming stiffer as shown by an increase in initial modulus, an increase inbreaking load and a decrease in percent elongation at break. Taking thechange in the basic shape of the load-elongation curve into consideration, aswell as the statistically significant differences in initial modulus, breakingload and percent elongation, and the magnitude of the changes, the cotton/synthetic blends were the least sensitive to low temperatures; the nylonfabrics, whether they were coated with polyurethane or neoprene or not,more sensitive; and the PVC-coated nylons scrims tested here, the mostsensitive, and for all practical purposes, completely inappropriate for useat temperatures below 0OC.

UNCLASSIFIED

26 UNCLASSIFIED

REFERENCES

1. W.E. Morton and J.W.S. Hearle. Physical Properties of Textile Fibres,The Textile Institute, Manchester and Heineman, London, 2nd Edition, 1975.

2. A Study of the Effect of Temperature on Textile Materials, M.J. Coplanand E. Singer (July 1953). WADC Technical Report 53-21, Part 2.

3. Effect of Low Temperature on Properties of Fabrics, B.A. Buzov andA.V. Nikitin, 1975, Tekstil'naya Promyshlennost', 35, No. 11, 67-68(unedited translation).

4. Investigating the Properties of Waterproof Fabrics at Low Temperatures,A.V. Nikitin, B.A. Buzov and T.I. Somova, 1975, Shveinaya Promyshlennost',16, No. 6, 18-21 (unedited translation).

5. The Tensile Properties of Fibres and Yarns, R.W. Rennell, 1978,Textiles, 7, No. 1, 12-16.

6. Extensometric and Elastic Properties of Textile Fibres, B. Farrow, 1956,J. Text. Inst., 47, T58-TlOl.

7. The Mechanics of Twisted Yarns: Tensile Properties of Continuous-Filament Yarns. J.W.S. Hearle, H.M.A. El-Behery and V.M. Thakur, 1958,Mechanical Properties of Textile Materials, Textile Institute Conference,Gothenburg, 69-95.

8. F.W. Billmeyer, Textbook of Polymer Science, Interscience Publishers,a Division of John Wiley and Sons, New York, 2nd Ed., 1971.

UNCLASSIFIED

UNCLASSIFIED 27

APPENDIX A

Tables A-I to A-XIII give the breaking load, percent elongation,work to rupture and initial modulus and their related statistical parameters.The percent change in each of these parameters from one temperature to the

one below it is given. If the change is significant at the 95% level ofconfidence, it is underlined once; if it is significant at the 99% level ofconfidence, it is underlined twice. The presence or absence of yield andsecondary yield points is noted and if present, their coordinates are given.

The following abbreviations are used:

x = the mean

cv coefficient of variation (%)

vvsl = very, very slight

vsl = very slight

Figures A-1 to A-26 show typical load-elongation curves foreach fabric in the warp and weft direction at the four temperatures.

NOTE:

The x-values for the yield points and the secondary yield points reelongation in centimeters and the y-values in pounds force x 10-

The initial moduli were calculated using these units.

UNCLASSIFIED

W-l

28 UNCLASSIFIED

-4

wt

7 o CM 'Of CM 44 N

N4 N.4m14 -4 0 0

N in

T 0 0c4 4 4

c.4 04 lr-. r..a

' . c ' % O'-" 4) 44 -4 ,0

- 44-

0 N

:a~ ~ 04f( 44 4 m Q 1 0 %

-Lc 4 0 0 0P-4 r

cy O 4 00 44 4 -I .

el c4 4)

4o @0 N 0

w > o -* > .

u j 0n 0c

toCLtoIFlE

0 N 0

a a

A qo

44 a.

UNCLASIFIE

UNCLASSIFIED 29

Q 0

a* 4 %c -4

+ n + 41 m1 +

0 CIO Go W% co0 '

1- C4 00 0

1- 0'

+ + +

>N >E I~ 4> a I K~

0 40

fA

ON 0I 0 - -4 N '

1-4

4sA I 4 0 '4 1 .O0lNl0 6

UNCLASI0I0

30 UNCLASSIFIED

0 %0 01 c 0-

Lu -4

fd4.-~~~I -1- n

C. 0 T 1' Le)- a,- en

'- C4-4 -4

0) C4

1-4 + cc

co 00 '4

x >0x>0 1 x i

Q ~ ~ ~ a on j n u 0 ria 0

-4 4

'-44 liIu0 0

N 0 0 o

0o 0a'oI~

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.n 04 O.- N (

U)~ NCLASIIE

UNCLASSIFIED 31

C,-44 t .

6.

M e

r,-.

C4 4

+ 4

en 14fnn

+' +

C4C

Go Im INI

U . U OS .4 .4 .

. . . .I . . .. n . . . . .l . .. . 6 *

V- -4 .

to 2-S C .s

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UNCASSFIE

32 UNCLASSIFIED

0 in -4S P *0a ON C4

*0 ~0N

In

C44

N Ns co 4

0'o : 10 M 4

*0 IT c4 a4een -4 N 0 4e

an I

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04 0~- 00% MN-. 44j -4 I 4

w N NwH go

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UNCLASIF-IEDN -4 *

F,,UNCLASSIFIED 33

-ci;

oo -vI"

o C C4 .2 0 ccNt '

-S C-4

+ + +

-4 C4 . 0

-4-

F~' Q -I

o~~~( 0- 0 . N -

n . 01 m N 41 -1

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0 0

34 UNCLASSIFIED

onu

0 -- Ic-

In 4'D C.4 C4 m nIn 4 0- N- '4 '0 t

1 en 00 0 0

1%

0 C ON t r.1 ONO C4'0 on '

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4 n CLM 9 n 0V4 N, In 0 0

0 '0 Nz

00

.0 tn (4 I

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0 01- t

4J *- UNCLASSIFIED

UNCLASSIFIED 35

0

-4 C4

4- 4

M - j - . -1-4 N C4 r

+- It I.-4 4

4)'0

N 0

14 It) C

1-4 -- A -+ +, +

00 on 0-4 4;

c0 c" * m 0 N4rI.

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en 4

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N N 041 4 Nn

0 ba vI' . u D

to .- 4 0 N

v( -0 4 NL I

0A N 0 .((4w u0 V. .4)

N *d a.01 ~ ( 0lo

Nonu-

IV 4 XGJ I >) I>4 M 3

U ~UNCLASSIFIED

36 UNCLASSIFIED

40 0 . 04 . 4 .-4..4 %-4 m r.4 . -4 * *

0% %0 c

- 4.

0~ ~ ~ cn 0%

Nc ,-4 4 0 14

4.1 0

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0% 0 en 0 '

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c.4 -

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UNCLASSIFIE

UNCLASSIFIED 37

0 0 Cc ON a% 0.-4-4aa

0-.. 00 %0

o o e4 -O% 4 0%N 4 -i '*N ~~~C 0LA .41

0 0 U, N 04 00C4 I' *n

1.4 -4-4

+

LIN -tr4 00 'T *l

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+ .- + + In

C4 en r co N4 M

* U,

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X > W OX > w uI b, >'- 0 it I

u o 0o Q, O000.

% 0 ca to

3 - 00 4 (4 0 (D @

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v N - -4 610 N 0

N0 w, m 4

w~> :2~ I2~ I .. ~ Il IXeJ~G U QWcU

UNCASSFIE

38 UNCLASSIFIED

0 '0 (. m *-

C-4 -

- . .- 4s-

4 -C-44 I

w cy +C-4

+~O '. u o~- l

enI (" -*0V go E

a Uc~~0 inL

(.4~~~ owI * - '

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C4I N

0*0~ 00 r*

64- 0-4 *4 en 10~

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UNCLASSIFIED 3

0 C4 kn%#*

0 In c

at 0

0.% O. .

42)4

+

.4 A4 ) 04

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* N ~ 1- ~~.

UNCLASIFIE

40 UNCLASSIFIED

-104 0 gn 006-

cnn

K~ C4

mN 1.4 WT 4?

a * 44 00O?4

o o n Go? r4C 4 0&0

O vi? %c0 coo N Cf? N

5-44 I 4 TS- In r-1 -6 * .

v- C> V4 r, I p D

X .- 4 '- 4 - E4 I

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cn

UNCLASIFIE

UNCLASSIFIED 41

1200

N/C-G Warp /1

20*C ' 1600c800- .. ..20" C

-40" C

<60/1 / |

I, /

/

400 /

,/ // /

200--

0 5 10 15 20 25 30

% ELONGATION

Figure A-1: Load-Elongation Curves of N/C-G Warp at the

Four Temperatures.

UNCLASSIFIED

-..- -

42 UNCLASSIFIED

1200

N/cG WWI

20' C0

o C

.. .. 20°

C

aw - _ 40* C

0

400 I

• / /1-S ' I

i/ /

i 1200 1

12 15 20 25 30

% ELONGATION

Figure A-2: Load-Elongation Curves of N/C-G Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 43

14W0

,2W -1N/C-F Warp

/1

- -40° C

O - /

/

- J /i/2- /

% ELONGATION

Figure A-3: Load-Elongation curves of N/C-F Warp at the

Four Tenperatures.

UNCLASSIFIED

-- - Il i iI

. .. . ---- '- t *--. . . . . . . . .1 . .. . . l l l lE- "OJ [ .. ..

44 UNCLASSIFIED

1200-

/ ¢/'

'/ c.... -20

° C

--- 40' C

0 / i

/e7,

/ /40D --

_ i I I II200--

10 15 20 25 30 35 40

% ELONGATION

Figure A-4: Load-Elongation Curves of N/C-F Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 45

1wo- K/C Warp

100 40

400-

o510 15 20 25 30

% ELONGATION

Fi~gure A-5: Load-Eongztion Curves of PEIC Warp at theFour Temperatures.

UNCLASSIFIED

46 UNCLASSIFIED

w I

s - lo

20' C

.... - 4o°*° C/ ""

-J / /---/ /

3W) -2W-

5 1 I 0 2

% ELONGATION

Figure A-6: Load-Elongation Curves of PE/C Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 47

800- Warp 10* c0 --- .20- C

-- I-/ -

400 -

k- L

10 is 2D 25 J% ELONGATION

Figure A-7: Load-Elongation Curves of N-R Warp at theFour Tenmperatures.

UNCLASSIFIED

48 UNCLASSIFIED

Sa-N-R Weft

500

400-

z /0,/

10 is2I53 54% ELNATO

FigreA-: oa-Eonaton uresofN- Wftatth

Four empertures

UNCLASSIFIE

UNCLASSIFIED 49

800- N-R-PU Warp I

. ... .~20° C,,,, "

o- - I- I

6w - -20* C

-- 40* C

/ 1,- I i;" 4 I I I

2 00-

0 5 10 15 20 25 30 35

% ELONGATION

Figure 4-9: Load-Elongation Curves of N-R-PU Warp at theFour Temperatures.

UNCLASSIFIED

so UNCLASSIFIED

800-N-R-PUI Weft

20* C

-20' C

600 -40* C -

0J 400-

200 -

0 5 10 15 20 25 L0JJ 5

% ELONGATION

Figure A-10: Load-EVongation Curves of N-R-PU Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 51

N Wop

2000. 20" c ....

-,v

aw

SIX -

0 5 10 15 20 2L 30 30

% ELONGATION

Figure A-11: Load-Eongation Curves of N Warp at theFour Temperatures.

UNCLASSIFIED

52 UNCLASSIFIED

NW

-- 4 C /...... 20" C

10(0 ,-

Ow

io/

4, _

200 I

10 1 2 25 30 35 40 45

% ELONGATION

Figure A-12: Load-Elongation Curves of N Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 53

300

2500 -N-PU Warp

20"C

owc2000- --- 20'C

1_ ,-40

° C ,'

00

I '

0510 Is 20 25 30 35 40

% ELONGATION

Figure A-13: Load-Elongation Curves of N-PU Warp at the

Four Temperatures.

UNCLASSIFIED

54 UNCLASSIFIED

U-!

2WP Ci

OI :

-

....--- 1I"-- -- '

5N00 -- 40 C 7 -

0 5 10 25 30 * - 40 --

% ELONGATION

Figure A-14: Load-Elongation Curves of N-PU Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 55

UP c20C

Z Ir

law0 / 2,

lw - d

0

,ow

A

/."//400-

w -

'II

//

0 5 10 15 20

% ELONGATION

Figure A-15: Load-Elongation Curves of N-PU-L Warp at theFour Temperatures.

UNCLASSIFIED

56 UNCLASSIFIED

law/1/ /"

00 //

2 C

200 00

Figure A-16: Load-longation Curves of N-PU-L Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 57

am ~N-E W&

2V C01c

-2'

00

200

I - AI

% ELON4GATION4

Figure A-17: Load-Elongation Curves of N-NE Warp at theFour Temperatures.

UNCLASSIFIED

58 UN~CLASSIFIED

N-NE Wth --

aw20C - -----

o*c

% ELONGATION

Figure A-18: Load-Elongation Curves of N-NE Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 59

1000- N-PVC-L Warp -

/w I

400 - 20c

200 - .-

0 510 15 20 25 30

% ELONGATION

Figure A-19: Load-Elongation Curves of N-PVC-L Warp at theFour Temperatures.

UNCLASSIFIED

60 UNCLASSIFIED

N-PVC-L Weft

20C

-- 40 ° C /

/ -

200

0 5 10 15 20 25 No

% ELONGATION

Figure A-20: Load-Elongation Curves of N-PVC-L Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 61

3000-

N-PVC-H Warp o2500- ar.. 0c jl .,,'-'

... . 0* C sos0. / -/"

2000 -

~/ /S1500 -/

/ X/

/ /

II500 I

0 o1 15 20 25 30% ELONGATION

Figure A-21: Load-Elongation Curves of N-PVC-H Warp at theFour Temperatures.

UNCLASSIFIED

62 UNCLASSIFIED

2500 -

N-PVC-H Wf

20C

500I

O0 5 -- 10C 15 20203

% ELONGATION

Figure A-22: Load-Elongation Curves of N-PVC-H Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 63

-- -2w c2BOW -I;-

lo -

SI-0o -10 Is-S I

% ELONGATION

Figure A-23: Load-Elongation Curves of N-PVC-HT Warp at theFour Teperatures.

UNCLASSIFIED

64 UNCLASSIFIED

25W

N-PVC-NT Weft

20W0 20*C0.c

-40 C.* '

<15W0 -

% ELONGATION

Figure A-24: Load-Elongation Curves of N-P VC-RT Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED 65

4M -I

/

/7/ I

/,

/,

3M. , /4 W

S /

%k ELONGATION

5 10

Figare A-25: Load-Elongation Curves of N-PVC Warp at theFour Temperatures.

UNCLASSIFIED

c

66 UNCLASSIFIED

3000-

N-pVc Woft

-2V C

2000 -4 0I

w- -

% ELONGATION

Figure A-26: Load-Elongation Curves of NV-PVC Weft at theFour Temperatures.

UNCLASSIFIED

UNCLASSIFIED

Security Classification

DOCUMENT CONTROL DATA - R & DK ., ,r ,l ,I II of hl y ill I,) lt t ,. II xrAtq dlnot1,,Il( 1no st15 t ,te en (I W ni It. Ov al ll d I m,.t .% c(d siledl

I 1 "h-NA IN, A(:;IVIIN 2a. DOCUMENT SECURITY CLASSIFICATIONDefence Research Establishment Ottawa UNCLASSIFIEDDepartment of National Defence 2b GROUP

IOttawa- Ontario, na~da KIA Q Z4

OCuMNE NT TITLE

THE EFFECT OF LOW TEMPERATURES ON COATED AND UNCOATED FABRICS

1 GC-.(:r4PT IVE NOTES (Type of eport and ,nclu ,ve dates)REPORT

h 4. TH)H(S) tist name. 1,rt lame. middle nitial)

CROW, Rita M. and DEWAR, Malcolm M.

1I DOCUMENT DATE 7a. TOTAL NO OF PAGES 7b NO. OF REFSMARCH 1982 66 8

8d. PH1 J1-CT OR GRANT NO 9a ORIGINATOR'S DOCUMENT NUMBER(S)

DREO REPORT NO. 858

8I, CONTRACf N) 9b. OTHER DOCUMENT NO.(S (Any other numbers that may beassigned this document)

10 DISTRIBlUTION STATEMENT

UNLIMITED DISTRIBUTION

11 SUPPLEMENTARY NOTES 12. SPONSORING ACTIVITY

13 ABSTHACT

The effect of low temperatures on the shape of the load-elongationcurve, the initial modulus, breaking load, percent elongation and work torupture of 13 coated and uncoated fabrics was examined. It was found thatthe cotton/synthetic blends were least sensitive to low temperatures, thenylon fabrics, be they coated with polyurethane or neoprene, or uncoated,were more sensitive, and the PVC-coated nylon scrims, the most sensitive,and for all practical purposes, completely inappropriate for use attemperatures below OC.

UNCLASSIFIED

UNCLASSIFIED

Security Classification

KEY WORDS

LOW TEMPERATURE TESTS

COATED FABRICS

WOVEN FABRICS

BREAKING LOAD

ELONGATION

YIELD POINT

INITIAL TANGENT MODULUS

INSTRUCTIONS

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