Keywords : structure


Influence of Processing Induced Morphology on the Performance of PP Injected Intricate Pieces Modified with MWCNT as a Painting Aide

Alejandra Costantino; Leandro Ramajo; Julio Viana; Caren Rosales; Antonio Pontes; Valeria Pettarin

Advanced Materials Letters, 2021, Volume 12, Issue 4, Pages 1-10
DOI: 10.5185/amlett.2021.041618

Carbon nanotubes are currently added to polymers to avoid extra-stages in the electrostatic painting process. However, the attained particle network after processing a final part could affect the mechanical properties and thermal stability of nanocomposites. It is then important to evaluate not only the functional properties, but also the overall performance of these pieces. In this work, boxes of polypropylene (PP) modified with multi-walled carbon nanotubes (MWCNT) were injection molded. Morphology induced by processing was characterized at different locations of the moldings to correlate the influence of in-homogeneities and flow pattern with the overall performance of the molded boxes. PP/MWCNT presented a better aesthetic quality and a markedly better thermal stability than pure PP. It was confirmed that the nanocomposite has high dielectric permittivity, low dielectric losses and relatively good DC conductivity. Regarding mechanical properties, MWCNT induced a slight improvement in flexural elastic modulus. Although fracture initiated at practically the same loading levels for both materials, the propagation energy was deteriorated by MWCNT presence. Differences in both electrical and mechanical behavior were found trough out the PP/MWCNT pieces as result of distinct MWCNT orientation and distribution. It was then concluded that processing has a great influence on parts performance.

Fibril orientation and strength in collagen materials and adaptation to strain

Hannah C. Wells; Hanan R. Kayed; Katie H. Sizeland; Susyn J.R Kelly; Melissa M. Basil-Jones; Richard L. Edmonds; Richard G. Haverkamp

Advanced Materials Letters, 2018, Volume 9, Issue 6, Pages 411-418
DOI: 10.5185/amlett.2018.1844

Collagen based soft materials are important as medical materials and as consumer products. Strength is a crucial parameter. A better understanding of the structural factors that contribute to strength is sought. Synchrotron based small angle X-ray scattering was used to characterize the collagen fibril structure and structural arrangement in a range of collagen based materials including leather, surgical scaffold materials and glutaraldehyde stabilized pericardium. Structure was compared with strength and was also characterized during strain. When collagen fibrils are orientated in a highly layered structure (with a high orientation index) the materials exhibit higher tear strength. This applies to leather, surgical scaffolds derived from dermis and pericardium. A more layered structure is found in stronger leather, and depends on the species of the source animal and processing conditions. For surgical scaffolds and stabilized pericardium stronger material is found also to have a more layered structure. In pericardium it is affected by the age of the source animal with younger animals having a more layered fibril arrangement in the pericardium. When collagen based soft materials are strained, the material responds first by a reorientation of the fibrils then by extension of individual fibrils, and this enables them to withstand high stresses. 

High visible-light photocatalytic performance of natural hematite ore composited with ZnO nanomaterials

Xin X. Yu; Fang Z. Dong; Bao Dong; Liang Liu; Yan Wu

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 393-397
DOI: 10.5185/amlett.2017.7079

Natural hematite ore is used as a novel material for visible photocatalyst. The hematite was composited with needle-shaped ZnO via a hydrothermal approach. This hematite-based system exhibits excellent photodegradation for rhodamine (RhB) within 30 min when the hematite is hybridized with wurtzite -structured ZnO under visible light irradiation. The formation of a hybrid hetero-junction was shown by transmission electron microscope. The photocatalytic activity of the hetero-junction was evaluated by the photodegradation of RhB dye. The high photocatalytic activity observed under visible light is discussed on basis of the coupling of the hybrid hetero-junction band structure. 

Nano-textured Pb (Zr0.52Ti0.48)O3/ZnO Hetero-structure On Silicon Substrate   

Govind N. Sharma; Shankar Dutta; Ratnamala Chatterjee; Sushil Kumar Singh

Advanced Materials Letters, 2016, Volume 7, Issue 12, Pages 951-956
DOI: 10.5185/amlett.2016.6509

Metal oxide based hetero-structures (like Pb (ZrxTi1-x) O3 – ZnO) can be used for wide variety of future sensors and electronic devices. This paper presents growth and electrical properties of nano-textured (110) Pb (Zr0.52Ti0.48) O3/ (001) ZnO hetrostructure on oxidized silicon substrate by RF sputtering technique. The grain sizes of ZnO and PZT films are found to be around 30 nm and 80 nm respectively. Resistivity of the ZnO layer is found to be 1x10 9 ?-cm. The electrical properties of the film are studied by creating in-plane electrodes on top of the PZT/ZnO hetrostructure film. The remnant polarization of the film is found ~ 47 µC/ cm 2 at 200 kV/ cm 2 . Dielectric constant of the film is found to be 300 at 1 kHz. The film also showed a low leakage current density of ~ 10 -5 A/cm 2 at 200 kV/ cm applied electric field. The nano-textured (110) Pb (Zr0.52Ti0.48) O3/ (100) ZnO hetrostructure integrated with inter-digital-transducers and microelectronic is well suitable for low-cost, robust, programmable passive micro sensors for military structure and systems such as aircraft, missiles.

Structural, Electrical and Optical Properties Of Molybdenum Doped Zinc Oxide Films Formed By Magnetron Sputtering

R. Subba Reddy; K. Radhamma; A. Sivasankar Reddy; S. Uthanna

Advanced Materials Letters, 2015, Volume 6, Issue 9, Pages 834-839
DOI: 10.5185/amlett.2015.5920

Thin films of molybdenum doped (2.7 at.%) zinc oxide (MZO) were deposited on glass substrates held at room temperature by RF magnetron sputtering of mosaic target of Mo-Zn at different substrate bias voltages. The influence of substrate bias voltage on the structural, electrical and optical properties was investigated. The MZO films deposited on unbiased substrate were of amorphous, while those formed at substrate bias voltage of -40 V and above were of nanocrystalline. The crystallite size of the films improved with the applied bias voltage. At higher substrate bias voltage of -120 V the ion bombardment induced the high defect density in the films hence decrease in the crystallinity. The films formed at substrate bias voltage of -80 V exhibited low electrical resistivity of 1.2x10 -2 Ωcm and optical transmittance of about 79 %. These films showed optical band gap of 3.29 eV and figure of merit of 19 Ω -1 cm -1 .

Synthesis Of Poly(acrylamide-co-[2-acryloyloxy Ethyl]trimethyl Ammonium Chloride) Star-shaped Polymers By Inverse Microemulsion Polymerization

I. Katime; A. Alvarez-Bautista; E. Mendizabal; L.G. Guerrero-Ramirez; J.R. Ochoa-Gomez

Advanced Materials Letters, 2013, Volume 4, Issue 2, Pages 115-120
DOI: 10.5185/amlett.2012.6377

A series of star–shaped poly(acrylamide–co–[2–(acryloyloxy)ethyl] trimethyl ammonium chloride) were prepared by inverse microemulsion polymerization. The growth of side chains in the arms of the precursor has been carried out using different compositions of the comonomers acrylamide and [2–(acryloyloxy)ethyl] trimethyl ammonium chloride) (Q9). The characterization and star structure were determined by nuclear magnetic resonance, FTIR, MALDI–TOF and DSC. The dimensions of the particles were determined by quasielastic light scattering and transmission electron microscopy. Quasi–spherical particles of star polymers in the nanozise range were obtained which might be useful for the controlled transport and release of several biologically active drugs.

Effect Of Film Thickness On The Structural Morphological And Optical Properties Of Nanocrystalline ZnO Films Formed By RF Magnetron Sputtering

R. Subba Reddy; A. Sreedhar; A. Sivasankar Reddy; S. Uthanna

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 239-245
DOI: 10.5185/amlett.2012.3329

Zinc oxide (ZnO) thin films were formed by RF reactive magnetron sputtering onto p-type silicon and glass substrates held at room temperature. The thickness of the films deposited was in the range 160 – 398 nm. The thickness dependence structural, morphological and optical properties of ZnO films were systematically investigated. The maximum crystallite size of 21 nm observed at films thickness of 231 nm by X- ray diffraction. Scanning electron microscopic analysis revealed that the growth of nanowires in all the films. The root mean square roughness of the films increased from 7.3 to 53 nm in the thickness range of investigation. Fourier transform infrared analysis confirmed the Zn-O bonding located at wavenumber of 413 cm -1 . The average optical transmittance of the films was about 89 % in the visible region. The optical band gap of the ZnO films decreased from 3.14 to 3.02 eV with increase of film thickness from 160 to 398 nm respectively.