I D-RI61 925 CREEP OF THERNOSOFTENING PLASTICS IN AIR AM IN A i/i1 PHYSIOLOGICAL SOLUTION(U) FOREIGN TECHNOLOGY DIY

WRIGHT-PATTERSON AFB OH G 1 ROYTBERG ET AL. S1 NOV 85

I UNCLASSIFIED FTD-ID(RS)T-S±67-85 FI'G 20/11 ML

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MlIROCOPY RESOLUTION TEST CHART

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FTD-ID(RS)T-0167-85

FOREIGN" TECHNOLOGY DIVISION

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CREEP OF THERMOSOFTENING PLASTICS IN AIR AND IN APHYSIOLOGICAL SOLUTION

-by

G.I. Roytberg, V.N. Kestel'man, R.Z. Rakhimov

DTICVlELEC T E

DEC 3 18

Approved for public release;Cdistribution unlimited.

LES

85 11 29 125

FTD -ID(RS)T-0167-85

EDITED TRANSLATION

FTD-IDCRS)T-O167-85 1 Nov 85

MICROFICHE NR; FTD-,35-C-00102 7

CREEP OF THERMOSOFTENING, PLASTICS IN AIR AND TN APHYSIOLOGICAL SOLUTION

By: G.I. Roytberg, V.N. Kestel'man, R.Z. Rakhimov

English pages: 6

Source: Fiziko-Kiiimicheskaya Mekhanika Material ov,Nr.-5,. 1972, pp. 81=-84

Country of origin: USSRTranslated by: Robert D. HillRequester: FTD/TQTDApproved for publf,. release; distribution-unlimited.

THIS TRANSLATION IS A RENDITION OP THE ORIGI.MAL FOREIGN TEXT WITHOUT ANY ANALYTICAL OREDITORIAL COMMENT. STATEMENTS OR THEORIES PREPARED BY:ADVOCATEDOR IMPLIED ARE THOSE OF TH4E SOURCEAND DO NOT NECESSARILY REFLECT THE POSITION TRANSLATION DIVISIONOR OPINION OP THE FOREIGN TECHNOLOGY DI- FOREIGN TECHNOLOGY DIVISIONVISION. WP.AFS. OHIO.

FTDiD( RS )T-0167-85 . Date 1 Nov 19 85

U. S. BOARD ON GEOGRAPHIC NAMES TRANSLITERATION SYSTEM

Block Italic Transliteration Block Italic Transliteratici.

Aa A a A,a Pp p p R, r

6 6 6 B,b Cc Cc- S, s

BB Be V,v Tr T m t

Fr r G,g Yy Yy U, u

.4 )? a D, d *) (P 0 F, f'

E e E a Ye, ye; E, e* X x X X Kh, kh

M X Zh, zh QL 11 Li . Ts, ts

3 3 3 s Z, z H 4 V V Ch, ch

if H U I, i W W WI Sh, sh

R a1 Y, y 4 uA L Shch, shch

K 1 K X K, k bI if

.i n If. L, 1 i U h Y, y

M At M,m M b b h I

H H H X N, n 3 3 -E, e

O o 0 0 0, o hi 0 0 a Yu, yu

n n j,, P, p F 1 2 a Ya, ya

*• e initially, after vowels, and after -, b; e elsewhere.When written as 9 in Russian, transliterate as y4 or e.

RUSSIAN AND ZNGLISH TRIGONOMETRIC FUNCTIONS

Russian English Russian English Russian English

sin sin sh sinh arc sh sinh-cos cos ch cosh arc ch cosh-tg tan th tanh arc th tanhictg cot cth coth arc cth cothsec sec sch sech arc sch sech 1

cosec csc csch csch arc csch csch

Russian English

rot curllg log

GRAPHICS DISCLAIMER

All figures, graphics, tables, equations, etc. merged into this

translation were extracted from the best quality copy available.

i

CREEP OF THERMOSOFTENING PLASTICS IN AIR AND IN A

PHYSIOLOGICAL SOLUTION

G.I. Roytberg, V.N. Kestel'man, R.Z. Rakhimov

(Moscow Technological Institute of the Food Industry)

The creep of polymer materials is studied predominantly under

conditions of static uniaxial tension [l-4]. Established at present

is the existence of elastic, elasto-elastic (nonstationary) and vis-

cous (stationary) components of total creep strain. The total strain

Kat a constant tensile load and temperature and also the duration ofthe loading are connected Writh each other,[2]:

+ +

where 6 is the total creep strain; 1 - ela tic component; ly, -

elasto-elastic (relaxation) deformation; vi - viscous deformation

(, - rate of viscous deformation, t - time). Liquid media under

these conditions do not change the shape of the creep curves. It

was of interest to clarify the possibility of using~equation- 1) for

describing the creep of structural thermosoftening plastics with

S. other forms of the stressed state in air and in liquid media.

We studied the creep of polymers under normal conditions in air

and in the model medium - the physiological solution (0.9% solution

of NaCl in distilled water) under static bending and compression.)

The objects of the investigation were polyamide-12 (P-12), the co-

polymer of trioxane with dioxalane (STD), fluorinated polymeth eta-

crylate (PMMAF), and casting polyethylene terephthalate- TF). The

standard bars (for bending with a dimensi OX15X120 mm, for a

compression oQf - made by the casting method under

pressure (P-12, STD, PETF) and machining from a block (PMMAF). Tests

6were conducted under stresses 0, which comprise different portions

Vf the short-term breaking load p for each material. The

EDs

e. ~ /~744 4. t r-

'a ~ 4h *E v;y.,~4. ~- -* ~

short-term bending strength of the thermosoftening plastics was de-

termined at a rate of 50 mm/min and for compression and tension -

at a rate of 15 mm/min (Table 1). Creep strain was estimated with

a precision of up to 0.01 mm according to results of not less than

five experiments.

*. t

• . _1 1

%,,,

-. U N 4 N

- ... . / - ._ .-

.

* Fig. 1. Creep of P-12!a)STD (b), PETF (c), and PMMAF (d) in air (dashed

l. lines) and in a physiological solution (solid lines) in the compres-

sion process at different values of v-1/ : 1 - 0.05; 2 - 0.1; 3 - 0.2;4 - 0.3; 5 - 0.4. Key: (1) days.

As is evident from Fig. 1, all the obtained creep curves consist

of two main sections: nonstationary and stationary creep strains

.. (the instantaneous elastic strain is not reflected on the figures).

These curves concur in shape with the known creep curves under con-

ditions of static tension of the majority of the solid polymer ma-

terials. Under static bending the picture was similar. In the

physiological solution the intensity of the creep strains is differ-

*, ent than it is with tests in air, but the nature of the curves re-

mains unchanged.

Usually, it is accepted to consider that in the region of the

stationary strain, when the rate of the process is constant, a viscous

2

% t - . . . . . *. * • . . *..

deformation is observed, and in the region of the nonstationary strain,

an elasto-elastic deformation is observed. To separate the elasto-

elastic deformation, individual investigators [5] continued the lin-

ear segment of the curve in coordinates t.- to the intersection

with the ordinate E., thereby disregarding the time to the approach

of the maximum of the nonstationary creep strain. But under the

conditions accepted by us, the time of the deformation of the non-

stationary creep is very significant with respect to the total time

of action of the load, and, therefore, we cannot disregard it.

Table 1

j"- Short-term strength of thermosoftening plastics (kg/cm2 )

n InP flow

fl-1 112 1 6 130*CTfl 656 OWu IWm

WO, A' go 1333 1350160 1040 552

Key: (1) Material; (2) Under tension (3) Under compression; (4)

Under bending.

441I

B G.AW'c (1)s

-N Fig. 2. Dependence of the maximum of nonstationary creep P-12 (1),STD (2), PETF (3), and PMMAF (4) in air (a) and a physiological solu-

L 2tion (b) on stress o under compression. Key: (1) kg/cm

In logarithmic coordinates Fig. 2 gives the dependence of the

magnitude of the elasto-elastic strain on stress a under compres-

sion in air and a model medium. The rectilinearity of the graphs

confirms the earlier proposed exponential function between the strain

and stress (5]:

tr. -AaA, (2)3

.°...* * . ** *'* S **

' .where A is the parameter dependent on the medium; k - the coefficient

determined by the form of loading (Table 2). Straight lines of the

nonstationary creep in a physiological solution are located somewhat

higher than the similar curves obtained during the test in air.

* Table 2Values of parameters for the creep equation for thermosofteningplastic P-12

(1) "_e, s . al. -F-

" s ""'v sop , seI opo,

39~ 213 I 0tO 0.015479 30.40230 0,04.%76

H'r6() 2. 4 4 11 31210- 4,07-101 1.0 1.0 0.0EI3 0.0920.12 a 9 0.14110 .1203'J0 10 9 0,1430 0,2040

o4 7 O.00 C 7 O.P0O1719.A I Ii 1 2.4&.10-' .2.10 -2 O.K% 0.85 O.A OMs .00 6 0 1270

17.;1 0 _ O.0 M 0.003300" i .4 10 tO 0.0027 0,0(O0

( e) m Pauu rw V', aM oo PWoe AN4tyma , MWC O I'tfmgM.

Key: (1) Form of deformation; (2) Stress, kg/cm ; (3) Time to ap-

proach of maximum of nonstationary deformation, days; (4) Air; (5)

.. Physiol. solution; (6) Constants; (7) Bending; (8) Compression;(9) *Dimensionality v. with bending - mm/days and with compression -

1/days.

In considering the dependence (2) and also the time to the ap-

proach of the maximum of the nonstationary deformation of creep, we

can present equation (1) in the following form:

=t, -p ,.4+ A + (,(t--l ,,.,). ( 3)

where t is the time during which the maximum of the nonstation-

ary strain is achieved. The deviation of values of creep strain,

obtained according to relation (3), from the experimental values

for the P-12 was more than 6%, for the STD - 8%, the PMMAF - 6%, and

PETF - 9%.

In formula (3) the rate of the stationary creep strain w, and

the time of achievement of the maximum of nonstationary strain t

4

'%%

-. w- -7 -7 77.-

are also a stress function. In conditions of our experiment, it is

impossible to disregard the time t1 due to the comparatively short

total time of the test. Considering this, we made an attempt mathe-

matically to describe the dependence of the deformation of the sta-

tionary creep on stress. It was found that for thermosoftening plas-

tics P-12 and STD undergoing static bending, the dependences v(o)

and t,(a) in air and in a model medium are linear in logarithmic co-

ordinates (Figs. 3 and 4) and, consequently, are described by the

exponential function:

v" -om (4)

andt,-Can, (5)

where B, C, m, and n are constants. For the STD with bending in a

model medium, the linearity is retained to or=200 kg/cm2 .

0. a.

,o wth stti bedn.o -2 (I n T 2 nai dse uvs

0.8'

'/ A0

/2an . m ed (solid ne. Key () OW 1(2k

*Fig. 3. Fig. 4.

Fig. 3. Dependence of the rate of stationary creep strain on stress

cr with static bending of P-12 (1) and STD (2) in air (dashed curves)2band in model medium (solid lines). Key: (1) min; (2) kg/cm

Fig. 4. Dependence of time of achievement of maximum of nonstationary

creep strain on stress 0' with static bending of P-12 (1) and STD (2)

in air (dashed line) and in model medium (solid lines). Key: (1)

mm/days; (2) kg/cm2

Thus for thermosoftening plastics with a high degree of crystal-

linity (P-12 and STD), the creep in the process of static bending

at high stresses in air and in a physiological solution can be des-

cribed by the following equation:

+ A o + Bw(t-C). (6)

1 5o.- , ' "- : ", ' " "-". -. ",' ",, ., - . " . ., . ... . .-.-.. . ,' Z %"/ .'.E

, ,*, ,_, ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~_ 1.0- . ,,. .f ''. ' .f . .k .. ,,/..'

• ,

,-7r.-.d-*t 'T-rr r . -7 V V V

References

1. A.H. Stuart. Physics of High Polymers, Springer-Verlag, Berlin,

1956.

2. W. Holzmuller, K. Altenburg. Physics of Plastics, Akademie-Verlag,

Berlin, 1961.

3. J. Marin. Appl. Mech. Rev., 1951, 4, 683.

4. W. Findley. Appl. Mech. Rev., 1953, 6, 49.

5. H.A. Bokshitskaya. Khimicheskoye mashinostroyeniye [Chemical

Machine Building], 1963, No. 2.

Received 15 July 1971

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