The present study aims at development of composites based on powdered phenolic matrices (novolac) and both untreated and alkali treated bamboo fibers by a compression molding technique. Bamboo strips were treated with varying concentration (10, 15, and 20%) of caustic soda solution. The concentration of alkali solution used for treatment is the main influencing factor on the dynamic mechanical and thermal properties. The composites were evaluated by means of dynamic mechanical and differential scanning calorimetry analysis. The results reveal that the elastic and thermal properties are also dependent on the concentration of alkali used for treatment. DSC study reveals that the thermal stability of the cured resin has been lowered by the incorporation of the resin, though the alkali treatment of the fiber imparts better thermal stability to the composites than the untreated one. DMT analysis reveals that the dynamic mechanical properties are best with 20% alkali-treated fiber composites. The success of composite formation of a powdered phenolic resin is evident by the IR study of the composite. © 2009 SAGE Publications.

M DAS

D CHAKRABORTY

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Processing of the Uni-directional Powdered Phenolic Resin—Bamboo Fiber Composites and Resulting Dynamic Mechanical Properties

Journal of Reinforced Plastics and Composites

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 -15%, 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. © 2007 Wiley Periodicals, Inc.

Journal of Applied Polymer Science

Evaluation of improvement of physical and mechanical properties of bamboo fibers due to alkali treatment

Bamboo strips were mercerized with varying concentrations of NaOH (10, 15, 20, and 25%). Impact test was made on composites made from the untreated as well as from the mercerized strips. Works of fracture for all the composites were evaluated and it was observed that the fracture energy undergoes an increase from composites made of untreated bamboo strips to those made from mercerized bamboo strips. Mercerization removed alkali sensitive material from the bamboo matrix and it leads to more cellulose fibril pull-out from the lignocellulosic composites, which plays a great role in improving the work of fracture value. © 2007 Society of Plastics Engineers.

Polymer Composites

Role of mercerization of the bamboo strips on the impact properties and morphology of unidirectional bamboo strips-novolac composites

Bamboo fibers that have been treated in NaOH solutions of varying concentrations were subjected to differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) studies, respectively. The moisture desorption peak (and the enthalpy values associated with it) was moved to higher values as the alkali concentration increased up to 15% and shifted to lower values beyond that temperature. A broad exotherm was observed in all of the DSC curves for alkali treatments up to 15%. Beyond that concentration, two comparatively smaller exothermic peaks appeared for the 20% and 50% alkali-treated samples. DMTA study of bamboo strip samples reveals that the room-temperature value for the storage modulus (E′) of the untreated bamboo strips is increased by ∼400% in the case of 15% alkali-treated samples, and the rate of decrease in the modulus over the temperature range of 140-180 °C is also maximum for those samples. The untreated bamboo samples show a primary loss modulus (E″) peak at 111.8 °C, which is shifted to higher temperatures for alkali-treated samples. The damping parameter (tan δ) is also maximum for untreated samples. © 2006 American Chemical Society.

Industrial and Engineering Chemistry Research

Influence of mercerization on the dynamic mechanical properties of bamboo, a natural lignocellulosic composite

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 fx, was calculated from the FWHM and it was found that fx 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. © 2006 Wiley Periodicals, Inc.

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

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 - OH 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. © 2006 Wiley Periodicals, Inc.

Journal	Journal of Reinforced Plastics and Composites
Publisher	-
ISSN	0731-6844