Improvement of mechano-chemical properties of bamboo by bio-chemical treatment

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Highlights

  • Bio-chemical formulation (BF-N/14) is prepared and applied bamboo stem.

  • Maximum ultimate tensile strength and modulus of rupture values obtained after BF-N/14 treatment.

  • Prevents significantly the fungal and insect attack on bamboo after BF-N/14 application.

Abstract

Improvements of mechano-chemical properties of bamboo by a bio-chemical formulation (BF-N/14) have been studied. Among the three bamboo species Bambusa balcooa shows higher stem density (0.9 g/cm3) with high cellulose (44.52%) and lignin (23.43%) content. The initial cellulose content (44.5%) was reduced to 40.2% after 12 month, kept under open environmental condition. BF-N/14 treatment prevents significantly the degradation of cellulose and pentosan and recorded only 2.51% and 2.30% degradation after 12 month. Also, it enhances the density by 15–18%. The tensile strength (173.10 N/mm2) and modulus of rupture (MOR) (370.31 N/mm2) have also been recorded higher after treatment. Scanning electron microscope (SEM) of BF-N/14 treated bamboo reveals the penetration and accumulation of ingredients inside the cells. X-ray diffraction (XRD) study shows higher crystallinity in treated bamboo than untreated one, which is also supported by Fourier transform infrared spectroscopy (FT-IR) study. The performance of BF-N/14 treatment has been found better to that of commercially available CCB (copper-chrome-boron) in terms of density, tensile strength and MOR significantly.

Introduction

Bamboo is a renewable and versatile resource, characterised by high strength and low weight and is widely used for many forms of construction, particularly for housing in rural areas. It has a long and well established tradition as a building material throughout the world’s tropical and subtropical regions in addition to use as a principal raw material for pulp and paper in South-East Asia. As such, bamboo constructions are easy to build, resilient to wind and even earthquake force and readily repairable in the event of damage. Certain products e.g. bamboo based panels and bamboo reinforced concrete also find wide application in the construction process.

The fibre characteristics, chemical constituents and mechanical strength of bamboo vary greatly from species to species or even in the position within the culm [14], [18] which is also observed in certain pulp wood species [6], [7]. It also vary with age in certain potential pulp wood species [11]. Bamboo consists of 50–70% cellulose, 25–30% pentosan and 20–28% lignin [22], [5]. Because of the lack of any toxic constituents, bamboo forms a ready food source for a variety of organisms. The presence of considerable quantities of carbohydrate material in green or dry bamboo makes it more attractive to organisms like fungi or borer beetles [2], [10], [17], [12]. The most serious borers of felled bamboo are Lyctus and three species of Dinoderus (celluris, minutes, brevis), which attack bamboo rich with carbohydrate material [4], [20]. The major problem associated with the bamboo is the fall of physical strength due to the attack of borer and fungus on long storage [23]. Starch, soluble carbohydrates and protein content in the bamboo increases the susceptibility to borer attack. They construct tunnels in an irregular manner either vertically or horizontally inside the tissue and converted to dust. As a result, it decays internally and mechanical property falls significantly. This problem is very common in the bamboos of South-East Asia because of the favourable climate conditions for borer attack and fungal growth. Although efforts are being made to prevent the above problem but no suitable eco-friendly treatment to protect the bamboo have been established so far for commercial application. Considering the problem associated with bamboo, a study was undertaken to prevent the fungal and borer attack in certain bamboo species available in Assam and improvement of properties of such bamboos by application of a suitable eco-friendly formulation (BF-N/14) developed by CSIR-NEIST, Jorhat, India. The results of the investigation are recorded and presented in this paper.

Section snippets

Materials and methods

Three species of bamboo (Bambusa tulda, Dendrocalamus giganteus and Bambusa balcooa Roxb) samples of 5 years maturity were collected from a village near Jorhat, India. The samples were cut initially into the size of (30 cm × 5 cm) length to carry out the experiments. All the chemicals used for the experimental work were of analytical grade procured from the local market.

Proximate chemical constituents of bamboo, was carried out using the analytical method suggested by Technical Association of Pulp

Results & discussion

Certain plant constituents e.g. cellulose, lignin, pentosan etc are important as these affects the mechanical strength properties [18]. Table 1 shows the physico-chemical properties of untreated and treated bamboo after 6 and 12 month of application of the bio-chemical (BF-N/14) and commercial CCB formulation [13]. Among the three bamboo species, B. balcooa shows higher cellulose, lignin and pentosan content i.e. 44.5%, 23.4% and 16.9% while 42.5%, 21.9% and 16.2% were recorded for B. tulda and

Conclusion

From the above study, it may be concluded that the use of BF-N/14 not only enhance the tensile strength and modulus of rupture values of bamboo but also prevents the degradation as well as its major constituent’s like cellulose, lignin, pentosan etc. Hence, BF-N/14 formulation has been found superior to that of commercially available CCB. As BF-N/14 is an emulsion, prepared from natural products it is eco-friendly in compare to commercially available products. Hence, application of BF-N/14

Acknowledgement

The authors wish to thank Council of Science & Industrial Research, New Delhi, for providing financial support to carry out the projects MLP 6000/04 and Network Project CSC-0131 as the above R&D work is based on the above projects. Also, the authors are grateful to Dr. D. Ramaiah, Director, CSIR-North-East Institute of Science and Technology, Jorhat, Assam, India, for his kind permission to publish the work.

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