Thermal conductivity, structure and mechanical properties of konjac glucomannan/starch based aerogel strengthened by wheat straw

In order to meet the requirement of sustainable development, building materials are increasingly environmentally friendly. They can be partially or fully bio-based or recycled. This paper looks at the development of fully bio-based composites where agro-resources are valued as bio-based aggregates (hemp) and as binding materials (wheat). In a previous work, a feasibility study simultaneously investigated the processing and ratio of wheat straw required to ensure a gluing effect. In this paper, three kinds of hemp-straw composites are selected and compared with a hemp-polysaccharides composite. The gluing effect is analyzed chemically and via SEM. The developed composites were characterized multi-physically. They showed sufficiently high mechanical properties to be used as insulating materials. Furthermore, they showed good thermal performances with a low thermal conductivity (67.9–69.0 mW/(m · K) at 23 ° C, dry).

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Microstructure, Thermal Conductivity, and Flame Retardancy of Konjac Glucomannan Based Aerogels

Polymers ◽

10.3390/polym13020258 ◽

2021 ◽

Vol 13 (2) ◽

pp. 258

Author(s):

Ying Kuang ◽

Lijun Chen ◽

Junjun Zhai ◽

Si Zhao ◽

Qinjian Xiao ◽

...

Keyword(s):

Thermal Conductivity ◽

Heat Release ◽

Wheat Straw ◽

Flame Retardancy ◽

Sol Gel ◽

Three Dimensional ◽

Konjac Glucomannan ◽

Expanded Polystyrene ◽

Limiting Oxygen Index ◽

Cavity Structure

With abundant renewable resources and good biodegradability, bio-based aerogels are considered as promising insulating materials for replacing the conventional petroleum-based foam. In this study, konjac glucomannan (KGM)-based aerogels were prepared as thermal insulation materials via a convenient sol–gel and freeze-drying progress with different content of plant polysaccharides, proteins, and wheat straw. The morphology, thermal conductivity, and flame retardancy of KGM-based aerogels were determined. The KGM-based aerogels showed a uniform three-dimensional porous microstructure. The addition of wheat straw could significantly reduce the pore size of aerogels due to its special multi-cavity structure. KGM-based aerogels showed low densities (0.0234–0.0559 g/cm−3), low thermal conductivities (0.04573–0.05127 W/mK), low peak heat release rate (PHRR, 46.7–165.5 W/g), and low total heat release (THR, 5.7–16.2 kJ/g). Compared to the conventional expanded polystyrene (EPS) and polyurethane (PU) foam, the maximum limiting oxygen index (LOI) of KGM-based aerogels increased by 24.09% and 47.59%, the lowest PHRR decreased by 79.37% and 94.26%, and the lowest THR decreased by 76.54% and 89.25%, respectively. The results demonstrated that the KGM-based aerogels had better performance on flame retardancy than PU and EPS, indicating high potential applications as heat insulation in the green advanced engineering field.

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Microstructure and filtration performance of konjac glucomannan-based aerogels strengthened by wheat straw

International Journal of Low-Carbon Technologies ◽

10.1093/ijlct/ctx021 ◽

2017 ◽

Vol 14 (3) ◽

pp. 335-343 ◽

Cited By ~ 2

Author(s):

Yixin Wang ◽

Xi Chen ◽

Ying Kuang ◽

Man Xiao ◽

Yuehong Su ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Wheat Straw ◽

Freeze Drying ◽

Sol Gel ◽

Compression Modulus ◽

Filtration Efficiency ◽

Konjac Glucomannan ◽

Filtration Resistance ◽

Composite Aerogels

Abstract This study presents the preparation and measurement of a novel environmentally friendly konjac glucomannan (KGM)-based composite aerogels enhanced with wheat straw (WS) via a sol–gel and freeze-drying progress. With the addition of WS, the porosity of aerogels could be increased from 50 to 88.13%, the filtration resistance of aerogels could be reduced from 500 to 205 Pa, and the filtration efficiency could be improved to 90.38%. The addition of WS also enhances the mechanical properties of composite aerogels with compression modulus of 2000.66 Pa, compressive strength of 501.56 Pa and elasticity of 0.603. The results demonstrate the high potential of KGM-based composite aerogels enhanced with WS for applications in air filtering.

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An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v10i2.1336 ◽

2015 ◽

Vol 10 (2) ◽

pp. 2663-2681

Author(s):

Rizk El- Sayed ◽

Mustafa Kamal ◽

Abu-Bakr El-Bediwi ◽

Qutaiba Rasheed Solaiman

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Melt Spinning ◽

Elastic Moduli ◽

Mechanical Stability ◽

Microstructural Analysis ◽

Alloy System ◽

Antimony Content ◽

The Stability ◽

Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as meltâ€“spun ribbons Â as a function of antimony content .The stabilityÂ of these structures hasÂ beenÂ related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition. Â The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes.Â

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Incorporation of Iraqi Rocks in the Production of Eco-Friendly Cement Mortar

Engineering and Technology Journal ◽

10.30684/etj.v38i10a.1479 ◽

2020 ◽

Vol 38 (10A) ◽

pp. 1522-1530

Author(s):

Rawnaq S. Mahdi ◽

Aseel B. AL-Zubidi ◽

Hassan N. Hashim

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Compressive Strength ◽

Water Absorption ◽

Structural Properties ◽

Mechanical Milling ◽

Cement Mortar ◽

Cement Mortars

This work reports on the incorporation of Flint and Kaolin rocks powders in the cement mortar in an attempt to improve its mechanical properties and produce an eco-friendly mortar. Flint and Kaolin powders are prepared by dry mechanical milling. The two powders are added separately to the mortars substituting cement partially. The two powders are found to improve the mechanical properties of the mortars. Hardness and compressive strength are found to increase with the increase of powders constituents in the cement mortars. In addition, the two powders affect water absorption and thermal conductivity of the mortar specimens which are desirable for construction applications. Kaolin is found to have a greater effect on the mechanical properties, water absorption, and thermal conductivity of the mortars than Flint. This behavior is discussed and analyzed based on the compositional and structural properties of the rocks powders.

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A Study of Some Mechanical and Physical Properties for Palm Fiber/Polyester Composite

Engineering and Technology Journal ◽

10.30684/etj.v38i3b.598 ◽

2020 ◽

Vol 38 (3B) ◽

pp. 104-114

Author(s):

Samah M. Hussein

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Dielectric Constant ◽

Date Palm ◽

Volume Fraction ◽

Unsaturated Polyester ◽

Dielectric Strength ◽

Palm Fiber ◽

Mechanical And Physical Properties ◽

Polyester Composite

This research has been done by reinforcing the matrix (unsaturated polyester) resin with natural material (date palm fiber (DPF)). The fibers were exposure to alkali treatment before reinforcement. The samples have been prepared by using hand lay-up technique with fiber volume fraction of (10%, 20% and 30%). After preparation of the mechanical and physical properties have been studied such as, compression, flexural, impact strength, thermal conductivity, Dielectric constant and dielectric strength. The polyester composite reinforced with date palm fiber at volume fraction (10% and 20%) has good mechanical properties rather than pure unsaturated polyester material, while the composite reinforced with 30% Vf present poor mechanical properties. Thermal conductivity results indicated insulator composite behavior. The effect of present fiber polar group induces of decreasing in dielectric strength, and increasing dielectric constant. The reinforcement composite 20% Vf showed the best results in mechanical, thermal and electrical properties.

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BRUSH ALLOY 3

Alloy Digest ◽

10.31399/asm.ad.cu0454 ◽

1983 ◽

Vol 32 (3) ◽

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Corrosion Resistance ◽

Physical Properties ◽

Copper Alloy ◽

Elevated Temperatures ◽

Physical And Mechanical Properties ◽

Heat Treating ◽

Good Resistance ◽

Good Corrosion Resistance

Abstract BRUSH Alloy 3 offers the highest electrical and thermal conductivity of any beryllium-copper alloy. It possesses an excellent combination of moderate strength, good corrosion resistance and good resistance to moderately elevated temperatures. Because of its unique physical and mechanical properties, Brush Alloy 3 finds widespread use in welding applications (RWMA Class 3), current-carrying springs, switch and instrument parts and similar components. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, joining, and surface treatment. Filing Code: Cu-454. Producer or source: Brush Wellman Inc..

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850.0 and 852.0 ALUMINUM ALLOY BEARING BARS

Alloy Digest ◽

10.31399/asm.ad.al0290 ◽

1988 ◽

Vol 37 (9) ◽

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Corrosion Resistance ◽

Aluminum Alloy ◽

Heat Treating ◽

Light Metal ◽

General Purpose ◽

High Ductility ◽

Higher Temperature ◽

Bearing Alloy

Abstract 850.0 ALUMINUM Alloy can be considered the general purpose light metal bearing alloy. Its good thermal conductivity keeps operating temperatures low. It has high ductility. In many applications it has been found to be superior to steel backed bearings. 852.0 ALUMINUM Alloy has higher mechanical properties making it suitable for heavier load and higher temperature applications. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: Al-290. Producer or source: Federated Bronze Products Inc..

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