scholarly journals Texture and Strength Evolution in Deformed Polypropylene

1991 ◽  
Vol 13 (2-3) ◽  
pp. 101-122 ◽  
Author(s):  
J. R. Hirsch ◽  
P. T. Wang
Keyword(s):  
Stress Relaxation ◽  
Plastic Flow ◽  
Orientation Dependence ◽  
Elastic Response ◽  
Strain Rates ◽  
X Ray Diffraction ◽  
Compression Direction ◽  
Strength Evolution ◽  
Different Temperatures ◽  
High Concentrations

Semicrystalline polypropylene samples with high concentrations of crystallinity (≳62%) are deformed in uniaxial compression at different temperatures and different strain rates. The orientation changes of the crystalline part of the material are analyzed using X-ray diffraction methods. Pole figure evaluation is used to obtain information about the crystal structure, the geometry of slip, and its correlation with the characteristic of strength evolution in polymers. The contribution of the crystalline part of the material to plastic flow is estimated and the textures are related to the characteristic effects in plastic and visco-elastic response of the material during deformation and subsequent stress relaxation. The observed texture effects can be explained by the rotation of crystallographic c-axis (backbone axis) normal to the compression direction at high temperatures in a planar slip mode. The stress/strain and relaxation behavior of the material is interpreted as a combination of viscoelastic flow of amorphous volume and irreversible plastic flow of the crystalline part which contributes to an orientation dependence of deformation and stress relaxation.

Investigation of Deformation Induced Martensitic Transformation during Incremental Forming of 304 Stainless Steel Wires

2015 ◽  
Vol 651-653 ◽  
pp. 645-650 ◽  
Author(s):  
Bernd Kuhfuss ◽  
Eric Moumi ◽  
Brigitte Clausen ◽  
Jeremy Epp ◽  
Bernd Koehler
Keyword(s):  
Volume Fraction ◽  
Processing Parameters ◽  
304 Stainless Steel ◽  
Strain Rates ◽  
X Ray Diffraction ◽  
Forming Process ◽  
Cold Forming ◽  
X Ray ◽  
Steel Wires ◽  
Different Temperatures

Wires with 1 mm initial diameter have been reduced between 10 and 64 percent at different temperatures and strain rates by infeed rotary swaging, which is an incremental cold forming process mainly used for rods and pipes. The volume fraction of martensite in the deformed wires has been determined by X-Ray diffraction and by magnetic induction for different processing parameters. Measurements show that for already small percentage of reduction, martensite is present in the wires and its amount changes with the strain rate and temperature. While for smaller strain rates at room temperature the formation of martensite is promoted, it is restrained for higher strain rates and higher temperatures. Results also reveal that the martensite distribution in the sample is inhomogeneous. Further investigations have been made to analyze the microstructure by optical microscopy and to determine mechanical properties by tensile testing.

Deformation Mechanisms of Twinning-Induced Plasticity Steel Under Shock-Load: Investigated by Synchrotron X-Ray Diffraction

2019 ◽  
Vol 3 (3) ◽  
pp. 15
Author(s):  
Kun Yan ◽  
Mark Callaghan ◽  
Klaus-Dieter Liss
Keyword(s):  
High Strength ◽  
Orientation Distribution ◽  
High Energy ◽  
Mechanical Twinning ◽  
Deformation Mechanisms ◽  
Strain Rates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compression Direction ◽  
Twip Steels

As an ideal candidate material for automobiles, twinning-induced plasticity (TWIP) steels possess excellent formability, high strength and high energy absorption ability during collision. This is attributed to its deformation mechanism of mechanical twinning, resulting in a high work hardening rate. In the current study, deformation mechanisms of low-stacking fault energy TWIP steel, under different strain rates between 0.01/s to 1581/s, were investigated by high-energy X-ray diffraction. After compression, grains with {110}||compression direction became favourable. Higher intensity was observed near brass and A components in the selected orientation distribution function (ODF) section (φ2 = 45°) for all the compressed specimens. The activity of twinning was found to be the highest in the specimens that had been compressed with medium–high strain rates (e.g., 100/s and 10/s), while the texture component related to slip had stronger intensity in the specimen deformed with a quasi-static strain rate (0.01/s).

Structural and Elastic Response of Mo/Ni Multilayers to Ion Irradiation

2000 ◽  
Vol 615 ◽  
Author(s):  
Jérôme Pacaud ◽  
Franck Martin ◽  
Anny Michel ◽  
Christiane Jaouen ◽  
Philippe Djemia ◽  
...  
Keyword(s):  
Light Scattering ◽  
Stress Relaxation ◽  
Ion Irradiation ◽  
Growth Direction ◽  
Interplanar Distance ◽  
Elastic Response ◽  
X Ray Diffraction ◽  
X Ray ◽  
Induced Stress ◽  
Before And After

ABSTRACTMo/Ni multilayers are investigated by x-ray diffraction and Brillouin light scattering before and after ion induced stress relaxation and mixing. Study of the evolution of interplanar distances in both layers as a function of the period exhibits a strong anomaly of the Mo (110) distance (in the growth direction) that can be correlated with the elastic anomaly. The very low interplanar distance in the molybdenum layers found after stress relaxation seems to favor an explanation of this behavior based on the diffusion of Ni in the Mo layers during the growth.

Flow Stress Behavior and Microstructure Evolution Anisotropy of Extruded 7075 Aluminum Alloy Bar at Elevated Temperatures

2013 ◽  
Vol 740 ◽  
pp. 745-749 ◽  
Author(s):  
Yong Biao Yang ◽  
Zhi Min Zhang ◽  
Qiang Wang
Keyword(s):  
Flow Stress ◽  
Elevated Temperatures ◽  
Grain Structure ◽  
Strain Rates ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
Compression Direction ◽  
Grain Structures ◽  
Equiaxed Grain ◽  
Stable Flow

Hot compression tests of 7075 extruded bar were carried out on the Gleeble-1500 thermal simulation machine at strain rates of 0.1 s-1 and 1s-1 and at temperatures of 320°C. The compression direction are aligned at 0°, 45°and 90°to the axis direction of the extruded bar. Microstructure and texture was characterized using Optical Microscopy and x ray diffraction analysis. The results show that the true stress of all specimen increases with decreasing temperature and increasing strain rates. Both the yield strength and the stable flow stress of the 0° specimens is the highest among all three specimens, while that of 45° specimen is the lowest. This could be attributed to the lamellar grain structures and the texture of the extruded bar. The microstructure of 0°specimen are of equiaxed grain due to dynamic recrystallization after compression, while the grain shape of 45°and 90°specimens are still of lamellar grain structure.

Highly thermally conductive UHMWPE/NG composites with the segregated structure and their application for heat spreader

2020 ◽  
pp. 089270572096564
Author(s):  
Xiao Wang ◽  
Hui Lu ◽  
Jun Chen
Keyword(s):  
Thermal Conductivity ◽  
Laser Flash ◽  
Heating Process ◽  
X Ray Diffraction ◽  
Heat Spreader ◽  
Conductive Composites ◽  
Compression Direction ◽  
Thermal Analyzer ◽  
Thermally Conductive ◽  
Plane Direction

In this work, ultra-high molecular weight polyethylene (UHMWPE)/natural flake graphite (NG) polymer composites with the extraordinary high thermal conductivity were prepared by a facile mixed-heating powder method. Morphology observation and X-ray diffraction (XRD) tests revealed that the NG flakes could be more tightly coated on the surface of UHMWPE granules by mixed-heating process and align horizontally (perpendicular to the hot compression direction of composites). Laser flash thermal analyzer (LFA) demonstrated that the thermal conductivity (TC) of composites with 21.6 vol% of NG reached 19.87 W/(m·K) and 10.67 W/(m·K) in the in-plane and through-plane direction, respectively. Application experiment further demonstrated that UHMWPE/NG composites had strong capability to dissipate the heat as heat spreader. The obtained results provided a valuable basis for fabricating high thermal conductive composites which can act as advanced thermal management materials.

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

scholarly journals Gold Nanoparticles Synthesized Using Extracts of Cyclopia intermedia, Commonly Known as Honeybush, Amplify the Cytotoxic Effects of Doxorubicin

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 132
Author(s):  
Jumoke A. Aboyewa ◽  
Nicole R. S. Sibuyi ◽  
Mervin Meyer ◽  
Oluwafemi O. Oguntibeju
Keyword(s):  
Gold Nanoparticles ◽  
South African ◽  
Biological Activities ◽  
Mangifera Indica ◽  
Human Colon ◽  
Normal Breast ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Low Cytotoxicity ◽  
High Concentrations

Cyclopia intermedia (C. intermedia) is an indigenous South African shrub used to prepare the popular medicinal honeybush (HB) tea. This plant contains high levels of mangiferin (MGF), a xanthonoid that was reported to have numerous biological activities, including anti-tumor activity. MGF and extracts that contain high concentrations of MGF, such as extracts from Mangifera indica L. or mango have been used to synthesize gold nanoparticles (AuNPs) using green nanotechnology. It has previously been shown that when AuNPs synthesized from M. indica L. extracts are used in combination with doxorubicin (DOX) and Ayurvedic medicine, the anti-tumor effects appear to be augmented. It has also been demonstrated that MGF used in combination with DOX resulted in enhanced anti-tumor effects. In this study, C. intermedia (HB) and MGF were used to synthesize HB-AuNPs and MGF-AuNPs, respectively. The physicochemical properties of the AuNPs were characterized by the UV-Visible Spectroscopy (UV-Vis), dynamic light scattering (DLS), Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HR-TEM). The cytotoxicity of HB-AuNPs and MGF-AuNPs were assessed on human colon (Caco-2), prostate (PC-3) and glioblastoma (U87) cancer cells; as well as normal breast epithelial (MCF-12A) cells using the MTT assay. Both HB-AuNPs and MGF-AuNPs demonstrated relatively low cytotoxicity in these cells. However, when these nanoparticles were used in combination with DOX, the cytotoxicity of DOX was significantly augmented.

Critical damage value of AZ31B magnesium alloy with different temperatures and strain rates

Rare Metals ◽  
2015 ◽  
Author(s):  
Jing-Ren Dong ◽  
Ding-Fei Zhang ◽  
Yu-Feng Dong ◽  
Fu-Sheng Pan ◽  
Sen-Sen Chai
Keyword(s):  
Magnesium Alloy ◽  
Strain Rates ◽  
Az31b Magnesium Alloy ◽  
Different Temperatures ◽  
Critical Damage

scholarly journals Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3103
Author(s):  
Laurent Gremillard ◽  
Agnès Mattlet ◽  
Alexandre Mathevon ◽  
Damien Fabrègue ◽  
Bruno Zberg ◽  
...  
Keyword(s):  
Dental Implants ◽  
Fracture Load ◽  
Accelerated Ageing ◽  
Dental Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dental Restorations ◽  
Different Temperatures ◽  
Mechanical Performances ◽  
Kinetics Of

Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation.

scholarly journals Migration from acrylonitrile butadiene styrene (ABS) polymer: swelling effect of food simulants compared to real foods

2021 ◽  
Author(s):  
Valeria Guazzotti ◽  
Annika Ebert ◽  
Anita Gruner ◽  
Frank Welle
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
Polymer Swelling ◽  
Food Simulants ◽  
Diffusion Parameters ◽  
Compliance Testing ◽  
Diffusion Migration ◽  
Different Temperatures ◽  
Effect Of Food ◽  
High Concentrations ◽  
Butadiene Styrene

AbstractMaterials and articles made of acrylonitrile–butadiene–styrene (ABS) intended for contact with food must comply with the requirements of the European Plastic Regulation (EU) 10/2011, which lays down the food simulants and the time/temperature conditions to be applied for migration testing. Previous studies indicated that high concentrations of ethanol at temperatures above ambient may lead to swelling of ABS polymers resulting in increased migration. In this study migration kinetic data for a set of model substances at different temperatures were obtained using both food simulants stipulated in EU regulations and real food (milk, cream and olive oil). At the same time, the extent of polymer swelling was gravimetrically characterized after contact with simulants and different foods tested at several conditions to cover the majority of foreseeable applications of ABS. The obtained results confirmed that the use of high concentrations of ethanol–water, especially at high temperatures, causes the swelling of ABS polymers and results in significantly higher migration values compared to the tested foods as well as Tenax®. None of the real foods studied cause significant swelling of ABS. The widely used simulant 95% (v/v) aqueous ethanol proves not be suitable for compliance testing of ABS under the recommended conditions of Regulation (EU) 10/2011. Swelling of the polymer results in artificially higher diffusion coefficients or lower activation energies of diffusion. Migration prediction using polymer-specific diffusion parameters should therefore be considered to avoid over-conservative risk assessment for food contact materials and articles made of ABS.

Sign in / Sign up

Export Citation Format

Share Document