Im. Fouda et al., EFFECT OF THE OXIDATIVE POWER OF IODINATION ON THE OPTICAL-PROPERTIESOF ALPACA FIBERS, Polymer degradation and stability, 46(3), 1994, pp. 287-294
This study deals with the changes in the optical properties of Alpaca
fibres due to the effect of the oxidative power of iodine on the struc
tural characteristics of Alpaca fibres. The diffraction of a He-Ne las
er beam was used to measure the dimensional parameters, transverse sec
tional shape and area of the Alpaca fibre sections. Optical and scanni
ng electron microscopes were used to confirm the geometrical parameter
s of the cross-sections. Two methods were applied for the measurement
of the refractive indices and birefringence of the Alpaca wool fibres.
The first was concerned with the application of multiple-beam Fizeau
fringes in transmission before treating the fibre with iodine. The sec
ond method made use of a double refracting interference microscope (th
e Pluta polarizing interference microscope). The double beam technique
was considered the most suitable in determining the mean refractive i
ndices and the double refraction of the samples after the iodine treat
ment. Large changes were observed in the values of the refractive indi
ces due to the iodination process, while the birefringence exhibited n
o appreciable change. Examination of the Alpaca fibres by X-ray diffra
ctometry showed that the crystalline parts had been completely decompo
sed and degraded due to the effect of I2, which causes oxidative sciss
ion of the intermolecular disulphide bonds of the keratins.