Properties of xanthan gum in aqueous solutions: Role of the conformational transition

TI

ILAS, M. R~NAUDO

192

It is an extracellu Its solutions exhi uls~on stabilization in

tion exists as a

ion on the con-

cetate contents

194

ILAS, M. RINAUDO

SULTS AND DISCUSSION

b

RNL

R-

50

00

60

i0

1

tical rotation as a fun ; c, 10.8mM NaCl; d, 1 eating at different te

ncen~ation of a

e latter cures

‘9 ~g~oo for x~thao as fo~ct~oo of the (b), 0: from I in 0.01~ NaCi [c) add from I in O.lM Nail (d). ashed line: Qptical rotas wer v~iation with temperature for tbes~ solutions. x : relative varsity restored at 2.5”w en NaCl is added at 80” into a III form xant an solstice (see text). ah2 ~s~~~~

: ~0~

in the iower Ne~oo~a~

I1[in ~.~l~ NaCl (a), -t: horn II in

IN SOLU~ON

1

--------

c

s x

is? d 1

E

Fig. 3. Int~nsic vi sity vacation ~th temperate for the four xan~~ line: opti~l rotation vacation with temperature for ~ese solutions.

solutions (see Fig. 2). Dashed

1

M. MILAS, M. ~INAUDO

states were a

relative viscosit

RES~LTSFROMLIGHTSCA~ER~NGAND~I~~~~~~~F

Form

-

w

Na XA~AN

I71

7.0 x 106 6.5 x 106 h from Eq. I. bFrom Eq. 2.

1~ AQUEOUS

“Ib

(mL .g-“) I II

SA~LESIN~.

31 39

1

(A,

2 410

730

NaCl

1

an inundation

for fogs

_-

Fig. 5. Vacation

of the ~nductan~ ratio ndu~an~ at 25” as union

not fractionate

nd NaCl solutions ed ~nfo~ations I

GUM IN SOL~ON

~scosity at low shear rate limit versus the n in form II. a: i~eve~ible pr = 0.6 ~lutions (a,b).

1

cheating temperature for an initially beyond T,; b reve~ible

2

S, M. RiNAUDO

CONCLUSIONS

attern 1s not re-esta

NGU

SOLU~ON

. 7. Po~ible hydrogen bon bonds are omi~ed for cla~ty and

kinetic factors in a

A

S

an moi~les.

Some adjoinin lative; a-9’; l-@.

204

M. MILAS, M. RINAUDO

7 J. G. SOUTHWICK,H. LEE, A. M. JAMIESON, AND J. BLACKWELL, Carbohydr. Res., 84 (1980) 287295. 8 J. G. SOUTHWICK, A. M. JAMIESON, ANDJ. BLACKWELL, Curbohydr. Res., 99 (1982) 117-127. 9 F. R. DINTZIS,G. E. BABCOCK, ANDR. TOBIN,Carbohydr. Res., 13 (1970) 257-267. 10 S. A. FRANGOU,E. R. MORRIS,D. A. REES, R. K. RICHARDSON,AND S. B. ROSS-MURPHY,J. Polym. Sci., Polym. Lett. Ed., 20 (1982) 531-538. 11 G. HOLZWARTHAND E. B. PRE~TRIDGE, Science, 197 (1977) 757-759. 12 G. PARADO~~I ANDD. A. BRANT,Macromolecules, 15 (1982) 874-879. 13 G. HOUWARTH, Curbohydr. Res., 66 (1978) 173-186. 14 T. SATO, T. NORISUYE, ANDH. FUJITA,Macromolecules, 17 (1984) 2696-2700. 15 T. SATO, T. NORISWE, ANDH. FIJJITA,Polym. J., 16 (1984) 341-350. 16 M. RINAUDOAND M. MILAS, Biopolymers, 17 (1978) 2663-2678. 17 I. T. NORTON,D. M. GOODALL,E. R. MORRIS,ANDD. A. REES,J. Chem. Sot., Chem. Commun., (1980) 545-547. 18 M. MILASAND M. RINAUDO,Polym. Bull., 12 (1984) 507-514. 19 P. J. FU)RY, 0. K. J. SPURR,AND D. K. CARPENTER,1. Polym. Sci., 27 (1958) 231-240. 20 D. W. TANNERAND G. C. BERRY,J. Polym. Sci., Polym. Phys. Ed., 12 (1974) 941-975. 21 T. SATO, S. KOJIMA,T. NORISUYE,AND H. FUJITA, Polym. J., 16 (1984) 423-429. 22 C. ROCHASAND M. RINAUDO, Curbohydr. Res., 105 (1982) 227-236. 23 G. S. MANNING, in E. SELEGNY(Ed.), Polyelectrolytes, Vol. 1, Reidel, Dordrecht, Holland, 1974, pp. 9-37. 24 H. YAMAKAWA AND M. Furrr, Macromolecules, 7 (1974) 128-135. 25 H. BENOITAND P. Doru, J. Phys. Chem., 57 (1953) 958-965. 26 G. MUL.LER, J. LECOURTIER, G. CHAUVETEAU, AND C. ALLAIN, Makromol. Chem., Rapid Commun., 5 (1984) 203-208. 27 R. Moomous~, M. D. WALKINSHAW,AND S. ARNOTI-,in P. A. STANFORDAND A. I. LASKIN(Eds.), Extracellular Microbial Polysaccharides, A. C. S. Symp. Ser., 42 (1977) 90-102. 28 K. OKWAMA, S. ARNOTT,R. M~~RHOUSE,M. D. WALKmsHAw, E. D. T. ATKINS,AND C. WOLFULLISH,in A. D. FRENCHAM) K. H. GARDNER(Eds.), Fiber Diffruction Methods, A.C.S. Symp. Ser., 141 (1980) 411.