scholarly journals A New Industrial Technology for Mass Production of Graphene/PEBA Membranes for CO2/CH4 Selectivity with High Dispersion, Thermal and Mechanical Performance

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 831 ◽  
Author(s):  
Samy Yousef ◽  
Zahid Sarwar ◽  
Justas Šereika ◽  
Nerijus Striūgas ◽  
Edvinas Krugly ◽  
...  
Keyword(s):  
Mass Production ◽  
Mechanical Performance ◽  
Testing Machine ◽  
Adhesive Layer ◽  
Extrusion Process ◽  
High Dispersion ◽  
Second Phase ◽  
Solution Casting Method ◽  
Feeding Pressure ◽  
Main Barrier

Polyether block amide (PEBA) nanocomposite membranes, including Graphene (GA)/PEBA membranes are considered to be a promising emerging technology for removing CO2 from natural gas and biogas. However, poor dispersion of GA in the produced membranes at industrial scale still forms the main barrier to commercialize. Within this frame, this research aims to develop a new industrial approach to produce GA/PEBA granules that could be used as a feedstock material for mass production of GA/PEBA membranes. The developed approach consists of three sequential phases. The first stage was concentrated on production of GA/PEBA granules using extrusion process (at 170–210 °C, depending on GA concentration) in the presence of Paraffin Liquid (PL) as an adhesive layer (between GA and PEBA) and assisted melting of PEBA. The second phase was devoted to production of GA/PEBA membranes using a solution casting method. The last phase was focused on evaluation of CO2/CH4 selectivity of the fabricated membranes at low and high temperatures (25 and 55 °C) at a constant feeding pressure (2 bar) using a test rig built especially for that purpose. The granules and membranes were prepared with different concentrations of GA in the range 0.05 to 0.5 wt.% and constant amount of PL (2 wt.%). Also, the morphology, physical, chemical, thermal, and mechanical behaviors of the synthesized membranes were analyzed with the help of SEM, TEM, XRD, FTIR, TGA-DTG, and universal testing machine. The results showed that incorporation of GA with PEBA using the developed approach resulted in significant improvements in dispersion, thermal, and mechanical properties (higher elasticity increased by ~10%). Also, ideal CO2/CH4 selectivity was improved by 29% at 25 °C and 32% at 55 °C.

Improving the mechanical performance of Cu Cr alloy by dissolving Cu in the Cr second phase

2021 ◽  
pp. 111104
Author(s):  
Liyuan Shan ◽  
Xueliang Wang ◽  
Yanli Chang ◽  
Yaping Wang
Keyword(s):  
Mechanical Performance ◽  
Second Phase

Basic Experimental and Numerical Investigations on Chip Pressing

2013 ◽  
Vol 554-557 ◽  
pp. 630-637 ◽  
Author(s):  
Martin Grüner ◽  
Marion Merklein
Keyword(s):  
Numerical Simulation ◽  
Aluminium Alloys ◽  
Testing Machine ◽  
Material Model ◽  
Extrusion Process ◽  
Milling Process ◽  
Numerical Investigations ◽  
Compression Direction ◽  
Universal Testing ◽  
The Stability

Aluminium alloys show a great potential for lightweight constructions due to their high strength and low density but the production of this material is very energy consuming. Also the recycling of aluminium alloys, e.g. chips from the milling process, shows different challenges. Beside contamination by cooling lubricant and oxidation of the surface of the chips the melting and rolling process for new semi finish products needs a high amount of energy. TEKKAYA shows a new approach for recycling of aluminium alloy chips by an extrusion process at elevated temperatures producing different kinds of profiles. A new idea is the production of components directly out of chips using severe plastic deformation for joining of the chips similar to the accumulative roll bonding process in sheet metal forming. In a first approach aluminium alloy chips out of a milling process were uniaxial compressed with different loads inside an axisymmetric tool installed in a universal testing machine. The compressed chip disks subsequently were tested with two experiments to gain information on their stability. First experiment is a disk compression test with the disk standing on its cylindrical surface, giving information on the stability perpendicular to the compression direction. Second experiment is a stacked disk compression test with three disks to investigate the stability parallel to compression direction. During all three tests force and displacement values are recorded by the universal testing machine. These data are also processed to calculate or identify input parameters for the numerical investigations. For numerical simulation ABAQUS in conjunction with the Drucker-Prager-Cap material model, which is often used for sintering processes, seems to be a good choice. By numerical simulation of the experiments and comparison with the experiments input parameters for the material model can be identified showing good accordance. This material model will be used in future numerical investigations of an extrusion process to identify tool geometries leading to high strains inside the material and by this to an increased stability of the parts.

Mechanical Properties Comparison of Different La Content in AZ91

2014 ◽  
Vol 620 ◽  
pp. 67-72 ◽  
Author(s):  
Yan Yan Zhang ◽  
Chun Xia He ◽  
Hang Song Yang ◽  
Jian Xiu Liu
Keyword(s):  
Magnesium Alloy ◽  
Mechanical Performance ◽  
Testing Machine ◽  
Powder Metallurgy Method ◽  
Az91 Magnesium Alloy ◽  
Compression Performance ◽  
Hardness Tester ◽  
Mechanics Performance ◽  
Tension And Compression ◽  
Az91 Magnesium

In order to improve the comprehensive mechanics performance of AZ91 magnesium alloy which is used as car's material, the La element was added in AZ91 magnesium alloy and specimens was prepared by powder metallurgy method. The influence of La on microstructure, hardness and compression performance of AZ91 a magnesium alloy specimen was studied using metallographic electronic microscope, hardness tester, universal tension and compression testing machine. The experimental results show that when amount of La's addition is 1.2%, its mechanical performance is best, hardness is 67.1 HV, compressive strength is 115.8 MPa, increased respectively by 20.0% and 29.5% compared the AZ91 magnesium alloy substrate, and the grain refinement effect of AZ91 magnesium alloy is the best at this time.

scholarly journals Effect of Heat Treatment on Microstructure and Mechanical Properties of New Cold-Rolled Automotive Steels

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1414
Author(s):  
Fei Huang ◽  
Jian Chen ◽  
Zhangqi Ge ◽  
Junliang Li ◽  
Yongqiang Wang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Testing Machine ◽  
Second Phase ◽  
Isothermal Heat Treatment ◽  
Austenitizing Temperature ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Microstructure And Mechanical Properties ◽  
Cold Rolled

The effect of austenitizing temperature and aging treatment on the microstructure and mechanical properties of two new cold-rolled automotive steel plates (20Mn2Cr and 20Mn2CrNb) was investigated by using isothermal heat treatment, optical microscope, scanning electron microscope, microhardness tester, and tensile testing machine. The results show that as the austenitizing temperature increased, the original austenite grain sizes of both steels increased. The original austenite grain size of 20Mn2CrNb was smaller than that of 20Mn2Cr. The microhardness of 20Mn2CrNb gradually decreased with increasing aging temperature, while the hardness of 20Mn2Cr varied irregularly. The mechanical properties of 20Mn2Cr were better than those of 20Mn2CrNb under the same heat-treatment process. The effect of heat treatment on microstructure and mechanical properties was related to the martensite content, dislocation density, and precipitation of second-phase particles.

Claw-Pole Closed Forging Process

2014 ◽  
Vol 912-914 ◽  
pp. 605-608 ◽  
Author(s):  
Xuan Rong Xin ◽  
Ding Xu ◽  
Cheng Song He ◽  
Xin Cheng Liu
Keyword(s):  
Mass Production ◽  
New Technology ◽  
Extrusion Process ◽  
Forming Force ◽  
Short Life ◽  
Forging Process ◽  
New Process ◽  
Corner Filling ◽  
Hot Die Forging ◽  
Deform 3D

Aimed at the present domestic problems in the forging process of claw pole, such as insufficient corner filling, excessive forming force and short life of dies. On the basis of the analyzing in the claw pole, a new process named the closed hot die forging, direct extrusion process of claw pole is constituted. The numerical simulation using DEFORM-3D and the special mould are used in the forging experiment in order to check the new process. The results show that, new technology has greatly reduced the forming force, thereby reducing the production processes and improving the life of dies for mass production.

scholarly journals Self-Heating Graphene Nanocomposite Bricks: A Case Study in China

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 714
Author(s):  
Zhuo Tang ◽  
Dong Lu ◽  
Jing Gong ◽  
Xianming Shi ◽  
Jing Zhong
Keyword(s):  
Mechanical Performance ◽  
Electrical Energy ◽  
Cold Climate ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Firing Process ◽  
High Dispersion ◽  
Water Pipelines ◽  
Graphene Nanocomposite ◽  
Save Energy

In cold climate regions, the energy associated with indoor heating constitutes a large portion of energy consumption. Increasing energy utilization efficiency is critically important for both economic and environmental reasons. Directly converting electrical energy to thermal energy using joule heating construction elements can save energy and investment to the water pipelines which have been extensively used for indoor heating in China. The fired brick has been extensively used to make pavements, walls and other masonry. Taking advantage of the high dispersion quality of graphene oxide (GO) in water, as well as the firing process used to make fired bricks, graphene nanocomposite bricks with excellent electrical properties and improved mechanical performance were prepared in China. The compressive strength of the bricks showed a substantial increase from 3.15 MPa to 7.21 MPa when GO concentration was 0.1 wt.%. Through applying 5 volts of electrical field within 5 minutes, the nanocomposites can be heated from room temperature to 60 °C, 110 °C and 160 °C for the nanocomposite bricks with graphene concentration of 3 wt.%, 4 wt.% and 5 wt.%, respectively, due to the extremely low percolation threshold (~0.5 wt.%) and high conductivity (10 Ω·cm at 1 wt.%). The sheets were connected more tightly when the GO content was increased. The thermal efficiency can reach up to 88% based on the applied voltage, measured resistance and temperature rise curves.

Comparison between traditional and alternative biocompatible welding techniques used in orthodontic devices

2020 ◽  
pp. 146531252097240
Author(s):  
Fernanda de Souza Henkin ◽  
Luciane Macedo de Menezes ◽  
Berenice Anina Dedavid ◽  
Cátia Abdo Quintão
Keyword(s):  
Tensile Strength ◽  
Laser Welding ◽  
Mechanical Performance ◽  
Steel Wire ◽  
Testing Machine ◽  
Mean Values ◽  
Welding Spot ◽  
Microstructural Morphology ◽  
Orthodontic Devices

Objective: To compare the mechanical strength of joints made by conventional soldering with those made by alternative, more biocompatible, methods (spot, tungsten inert gas [TIG] and laser welding), and to compare the microstructural morphology of wires welded with these techniques. Design: In vitro, laboratory study. Methods: Forty stainless-steel wire segments with 0.8-mm diameter were joined by silver soldering, spot, laser and TIG welding. Ten specimens were produced for each one. Tensile strength test was performed 24 h after welding on the Emic DL2000™ universal testing machine, using a load cell of 1000 N with a crosshead speed of 10 mm/min. Results: The highest tensile strength mean values were obtained with silver soldering (532 N), next were laser (420 N), spot (301 N) and TIG (296 N) welding. Statistically significant differences were observed between the groups; the Dunn post-hoc test revealed differences between laser and spot welding ( p=0.046), laser and TIG ( p = 0.016), spot and silver ( p <0.001), and silver and TIG ( p <0.001). Conclusion: Laser welding strength is high, and comparable to silver welding. Spot and TIG techniques present comparable and significantly lower strengths. The four methods presented resistance values compatible with orthodontic use. The microstructural morphology is different for each technique. The association between the mechanical performance and the microstructure evaluation shows that laser presented the highest quality joint.

scholarly journals On the Feasibility of Printing 3D Composite Objects Based on Polypropylene/Multi-walled Carbon Nanotubes

2019 ◽  
Vol 290 ◽  
pp. 03017 ◽  
Author(s):  
Nicoleta-Violeta Stanciu ◽  
Felicia Stan ◽  
Catalin Fetecau ◽  
Florin Susac
Keyword(s):  
Fused Deposition Modeling ◽  
Mechanical Performance ◽  
Extrusion Process ◽  
Flow Activation Energy ◽  
Fused Deposition ◽  
Multi Walled Carbon Nanotubes ◽  
3D Composite ◽  
Trial And Error Method ◽  
Walled Carbon Nanotubes ◽  
Printing Direction

In this paper, the feasibility of 3D printing polypropylene/ multi-walled carbon nanotube (PP/MWCNT) composites by fused deposition modeling. First, the rheological behavior of PP with 0.3, 0.5 and 1 wt.% of MWCNT was investigated in order to determine the printability in terms of melt shear viscosity and flow activation energy. Second, the filament extrusion process was optimized by the trial-and-error method in order to obtain round and constant filaments. Finally, tensile specimens were printed and tested in order to determine the mechanical properties at various printing direction. Experimental results show that the PP/MWCNT composite filaments with MWCNT loading up to 1 wt.% have good printability characteristics and can be successfully 3D printed with good mechanical performance.

scholarly journals Hot Deformation Behavior of Cu–Sn–La Polycrystalline Alloy Prepared by Upcasting

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3739
Author(s):  
Siming Hua ◽  
Pingze Zhang ◽  
Zili Liu ◽  
Lin Yang
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Extrusion Process ◽  
Hot Deformation Behavior ◽  
Polycrystalline Alloy ◽  
Promising Application

In this study, the hot deformation of a Cu–0.55Sn–0.08La (wt.%) alloy was studied using a Gleeble-3180 testing machine at deformation temperatures of 400–700 °C and various strain rates. The stress–strain curve showed that the hot deformation behavior of the Cu–0.55Sn–0.08La (wt.%) alloy was significantly affected by work hardening, dynamic recovery, and dynamic recrystallization. The activation energy Q was 261.649 kJ·mol−1 and hot compression constitutive equation was determined as  ε˙=[sinh(0.00651σ)]10.2378·exp(33.6656−261.649RT). The microstructural evolution of the alloy during deformation at 400 °C revealed the presence of both slip and shear bands in the grains. At 700 °C, dynamic recrystallization grains were observed, but recrystallization was incomplete. In summary, these results provide the theoretical basis for the continuous extrusion process of alloys with promising application prospects in the future.

scholarly journals Hybrid Biocomposites Based on Poly(Lactic Acid) and Silica Aerogel for Food Packaging Applications

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4910 ◽  
Author(s):  
Alejandro Aragón-Gutierrez ◽  
Marina P. Arrieta ◽  
Mar López-González ◽  
Marta Fernández-García ◽  
Daniel López
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Silica Aerogel ◽  
Food Packaging ◽  
Mechanical Performance ◽  
Composite Films ◽  
Barrier Properties ◽  
Extrusion Process ◽  
Poly Lactic Acid ◽  
Barrier Performance

Bionanocomposites based on poly (lactic acid) (PLA) and silica aerogel (SiA) were developed by means of melt extrusion process. PLA-SiA composite films were plasticized with 15 wt.% of acetyl (tributyl citrate) (ATBC) to facilitate the PLA processability as well as to attain flexible polymeric formulations for films for food packaging purposes. Meanwhile, SiA was added in four different proportions (0.5, 1, 3 and 5 wt.%) to evaluate the ability of SiA to improve the thermal, mechanical, and barrier performance of the bionanocomposites. The mechanical performance, thermal stability as well as the barrier properties against different gases (carbon dioxide, nitrogen, and oxygen) of the bionanocomposites were evaluated. It was observed that the addition of 3 wt.% of SiA to the plasticized PLA-ATBC matrix showed simultaneously an improvement on the thermal stability as well as the mechanical and barrier performance of films. Finally, PLA-SiA film formulations were disintegrated in compost at the lab-scale level. The combination of ATBC and SiA sped up the disintegration of PLA matrix. Thus, the bionanocomposites produced here show great potential as sustainable polymeric formulations with interest in the food packaging sector.

Sign in / Sign up

Export Citation Format

Share Document