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.

Bamboo strips treated with caustic solutions of different concentrations, e.g., 5%, 10%, 15%, 20%, 25%, and 50%, were subjected to mechanical testing giving stresses on tensile strength, percent elongation at break, flexural strength, flexural modulus, and toughness. The change in average density was À15%, and the weight loss value shows a maximum of 21.94% at 50% alkali treatment. The mechanical properties of bamboo strips increase steadily with increasing concentration of caustic soda, showing a comparable increased value at 15 and 20%, and then exhibiting a gradual fall. The percent elongation at break corroborates these observations showing a continuous decreasing trend. The properties under investigation exhibit a clear transition in between 15 and 20% alkali concentration. The morphology of strips was studied by scanning electron microscope and polarizing light microscope. The crystal structure of both untreated and treated strips was compared by XRD analysis. In both cases, the breakdown of the crystal structures of the cellulose fibers and the recrystallization or reorientation of the degraded chains that are devoid of hemicellulose are quite apparent. However, at a very high concentration (to the extent of 25%) the breakdown of structure predominates much more over the reorientation or recrystallization.

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Bamboo strip reinforced novolac resin composites were fabricated using bamboo strips that were treated with varying concentrations of sodium hydroxide solution at a constant filler loading (25%). The mechanical properties of various composites (flexural modulus, toughness, tensile strength, and elastic modulus) were determined. The physical characteristics, such as the wetting ability of the alkali treated reinforcements, were increased because of alkali treatment. With increasing concentrations of alkali, a higher percent loss in weight occurred. The mechanical properties were increased with increasing mercerizing strength. Maximum improvement in properties was achieved with 16 -20% of caustic treated reinforcements. An FTIR study indicated aryl alkyl ether formation with OOH groups of cellulose and methylol groups of novolac resin. Beyond 20% there was degradation in all strength properties because of the failure in the mechanical properties of the reinforcements. A correlation was found to exist between the mechanical properties and the developed morphology.

Abstract:The effect of blending poly (methyl methacrylate) (PMMA) in various proportions with suitably stabilized and plasticized poly (vinyl chloride) (PVC) was studied with reference to their physical, mechanical, and thermal properties. The resulting morphologies of the various blends were also studied to find a suitable explanation of these properties. The physical and mechanical properties of such polyblends revealed a substantial increase in toughness accompanied with unusual increase in modulus and ultimate tensile strength after an initial drop at the initial stages of PMMA incorporation compared to pure reference compound PVC. The toughening effect, however, undergoes a reduction with increasing proportion of PMMA but it never goes below that of pure PVC (reference compound) within the ranges of PMMA incorporation under study. The various polyblends exhibit the two-stage degradation typical of PVC and all of them possess higher thermal stability as manifested in their characteristic thermograms. The softening characteristics imparted by PMMA were also reflected in their respective TMA curves.