Dr. Dipul Kalita - Academia.edu (original) (raw)

Papers by Dr. Dipul Kalita

Microbiology, Jun 1, 2022

Utilization of banana plant for making hand made paper and certain grades of specialty paperboard... more Utilization of banana plant for making hand made paper and certain grades of specialty paperboards have been investigated. The physiochemical characteristics of the three species of banana plants viz. Musa velutina, M. paradisica and M. sapientum available in NE region of India were studied. The plants consists an average of 25-27 % sheath, 42-48 % core and 27-30 % leaves. The cellulose content was varied from 59-63 %, lignin from 15.3-18.2 % and pantosan from 13.5-15.2 %. in all the three plant species. The cooking experiments were conducted in an open vat under pressure free condition using NaOH and Na2C03 as cooking chemicals. The percentages of cooking chemicals were varied from 6-10 % maintaining bath ratio at 1:6. The unbleached pulp yield was recorded 48-52 %. The bleaching of the pulps was carried out using HE -H202sequence to get 60-65 % brightness. The physical strength properties of hand made paper made from these three plant species showed tensile index 55.4-62.8 Nmg-1,Tearindex 10.4-15.2 mNm2t, Burstindex 6.2-8.7 Kpm2g-1with Double fold values 300+. However certain specialty paperboard such as leatherboard made out of banana pulp in combination 'with bamboo pulp showed breaking load 120-145 (Kg),Tensile strength (dry)220-250 Kg/cm2,elongation 39-42 %, linearshrinkage 4.0% and areashrinkage 4.2-4.5%. Another specialty boards such as solid toughened board made from the blends of ragand banana pulp showed very good physical strength with breaking load value 160 kg and 90 kg respectively for30 cm and 60cm span with minimum absorption of moisture.

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Mar 1, 2013

Martensitic precipitation hardening steels are characterised by high strength which is achieved b... more Martensitic precipitation hardening steels are characterised by high strength which is achieved by a martensitic matrix and precipitates. The material also shows a good ductility and toughness if properly heat treated. But welding of these steel types is often problematic and requires a special procedure (e.g. post-weld heat treatment) in order to achieve satisfactory results. In this contribution, the solid state welding process-friction stir welding was used to weld 15-5PH and the results of the investigations are shown. The butt welds for 2?6 mm thick steel sheets have been carried out at Institute for Materials Science and Welding at Graz University of Technology using tungsten based tools, different welding speeds and tool rotational rates. Temperature measurements using thermocouples have been performed on the advancing and retreating sides of the weld. Detailed microstructural observations were performed for base material, heat affected zone, thermomechanically affected zone and stir zone. The appearance of retained austenite, which reduces the strength of the material, has been studied for the distinct regions of the friction stir weld. A quantitative spot analysis by energy dispersive spectroscopy was performed to identify tool remanents in the stir zone of the weld. For further characterisation, hardness profiles of the weld have been created. Tensile tests and surface fracture analysis using scanning electron microscopy have been performed. Welds with low energy input have shown better results than welds with high energy input. Additionally, effects of post-weld heat treatment on microstructure and properties of the joint have been analysed.

Journal of Scientific & Industrial Research, 1999

Medium density panicle boards were prepared from three species of weeds viz. Melastoma l11alabath... more Medium density panicle boards were prepared from three species of weeds viz. Melastoma l11alabathricul11, Eupatorium odoratlllll and Thvsan olaell1a mClxim.a, which were co ll ected from reserve forests of Assam and Aru nac hal Pradesh. The proxi mate chemical analys i·s of the plant raw materi als was carried oul. The cellulose contents in the plant va ri ed from 52.6-59.7 percent , the ash and silica contents from 4.6-8.9 percent and 1.78-2.90 percent respectively. The effect of wood panicle sizes on strength properties of the boards was studied and boards prepared with 20 percent UF res in from particles of -10M and +20M , showed the max imull1modulus of rupture (MOR) ( 143152 kg/cm2), wh ile MOR had grad uall y decreased in the boards prepared wit h finer panicles . When quantity of bi nder was reduced, MOR had decreased and water absorption increased. Boards prepared with mixtures of UF and PF res ins in different proportions gave va ri able MOR (149-159 kg/cm2) and water absor...

Reviews of Adhesion and Adhesives, 2015

This manuscript reviews various aspects of fiber/resin interface in fiber reinforced composites, ... more This manuscript reviews various aspects of fiber/resin interface in fiber reinforced composites, with special emphasis on green composites that use plant based fibers and sustainable resins. In this chapter we describe the importance of fiber/resin interface, factors affecting it, various modifications of fiber and resin that can be employed to improve the interfacial property and the experimental techniques to characterize the interface. The nature of the bonding between the fiber and resin and the mechanism of fiber/resin interaction are also discussed. Improving the fiber/resin interface is critical in the case of green composites since the hydrophilic plant fibers and some of the hydrophobic resins have very poor bonding. Strong adhesion at the fiber/resin interface is desirable for effective transfer of stress from broken fibers to intact fibers and, thus, to obtain good mechanical properties of the composites. However, weak bonding can provide energy absorbing modes through interface failure, making the composites tough. Thus, from the same set of fibers and resin it is possible to obtain composites with different properties simply through the control of fiber/resin interface.

Indian Journal of Chemical Technology, 2001

Calotropis procera and Nerium indicum were evaluated as potential renewable sources of energy and... more Calotropis procera and Nerium indicum were evaluated as potential renewable sources of energy and chemicals. The different plant parts-leaf, stem, bark and the plant as a whole were analysed separately for α-cellulose, lignin, ash and elemental compositions. α-cellulose in the whole plant portion were 56.42 % and 57.35 % for C procera and N indicum, while lignins were 20.42 % and 23.25 % respectively. The elemental composition of C, H and N in the plant were 40.36, 6.19 and 2.06 % for C procera, while for N indicum, the C, H and N were 38.54, 5.86 and 1.82 % respectively. Of the two species, C procera contained 4.71 % oil, 11.45 % polyphenol, 3.46 % hydrocarbon, 7.20 % protein and 22.8 % unsaponifiable matter, while N indicum was found to contain 4.36 % oil, 8.62 % polyphenol, 2.18 % hydrocarbon, 7.55 % protein and 49.8 % unsaponifiable matters. The calorific values of the plant species were also determined and found to be 17.5 MJ/kG and 15.3 MJ/kG for C procera and N indicum respec...

Construction and Building Materials, 2015

Abstract Improvements of mechano-chemical properties of bamboo by a bio-chemical formulation (BF-... more 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.

Journal of Natural Fibers, 2021

In the present study, an effort has been made to develop a quality composite material using coir ... more In the present study, an effort has been made to develop a quality composite material using coir fibre and waste polyethylene by improving the surface properties of coir fibre with the help of chemical treatment under controlled conditions. Chemical constituents of untreated and treated fibre were analysed by TAPPI standard method. Structural analyses of these fibres were carried out by FTIR, Electron microscopy, Powder-XRD and Thermogravimetric analysis. From powder-XRD crystallinity index was found to be higher for chemically modified fiber than untreated fibers. The characteristics properties i.e. water absorption, total swelling values of the composite board made from different chemically treated fibers reduced drastically and the mechanical strength properties i. e. ultimate tensile strength (UTS) and modulus of rupture (MOR) increase significantly. Surface modifications of coir fiber increased the adhesion of fiber matrix which improves the quality characteristics properties o...

Now a day, the dependency of mankind on polythene has grown to larger extent because of its wide ... more Now a day, the dependency of mankind on polythene has grown to larger extent because of its wide applications in storing food without allowing the moisture inside the packing and also as carry bags. But polythene is a non-biodegradable material which when buried in the soil doesn’t decompose. Because of this reason the soil looses it’s fertility due to the toxic chemicals it release by the action of temperature and also killing the micro organisms that are essential in the soil. In view of this, several attempts were made in recent years to develop paper that can show the oil proof as that of polythene. This project involves not the production of paper but the basic raw material for paper production that is pulp from banana plant (abundantly available on earth). Later this pulp can be blended with pulp obtained from bamboo which is less abundant, to obtain oil proof paper. The reason behind the selection of banana as raw material is, in banana plantations, after the fruits are harve...

Utilization of banana pulp fibre for producing greaseproof paper has been investigated. The morph... more Utilization of banana pulp fibre for producing greaseproof paper has been investigated. The morphological characteristics of plant and fibre, chemical constituents of the sheath, characteristics of pulp and physical strength properties of hand sheet of 45+5 gsm made from banana pulp alone or in combination with bamboo pulp fibre are presented. Results of the laboratory investigation show that Musa paradisica contain high quantity of gums and mucilage inside the sheaths. The pentosan content (13.5%) may also impart the greaseproof properties. The drainage time of the banana pulp increases with the increase of beating time. At 80 0 SR freeness, the pulp becomes hydrated and forms a jelly like stock. The paper made out of this hydrated pulp stock shows the characteristics of greaseproof paper with burst index 6.10 kpam 2 g -1 , tear index 7.00 mNm 2 g -1 and tensile index 51.2 N mg -1 with very good blister and oil resistibility. The physical strength properties of the paper may furthe...

Materials Science and …, 2013

The paper shows the results of metallographic examination and mechanical properties of electron b... more The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material. Metallographic examination revealed that the concentrated electron beam significantly affects the changes of microstructure in the weld and the adjacent heat affected zone (HAZ) in both steel grades. The microstructure of the welded joints is not homogeneous. The four zones, depending on the distance from the weld face, can be distinguished. Basically, the microstructure of the weld consists of a mixture of martensite and bainite. However, the microstructure of HAZ depends on the distance from the fusion line. It is composed of martensite near the fusion line and a mixture of bainite and ferrite in the vicinity of the base material. Significant differences in mechanical properties of the welded joints were observed. For a butt welded joint of the S960QL steel grade the strength is at the level of the strength of the base material (R m = 1074 MPa). During the bending test the required angle of 180° was achieved. The impact strength at-40°C was 71,7 J/cm 2. In the case of the Weldox 1300 steel grade butt welded joints exhibit high mechanical properties (R m = 1470 MPa), however, the plastic properties are on the lower level than for the base material.

Process Safety and Environmental Protection

Journal of Polymers and the Environment

Microbiology, Jun 1, 2022

Utilization of banana plant for making hand made paper and certain grades of specialty paperboard... more Utilization of banana plant for making hand made paper and certain grades of specialty paperboards have been investigated. The physiochemical characteristics of the three species of banana plants viz. Musa velutina, M. paradisica and M. sapientum available in NE region of India were studied. The plants consists an average of 25-27 % sheath, 42-48 % core and 27-30 % leaves. The cellulose content was varied from 59-63 %, lignin from 15.3-18.2 % and pantosan from 13.5-15.2 %. in all the three plant species. The cooking experiments were conducted in an open vat under pressure free condition using NaOH and Na2C03 as cooking chemicals. The percentages of cooking chemicals were varied from 6-10 % maintaining bath ratio at 1:6. The unbleached pulp yield was recorded 48-52 %. The bleaching of the pulps was carried out using HE -H202sequence to get 60-65 % brightness. The physical strength properties of hand made paper made from these three plant species showed tensile index 55.4-62.8 Nmg-1,Tearindex 10.4-15.2 mNm2t, Burstindex 6.2-8.7 Kpm2g-1with Double fold values 300+. However certain specialty paperboard such as leatherboard made out of banana pulp in combination 'with bamboo pulp showed breaking load 120-145 (Kg),Tensile strength (dry)220-250 Kg/cm2,elongation 39-42 %, linearshrinkage 4.0% and areashrinkage 4.2-4.5%. Another specialty boards such as solid toughened board made from the blends of ragand banana pulp showed very good physical strength with breaking load value 160 kg and 90 kg respectively for30 cm and 60cm span with minimum absorption of moisture.

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Mar 1, 2013

Martensitic precipitation hardening steels are characterised by high strength which is achieved b... more Martensitic precipitation hardening steels are characterised by high strength which is achieved by a martensitic matrix and precipitates. The material also shows a good ductility and toughness if properly heat treated. But welding of these steel types is often problematic and requires a special procedure (e.g. post-weld heat treatment) in order to achieve satisfactory results. In this contribution, the solid state welding process-friction stir welding was used to weld 15-5PH and the results of the investigations are shown. The butt welds for 2?6 mm thick steel sheets have been carried out at Institute for Materials Science and Welding at Graz University of Technology using tungsten based tools, different welding speeds and tool rotational rates. Temperature measurements using thermocouples have been performed on the advancing and retreating sides of the weld. Detailed microstructural observations were performed for base material, heat affected zone, thermomechanically affected zone and stir zone. The appearance of retained austenite, which reduces the strength of the material, has been studied for the distinct regions of the friction stir weld. A quantitative spot analysis by energy dispersive spectroscopy was performed to identify tool remanents in the stir zone of the weld. For further characterisation, hardness profiles of the weld have been created. Tensile tests and surface fracture analysis using scanning electron microscopy have been performed. Welds with low energy input have shown better results than welds with high energy input. Additionally, effects of post-weld heat treatment on microstructure and properties of the joint have been analysed.

Journal of Scientific & Industrial Research, 1999

Medium density panicle boards were prepared from three species of weeds viz. Melastoma l11alabath... more Medium density panicle boards were prepared from three species of weeds viz. Melastoma l11alabathricul11, Eupatorium odoratlllll and Thvsan olaell1a mClxim.a, which were co ll ected from reserve forests of Assam and Aru nac hal Pradesh. The proxi mate chemical analys i·s of the plant raw materi als was carried oul. The cellulose contents in the plant va ri ed from 52.6-59.7 percent , the ash and silica contents from 4.6-8.9 percent and 1.78-2.90 percent respectively. The effect of wood panicle sizes on strength properties of the boards was studied and boards prepared with 20 percent UF res in from particles of -10M and +20M , showed the max imull1modulus of rupture (MOR) ( 143152 kg/cm2), wh ile MOR had grad uall y decreased in the boards prepared wit h finer panicles . When quantity of bi nder was reduced, MOR had decreased and water absorption increased. Boards prepared with mixtures of UF and PF res ins in different proportions gave va ri able MOR (149-159 kg/cm2) and water absor...

Reviews of Adhesion and Adhesives, 2015

This manuscript reviews various aspects of fiber/resin interface in fiber reinforced composites, ... more This manuscript reviews various aspects of fiber/resin interface in fiber reinforced composites, with special emphasis on green composites that use plant based fibers and sustainable resins. In this chapter we describe the importance of fiber/resin interface, factors affecting it, various modifications of fiber and resin that can be employed to improve the interfacial property and the experimental techniques to characterize the interface. The nature of the bonding between the fiber and resin and the mechanism of fiber/resin interaction are also discussed. Improving the fiber/resin interface is critical in the case of green composites since the hydrophilic plant fibers and some of the hydrophobic resins have very poor bonding. Strong adhesion at the fiber/resin interface is desirable for effective transfer of stress from broken fibers to intact fibers and, thus, to obtain good mechanical properties of the composites. However, weak bonding can provide energy absorbing modes through interface failure, making the composites tough. Thus, from the same set of fibers and resin it is possible to obtain composites with different properties simply through the control of fiber/resin interface.

Indian Journal of Chemical Technology, 2001

Calotropis procera and Nerium indicum were evaluated as potential renewable sources of energy and... more Calotropis procera and Nerium indicum were evaluated as potential renewable sources of energy and chemicals. The different plant parts-leaf, stem, bark and the plant as a whole were analysed separately for α-cellulose, lignin, ash and elemental compositions. α-cellulose in the whole plant portion were 56.42 % and 57.35 % for C procera and N indicum, while lignins were 20.42 % and 23.25 % respectively. The elemental composition of C, H and N in the plant were 40.36, 6.19 and 2.06 % for C procera, while for N indicum, the C, H and N were 38.54, 5.86 and 1.82 % respectively. Of the two species, C procera contained 4.71 % oil, 11.45 % polyphenol, 3.46 % hydrocarbon, 7.20 % protein and 22.8 % unsaponifiable matter, while N indicum was found to contain 4.36 % oil, 8.62 % polyphenol, 2.18 % hydrocarbon, 7.55 % protein and 49.8 % unsaponifiable matters. The calorific values of the plant species were also determined and found to be 17.5 MJ/kG and 15.3 MJ/kG for C procera and N indicum respec...

Construction and Building Materials, 2015

Abstract Improvements of mechano-chemical properties of bamboo by a bio-chemical formulation (BF-... more 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.

Journal of Natural Fibers, 2021

In the present study, an effort has been made to develop a quality composite material using coir ... more In the present study, an effort has been made to develop a quality composite material using coir fibre and waste polyethylene by improving the surface properties of coir fibre with the help of chemical treatment under controlled conditions. Chemical constituents of untreated and treated fibre were analysed by TAPPI standard method. Structural analyses of these fibres were carried out by FTIR, Electron microscopy, Powder-XRD and Thermogravimetric analysis. From powder-XRD crystallinity index was found to be higher for chemically modified fiber than untreated fibers. The characteristics properties i.e. water absorption, total swelling values of the composite board made from different chemically treated fibers reduced drastically and the mechanical strength properties i. e. ultimate tensile strength (UTS) and modulus of rupture (MOR) increase significantly. Surface modifications of coir fiber increased the adhesion of fiber matrix which improves the quality characteristics properties o...

Now a day, the dependency of mankind on polythene has grown to larger extent because of its wide ... more Now a day, the dependency of mankind on polythene has grown to larger extent because of its wide applications in storing food without allowing the moisture inside the packing and also as carry bags. But polythene is a non-biodegradable material which when buried in the soil doesn’t decompose. Because of this reason the soil looses it’s fertility due to the toxic chemicals it release by the action of temperature and also killing the micro organisms that are essential in the soil. In view of this, several attempts were made in recent years to develop paper that can show the oil proof as that of polythene. This project involves not the production of paper but the basic raw material for paper production that is pulp from banana plant (abundantly available on earth). Later this pulp can be blended with pulp obtained from bamboo which is less abundant, to obtain oil proof paper. The reason behind the selection of banana as raw material is, in banana plantations, after the fruits are harve...

Utilization of banana pulp fibre for producing greaseproof paper has been investigated. The morph... more Utilization of banana pulp fibre for producing greaseproof paper has been investigated. The morphological characteristics of plant and fibre, chemical constituents of the sheath, characteristics of pulp and physical strength properties of hand sheet of 45+5 gsm made from banana pulp alone or in combination with bamboo pulp fibre are presented. Results of the laboratory investigation show that Musa paradisica contain high quantity of gums and mucilage inside the sheaths. The pentosan content (13.5%) may also impart the greaseproof properties. The drainage time of the banana pulp increases with the increase of beating time. At 80 0 SR freeness, the pulp becomes hydrated and forms a jelly like stock. The paper made out of this hydrated pulp stock shows the characteristics of greaseproof paper with burst index 6.10 kpam 2 g -1 , tear index 7.00 mNm 2 g -1 and tensile index 51.2 N mg -1 with very good blister and oil resistibility. The physical strength properties of the paper may furthe...

Materials Science and …, 2013

The paper shows the results of metallographic examination and mechanical properties of electron b... more The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material. Metallographic examination revealed that the concentrated electron beam significantly affects the changes of microstructure in the weld and the adjacent heat affected zone (HAZ) in both steel grades. The microstructure of the welded joints is not homogeneous. The four zones, depending on the distance from the weld face, can be distinguished. Basically, the microstructure of the weld consists of a mixture of martensite and bainite. However, the microstructure of HAZ depends on the distance from the fusion line. It is composed of martensite near the fusion line and a mixture of bainite and ferrite in the vicinity of the base material. Significant differences in mechanical properties of the welded joints were observed. For a butt welded joint of the S960QL steel grade the strength is at the level of the strength of the base material (R m = 1074 MPa). During the bending test the required angle of 180° was achieved. The impact strength at-40°C was 71,7 J/cm 2. In the case of the Weldox 1300 steel grade butt welded joints exhibit high mechanical properties (R m = 1470 MPa), however, the plastic properties are on the lower level than for the base material.

Process Safety and Environmental Protection

Journal of Polymers and the Environment