Influence of alkali treatment on the fine structure and morphology of bamboo fibers

Abstract

Bamboo fibers in the form of strips and dust were treated with NaOH solution of varying concentration (10, 15, and 20%). These treated and untreated samples were then subjected to FTIR and morphological studies. Again XRD study was carried out on those treated and untreated bamboo samples in both strip and dust form. It was found that during alkali treatment a lattice transformation from cellulose-I to cellulose-II took place. It is observed from IR index value that the conversion is maximum in between 15 and 20% of alkali treatment. Swelling in NaOH introduces considerable changes in crystallinity, orientation angle, etc. Degree of crystallinity and crystallinity index for bamboo strips increases with increasing treatment concentration of alkali and falls off after 15% alkali concentration. This is also supported by d-spacing value. Orientation factor f x was calculated from the FWHM and it was found that f x value has been increased from 0.9879 to 0.9915 for 15% alkali treated and again lowered to 0.8522 for 50% alkali treated samples. Same observation of X-ray study was obtained for dust samples but at an earlier concentration. Morphological study of bamboo dust with scanning electron microscope indicates fibrillation at higher alkali concentration.

Effect of Chemical Treatments on the Physical Properties of Non-woven Jute/PLA Biocomposites

“…When the hemicelluloses are removed, the interfibrillar region is likely to be less dense and less rigid, thereby making the fibrils more capable of rearranging themselves along the direction of tensile deformation. Similar observations have been reported for mercerized coir, flax, and bamboo fiber (Sharma et al 1995;Sreenivasan et al 1996;Das and Chakraborty 2006;Moryganov et al 2008). During fabrication of the composites, the PLA penetrates the fabric surface pores as well as the pores inside the microfibrillar bundles, so that the composite failure cannot occur by simple interfacial failure.…”

Interfacial Characterization by Pull-Out Test of Bamboo Fibers Embedded in Poly(Lactic Acid)

“…Figure 4d shows that roughness changed and Figure 4e proves that the removal of the lignin loosened the bundles. The literature reports that NaOH solutions make the fibers swell by attacking and destroying their non-cellulosic structure [42]. Having the elementary fibers loosened is good when the objective is dispersing the bamboo fibers within a matrix to obtain the final green composite; however, in terms of pull-out tests, this condition is probably the most complicated to interpret.…”

Characterization of Natural Fiber Reinforced Composites-Bamboo and Sisal: A Review

“…Alkali (NaOH) treatment (mercerization) is one of the commonly used techniques for extracting and surface modification of the bamboo fibers [12][13]. The degree of surface modification varies with the concentration of the alkali solution [14]. The alkali treatment helps in removing the hemicelluloses and the lignin parts from the bamboo fiber and also results in an increase in its fibrillation.…”

“…The mercerization process has resulted in an increase in the thermal properties of the BFRCs [14,17,24,34]. With the alkali treatment, bonding between the cellulose molecules in the fibers increases while making a decrease in the affinity of the bamboo fiber towards water.…”