| In recent years, China has been developing rapidly in building industry. Not only have to meet the needs of new residential population, but also faced enormous growing population demand for residential upgrade and replacement. In this situation, China’s demand for housing will keep increasing. At the same time, new policies have been introduced in energy conservation and green building and people’s concern of energy consumption in building application was raised. Building energy consumption in China is not only very low, but low energy efficiency, which going to an opposite direction from the strategy of sustainable development. As we can see, the study of energy-saving material and technology has very important significance.In this research, usage of waste hemp fibers as main materials for building thermal insulation has been researched. Waste hemp has significant advantages due to its environmentally friendly nature and low cost. Also hemp fiber has good strength, heat resistance and has a cavity structure, which make it has the potential for thermal insulation materials. PET/PET bicomponent fiber has a core-sheath structure, which is used for thermal bonding and can increase the thermal insulation property with its structure after bonding.The insulation consisted of nonwoven fabric composed of waste hemp and bicomponent fibers with no preferential orientation. The fibers were blended before they were airlaid into webs and then thermally bonded in an oven. This technique was used to produce four different proportions of hemp fibers and bicomponent fibers, which were50%,75%,90%, and95%, by weight of hemp fibers. Hemp fiber is short, thick, and has poor cohesion, which cannot be spin. However, airlaid just apply to such fibers. Oven used for thermal bonding can meet the requirements of thickness and realized the maximum adhesive use of the bicomponent fibers.These materials were evaluated for thickness, basis weight, density, mechanical properties and thermal performance. Also analysis effects of heat time and air temperature on above properties. With increasing content of hemp fiber, insulation’s thickness and density were increased, but mechanical properties. Insulation’s bursting strength was increased when air temperature between140℃and150℃. Bursting strength was decreased once beyond150℃. When heat time up to160s, insulation had the best strength, which caused by melting effect, sufficient adhesion.The study concerns the evaluation and comparison of thermal property with different thickness, density, heating time and temperature. The study found that thermal conductivity was increased with the increased of the ratio of hemp fiber. Thermal conductivity was decreased with the increase of the thickness. The insulation had the best thermal insulation when hemp proportion up to95%. Hemp fiber and bicomponent fibers was fully bonded only with150℃and160s. Otherwise, insulation will easy to bend, which will affect its structure significantly. Insulation cannot be applied on building material finally.In addition, same tests were performed on some insulation bought from market. Through the comparison and analysis with the hemp fiber insulation,90%hemp fiber insulation has the potential to be used as building thermal insulation materials.Finally, heat transfer model of Schuhemister, Baxter and Stark-Fricke were introduced for evaluate the thermal conductivity. After calculation, the test results cannot fit the model. |
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