| The lightweight ultra-fine glass fiber felts are widely used as sound and heat insulation material in the fields of building energy and rail transportation because of its ultra-low bulk density,good fire resistance property and excellent sound and heat insulation performance.However,lightweight ultra-fine glass fiber felt has the problems of low strength and poor sound insulation at mid-frequency(2000Hz)due to its ultra-low bulk density,which is not conducive to the long-term stable usability and performance improvement of the material.The epoxy resin were used to strengthen the bonding strength of the phenolic resin.The effects of curing temperature,resin content and structural parameters of glass fiber felt on sound insulation and strength were studied.A BP neural network was established to predict medium frequency sound insulation and longitudinal breaking strength of lightweight ultra-fine glass fiber felt.The main research contents and results are as follows:(1)The phenolic-epoxy resin was successfully prepared.Scanning electron microscopy,energy dispersive spectrometer,thermogravimetric analyzer,etc.were applied to characterize the effect of the epoxy resin on adhesive performance.The results showed that the amount of epoxy resin 8%by weight was better,which had little effect on the heat resistance of the phenolic resin.The adhesive formed a uniform coating on the glass fiber surface when the viscosity of the adhesive was 19.4m Pa·s.As well as,the flexibility of glass fiber coated with adhesive coating was increased by 43.3%while the adhesive bond strength was increased by 21.3%,and the strength of glass fiber felt was increased by 27.9%after adhesive modification.(2)The influence mechanism of characteristic parameters on transverse and longitudinal breaking strength of glass fiber felt was explored.The results showed that the cracks,pores,debonding and other brittle defects disappeared in the coating,and the transverse and longitudinal strength of the glass fiber felt reached the maximum value when the curing temperature was 180±5℃.With the increase of the resin content,the transverse strength of the glass fiber felt was gradually increased,the resin content20%was the best for longitudinal breaking strength.The greater the areal density and the fiber aspect ratio,the better the strength of the felt,and the aspect ratio affected the longitudinal strength dramatically.(3)The attenuation mechanism of acoustic waves of different frequencies in lightweight ultra-fine glass fiber felt was analyzed.The results showed that when the curing temperature was 180±5℃,the capillary absorbing effect of the pore structure on sound waves was enhanced,which makes the glass fiber felts had the best sound insulation performance.The sound insulation of glass fiber felt reached the maximum when the resin content was 10%.The increase of the area density and the decrease of the fiber aspect ratio were beneficial to the sound insulation performance of the felt.(4)Based on the experimental data,a BP neural network model with structure of[3-(7,8)-2]was established to optimize the characteristics parameters of lightweight ultra-fine glass fiber felt.The results showed that the average relative error MRE of the BP neural network model was far less than0.1,and the correlation coefficient R>0.97.The model had a high prediction quality for the mid-frequency sound insulation and strength performance of lightweight ultra-fine glass fiber felt.When the fiber diameter was 1.1～1.4μm,the content of resin was 16%～21%,and the areal density was 220～230g/m~2,acoustical and mechanical properties of premium glass wool felt were in the optimum range,with the breaking strength was≥371.5N/m and the STL was≥18.89d B. |
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