Lab

Rameshwar Adhikari's Lab

Featured projects (1)

Project
Goal: The international conference „POLY-CHAR 2020 [Venice]“ will take place on 18–21 May 2020 in Mestre/Italia. For more information see: https://www.poly-char2020.org.

Featured research (5)

For the investigations, scaffolds for bone regeneration (in the form of non-woven mats) were fabricated based on a polymer blend based on polycaprolactone, poly-L-lactic acid and gelatin by electrospinning which were partly modified using vitamin D3 and reinforced with 0 – 12 % nano-hydroxyapatite (nano-HAp extracted from ostrich bones) to improve both biocompatibility and mechanical performance. Electron microscopic approaches were applied to analyse the fiber microstructure due to phase separation and the microdeformation mechanisms after testing, as well as the fiber diameter as a function of the nano-HAp fraction. From uniaxial tensile testing it has been found that incorporation of nano-HAp into the blend triggers the mechanical properties of the scaffolds to a high degree, which results in an increase in tensile strength from 0.7 MPa to 5.6 MPa and an increase in strain at break from 2 % to 37 %. The transition from the very brittle behavior of the neat blend fiber mats to the highly ductile behavior of the blend fiber mats containing 12 % nano-HAp is related to a change in the microdeformation behavior of the nano- or micro-sized fibers. Whereas at lower nano-HAp content, crazing inside the fibers is prominent, thin-layer yielding becomes dominant at higher nano-HAp content.
Multi-walled carbon nanotubes and graphite nanoplatelets were functionalized via acid treatment to overcome the problem of agglomeration. Fourier transform infrared spectroscopy showed the chemical modification of the nanocarbons while the general relationship between the chemical treatment and the defects population was analyzed by Raman spectroscopy. The information regarding the mass loss and impurities is obtained from the thermogravimetric analysis. X-ray diffraction showed the effect of acid treatment on the physical states of the nanocarbons including the crystalline texture. The comparative high interlayer distance in graphite suggested that graphite particles are exfoliated into sheets of graphene by this technique with smaller particle sizes. The thermogravimetric analysis confirmed the complete removal of impurities in the case of multi-walled carbon nanotubes (MWCNTs) and about 20 % of impurities as seen in oxidized graphite attributable to the presence of residual manganese that might have been introduced during the functionalization process. Moreover, the thermal stability was also observed well in the case of MWCNTs with lesser impurities left. Overall, two different nanocarbons with well-structured chemical modifications were obtained with a variation in the feasibility of functionalization.
In recent years, considerable attention is given in various nanomaterials development using biodegradable wastes for establishing more eco-friendly technologies. Due to the biocompatible, biodegradable, and non-toxic nature hydroxyapatite (HAp) and chitosan (CS) are highly studied in recent times. In this research work, HAp and CS were synthesized in a nanometric range using the bio-wastes obtained from chicken bones and pila shells, respectively. In addition, HAp/CS nanocomposites were also prepared through the co-precipitation method in various weight ratios. The synthesized nanomaterials and nanocomposites were characterized by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The XRD pattern analysis revealed the hexagonal crystalline structure of HAp and orthorhombic crystallite structure of CS with crystallite sizes of 40.52 and 39.51 nm, respectively. The physical parameters such as d-spacing, dislocation density, stacking fault probability, and lattice strain of HAp and CS were also analyzed. The FTIR spectra analysis confirmed the formation of HAp and CS. Likewise, the broadening and weakening of the chemical bond between two phases of HAp and CS indicated the bond formation and compatibility between HAp and CS.
Urea Formaldehyde (UF) resins have good chemical resistivity and high thermal stability, making them an excellent choice in the construction industry. They, however, pulverize quickly and have low strength and toughness. In this work, magnesium oxide (MgO) nanoparticles were added to UF as nanofillers to influence its compressive strength. MgO nanoparticles were synthesized by reducing magnesium nitrate at different concentrations, using orange peel extract. X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) techniques were used to confirm the formation of MgO nanoparticles. XRD results showed the formation of 43 nm, 35.28 nm, and 32.5 nm sized nanoparticles for 0.1 M, 0.2 M, and 0.4 M concentrations respectively. The varying-sized MgO nanoparticles were used for the preparation of UF/MgOnanocomposite at different weight-percentage (wt-%) ratios. A comparative study on the compressive strength of Urea Formaldehyde resins and UF/MgO was performed. From the results, it was found that the addition of MgO nanoparticles to UF resin enhances the compressive strength at certain wt-% ratios.
ABSTRACT Starch was extracted from potato (Solanum tuberosum) cultivated in Nepal. The yield of starch of different sorts of the species S. tuberosum was compared with each other. Extracted starch (E St.) Kufre Sindure was characterized and compared with commercial starch (Com St.) by the Fourier transform infrared spectroscopy (FTIR). The properties of extracted starch were evaluated by measuring ash content, moisture content and amylose content. A series of butylene adipate-co-terephthalate (PBAT)/TPS blend of varying concentration (5%, 10%, 20% and 30%) were prepared using citric acid (compatibilizer) and glycerol as plasticizer, respectively, via solution casting method. The physical and chemical properties of resulting blends were characterized by FTIR and X-ray photoelectron spectroscopy (XPS). The FTIR results proved the esterification reaction between PBAT, thermoplastic starch (TPS) and citric acid in blends. Morphology of the PBAT/TPS film was studied through scanning electron microscopy (SEM) and XPS analysis. Microindentation measurements revealed improvement in mechanical properties of PBAT with the loading of starch. Thermogravimetric analysis (TGA) showed decrease in the thermal stability of PBAT/TPS blend. Degradation behavior of blend showed that rate of degradation was increased with increase of starch content. KEYWORDS: Biodegradable; FTIR; PBAT; starch; SEM; TGA

Lab head

Rameshwar Adhikari
Department
  • Central Department of Chemistry

Members (13)

Goerg Hannes Prof. em. Dr. habil. Michler
  • Martin Luther University Halle-Wittenberg
Ralf Lach
  • Martin Luther University Halle-Wittenberg
Sagar Regmi
  • Case Western Reserve University School of Medicine
Jyoti Giri
  • Tribhuvan University, Tri-Chandra Campus, Ghantaghar, Kathmandu, Nepal.
Rajesh Pandit
  • Tribhuvan University Tri-Chandra Multiple Campus Kathmandu Nepal
Netra Lal Bhandari
  • Tribhuvan University
Shankar P. Khatiwada
  • Leibniz Institute of Polymer Research Dresden
Prasamsha Panta
  • Tribhuvan University
Binod Shrestha
Binod Shrestha
  • Not confirmed yet
Pritam Sapkota
Pritam Sapkota
  • Not confirmed yet
J.M. saiter
J.M. saiter
  • Not confirmed yet