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Fabrication of Porous Silica Fibers by Electrospinning for Sound Absorbing Materials

100%

Cho Y.-S. , Lee H. J.

Archives of Metallurgy and Materials

2018

tom Vol. 63, iss. 3

1497--1502

Macroporous silica fibers having spherical cavities were fabricated by electrospinning using the spinning solution prepared from the mixed dispersion of tetraethylorthosilicate (TEOS) and polystyrene nanospheres as precursor and sacrificial templates, respectively, by injection through metallic nozzle. By applying electric field, the electro-spun fibers obtained by evaporation-driven self-assembly were collected on flat substrate or rotating drum, followed by the removal of the templates by calcination. The sound absorption coefficient of the porous fibers was measured by impedance tube, and the measured value was larger than 0.9 at high frequency region of incident waves. The surface of the resulting fibers was modified using fluorine-containing silane coupling agent to produce superhydrophobic fibrous materials to prevent the infiltration of humidity.

The impact of additives on the insulation properties of the epoxy resin building substance

63%

Mashkoor I. A. , Jabbar M. A. , Yousif M. Y.

2024

tom Vol. 125, nr 2

49--57

Purpose: Investigation of the possibility of converting a material from outside the scope of thermal insulation (building thermal insulator) to entire it. Design/methodology/approach: Epoxy resin was used for this purpose, and this was done in two ways. First, the composite thermal insulators were prepared using the weight percent method, where the following additive materials were added to the epoxy (sunflower seed husks, used utensil waste, titanium dioxide powder). The other method, the above-manufactured materials, was used to prepare the composite thermal insulators using the volume ratio method, where the base layer was always epoxy, while the other two layers were among the other materials. The suitability and applicability of the insulator were assessed through the evaluation of its thermal conductivity, specific heat capacity, and hardness tests. All tests were performed under standardized conditions. Findings: Significant findings were achieved in this study where the thermal conductivity of the epoxy (0.24 to 0.08 W/m.°C) after adding sunflower seed husks based on the weight percent method. Furthermore, when mixing epoxy with utensil waste materials, the specific heat capacity was lowered to 0.31 kJ/kg.K. It is important to note that all of these outcomes are within the methods’ defined insulating range. Adding titanium dioxide, and TiO2 powder was improved the surface hardness of epoxy, where the highest hardness value was obtained after adding this material compared to other additives. Research limitations/implications: Sustainability and reducing energy consumption are among the most important aspects addressed in this research. Originality/value: This research aims to study the impact of various additives, namely, Sunflower Seed husks, used utensil waste, and titanium dioxide powder for epoxy resin for obtaining a new material that serves as an efficient insulator inside buildings.

Textile fabrics as thermal insulators

63%

Abdel-Rehim Z. S. , Saad M. M. , El-Shakankery M. , Hanafy I.

Autex Research Journal

2006

tom Vol. 6, no. 3

148--161

In recent times, a wide range of textile materials has been used as thermal insulators in many industrial applications. The thermal insulating properties of textile fabrics depend on their thermal conductivity, density, thickness and thermal emission characteristics. Experiments have been made with the aim of studying heat transfer by conduction through the different types of fabrics used as thermal insulators. 100% polyester and 100% polypropylene nonwoven fabrics are used in this work as case studies. The temperature variation through the selected fabrics is measured under different operating parameters such as densities and inlet temperature. The thermal response and behaviour for the selected fabrics used in this work as thermal insulators are illustrated. The relationship between the thermal conductivity and material density of the selected fabrics is studied. Polyester fabric has higher thermal resistance and specific heat resistance than polypropylene. Fabric thickness has a significant effect on the fabric temperature variations. The results of Anova-two way measurements are presented for 100% polyester and 100% polypropylene nonwoven fabrics. The temperature variation of the fabric increased with the testing time, and also decreased with the increase of fabric weight up to a certain limit beyond its optimum level. The results show that the selected nonwoven fabrics are suitable for usage as thermal insulators.