46
MEDULLATION
IN
WOOL
[Vol. XXVI, Part II,
Secondly the polypeptide synthesis from anhydrocarboxy acids has to be consi-
dered inside the fibre. The possibility of such synthesis inside the fibres has not
been tried so far though it sounds promising. It is proposed to be undertaken.
The last choice is on the lines of the present work where the techniques of regene-
ration of keratin fibres is tried to fill up the medullary hollow space in coarse wool.
Such an investigation is very useful specially for the hairy coarse Indian wool,
since if the hairy portions could be filled by appropriate polypeptides, the physical
properties of the fibres would change to make it suitable for more useful purpose
than merely as carpet wool. The methods tried during the present work were
almost similar to those used for the synthetic polypeptide fibres but suitably
modified to suit the present problem. Proteins were extracted by aqueous solutions
of sodium sulphide and also of urea and precipitated by hydrochloric acid. The
precipitated proteins were dissolved in alkali either alone or after blending with
casein. A coarse hairy sample of wool with degree of medullation (hairiness) was
treated with a solution similar to the one used in the spinning bath and was subse-
quently treated with solution of proteins and finally given the hardening treatment.
EXPERIMENTAL
The diameter of the sample was measured by microprojection by taking over
200 readings and mean-diameter and coefficient of variation calculated by the
usual statistical methods. The percentage of medullation is described as the per-
centage of the length of hairy portion in the fibre to the total length and is measured
by microprojections as discussed in part II of the present series.
Extraction of proteins from wool
Seventy grams of wool was dispersed in 2 litres of 25 per cent sodium sulphide
under inert atmosphere of argon form 48 hours and undissolved portion was filtered
off through a metal gauze. The dissolved protein was precipitated by bringing the
clarified extract to pH 4 by the addition of hydrochloric acid. The precipitate was
washed and dried. It was found that when extraction was done in air the yield
was very poor and the mass became rather pulpy but under inert atmosphere the
yield was over 60 per cent and the extraction neat. The precipitated protein was
used to prepare two solutions for treatment.
Solution I. Five grams of protein was mixed with 15 gm. of lactic casein in
75 cc. of distilled water and kept stirring for one hour. 5 cc. of 20 per cent caustic
soda was added and the concentration of free caustic soda in the solution adjusted
to 0.5 per cent.
Solution II. Fifteen grams of protein was soaked in 50 cc. of distilled water for
one hour. Cuprammonium solution was prepared and precipitated according to
the method of Happey and Worwell. The precipitate was dissolved in concentrated
ammonia and finally adjusted to pH 8.
Solution III. Five grams of wool was dissolved in saturated aqueous urea at
room temperature and the undissolved portion filtered off. The protein solution
was diluted to 400 cc.
Preparation of wool samples
The samples were carefully scoured, first with 0.1 per cent neutral soap solution
at about 70°C and then degreased by soxhlet extraction with benzene (20 times).