In recent years energy saving, economic saving, recycling and solace for humanity as an essential requirement has become very important. Therefore, the human uses acoustic and thermal insulations and sound absorbers in various industries such as automotive and construction. Resin bonded felts are used as acoustic insulation materials mainly for the automotive industry but also in white goods such as washing machines. Industrial felts are porous composite materials that are mainly made from recycled cotton and denim fabrics. Powder resin or bico fibres as the binder are added to the felt. Other additives such as flame retardants, processing aids, water repellents and etc may also be added to the felt. Cellulosic recycled fibers length is usually in the order of two or three centimeters. Phenolic resins are based on phenol and formaldehyde condensation reaction results in creation of solid phase and liquid phase that are respectively known as Novolac and Resol. Thermal and sound absorption properties of these products render them as insulation material with energy and economic saving and human comfort. EPDM is an engineered polymer that can be laminated on the industrial felt by different method. The properties of the bonded felt including thermal resistance and sound absorbance are dependent on type of resin used and the composition of the felt. In this work 14 samples felts were produced. The effect of parameters such as thickness (mass per unit area) and percentage of added binder on acoustic and thermal behavior of the samples were investigated. Thermal conductivity and thermal resistance of the samples were measured and were compared using Fourier law. Sound absorption coeiffecient of the samplers were determind using a two-microphone impedance measurement tube. The results showed that an increase in the thickness and mass per unit area leads to increase in the thermal resistance. It was also found that the increase in the percentage of solid phenolic resin leads enhancement of thermal resistance. Comparison of the type of binder showed that under equal percentage, as far as effect of type of resin is concerned, phenolic resin and bico fibers behave equally. It was also found that in general the effect of percentage of added binder is predominating in comparison to the effect of fabric thickness (mass per unit area). Results showed that under given percentage of phenolic resin, the effect fabric thicknesses and mass per unit area is unchanged. Results also tend to indicate that sound absorption increases vastly as percentage of added resin increases. Additionally it was found that the effect of bico fibers on sound absorption is less than of phenolic resin. Statistical analysis models capable of predicting optimal thermal and acoustic properties of industrial felts was developed. Keywords: Phenolic resins (Novolac) , Bicomponent Fiber, Industrial Felt, recycled denim fibres, Sound Absorption, Thermal conductivity, Thermal resistance.
