75 ~ C ~ O5Ie2 UNCLASSIFIED TR 12 NL

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1 ANAO&4 552 MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MATERXA ETC FIG 1115 OXIDATIVE STABILIZATION OF ACRYLIC FIBERS IV MOISTURE SENSITI ETC U) JAN 79 S B WARNER, L H PEEBLES D R UHLMANN NOOO1li 75 C O5Ie2 UNCLASSIFIED TR 12 NL t I a

_s uir Y C L A S S I F I C A T I O N OF TS DA G E lth n Oat Entrd) r I R EPO R I N U M 9 E R Technical Report 1, 12 4 t kbtltltl Tj _ 9 14 16 C) 1 I 4 V o,strnsution STATEMEN T (of cal R N owr I OI

2 _s uir Y C L A S S I F I C A T I O N OF TS DA G E lth n Oat Entrd) r I R EPO R I N U M 9 E R Technical Report 1, 12 4 t kbtltltl Tj _ C) 1 I 4 V o,strnsution STATEMEN T (of cal R N owr I OI li c) A ;/ 12: EPOR T O A T E Jany 979 I U M B E R O F D A G ) abstract ntrd in Block 20 if dl(lrnt from _ / Unclassified 15 D E C L A S SIF I C A T I O N S E C U R IT Y CLAST 7 T thii r po t, II # /f)) pø, O O *N G RA ING / L 11 _ /7, ) ( 16 WI) LaJ D I S TR I B U T I O N S T A T E M E N T (of A NU P RO G R A M EL EMENI PROJ ECT, T A S K A R E A 8 WO K U N I T N U M B E R S 10 Approved for public release; distribution unlimitted UI flt NOOO1475CiJ! Department of Materials Science and Engineering Massachusetts Institute of Technology Canbridge, Mass MONITORING AGENCY NAME & A D OR E S S (i ( d I l t r n t fro Qp 1 PE 8 CO PERFORMING O R G A N IZ A T I O N NAME AND A D D R E S S Office of Naval Research 800 N Quincy Street Arlington, VA PER I OD C OV E R E D 6 NUMB ER ( I jteclinica1 I t CONT ROLLING OFFICE NAME AND ADDRESS R EC I P I E N T S C A T A L O G 5 S \, 41arner, LL /Peebles, Jr 4uid 3 _ Moisture Sensitivity READ INSTRUCTION S BEFORE COMPLETTNG FORM _ IV /Ox idative Stabilization of Acrylic Fibers, 1 D A fl 2 GOVT ACCESSION NO ii, :1 S U P P L E M E N T A R Y NOTES I Prepared for publication as a note in Journal of Materials Science 19 KEY i OROS (Contlnu on rv r sld if ncsary aid idritl y by block number) Acrylic f ibers Carbon Fibers Stabilization Moisture Regain AB S R A C T (Contlnu on rvrs sid if nc aaiy and idntify by block numbr) Stabilized acrylic fibers are very hygroscopic Dried fibers rapidly equilibrate under ambient condition with a gain in moisture of about 8 wt percent and concurrently elongate about 15 percent, DO, (2 EDITION OF I NOV 65 IS O B S O L E T E o S E t U R IT Y C L A S S I F I C A T I G N OF I4I A G E en nat fe r % I

F _ _T T TT7 1 OFFICE OF NAVAL RE SEARCH Contract N00014 75 C 0542 Task No 356 534 Technical Report No 12 OXIDATIVE STABILIZATION OF ACRYLIC FIBERS IV MOISTURE SENSITIVITY by SB Warner, LH Peebles,

3 F _ _T T TT7 1 OFFICE OF NAVAL RE SEARCH Contract N C 0542 Task No Technical Report No 12 OXIDATIVE STABILIZATION OF ACRYLIC FIBERS IV MOISTURE SENSITIVITY by SB Warner, LH Peebles, Jr, and D R Uhlmann Depar tment of Mater ials Science and Engineering Massachuse tts Institute of Technology Cambridge, Mass January 1979 Technical Report prepared for publication as a note in Journal of Materials Science Approved for public release, distribution unlimited Prepared f or Off ice of Naval Research 800 North Quency Street Arlington, Virginia

OXIDATIVE STABILIZATION OF ACRYLIC FIBERS IV MOISTURE SENSITIVITY + * SB Warner, LH Peebles, Jr and DR Uhlmann Department of Materials Science and Engineering Massachusetts Institute of Technology

4 OXIDATIVE STABILIZATION OF ACRYLIC FIBERS IV MOISTURE SENSITIVITY + * SB Warner, LH Peebles, Jr and DR Uhlmann Department of Materials Science and Engineering Massachusetts Institute of Technology Catnbrid ge, Mass based in part on a thesis submitted by SBW in partial fulfillment of the requirements for the ScD degree in materials engineering, IIT, 1976; current address: Celanese Research Co, Summit, N J * 1IT and Off ice of Naval Research, Bos ton, Mass [i : /

ABSTRACT Stabilized acrylic fibers are very hygroscopic Dried fib s rapidly equilibrate under ambient conditions with a gain in moisture of about 8 wt pct and concurrently elongate about 15% A number

5 ABSTRACT Stabilized acrylic fibers are very hygroscopic Dried fib s rapidly equilibrate under ambient conditions with a gain in moisture of about 8 wt pct and concurrently elongate about 15% A number of accounts in the literature on producing carbon fibers allude to the moisture sensitivity of stabilized acrylic fibers (see, eg, Ref s 1 and 2) Indeed, Kinoshita (3), uses the moisture regain at 25 C, 81% RH as a measure of the extent of stabilization : fibers with less than 57 regain are understabilized, those with more than 15% regain are over stabilized But to date no detailed account of moisture regain i as been presented This paper reports such data and directs attention to some of the important consequences of the pronounced moisture sensitivity of these materials The equilibrium moisture regains (under ambient conditions) of four acrylic fibers heat treated in air at 255 C for various t imes while wrapped about a glass mandrel are shown in Fig 1 Virgin acrylic fibers are seen to absorb pct by weight of water, in agreement with previously published data Well stabilized fibers absorb 8 pet or more by ;eight The most remarkable features about Fig 1 is the similarity in the shape of these curves to those of oxygen uptake (4, 5) The dynamic moisture regain of well stabilized ionsanto acrylic and Courtelle is shown in Fig 2 (cf Ref A for details on fib s) The data points were determined as follows : (1) Fibers were I at treated at 253 C

2 in air while wrapped about a glass mandrel; (2) after 230 minutes of heat treatment time, the fibers were removed from the furnace and separated from the mandrel;(3) the fibers were reheated to

6 2 in air while wrapped about a glass mandrel; (2) after 230 minutes of heat treatment time, the fibers were removed from the furnace and separated from the mandrel;(3) the fibers were reheated to about 150 C for several hours, a treatment which has been found to eliminate all but tenaciously bound water; and (4) the fibers were removed from the drying oven and immediately placed on a Mettler balance where weight was monitored as a function of elapsed time The data indicate that the uptake of moisture occurs with similar kinetics in stabilized material, independent of the precursor Within just a few minutes of exposure to the ambient (in excess of 50 pet relative humidi ty), the fibers absorb a considerable amount of water This behavior can be of major importance, for example, when analyzing the fibers for oxygen Fig 3 shows the effect of moisture content on the measured length of the stabilized fiber The designation Gas ON indicates the time when the relative humidity of the environment around the fibers was changed from ambient to essentially zero by flowing dry forming gas (5 pet hydrogen; the balance, ni trogen) around the fiber The designation Gas OFF indicates the time when the gas was shut off and ambient air was allowed to diffuse back into the vicinity of the fiber tow The length changes were measured directly with a cathetometer; the fibers were subjected to a stress of 5 l2 x gms denier 1 (05 12 MPa) during the experixuent Clearly, the uptake of moisture is accompanied by expansion of the f ibers, as is the case with cotton, wool and nylon even at temperatures as high as 16 0 C The data indicate the occurrence of another phenomenon which I

3 may have important consequences in processing As the temperature of a stabilized fiber is cycled about 90 100 C, the length of the fiber changes dramatically flence when a fiber is cooled from the

7 3 may have important consequences in processing As the temperature of a stabilized fiber is cycled about C, the length of the fiber changes dramatically flence when a fiber is cooled from the reaction temperature, it expands in length On a molecular level, the process may be envisioned as follows: Polar groups which bind molecular segments in the polymer are solva ted by the wa ter, and Van der Waals bonds are formed between the polymer and the water In this way the polymer is allowed to relax or swell, leading to fiber extension Any model of the stabilized material must, therefore, have extensive secondary bonding In summary, the strong secondary forces between molecular segments in stabilized acrylic fibers make the material very hygroscopic Upon exposure to moisture the stabilized acrylic fibers rapidly equilibrate with a gain in moisture of about 8 wt pet and concurrently elongate about 15 pee As they exist in the laboratory, the stabilized fibers can therefore be regarded as a plasticized material AC Q OWLEDGEI NTS Financial support for the present work was provided by the Office of Naval Research This support is gratefully acknowledged

r W REFERENCE S 1 Houtz, R, Text Rest J, 20 (1950) 786 2 Johnson, J, Potter, ti, Rose, P, and Scott, C, Brit Pol J, 4 (1972) 527 3 Y

8 r W REFERENCE S 1 Houtz, R, Text Rest J, 20 (1950) Johnson, J, Potter, ti, Rose, P, and Scott, C, Brit Pol J, 4 (1972) Y Kinoshita, US Patent 4,065,549 4 Watt, W, Nature, 257 (1975) Warner, S, Peebles, L, Jr, and Uhlmann, DD, Part I, J of Materials Science (1979)

9 FIGURE CAPTIONS Fig 1 Equilibrium moisture regain at 22C (wt pct) Fig 2 Moisture regain at 22C (wt %) Fig 3 Effect of relative humidity on isothermal length of stabilized Monsanto acrylic at 22 and 160

10 C) :: = rh 72 4 / o CourteUe R Orion, o + Draion E 2 t o Monsanto Acrylic OI I I I I I ILl Time at in air (mm ) I,

11 6 I I 0 CourteI1e C,, Monsanto Acrylic rh 59 i i Fibers t reated 230 mm S o at 255 C I I I I I Time (minutes)

12 z Shrinkage (%) o 1 I

A0A TEXAS UNIV AT AUSTIN DEPT OF CHEMISTRY F/G 7/5 PHOTOASSISTED WATER-GAS SHIFT REACTION ON PLATINIZED T7TANIAI T--ETCIUI

A0A TEXAS UNIV AT AUSTIN DEPT OF CHEMISTRY F/G 7/5 PHOTOASSISTED WATER-GAS SHIFT REACTION ON PLATINIZED T7TANIAI T--ETCIUI AA113 878 TEXAS UNIV AT AUSTIN DEPT OF CHEMISTRY F/G 7/5 PHOTOASSISTED WATER-GAS SHIFT REACTION ON PLATINIZED T7TANIAI T--ETCIUI APR 82 S FANG. 8 CHEN..J M WHITE N14-75-C-922 UNCLASSIFIED NL OFFICE OF