scholarly journals The mechanical properties and thermal conductivity of bamboo with freeze–thaw treatment

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Jieyu Wu ◽  
Xianke Wang ◽  
Benhua Fei ◽  
Xiang Xu ◽  
Caiping Lian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Chemical Composition ◽  
Moisture Content ◽  
Bending Strength ◽  
Testing Machine ◽  
Initial Moisture Content ◽  
Crystallinity Index ◽  
Phyllostachys Pubescens ◽  
Freeze Thaw

AbstractThe aim of this research was to investigate the effect of freeze–thaw treatment on bamboo with different initial moisture content (water-saturated, air-dried and oven-dried). Bamboo (Phyllostachys pubescens) were treated with two freeze treatments and its microstructure, chemical composition, mechanical properties and thermal conductivity were characterized by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), mechanical testing machine and thermal conductivity tester, respectively. The results showed that the freeze–thaw treatment had little influence on the microstructure of bamboo, the chemical composition content and the cellulose crystalline structure of bamboo were also not altered. The crystallinity index was found to increase with the increase of initial moisture content. The bending strength and elastic modulus of the treated bamboo increased, the extent of the increase was dependent on the initial moisture content and the freezing temperature. The thermal conductivity of the treated bamboo increased remarkably, which might be possibly determined by the cellulose crystallinity, moisture content, and density of bamboo.

Preparation and Properties of SiC/Phenolic Resin for the Heat of LED

2016 ◽  
Vol 848 ◽  
pp. 454-459
Author(s):  
Cong Wu ◽  
Kang Zhao ◽  
Yu Fei Tang ◽  
Ji Yuan Ma
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Powder Metallurgy ◽  
Phenolic Resin ◽  
Bending Strength ◽  
Experimental Results ◽  
Low Thermal Conductivity ◽  
Industry Standard ◽  
Insulation Performance

In order to solve the problem that low thermal conductivity of the plastics for the heat of LED, SiC/Phenolic resin for the heat of LED were fabricated combining powder metallurgy. The effects of particles diameters, content and adding nanoparticles on thermal conductivity of the fabricated composites were investigated, the mechanical properties were also characterized. The experimental results showed that the materials were obtained, and the insulation performance of the fabricated SiC/Phenolic resin was higher than the industry standard one, the thermal conductivity reached 4.1W/(m·k)-1. And the bending strength of the fabricated composites was up to 68.11MPa. The problem of low thermal conductivity of the material is expected to be solved. In addition, it is meaningful for improving LED life.

Physical Properties of Building Blocks from Hemp Shives Aggregate and Cementitious Binder, Manufactured in the Expanded Clay (Vibro Pressing) Production Line

2017 ◽  
Vol 908 ◽  
pp. 118-122 ◽  
Author(s):  
Giedrius Balčiūnas ◽  
Viktor Kizinievič ◽  
Justinas Gargasas
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Physical Properties ◽  
Production Line ◽  
Scientific Literature ◽  
Building Blocks ◽  
Freeze Thaw ◽  
Cementitious Binder ◽  
Pressing Technology

Scientific literature mostly aims at investigation of composites with fibre hemp shives (FHS) aggregate and lime binder, although, such materials are characterised by pretty low mechanical properties. In order to obtain higher mechanical properties of a composite, it is appropriate to use cementitious binder. This work investigates physical properties of blocks from hemp shives aggregate and cementitious binder, manufactured in the expanded clay production line using vibro pressing technology. Following properties of the blocks are determined: freeze-thaw resistance, compressive strength, thermal conductivity and density. Thermal resistance according to EN ISO 6946 for the block with cavities is calculated as well. It is found that compressive strength of FHS-cement blocks may be up to 3.18 MPa when the density is of ~850 kg/m3 and thermal conductivity up to 0.135 W/(m∙K). It is found as well that the decrease of compressive strength is 8.7% after 25 freeze-thaw cycles.

Glass Transition Temperature, Mechanical Properties of Rice and their Relationships with Milling Quality

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Kobra Tajaddodi Talab ◽  
Mohd. Nordin Ibrahim ◽  
Sergey Spotar ◽  
Rosnita A. Talib ◽  
Kharidah Muhammad
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Moisture Content ◽  
Bending Strength ◽  
Bending Test ◽  
Transition Line ◽  
Transition Temperatures ◽  
Drying Process ◽  
Glass Transition Temperatures ◽  
Grain Moisture

Abstract Glass transition temperatures (Tg) of MR219 rice variety were measured by differential scanning calorimeter (DSC). State diagram was developed and used to evaluate drying process in this study. Glass transition temperatures range of 9.65- 61.79°C were observed for gains with moisture content of 26.8 – 7.4% (w.b.). For mechanical properties and milling test, statistical analysis was performed by using a two factor experiment in completely randomized design (CRD). Two selected factors were drying temperatures at 5 levels (40, 45, 50, 55, and 60°C) and final moisture content (FMC) at 4 levels (10-10.5, 11-11.5, 12-12.5 and 13-13.5%). Three–point bending test was applied to measure the mechanical properties of rice kernel. Generally, bending strength, apparent modulus of elasticity and fracture energy of brown rice kernel increased with decreasing the grain moisture content. Maximum bending strength was 35.69 and 33.64 MPa for 55, and 60°C, respectively. All samples that were dried at 55 and 60°C experienced to go through the glass transition line after reaching their temperature to the room temperature at the end of drying process. The effect of drying temperature, paddy FMC and their interactions on whole kernel percentage (WKP) and mechanical properties were significant (α = 0.05). An inverse relationship was observed between WKP and the percentage of strong kernels for all treatments.

Mechanical properties and freeze-thaw resistances of bronze-concrete composites

2021 ◽  
Vol 12 (2) ◽  
pp. 39
Author(s):  
Tuba Bahtli ◽  
Nesibe Sevde Ozbay
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Test Methods ◽  
Pulse Velocity ◽  
Plastic Energy ◽  
Freeze Thaw ◽  
Schmidt Rebound Hammer

Studies in the literature show that the physical and mechanical properties of concrete could be improved by the incorporation of different kinds of industrial waste, including waste tire rubber and tire steel. Recycling of waste is important for economic gain and to curb environmental problems. In this study, finely ground CuAl10Ni bronze is used to improve the physical and mechanical properties, and freeze-thaw resistances of C30 concrete. The density, cold crushing strength, 3-point bending strength, elastic modulus, toughness, and freeze-thaw resistances of concrete are determined. In addition, the Schmidt Rebound Hammer (SRH) and the ultrasonic pulse velocity (UPV) tests, which are non-destructive test methods, are applied. SEM/EDX analyses are also carried out. It is noted that a more compacted structure of concrete is achieved with the addition of bronze sawdust. Then higher density and strength values are obtained for concretes that are produced by bronze addition. In addition, concretes including bronze sawdust generally show higher toughness due to high plastic energy capacities than pure concrete.

scholarly journals Durability of Structural Lightweight Concrete with Sintered Fly Ash Aggregate

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4565 ◽  
Author(s):  
Lucyna Domagała
Keyword(s):  
Fly Ash ◽  
Moisture Content ◽  
Water Absorption ◽  
Water Permeability ◽  
Lightweight Concrete ◽  
Concrete Strength ◽  
Initial Moisture Content ◽  
Cement Matrix ◽  
Secondary Importance ◽  
Freeze Thaw

The aim of this study was to present the problem of durability of structural lightweight concrete made of a sintered fly ash aggregate. The issue of durability was researched for 12 concrete series in terms of their water absorption, water permeability, and freeze-thaw resistance. Additionally, the microstructure of several concretes was analyzed with a scanning electron microscope (SEM). In the durability research, the influences of the following parameters were taken into consideration: The initial moisture content of sintered fly ash (mc = 0, 17–18, and 24–25%); the aggregate grading (4/8 and 6/12 mm); and the water-cement ratio (w/c = 0.55 and 0.37). As a result of various compositions, the concretes revealed different properties. The density ranged from 1470 to 1920 kg/m3, and the corresponding strength ranged from 25.0 to 83.5 MPa. The durability research results of tested lightweight concretes showed that, despite considerably higher water absorption, a comparable water permeability and comparable or better freeze-thaw resistance in relation to normal-weight concrete may be present. Nevertheless, the fundamental requirement of lightweight concrete to achieve good durability requires the aggregate’s initial moisture content to be limited and a sufficiently tight cement matrix to be selected. The volume share of the cement matrix and aggregate, the cement content, and even the concrete strength are of secondary importance.

Measurement of Physical and Mechanical Properties of Russian Olive (Elaeagnus Angustifolia L.) Fruit

2016 ◽  
Vol 12 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Mohammad Hossein Nadian ◽  
Mohammad Hossein Abbaspour-fard
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Loading Rate ◽  
Geometric Mean ◽  
Testing Machine ◽  
Physical And Mechanical Properties ◽  
Angle Of Repose ◽  
Shear Mode ◽  
Russian Olive ◽  
Double Shear

Abstract The effect of moisture content on some properties of two varieties (Meymeh and Maragheh) of Russian olives was studied. The physical and mechanical properties including: dimensions, geometric mean diameter, thousand mass, volume, sphericity, surface area, true and bulk densities, porosity, angle of repose, coefficient of friction, rupture force, and rupture energy. The changes of moisture content levels from 17% to 25% (w.b.) indicated a statistically significant effect on all studied physical properties, except bulk density for Russian olive fruits. Shearing force was applied to the fruit using a testing machine in double shear mode. Shear strength and shearing energy increased with increase of loading rate; however, they were higher in Meymeh variety than Maragheh variety. Therefore, the lowest loading rate, with up to about 10 mm/min is desirable to design a suitable pulverizing mill in the herbal medicine industries.

Development of a Silicon-Infiltrated Silicon Carbide (SiSiC) Friction Layer by the Doctor-Blade Technique Using a Computer-Optimized Calculation for the Packing Density

2015 ◽  
Vol 825-826 ◽  
pp. 264-270
Author(s):  
Pascal Seffern ◽  
Lee Klein ◽  
Daniel Tischer ◽  
Antje Liersch
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Matrix Material ◽  
Particle Packing ◽  
Friction Layer ◽  
Solid Mixture ◽  
Particle Parameter ◽  
Tape Cast

This paper focuses on an iterative algorithm for setting and attaining particle packing densities by means of different concentrations of a matrix material. The mechanical properties of a product, such as fracture toughness, bending strength and thermal conductivity are directly dependent on the amount of matrix material present. A tape cast friction layer was developed, in order to investigate the dependence of the parameters of the RRSB distribution on concentration of matrix material. The results verify the calculation method of a solid mixture and show a linear dependence of the RRSB particle-parameternon the concentration of matrix material (SiC-content).

Mechanical Properties of α- and β-SiAlON Composite Ceramics Using β-SiAlON Powder

2008 ◽  
Vol 403 ◽  
pp. 111-114 ◽  
Author(s):  
Kei Asakoshi ◽  
Junichi Tatami ◽  
Katsutoshi Komeya ◽  
Takeshi Meguro ◽  
Masahiro Yokouchi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rare Earth ◽  
Chemical Composition ◽  
Metal Oxides ◽  
Bending Strength ◽  
Rare Earth Oxide ◽  
Composite Ceramics ◽  
Oxide Powders ◽  
Sialon Powder

β-SiAlON powder was used as a raw powder to fabricate α/β-SiAlON composite ceramics with different rare earth elements. The phases present in the sample fabricated from -SiAlON, α-Si3N4, AlN, and rare earth oxide powders were - and -SiAlONs. The composition was dependent on the chemical composition and firing profile. The sample obtained by adding Yb2O3 had a high -SiAlON content. The /-SiAlON composite ceramics had high densit. Their microstructures depended on the used metal oxides, namely, the addition of Nd2O3 and CaCO3 resulted in the elongation of the -SiAlON grains. The bending strength, fracture toughness, and hardness were influenced by the -SiAlON content, amount of elongated grains, and density of the sample.

Preparation and Properties of Rigid Carbon Felt Thermal Insulation

2015 ◽  
Vol 833 ◽  
pp. 48-51 ◽  
Author(s):  
Wei Shi ◽  
Jia Yan Li ◽  
Qi Fan You ◽  
Tong Lu ◽  
Yi Tan
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Bending Strength ◽  
High Thermal Conductivity ◽  
Carbon Felt ◽  
Matrix Concentration ◽  
Thermal Conductivities

Matrix derived from resin after carbonization in rigid carbon felt thermal insulation has many advantages. The microstructures and properties of these materials were investigated in this paper. Results showed that matrix tend to accumulate at the intersections of fibers. This can improve mechanical properties and have a little influence on thermal conductivities of the composites. The excellent bending strength of 2.66MPa, compressive strength of 0.91MPa and a high thermal conductivity of 0.81W/(m·K) (at 1500°C) with a matrix concentration of 32.7% is achieved. However, high thermal conductivity is harmful for those materials which are used as thermal insulators.

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