Nylon research

Nylon research

Citation for published version (APA):

Richards, C. W., & Gorter, W. K. (1962). Nylon research. Technische Universiteit Eindhoven.

Document status and date: Gepubliceerd: 01/01/1962 Document Version:

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'l'echnische "[ l5eschool Eindhoven.

Pregress Report

Introductio.

ETer since its iAtroductien iA

1938

the plastic Dylon has bee. aoted tor its extraordiaary tou~hne.8 aad resistaace t. wear. IR the past few years it has found rapidly increaei.g use in all kinds of machine part. such as gears, bearings, nuta and bolts, and eve. shi,'_ prepellers. It no. appeara to be tbe most widely used plastic in this field. This

iAvestigation was started with the idea of determiniAg the basic reasons for this auperiority of nylon.

The cboice of a plastic for machine applicatioas involves many factors, such as Jlold.ability, chemical and thersal stability, toughness, stiffaeSB, reeista.ce t. wear, moisture absorption, aad coat. In a.y comparisen betwee. plastic. all pertiAeBt factors must be taken iato accouat, and t. lead tue

field a give. plastic must shaw a faver.ble combi.atie. in a majority

of applicatioBs. }or example, whe. we compare nyl~n aRd polytetr.flu.retbylen.

(Tefloa) we find that the latter has superior thermal etability, ud may also be tougher and stronger thaa ~l ••• But tbe superior moldability anel much lower cost ef aylo., amon~ other th1ngs, make it the Ilere attractiYe materiali» & majority of applicatioa •• Similarly, many.f

t~properties of pelythyle.e, such as toughaess and coat, compare favorably wi th thoae of nylon, but because polyetbyle.e ta lo·.'óer stiff.es8 (m.dulua) and lower theraal stability, nylon is preferred in most .pplicati ••••

O.e of the ne.eat plastica, polyacetal (Delrin) givee eYidence of competin« quite sucessfully with nyloa. ~~y of its properties are equal tG .r

superior to those ot nylon, e.g. its Quch lower absorption of moisture

from the air. It has oae rIa .. , however, in that it is lese stable chemically

than nyloa, and this may prevent it from taY~a! the lead.

There are three properties in which .ylon has moet cODaisteatly b~e.

superior: toughne88, resistance tG wear, aJld moldabili ty • . ior this reason we decided to be~a our investigation with • study of .ae of these prepertiea, nylo.'. extraordinary tou~hnes •• ~esistaace t. wear will be stud1ed at a later date.

Toughaess

Th. property of toughness i . aR en~ineering material meaas i t . ability to absorb energy without fracture. Tlr twe factors directly involved are strength and defor~ability, and both must be preseat to have a tough material.

Strength depends ultimately on the bonde that caa exist between atoms alld molecules ia the material. In linear polymers the stoms in the polymer chain are held together by very stron~ interatomic bon~s, but the overal l streRgth of the material depends principally on the bOBds between the chaina. In a nonpolar polywer in the ru'Il.rphouB state these bonds are very weak and the polymer tends to be soft. lhe strerll~·th of such a polymer is sE>mewhat il!1proved by tbe natural eatant;lemeat of the chains caused by thermal a@';itation. l'!oW"ever, if the chains ctJ.n be properly aligned they can be broujtht so much closer to each otLer ti,at

tli.ey form crystalli tes, and sil:lce in termoleculllr bonds increase rapidl.

rlth decreasin~ separatioD the mi.. terial becoaes considerably stronger. Nylon is a po lar polymer whose molecules tand to form dipole or hyd:ot;en bonds which are stronger than those between nonpolar mole-cules. This weIl kJlown f, ct accounts for much of the :ligh strength of nylon, as well as for its high stiffnes5. üf equal or greater

import8J1ce, however, is the natura.l tendency of nylon te form cryetallitre.

~'he chain molecules in nylon are of a very regular fornl, ithout ",ide

groups or branches. Hence they easily aligR themselvee adjacent t. oae another under the influence of thermal agitation and st rong inter-molecular bonde. 'I'he result is that the interm.,lecular forcee are further i.creas.~ by close preKimity and a very strong stabl. crystal structure is forme«. The crystallinity of nylon ie commonly as hi~h

. . 50 per cent. The crystallites are forme. durin~ the process of cooliR~

fro. the melt, and once for.ed are Dot significantly affected by further chaRges in temperature belo. 215·C: Ot~ v e_SUZ'e_{ll •• t8, wiotieh-shew the}

~~t vari~t~o~& irom can~r to-eutsi~ surface, ~ sho~e

att.ch~~letter from

Dr.

Oo~r ••••

The streagth of nylon can therefore be attributed t. its ehe.ieal structure aBd t. the eimplicity and regularity of its moleculee, which allewe easy cryatallizatioa. It ie n~t greatly influellced by ordiaary temperature chaages.

1eformability, the other factor involved in teu~hness, includea three types of deformation: instantaneous elast~c, delayed elastic and plastic.

-3-The f1rst ie

ot

l1ttle censequence since it is co~en t. all ma::erial. and is assoc1ated with very small d1splacementa of 1ndiv1àual ato~s. The other two, ho.ever, iAvolve lar~e melecular motions and can absorb

ceneiderable amounta of energy.

Tha ability of a material to absorb ener~ thr.u~h deformat1oA can be studied by observ1!l~ its reaetion tI!) small etreeeee dynamically appl1ed. at different ratea and. temperaturea. Each molecular mechaa1s. by which energy can be absorbed ie act1vateà at a certaiA rate and. temperature. At lower temperatures there is 1nsufficient thermal energy to activate the mechan1sm and at higher rates there 15 insuîfice1ent time. however at higher temperatures or lower rates the mechanism is always availahle.

The common procedure for studying the dynamic mechanical behavior of materials is by means of vibration experiaents, Buch ae the torsion

pendulum. The dynamio modulus curve~odulus and 10s6 factor vs. temperature} reveal the temperature(for that particular frequency) at which each

molecular mechanism is activated. Below that temperature ener(!;Y cannot be absorbed by that mechanism, and the toughnes5 of the polymer is therefore l.wer than it is at higher temperatures.

In some polymers (e.g. polystyrene and P 11 A) no significant

transitions in the dJnamic modulus have bee~ observed below th. ordinary

operatin~ range of temperaturee. 'J.'hus in thee. polymere no important

energy absorb1ng mechan1sl113are available unless the temperature is weIl within or above the operating range. In the operating range these

polymere therefore tend te have low toughne5s.

Ia other polymere one or more traneitions occur at temperatures well below the operating range. Thie indicates that energy absorbin~ meel. i s . are available threughout the operatill~ temperature range, 8-nd t:;eee

polymere show greater toughness. In polypropylene, fer example, a traae1tion is observed at

oOe

(frequeney

6

Hz),

and in polyethy1ene there 1& one at - 110·C (slso at 10. frequency). Doth of these po1~er8 are quit. tough at room tem~·erature.

Our first subjeet of study, then, was the 1 •• temperature transitions in th. dynaaie modulus of nylon. In view of the foregoin~ remarks these low temperature transitions, which pr.duee the character1et1c shape of th. dynamic modulus curve, shouli be sn iaportant faetor in ny10n'& t.ughna&8.

PreTieue 1nvestigatio~

Several investigations have been made cover1ns the dyn8.1uic behavier of nylon over a range of te~peraturee. ~ntil

1960,

however, insufficient eonsideration was given t. the influence of abeorbed moisture on the properties of the material. Specimens were conditioned for periods of time far toe short te insure anything approachin~ uniform distril:uti.:ln

:;f moisture content. Sinee the dynamic mO,dulus of dry nyl.r. ean be as much

4

times as high as th at of nylon contdining ~~ moisture, the rp.snlts

of "'\Joch eX!2~riruents are hip;hly uncertai. .

~hnce .1<:;bO resulte have been reported on twe inveetigatiolU!J in which

gre~t care was taken to insure uniform distributio. of moisture in the

speoimens. Jacebe, at Aachen, for example, placed dry specimens in water until they had absorbe4 the required amount, and fellowei this by melting and resol1d1ficatien uader eareCully controlled conditiens to produce hGmogeaeity. Wh1le this aethed ean preduce a homogeneous distribution of moisture, it eertainly must have marked effects on the structure of the nylon iteelf. Furthermore, none of the moieture contente produced was near th. standard equilibriua content of

3%.

Ne therefore felt that the information available in the literature was inadeguate and open to questien, aad decided to eonduct carefully controlled experiments of our own. The aim of these experiments was te establisk accurately the shape of the dyna*1e ~odulus curves, especially in the low temperature region.

Experimental preeedur.

Af ter investigating possible sources of material we deeidea that

the most uniform and homegeneous material could be produced by extrusien, as in the 20 em diameter nylon -6 reds produeed at AKU, Arnhea. Th1s material has a completely diaturbea - spherulitic crystal strueture a.nd is alJust perfectly isetrepia. Dr. Oosterman of AKU (.:. V. }<esearch) very kindly suppli.a us with a sample et rod about

35

cm long for use in our experimente. Measuremente made by AKU showe' the followins properties at the center of th. re'. Other measurements, which show the slight variations form center t. outside surface, are shown in the attached letter frem Dr.Oesterman.

Deneity

RelatiTe viscosity

NUIlber average molecular weight

Lew moleoular methaRol extract

1.150

3.61

35700

-5-The attached photomicrograph shows the structure, uBin~ a microtome sectien under tbe polarizin~ mierescepe in our laberatory.

Tne next problem waB that of cenditiening the samples t. the proper moisture content, uniformly distributed. The most promising method

appeared to be one just being develepeà by engineers at AKU. ~eliminary

measuremente indicated that dry samples of nylon 3 mm tllick would reaeh an equilibrium moisture content of about 3% within 3 days if exposed to an atmosphere containing

65%

relative humidi ty at 80o

e

.

,;.ssuming that at equilibrium the moisture is uniformly distributed, this method should produca the same conditions that could be obtained af ter several monfhs at room temperature.

eonditioni~g was carried out by placing the 6peci~ens in a desiccator

over a saturateà solution of Na N0

3 with the entire desiccator in an

oven at Booe. Measurements on the conditioned specimens confirmed those made at AKU, ana indicated a moisture content averaging 3F ... .rha temperature was low enough, and tha exposure time short enough so that no significant oxidatien of the specimens was produced. The conditioned specimens were

o

stored for use i . a desiccator above a saturated 6olution of na hO, at 20 C,

<:. which maintains the relative humidity at

65%.

To thoroughly investigate the dynamie behavior of nylon we decided te make tests over as wide a range of tezaperatul'es and frequencies as possible, and to supplement the mechanical tests with dielectric me~6ure­

ments.

In the low frequency range we used the torsion pendulum apparatus whieh was already available in the laboratory. 'idth it tests were made at

frequenciee between 1 and 10 Hz, while the temperatures was varied between - 1500C and 2000e. A number of improvements ware made, such ae a better means of distributin« hot or cold air around the speclmen, a

guide for the supporting wire to reduce lateral vibration, end improvements

in the recorner.

In the hi~h frequency range the Elastomat can be used, with a specially

constructed insulated enclosure to permit control of temperature. Unfortunately, however, this equipment has been out of order so much of the time that to date no experiments other than preliminary trials have been carried out. The frequency range starts at

650

Hz or perhaps a little lower end goes up to very high values.

Hany possible designs were studied for intermediate frequency ap~ratus.

,

but we finally decided that there was insufficient time to develop a satisfactory oae.

Such equipment will l,robably be constructed at Stunford in the next year or so and we shall be ~lad to cooperate .. vi tb anyone at Eindhoven who may wiah to construct similar equipment here.

A creep tester was also built, for use if we should wish to incude long time effects in our study. Some prelim;l.nary tests have been made in compressive creep.

E'or the dielectric C01lstant and lOBS factor existing apparatus was employed, with conditioned samples of the same thickness as those in the mechanical tests.

' .. 'he experiments that have been performed to date are described in the fallowing pages.

'.rORSION PD:DULUN.

Description (see fig.2)

The sample is held in vertical position by two clamps. The shaft on

which the 10 er clamp is screwed is supported by blO balI bearings end can be rotated over a small angle r:i th the aid of a lever.

The torsional vibrations of the sample are started by operating this lever.

The upper clamp is also screwed on a circular shaft. This shaft carries a cross-bar with two movable weights. Thus the moment of inertia of the pendulum can be varied. The upper clamp is suspended from a thin wire and counterbalanced vii th a '.'/eight to avoid normal stresses in the sample o

At the end of the cross-bar an ink writer is attached and records the vibration. The paper on which the vibrations are recorded runs with constant speed from a drum over a cilinder. The cilinder is driven by a small electromotor.

The sample is enclosed by a chanber \uth heat - insulating walIs. The temperature is varied by blowing cooled or heated air in the

o 0

chamber and ranges from - 150 C to 200 C.

The temperature is measured with a copper constantan thermo -coupleo

fig.l

Recording of the ink-writer

From the recordings the dimensions A 1 t A2 and

·

t

can be measured

(see fig.1.) .By calculating the natural logarithm of the ratio

!~

the logarithm"decremens ..Ais obtnined and by dividing the length

:f.

of one vibration by the speed of the recording paper the vibration time T results. From the latter the torsional modulus G caD be _o calculated.

BothAand G in dependence of temperature give a good picture '

Pree damped vibrations with extra mass.

If the plastic sample is deformed the resisting force is assumed to be partial elastic and of partia~ plaati~ nature (acc. to Voigts model, fig.3. )

For torsion the following differential equation results:

c

lö<.

=

-co<

-n~ I = moment of inertia C = elastic co1lstant

Fi

g ___

J _ _

V_O_lJt

mo dd . D

₌

plastic constant

0<.=

deformation angle

The s01ution of eq.(1)

- D +

VIi -

4IC

---'t

gives:

•

_{_JD2}

..

- D

- 4rc

_t 2I 2I + K 2e K1' K₂

=

constants t = time

For most plastic materials the factor D2 is much smaller than the factor 4IC at room temperature so (2) can be written as:

0(= Ae - D 2I t C 06

(J

i \.

t +

'f )

A,y:>= constants

Dynamic shear modulu8 G and logarit~ic decrementJ\

From the angular frequenty W

=~

f0110w8:

27(f

=4

(f = frequency)

c

= 4

rc

2 f2 I

If we write for an elastic bar with a rectangular cross-section

eX=

J.1.l r-1

₌

the moeent

dl

G torsion modulus

p =

I = polar r..\oment of inertia

P

than is I according to de Saint Venant: p

(1 )

(2)

(4)

-3-b

=

width of the sample

h

=

thickness From (6) follows: M = G I .L _p 1 So the factor C = G I p (see eq. (1») 1

Therefore

(5)

combined with

(9)

gives:

or G =

4"

2 1 I. f2 I P 2 G :zo 41'i 1 I. g.Ip 1

---r

To

The formula with which G can be calculated out of the vibration

time T_o•

The logari thmic decrement ..A.. is:

or D (n + 1) To 2I In Aa f) Ae - 2I n To n

=

1, 2,

3 ••••••••

number of vibrations Ä= - In e D

2I

To = D 2I To

AD, An + 1 are two 5ubseqnent amplitudes

(7)

(8)

(11 )

Storage and loss modulus

Diff. eq. (1) can also be written as:

I Ö<. + G2 Ö( + G

1

ot..

=

0

We

_G

1

=

storage shear modulus

G₂

=

10s8 shear modulus

We

= "

eigen frequentie"

The solution of (13) is

=

Ae - Gal2Iwe nOlf: cos ( '

The logari thmic decrement A is:

-~

A=-ln

e 2 IW_e

=

GI T 2 We

I

and as We

=

274

T or The constant E

1 CaD be derived from:

or so G ₁

=

IG,

Q...L-\Je

=

412. ( 1 + AI. )

=

..§..

-zj:'"jf"

I IG1 _

(~)~t

+f)

4 IJ. A, of are constants T

=

vibration time (14) (16 ) ( 18) (20)

-5-For the loss angle tanJ we obtain

= A / / n

In the case of scall damping where~(l~we neglect the terms of

second order so:

I lJ

_e

Z

tand ~ A

~

Thus are the physical quantities G_1t G

2 and tancf related to

experimental quantities ..I\.and

We-(21 )

List of sY!lbols

0(

=

de fort:1ati on angle

oe

₌

phase angle

~

₌

angular

_"

eigen frequency"

A

=

logarithmic decrement

A

₌

constant

b

₌

width of the sample

C

₌

elastic constant

D

₌

plastic constant

f

₌

frequency

g

₌

gravity const.

G₁

₌

storage shear modulus

G

2

=

loss shear modulus

h

₌

thickness of the sample

I

₌

moment of inertia

lp

=

polar mooent of inertia

K_1,K2

_,

=

constants

1

=

length of the sample

t

=

tille (ca) lKg( f) -

cm]

~g(f) - cm -~ec -

1J

~m sec-

2]

beg

(f) - cJll2J [Kg (f) - cm2

J

(Cll)

beg

(m) -

cm~

fm

4 ] (cm) (sec) e, •

. _ .

__

. _

-_ - Pen du/um

~ . r '._ r

- -"\0--0 +,---~---Hecd insu/at/Y/3 chomker -t i-I',

,'-' ~ioVJ .s~ayt;no, lever

'. 1--" \

, I" ' ... ---,

I

I

I

r,-I I 1/ I':J~/ ~"T'T"-_...J I J

.5et-:j

·r

J

t

éhe " TOY5IÓn -?en du/u m"

.... 4~-8/owey air

HeatJng COl, ,

!llon

6

(UDcoad1tioaed)

TABEL I: ( ~NI.ph 1.) /-3

Iierz

T l.noC

I = 57,55 kga.ca

2

J\..

To (sec:

4

in k~\ _cm

°

0,0214 0,4275 14700

-

2

-

5

- 10

0,0242 0,4240 14900

- 15

- 20

0,0317 0, 4205 15200

- 25

- 29

0,0486 0,4190 15400

- 31

- 35

- 37

0,0735 0,4135 15700

-40

- 45

- 48

0,0976 0,4050 16300

-50

- 54

0,1099 0,4000 16800

- 56

- 59

0,1097 0,3950 17200

- 60

- 63

0,1032 0,3935 17400

- 65

- 70

0,0820 0,389

17800

- 75

-80

- 81

0,0617 0,380

18600

- 85

- 90

0,0475 0,374

19200

- 95

-100

0,0557 0,368

19900

-1°5

-108

0,0672 0,363

20400

-111

0,0862 0,360

20600

-116

-117

0,0988 0,3503 21600

-120

-121

0,0975 0,350

21700

-125

-128

0,102

0,345

22500

-130

-135

-136

0,0988 0,340

23200

-139

0,0980 0,337

23800

-140

-144

0,092

0,332

24500

-145

-150

0,089

0,330

24800

-155

-160

._.

-aample 120

x

11

x

3 . .

- erz

2

I =10,73

kga.ca

/'\..

To (sec) G ia

-'§á

~.,.,

0,0382 0,1616

19200

0,0398 0,1610

19300

0,0416 0,1614

19200

0,0438

1

0 ,1618

19200

0,0520 0,1605

19500

0,0646 0,1575

20200

0,0835 0,1560

20600

0,0960 0,1556

20700

0,1140 0,1550

20800

0,1180 0,1545

21000

0,1220 0,1530

21400

0,1210 0,1500

22300

0,1160 0,1490

22600

0,0958 0,1470

23200

0,0850 0,1430

24500

0,0800 0,1420

24800

0,0693 0,141

25200

0,0617 0,140

25600

0,0607 0,140

25600

0,0716 0,139

25900

0,0868 0,138

26300

0,1080 0,137

26700

0,1160 0,1345

;>7700

0,1 230 0,1345

27700

I

0,121

0,1335

28100

0,122

0,1325

28600

0,122

0,132

28800

0,123

0,131

29200

0,108

0,128

30500

0,108

0,127

31100

0,104

0,125

32000

0,097

0,124

32600

0,090

0,122

33700

•• - - - - ' 0 •• • ..

-8-NYlon 6 (uncopditioned) sample 120 x 11 x 3 . . 1 -

3

Herz T ge ••

[oe]

_.../\... To

~ec]

G 2690 I : t !

18°

0,137 0,470 1,22.10'f

22°

0,166 0,670 0,60 1C 'f

28°

0,190 0,702 0,545 Ol

32°

0,210 0,730 0,505 "

36°

0,242 0,759 0, 465 "

40°

0,264 0,793 0,438 "

45°

0,282 0,828 0,393 •

48°

0,288 0.853 0,370 11

53°

0,286 0,~80 0,347 .

55°

0,280 0,905 0,329 "

64°

0,250 0,970 0,285 q

72°

0,240 1,015 0,261 /1

79°

0,226 1,060 0,239 11

85°

0,212 1,079 0,235 "

93°

0,199 1,099

0,222

u 0,191 103 0,170 1,126 0,212 " 110 0,175 1,195 0,188 h 130 0,150 1,218

°

,

182 I, 140 0,170 1,349

°

,

148 " 155 0,180 1,460 0,126 " 180 0,236 1,683 0,095 •

Nylon (UNCt>N) iT·) ,. (minimale I)

(11

x

3

x

120)

rY\ Tl"\ treq. 3 - 8

H

e 1'"2. (Cjt'"oph I) T

tOe]

_../\.

t

[se~ _G

=

:202

_tI

4

I'"

20

0,256

0,205

1,20.10

23

0,295

I

0,214

1,10.

_"

31

0,370

0,242

0,..86. "

35

0,400

0,265

0,72. "

43

0,42

0,292

0,59. "

54-

0.36

0,320

0,49.

_"

57

0,33

0,320

0,4911 "

I

64

0,32

0,342

0,43. "

-10-Nylon -

6

(conditioned, 65

%

Rh)

(gro.ph I and.:Ir)

&.amp~e 120 % 11 x

3

lIIIIl

3 - 8

Hz

Low

temperature (thermo- couple: copper constantan)

i Temp. Temp. _~ To G I

[mVJ

CoC] (sec]

I

Jkgf/cm2]

I +

0,54

14

0,320

0,542

0,87 • 10

4

0,38

10

0,330

0,5

1

2

0,97 •

_"

0,00

0

0,120

0,376

1,

B

O

_•

_"

-

0,31

- 8

0,070

0,357

2,00 •

_"

,

0,58

-15

0,060

0,349

2,10 •

_"

0,82

-22

0,088

0,342

2,18

_•

_"

1,00

-27

0,105

0,338

2,23 •

ti

1,06

-28

0,100

0,335

2,27 •

_"

1,20

-32

0,093

0,320

2,48

_•

_"

J

1,39

-37

0,086

0,326

2,40

•

ti

1,75

-48

0,073

0,321

2,47

_•

_"

1,90

-52

0,074

0,318

2,52 •

_"

2,05

-57

0,078

0,316

2,55 •

_"

2,30

-64

0,086

_°9

312

2,62

ti •

2,45

-69

0,083

0,310

2,65

_•

_"

2,75

-79

0,087

0,307

2,70 •

11

3

ç

oO

-87

0,086

0,294

2,95 •

fI

-3,16

-93

0,074

0,288

3,08

_•

_"

3,21

-95

0,071

0,288

3,08

_•

_"

3,22

_-95

0,070

0,295

2,96 •

_"

3,30

-98

0,060

0,288

3,08

11

•

3

9

60

-109

0,053

0,284

3,16

•

"

3,92

-120

0,056

0,284

3,16

_•

_"

4,12

-128

0,053

0,284

3 .. 16

_•

_"

4,20

-132

0,050

0,281

3,23

0

"

i

,

I

I

I I ! I I

I

,

I

r

ylon - 6 (condi tioned, 655j Rh.)

(gt"opkI and.:n:)

High temperature (thermo- couple: copper constantan)

Temp. Temp.

...A

T

0 (m?) (oC) _(seo)

0,74

18

0,315

0,666

0,91

22

0,314

0,675

f..'-t

98

24

0,294

0,707

1,47

35

0,224

0,791

2,08

49

0,234

0,892

2,80

65

0,244

0,957

3,22

74

0,232

1,060

4,13

93

0,210

1,117

4,85

108

0,212

1,179

5,74

125

0,226

1,233

6,66

1

43

0,264

1

,L~02 I

6,84

147

0,248

1,l;.36

120

x

11

x

3

ma

3-8

Hz. G (Je

f/c.

2)

0,575. 10

4

0,560.

11

0,510.

_"

0,418.

ft

0,321.

_"

0

,278. "

0,240. "

0,205.

_"

0,184.

_"

0,158•

_"

0,130.

_"

0,124.

_"

_, (G- 2550 T 2 o

-,

1.-Nylon- 6 (conditioned- 65% Rh) (sample 120 x 10 x 3 cut from the center of

(<;jt'"Clph

JO

the bar in axial direction).

Low

temperature range

I temp. Temp. t G (mV) (oe) _(sec) (kgf/cm ) 2 0,65 + 16 0,340 0,680 _{6,85 • 10}

3

-0,57 + 14 0,339 0,659 7,30 11 • 0,24 + 6 0,295 0,509 12,20

·

_"

0,02

_°

0,172 0,434 16,80 I! • 0,10

-

3 0,080 0,401 19,60

_·

_"

0,49 _ 12 0,063 0,388 21,00

_·

_"

0,92 - 24 0,101 0,372 22,90 _•

_"

1,56 - 41 0,084 0,355 25,20 _•

_"

1,78

-

49 0,058 0,349 26,00 ti • 2,03

-

56

0,064 0,342 27,10

_·

_"

2,32

-

64 0,094 0,343 27,00 fI

·

2,67 - 75 0,118 0,337 27,90

·

_"

2,90

-

85 0,114 0,330 29,20 •

"

3,20 - 93 0,104 0,323 30,50 11 • I :~,47 -103 0,098 0,317 31,55 _•

_"

3,73 -111 0,059 0,3 12 32,60

_·

_"

3,90 -118 0,081 0,309 33,15

·

_"

3,94 -120 0,080 0,309 33,15 rr

·

I

I G

₌

4

rz

2 1 I 1 I

1

bh3 h ) 9g1 I •

~

= (1-0,63

b

p p 3 4ï1: 2. 10. 57,55. 1 1 3 (1-0,63

~)

7,3.10-:;'cm 4 G = _981. I = 1. 0,3

₌

7. 3. 10-J • t 2 P 3

.

IG

=

~ kg

f/

cm2 1 I 57,55 kg 2 t2 = cm 1 = 10 cm

( <j ra..

r

h JI ) I Temp. Temp. (mV) (oe)

0,77

I

19

1

,L~4

₃₅

1,86

44

2,44

58

3,00

70

3

,68

84

I

4,12

1

93

h,72.

105

5,85

127

6,45

139

6,96

1l!8

7,78

164

8,59

178

..A.

0,294

_I

0,212

0,213

0,222

0,225

0,214

0,211

0

,220

0,241

0,256

0,257

0,27)

0,

?

39

t (sec)

0,755

0,875

0,922

0,977

1,015

1,

0

70

1,115

1,1

9

0

Î

,340

1,414

1,505

1,650

1,910

the bar in axial èirection.

I

G

2

I

(kgf/cm )

103

I

5,55

•

Lj.,14

_•

_"

3,73 •

"

3,32 •

_"

3,08

_•

_"

2,77 •

_"

_I

2,55 •

11

2

,24

11 •

1,77

_• " !

1,59 "

11 I

1

,~·a _•

_"

I

1,16

11 ! •

a,B7

_"

I

•

Dielectric LoBs (tan

cf )

a.1tcrial:

Zgui:pment r

nylon-

6

(Alculon), conditioned, 65 ~~ Rh.

RC- generator, type

SRM,

lli~

4085

Dielectric test bridge, type

VKB,

ffi~ ~520

Indicator amplifier, type UBH, ffi~ 12121/2

Temperature range:

°

~

-

130°C.

Thermo coupIer

tand = A 0 B. F.

copper- constantan.

( 9 ra p

h

:DI)

Tempebeforel Temp.after me<;B Temp F

lmeasurJ!JS~·-i eaauremen t ( c) (kHz) (mV) , (IC) +

°9

2

3

+ 0,24 + 6 I + 0,01 0,00 0 11 - 1,20 - 1,45 _{- 35} 11 1,74 1,95 - 50

_"

2,14

2,26

- 61

"

2,59 2,67 _{- 75}

_"

2,94

2,97

.86

11 3,40 3,45 -101 fI 3,54 3,55 -105

_"

398

8

3,94

.118

"

4,11 4,19 -128

_"

see above

J

J

+

6

10 0

_"

- 35

"

- 50 n - 61

_"

• 75

_"

-86

_"

-101 n -105

_"

-118 11 -1.28

_"

A 34,5 30,0 19,0 17,5 13,5 12,5 11~6 10,5 10,0 9,5 8,0 6,5 8,5 4,5 4,5 4,0 5,0 3,7 4,0 I 3,5 3,5

3,3

Rohce und Sch arz, IJ!unich. B tancf 1Ö3 0,0345

"

°

9

°300

"

0,0190 11 _0,0175 11 _0,0135 11 _0,0125

"

0,0116 ft _0,0105

"

_°9°

100

"

0,0095 n _-.),0080 10-3 _0,065

"

0,085 11 _0,045

"

0,045

"

0040

,

JI _0,050

"

0,037

"

o

,

040

"

0,035

"

0~O35

"

0,033

DIELECT~IC LOSS (tan

cf)

(contimied) Tenp (mV) n€::m T Mp. F

I

A

13 ta~

J

(oC) _{(I~c/sec )} --0,585

i

+

14,0 1 52 10-3 :),052 1

O,9

G

O

25,8 1 77 .0

--

. /

-0,'J77 1 I~c/L:e c _1,355 34,6 1 109 10-3 0,109 "-1,93 L:-7,0 1 11₊₂ 10-':;> _{0, -;42} 2,30 56,2 1

I

14 10-'-: _0,149 2,76 65,9 1 174 10-3 0,174

3,19

,'5,0 1 ~7"" _c.../~ 10-3 ., _{u ,.:..;)&:-},....,. "" 3,74 85,6 1 323 10

-

3

0,323 3,78 38,0 1 381 10-3 0,381

4,58

104,0 1 700 10-':;- J,700 _ 7

5,15

114,0 1 1100 10 .:;> _1,100 I 5,70 124,0 1 I ₁₄₀₀ 10-;) _1,1.-1-00 I I 0,585 14,0 10 49,5 10-4 0,Ol195

"

"

10 75,0 10 -iJ- 0,C75

"

"

10 I 107,0 10 _L~ 0,107 10 Kc/s ep

_"

rr _{10 145 10-4 0,1l1-5}

"

"

10 151 10-4 0,15 1

"

ti ₁₀ 151 10--+ C,151

"

"

10 137,5 10-

4

0,1375 ,\

"

10 138 10-4 0,138 11 ft ₁₀ 137 10-4 0,137 11

"

10 300 10-4 0,300

"

"

10 114 10-3 _1,140

-16·

Maclining of the specimens.

Th. specimens were machined out of a bar with a diameter of abt.8"

and a,length of abt. 15".

The properties of the material called ior the following general requirements:

a. sharp tools.

b. high cutting speed.

c. not a high rate of feed.

d. use of a cooling fluid.

All the operations were divided in a rough pre - machining and a

fine af ter rnachining.

Conditioning.

fhe principal ai~ of conditioning is to improve the reproducebility

of test results.

The specimens v1ere placed in a des!ceator over a saturated solution

of NaN0

3• The desiccator was placed in an óven at Booc which caused

acontrolled atmosfere of 65

%

relative bumidity.

Before and af ter the conditioning the specimens were weighed on a

"MettIer" balance. For some results see the table below.

Con itioning of nylon-6

Bars: 120 x 12 x 3 rum

ISpecimen Letore Af ter 3 days Af ter 6 days Af ter 30 days

"0. cond. cond. cond. above 200C

NaI:02 Solution 1 5,0438 2 5,0431 3 4,9712

5,

0

977

5,0574 4 J+,' 321 4,96 45 4,9302 4,9415 Weight in grams (= 0,0005

rrn

p

.c.

A.C 3 days A.C. 6 days A.C. 30 days

I 4.90~3 5,067~ 4.9(86 11 4,9372 5,0661 4.9374 111 5,0090 5,0093 5,1534

1:0 Betore Aftar

3

daya Af ter

6

daye Af ter 30 dayE

cond. eond. cand. cand.

I I

4,4597

I :

4,63 18

!

4,4591

I

I

,

I

11

4,5950

I

4.7800

\

I

4,5948

0,3 I

I

0,1 -100

_-so

_{o 50 100} T-.°C

---.

--.--A

0,'+ 7 tem= 0,02 b 5 4 -6 [k9

km<]

3

I

0,3 2

e

2 S,-+·-4--+--'-i---l-.C-+ 3

I

2

I

I 0,1

110>-9 8 7-0,08 ₆ 0, 06 1 :J 4 3 0,0'+ 2 0,02 ~o '--_-'-1<...:::5=0 _ ___ ._ .. _ -100 -50 o 50 SClm;o/e 120X12X3 yY?yY) 100 -- 0' 9

~

I

(, -5 ! .$

I

!

- 10'! ;!-+--~+---9 -+ ---+- 8 ! -.-::-.:.f,....-;..-+- .. 7 . I 6 . ') 2

I

.

I

1

I

.

;.: • • .. J '.! 1" .om .. IIJIJ .. .,.;j . J 1 10 '-"fit .. ld ,0 mmo

--S-..!:..~J)h_

I

..

aoo

0.0

Based on the results of the first two series of tests using conditioned nylon specimens it appears that there are two and perhaps three emall transitions at temperatures below OOC. Their presence indicates that at least two ener!y absorbing mechanisme are activated in the operating range. It seerns evident that these mechanisme are directly responsible for at least part of nylons toughness. In what proportion they contribute to this tou~hness remains to be determined.

Further carefully controlled experiments are needed to fully define the dynamic properties of nylon. We have planned several more series to be:'onducted at Eindhoven and hope to get some ne .. experiments of this kind underway soon at Stanford. The projected series at Eindhoven includes teste over the same temperature range at seversl different frequencies using the modified Elastomst. and a correspondinC series of dielectric tests.

With the information thus obtained it will be possible tQ extend the

investigation to include a study of the correlation between mechanical and electrical properties. and a comparison of the effects of time and temperature.

To determine the extent of tbe contribution of the low temperature energy absorbing mechanisme to tou/r,hnes8 some insicht into the molecular mechanisms is needed. th. correlation between mechanical and electricBl properties should provide useful information. Beyond this it will

probably be necessary to employ experiments in which the molecular

structure is altered systematically whil. observing the resultin~ e lects on dynamic behavior. If the molecular mechanisme can be irientified and then immobilized by artificial. JIl.ans their contribution to tougnness should be easy to àetermine,

N. V. 0 N DER Z 0 E KIN G SIN ST IT U U T RE S E ARC H . A R N HEM

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