Keywords : morphology

Green Synthesis of ZnO and Ag-ZnO Nanoparticles using Macrotyloma Uniflorum: Evaluation of Antibacterial Activity

Raghavendra K. Sali; Malatesh S. Pujar; Shivaprasadagouda Patil; Ashok H. Sidarai

Advanced Materials Letters, 2021, Volume 12, Issue 7, Pages 1-7
DOI: 10.5185/amlett.2021.071645

In this work, using Macrotyloma Uniflorum leaves an affordable and eco-friendly, ZnO and Ag-ZnO metal oxide nanoparticles were reported. Ensuing ZnO and Ag-ZnO nanoparticles were characterized by UV–visible spectroscopy, FT-IR Spectroscopy, X-ray diffraction, Scanning Electron Microscopy with Energy Dispersive Spectroscopy, Transmission Electron Microscopy, and Dynamic Light Scattering. The green synthesized ZnO and Ag-ZnO nanoparticles comprise an average size of about 120.16 nm and 91.17 nm respectively. The minimum inhibitory concentrations (MIC) of these ZnO and Ag-ZnO nanoparticles and mixtures thereof, Ag-ZnO, were determined on B.subtilis, Streptococci and E.coli cultures. MIC and their antimicrobial activity were studied in vitro; both types of nanoparticles showed high antibacterial activity. Also, it has shown excellent results with MIC value of 62.5 µg/ml for antibacterial activity against ZnO and Ag-ZnO nanoparticles. The Ag-ZnO nanoparticles were shown better antimicrobial effect than the ZnO nanoparticles. So, we can strongly suggest these green synthesized nanoparticles as a potent agent for biological applications.

Polymeric Energy Materials: Development and Challenges

Sugam Shivhare; Praveen Kumar Loharkar; Supriya Vyas; Malvika Sharma; Vivekanand S. Bagal

Advanced Materials Letters, 2020, Volume 11, Issue 11, Pages 1-6
DOI: 10.5185/amlett.2020.111571

The discovery of conjugated, conducting polymers (CPs) polyacetylene (PA) in 1977 opened up a new frontier in the field of polymer science for both academia and industries. CPs possess characteristics such as excellent tunability, ease of synthesis, eco-friendliness, processability etc. These features have enabled the exploration of its applicability in energy and electronics devices. It has also paved way for extensive research world over to develop novel methods for synthesizing CPs with required properties. An important area in the field of synthesis of CPs is to produce conducting nanocomposites with the combination of conducting polymers and inorganic materials in order to achieve high magnitude of electrical conductivity. Several polymeric materials such as, as poly(3,4ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), and polyaniline (PANI) have exhibited potential in various applications such as, “energy harvesting”, “energy storage”, “light emitting”, and “sensing”. The objective of this review is to develop better understanding on conducting polymers used for energy and electronics application. The review presents the state of research in the development of CPs with a focus on general synthesis method, morphology and dependent properties along with the discussion on challenges with possible solutions.

Morphology/tensile Performance Relationship for LLDPE/PP Double Gated Injected Blends

Caren Rosales; Diego Brendstrup; Celina Bernal; Valeria Pettarin

Advanced Materials Letters, 2020, Volume 11, Issue 2, Pages 22-27
DOI: 10.5185/amlett.2020.021472

Due to the large volume consumption of plastics, the treatment of the resulting solid waste is becoming a major concern. Polyethylene and polypropylene are two of the most abundant polymers in waste. Recycling them as a blend is an attractive way to reduce the impact of plastic wastes. This work is focused on the relationship between material morphology and tensile behavior, both under static and dynamic loading conditions, of PP/LLDPE blends with varying relative content. Blends present a biphasic morphology with distinctive characteristics that depends on blend composition. Their tensile properties are significantly affected by composition and corresponding morphology: mechanical behavior varied from ductile to brittle under both quasi-static and dynamic loading conditions. The blend with the better and most reliable behavior was found to be the one with 75% of LLDPE, and in a next work it will be used to obtain a ternary composite reinforced with recycled rubber particles obtained from scrap tires.

Effect of reaction time on LiMn2O4 nanostructures prepared by modified chemical bath deposition method

Lehlohonolo F. Koao; Setumo V. Motloung; Tshwafo E. Motaung

Advanced Materials Letters, 2018, Volume 9, Issue 10, Pages 703-707
DOI: 10.5185/amlett.2018.2137

LiMn2O4 (LMO) powders were prepared by modified chemical bath deposition method. The effect of reaction time on the structure, morphology and optical properties of LMO nanostructures were investigated. The reaction time was varied from 1 - 120 min. The X-ray diffraction (XRD) patterns of the powders correspond to the various planes of a cubic spinel LMO phase. It was observed that the secondary phases decreases with an increase in reaction time. The diffraction peaks increase in intensity with an increase in reaction time up to 10 min. The estimated average grain sizes calculated using the XRD spectra were found to be in the order of 60 ± 1 nm. The scanning electron microscope (SEM) image suggested that the reaction time influences the morphology of the prepared powders. The irregular nanoparticle increased in size with an increase in reaction time. The UV-Vis spectra showed a red shift with an increase in reaction time up to 10 min. 

Morphology Control In The Bulk Heterojunction Blend Of Inverted Organic Solar Cell Via Co- Solvent Addition

Sarita S Nair; D Kumar

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 806-812
DOI: 10.5185/amlett.2016.6204

This work is supposed to expand the concept of solvent induced crystallisation of donor poly(3-hexylthiophene) (P3HT) polymer, to the photoactive blend of inverted organic solar cells. With the optimised concentration of cyclohexanone (CHN) co-solvent and ageing period of 2 h for the active layer precursor solution, the power conversion efficiency of a typical device increased to 3.09% compared with 2.77% efficiency achieved in a similar kind of inverted device without CHN modification. This improvement of 10% in the efficiency of inverted device with CHN addition was related to the increased current density and fill factor of the device. Increased P3HT crystallinity for efficient photo-absorption and commensurate vertical concentration gradient observed in the P3HT fractions of the blend for efficient hole transport is possibly responsible for the betterment of the photovoltaic parameters in the modified device.

Study On The Effect Of Fuels On Phase Formation And Morphology Of Combustion Derived α-Al2O3 And NiO nanomaterials  

R. S. Raveendra; P. A. Prashanth; B. M. Nagabhushana

Advanced Materials Letters, 2016, Volume 7, Issue 3, Pages 216-220
DOI: 10.5185/amlett.2016.6202

In this study we present an effect of glycine and urea fuels on the phase formation and morphology of the α-Al2O3 and NiO nanomaterials. Materials were synthesized using facile solution combustion method at temperature 500 °C ± 10 °C. The synthesized products were characterized by various analytical techniques. PXRD results of α-Al2O3 confirm that the hexagonal phase is best represented using urea as a fuel compared to glycine. FE-SEM micrographs observed with urea are like flake like structure whereas with glycine net like porous structure is observed. TEM micrographs show the well crystalline nature of the nanomaterials. Large mismatching was observed in the FTIR spectra of synthesized materials using urea and glycine fuels with respect to the OH and metal to oxygen vibrational frequencies. PXRD results of NiO confirm that the cubic structure is obtained with urea fuel without any secondary phases, whereas with glycine a small peak of Ni was observed at 2θ = 44.5°. FE-SEM micrographs NiO with urea represents spherical like structure whereas large number of voids with porous structure was observed with glycine. The results of the study show that the fuels used for the synthesis of nanomaterials have a great effect on phase formation and morphology.   

Correlative Exploration Of Structural, Optical And Electric Properties Of Colossal Dielectric Ni Doped Sm Orthoferrites

Sajad Ahmad Mir; M. Ikram; K. Sultan; Z. Habib; H. Kausar; K. Asokan

Advanced Materials Letters, 2015, Volume 6, Issue 12, Pages 1081-1087
DOI: 10.5185/amlett.2015.5959

Structural, optical and dielectric properties of polycrystalline SmFe1-xNixO3 (x=0.0, 0.3 and 0.5) samples prepared by ceramic method is presented. Lattice parameters, unit cell volume and porosity were calculated and found decreasing with an increase in Ni concentration. SEM shows an increase in grain size (0.2 μm to 0.3 μm) with an increase in Ni doping. The influences of Ni doping on optical energy band gap are investigated in the wavelength range of 200-800 nm. Dielectric properties (dielectric constant and loss) for SmFe1-xNixO3 were studied in the temperature range 100-400K and in the frequency range 20 kHz-1MHz. AC conductivity of pristine sample is found to be less than Ni doped samples. Various possibilities were explored to explain the observed dielectric and electric behavior of Ni doped SmFeO3 ceramics.

Studies On The Chemical Resistance And Mechanical Properties Of Natural Polyalthia Cerasoides Woven Fabric/glass Hybridized Epoxy Composites  

J. Jayaramudu; S.C. Agwuncha; S.S. Ray; E. R. Sadiku; A. Varada Rajulu

Advanced Materials Letters, 2015, Volume 6, Issue 2, Pages 114-119
DOI: 10.5185/amlett.2015.5680

In the present work, natural Polyalthiacerasoide woven fabrics were extracted from the bark of the tree and using these woven fabrics/glass fibre as reinforcements and epoxy as matrix the hybrid composites were prepared by the hand lay-up technique, at room temperature. The effect of alkali treatment of Polyalthiacerasoide fabrics on the chemical structure and morphology was examined using Fourier transforms infrared spectroscopic (FT-IR) and scanning electron microscopic techniques respectively. FT-IR analyses indicated the lowering of hemi-cellulose and lignin contents by alkali treatment of the woven fabric. The scanning electron micrographs indicated the removal of hemicelluloses layer on the surface of the fabric by alkali treatment. The effect of alkali treatment of the natural fabric on the mechanical properties, chemical resistance, and interfacial bonding of the hybrid composites was examined.The mechanical properties of the woven fabric/glass fiber hybrid composites with surface modified natural fabric were found to be higher than those with untreated fabric. The fractographs indicated a better interfacial bonding between the woven fabric/glass fibres and the matrix, particularly when the alkali-treated natural fabrics were used in the hybrid composites. Furthermore, these hybrid composites showed resistance to acids, alkalis and various solvents and also possessed lower water absorption.The natural fabric/glass fibre hybrid composites have the properties which advise their relevance for application in the building and construction industries.

Bio- Polymer Assisted Solvothermal Growth And Optical Characterization Of CdS Nanostructures

J. S. Roy; K. Pal; T. Pal Majumder

Advanced Materials Letters, 2014, Volume 5, Issue 9, Pages 538-542
DOI: 10.5185/amlett.2014.4561

Various nanostructured CdS samples have been synthesized with assistance of starch (bio-polymer) by solvothermal method. We have synthesized nano-regime, nanorods and nanoparticles by simply changing the starch-solvent combinations. The highly polymeric (branched) structure of starch capped the CdS samples to modify the surfaces and hence tune the optical properties. The optical band gaps for three samples are 2.34, 2.37 and 2.38 eV. The photoluminescence emission peak also changes with surface modification of the nanomaterials. The sensitivity of the optical properties of CdS nanomaterials with structural modification by means of polymer may be used for practical application like solid state lighting.

Surface Modification Of Ramie Fibers Using Microwave Assisted Graft Copolymerization Followed By Brevibacillus Parabrevis Pretreatment

Susheel Kalia; Hemmant Mittal;Amit Kumar; Renu Sheoran

Advanced Materials Letters, 2013, Volume 4, Issue 10, Pages 742-748
DOI: 10.5185/amlett.2013.3441

Ramie fibers usually display poor interfacial adhesion when reinforced in hydrophobic polymer matrices. Hydrophilic nature of natural fibers becomes the most crucial issue in composites engineering. Surface modification of natural fibers has been found to be very effective in improving the fiber-matrix adhesion. In the present paper, we have reported the microwave assisted grafting of binary vinyl monomer mixtures on to ramie fibers (Boehmeria nivea) and bacterial cellulase assisted pre-treatment of ramie fibers using bacteria Brevibacillus parabrevis. The effects of these pretreatments on some properties of ramie fibers are discussed in the present paper. The modified fibers were characterized by scanning electron microscopy (SEM), X-ray diffraction, and TGA/DTA techniques to determine their morphology, crystallinity and thermal stability. Surface of ramie fiber becomes rough on grafting with synthetic polymers, whereas biologically modified ramie fibers showed the enhanced softness and smooth appearance due to the removal of gum materials and other impurities from the surface of fibers. Both the treatments have slightly changed the thermal stability and crystallinity of ramie fibers.

Spectroscopic And Morphological Analysis Of Graphene Vinylester Nanocomposites

Anupama Chaturvedi; Ashutosh Tiwari; Atul Tiwari

Advanced Materials Letters, 2013, Volume 4, Issue 9, Pages 656-661
DOI: 10.5185/amlett.2013.4469

This communication describes the development of graphene and graphene reinforced polyvinylester nanocomposites. Low concentration of graphene was incorporated in the polymer matrix with the help of two different solvents. The role of solvent in the nanocomposite was studied. The FTIR spectroscopy and electron microscopy have supported the presence of graphene in the nanocomposites. It was discovered that vehicular medium (i.e., solvent) plays a vital role in the properties of the ultimate nanocomposites. When dimethylacetamide was used as solvent, the morphological analysis suggested the increased toughness while in case when tetrahydrofuran was used as solvent, nanocomposite appeared brittle in nature.

Effects of chloride ions and poly (vinyl- pyrrolidone) on morphology of silver particles in solvothermal process

Yulan Zhang; Yingzi Wang; Ping Yang

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 217-221
DOI: 10.5185/amlett.2011.2223

Silver particles with various morphologies including cubic, spherical, and rod-shaped have been synthesized by a facile solvothermal procedure using poly (vinyl pyrrolidone) (PVP) as an adsorption agent and architecture soft template. Preparation conditions such as the molar ratio and concentration of starting materials were optimized for studying the growth kinetics of silver particles. The amount of chloride ions and PVP plays an important role for the morphology of silver particles during synthesis. Chloride ions as a stabilizer against the aggregation of particles could sufficiently retard particle growth. The selected bounding of PVP molecules on the silver particle is a key for morphological controlling. The morphological evolution of the silver particle was investigated by adjusting systematically preparation parameters. Because of PVP molecules are easily bounded to the (100) facet of silver crystals, the growth of the silver particle occurred around (111) plane. Silver particles with a series of morphologies were created via such anisotropic growth.

Sunn hemp cellulose graft copolymers polyhydroxybutyrate composites: morphological and mechanical studies

Susheel Kalia; Anil Kumar; B.S. Kaith

Advanced Materials Letters, 2011, Volume 2, Issue 1, Pages 17-25
DOI: 10.5185/amlett.2010.6130

For the synthesis of biocomposite materials for useful applications, it becomes necessary to modify the surface of natural fibers through chemical treatments. Morphology, structure and properties of natural fibers have an obvious effect on the mechanical properties of the biocomposite materials. It is thus necessary to know the morphology, thermal stability and crystalline behavior of original and modified fibers. In present paper, sunn hemp fibers (SHF) were chemically modified with ethyl acrylate and binary monomers (EA+MMA, EA+AA) through microwave radiations induced graft copolymerization. Various reaction parameters were optimized to get maximum grafting (91.8%). Morphology, thermal stability and crystalline behavior of original and modified fibers were investigated. Morphological and thermal studies showed that surface of sunn hemp fibers becomes rough and amorphous through graft copolymerization and thermal stability has been found to be increased. Microwave radiation induced grafting showed a diminutive effect on the crystalline behavior of the sunn hemp fibers as optimum time to get maximum grafting is very less (40 min) in comparison to conventional grafting. Synthesized graft copolymers were used as reinforcing material in preparation of polyhydroxybutyrate biocomposites. It has been observed that graft copolymers improved the interface between fiber and matrix and enhanced the mechanical strength of composites.

Effect Of Processing Parameters On Morphology And Thermal Properties Of Electrospun Polycarbonate Nanofibers

Advanced Materials Letters, 2010, Volume 1, Issue 3, Pages 200-204
DOI: 10.5185/amlett.2010.8148

In the present contribution, it has been reported about the effect of solvent, solvent concentration, flow rate and applied voltage on the fabrication of electrospun polycarbonate (PC) nanofibers. The morphology of fibers was studied by optical and scanning electron microscope. It is observed that morphology of fibers depends upon the concentration of PC or viscosity of the solution, vapor pressure and diffusion coefficient of solvent. In fact, when viscosity of the solution is very low, beads or droplets are formed instead of fibers. The same problem arises when the viscosity of the solution is too high due to high surface tension. In this case, jet formation will not be observed and the solution will coagulate at the tip of needle. Tetrahydrofuran (THF) easily diffuses with polymer, at higher concentration of PC and at higher flow rate of solution; fibers of micron size are formed because of high vapor pressure of THF. On the other hand, in case of mixed solvents (DMF and THF), by controlling processing parameters one can get fiber diameter up to 200 nm. The study of Differential Scanning Calorimetry (DSC) indicates that less amount of heat energy is absorbed during endothermic reaction and there is a slight increase in glass transition temperature of nanofibers. Thermogravimetric analysis (TGA) shows an increase in thermal stability of PC nanofibers by 40ºC as compared to PC granules. This is due to the alignment of PC polymeric chains during stretching and whipping that occurs while electro spinning process.