Tuesday, January 4, 2011

WATER SWELLING;

Cameron and Morton's test; steep 0.5 gm. regenerated cellulose rayon in cold water,
centrifuge for five minutes at 1000 g. and weigh immediately. untreated fibres adn
borax treated fibres show 100% absorption; one per 40 glucse residues gives 35%
imbibition.

63% SULPHURIC ACID SWELLING :



Cameron and ,orton's test consists in steeping cellulose rayon
fibres for five seconds in the reagent; air five seconds, and wash with
an excess of water. uncross bonded viscose is completely parch mintised. Cross
bonded rayon varies from little change to high swenlling.

CUPRAMMONIUM SWELLING :


Cameron and morton's test; a few threads of cellulose rayon are shaken in Io
c.c. of (15 gms. copper.200 gms. NH3 per litre) for five
hours at room temperature. untreated viscose is completely soluble.
Highly cross bonded celluloses (e.g. one bond per 40 glucose residues)
are largely unchanged in appearance. intermediate cross bonding
(one bond per IOO glucose residues) gives rise to a highly swollen
condition.

WATER SOULBILLITY:

Soluble cold, insoluble hot; cold water solutions gel on heating :
lower methy celluloses. soluble in hot water and dilute alkalis;
higher methyl cellulose. soluble in cold and hot water : sodium
carbocymethyl cellulose. insoluble in water : ethyl cellulose.

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