Chemical Changes of Natural Fibers

No significant spectral changes in raw and electron beam-treated kenaf and henequen fibers were observed from ATR-FTIR measurement [43, 113]. However, from the earlier study using elemental analysis [111] and X-ray photoelectron spectroscopy (XPS) [15] by Cho et ul, it was pointed out that the [0]/[C] ratio of the electron beam-treated jute and henequen fibers was lower than that before the irradiation (OkGy). The ratio exhibited the lowest value at lOkGy [15, 111]. The decrease of the ratio after the irradiation indicated that the treated jute fibers have more hydrophobic character than the treated. It was suggested that the combination 

Sever et al. [123] analyzed the effect of oxygen plasma treatment on the functional groups of jute fibers using XPS. It was found that with an oxygen plasma, various oxygen-containing groups such as -C-OH, -C=0, -COOH, and introduced by the surfaces of treated jute fibers. 

Dynamic contact angle measurement indicated that the surfaces of flax fibers treated with ethylene plasma exhibited greater water contact angle than the untreated and the acetylated flax, reflecting that the plasma-treated flax surfaces became more hydrophobic [122]. The contact angle was increased on increasing the ethylene flow rate to 0.5 cm s and the plasma power to 50 W. 

The effect of surface treatment on the crystallinity of natural fiber has been explored by means of X-ray diffraction analysis [134]. ft was reported that the crystaUinity index of untreated hemp fiber was 84.7%. The value was increased to 89.6% for NaOH-treated hemp and 89.1% for Na0H/Na2S03-treated hemp. 

The explanation for this result was that NaOH treatment was responsible for the removal of a greater amount of amorphous component from natural fiber than NaOH/NajSOj treatment. 

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