Silkworm cocoon is a Natural biological and composite structure that has evolved over time and has high physical and mechanical properties against stress and acts as insulation against ambient temperature conditions. Understanding the relationships between the two-component structure of silkworm cocoons (sericin and fibroin) inspires the creation of composite structures, including lightweight, high-strength nonwoven biocomposites. In the present study, by analytical-descriptive method, we have tried to use cocoon sericin and introduce some famous and widely used Natural fibers in materials science and study their characteristics - because for various reasons such as lightness, lack of pollution and low cost, etc. can be suitable alternative for a replacement of synthetic fibers - suggest the production of non-woven bio-composite materials. Natural fibers such as jute, hemp, flax, etc. with different volume percentages in combination with sericin as a binder, were proposed for this biocomposite and the thermal performance of each of them was compared using Maxwell's theoretical model. All compounds show low thermal conductivity and jute-sericin biocomposite with 70% by volume and 0.061 W/m2-K performance has better performance.

Heat transfer in foams consists of conduction through solid and gaseous phases, convection within the cells as well as radiation through the whole medium. Radiation thermal conduction affects the overall thermal conductivity by 40% in a high porosity. Therefore, the investigation of that term seems to be necessary. Radiation thermal conduction depends on the extinction coefficient which its determination is experimentally complex. In this study, this coefficient is theoretically estimated using Glicksman model for polyolefin foams and is verified in comparison with the experimental data. Extinction coefficient which plays an effective role in the radiation thermal conduction depends on the morphological properties including foam and solid densities, cell and strut diameters. The results demonstrate that the radiation thermal conduction decreases by reducing cell size and increasing foam density and strut diameter. An L25 orthogonal array of Taguchi approach is used for optimization of radiation thermal conduction respect to foam density, cell and strut diameters as variable parameters. The analysis of variance results illuminate that foam density and cell diameter with 58 and 32% contribution are the most effective parameters on the radiation thermal conduction, respectively. At optimum conditions according to the prediction tool of Taguchi approach, the radiation thermal conduction significantly decreases to 1.0908 mW/mK.

Zirconia based thermal barrier coatings (TBCs) are extensively used in gas turbines engines to protect and provide thermal insulation for hot-section metal components. Consequently, the key parameter of these coatings is low thermal conductivity. The present paper deals with evaluation of effect of the microstructure and stabilizer type on zirconia based TBCs thermal insulation capability. For this scope, three type of coatings including conventional yttria stabilized zirconia (YSZ), conventional ceria and yttria stabilized zirconia (CYSZ) and nanostructured yttria stabilized zirconia have been prepared by atmospheric plasma spraying (APS) on NiCoCrAlY-coated Inconel 738 substrates. Microstructural evaluation and phase analysis were performed using field emission scanning electron microscope (FESEM) and X-ray diffractometry (XRD) respectively. Results revealed that with employing of ceria stabilizer and fabrication of nano-structure in coating, the thermal insulation capability of zirconia based TBCs were enhanced.

Alumina (Al2O3) nanoparticles were used as the additive for modifying a novolac phenolic resin using the solution mixing method. Different weight percentages of nano alumina 3 and 8 w% were loaded into the resin, called 3ARC and 8ARC nanocomposites, respectively. These nanocomposites were investigated by field emission scanning electron microscopy (FE-SEM), X-ray fluorescence spectroscopy (XRF), energy-dispersive X-ray spectroscopy (EDS), and oxyacetylene flame test (OFT). The FE-SEM images exhibited that at low concentrations (3ARC), the nano alumina particles were dispersed uniformly on the surface of novolac resin, however, at high concentrations, the dispersion was repressed by aggregation in the nanocomposites. OFT proved that with increasing alumina content in the nanocomposite, the back temperature of the sample decreases and thus improves the thermal insulation properties.

2Introduction: Numerous studies have been conducted on the development of modern insulators, including nano-insulators. However, a comprehensive study has yet to be performed to review and investigate the thermal properties of these insulators. Consequently, this study aimed to examine the effect of nanomaterials on thermal insulation function. Material and Methods: In this review, articles were searched for in English databases (PubMed, Web of Science, and ScienceDirect), Persian databases (Magiran, SID), and Google Scholar. The keywords used in the search were Nano Material, Nano insulation, thermal insulation, thermal Insulator Stability, and thermal Conductivity in both English and Persian. Results: Of the 4068 studies identified through search databases, 15 were selected according to the entry criteria. Among the studies, the three types of silicone, composite, and aerogel insulation had the highest frequency (each 26.67%), and SiO2 nanoparticles were the most prevalent nanomaterial (26.67%). According to the studies, the type of nanomaterial used in insulation will improve its properties such as thermal resistance, mechanical strength, dielectric strength, tensile strength, elasticity, and hardness. Conclusion: The results of this study showed that using nanotechnology could be an effective step in improving the properties of insulation materials, the most important of which is increased thermal resistance. Moreover, nanotechnology insulators can prevent thermal energy loss, reduce costs, and provide safety and comfort.