聚醚酰亚胺多孔膜结构调控及其声学超材料吸声隔声性能

Structure control of the polyetherimide porous membrane and its acoustical metamaterial sound absorption and the sound insulation properties

以聚醚酰亚胺(PEI)为膜材料、N-甲基吡咯烷酮(NMP)为溶剂,采用相转化法制备PEI多孔膜,并构建PEI多孔膜声学超材料,考察了PEI浓度、刮膜厚度和凝固浴组成对多孔膜厚度、密度、形貌结构、拉伸强度以及多孔膜声学超材料在低频范围吸声性能和隔声性能的影响.结果表明:PEI浓度增加抑制了多孔膜指状孔结构形成,使多孔膜密度增加,声学超材料的平均吸声系数由0.075减小到0.040,平均隔声量由4.126 dB增加到6.263 dB;刮膜厚度增加使多孔膜指状孔数量减少,厚度增加,声学超材料的平均吸声系数由0.113减小到0.043,平均隔声量由3.149 dB增加到8.317 dB;凝固浴中加入NMP促进了多孔膜海绵状孔结构形成,当NMP浓度达到80%(v/v)时,多孔膜基本为海绵状孔结构,增加NMP浓度使多孔膜密度增加、厚度减小,由于密度和厚度的相反作用,在实验频率范围内凝固浴组成对多孔膜声学超材料吸声性能和隔声性能的影响规律不明显.

The polyetherimide(PEI)porous membrane was prepared by phase inversion process using PEI as the membrane material and N-methylpyrrolidone(NMP)as the solvent,in which the PEI porous membrane acoustic metamaterial was further constructed.The effects of PEI concentration,scraping thickness,and coagulation bath composition on the thickness,density,morphology,and tensile strength of the PEI porous membrane,as well as the sound absorption properties and sound insulation properties of the porous membrane acoustic metamaterial in the low-frequency range were investigated.The results showed that increasing the PEI concentration inhibited the formation of finger-like pore structures and increased the density of the PEI porous membrane.By increasing the membrane density,the average absorption coefficient of the porous membrane acoustic metamaterial decreased from 0.075 to 0.040,and the average sound transmission loss increased from 4.126 dB to 6.263 dB.Increasing the scraping thickness decreased the number of finger-like pores and increased the thickness of the PEI porous membrane.The average absorption coefficient of the porous membrane acoustic metamaterial decreased from 0.113 to 0.043,and the average sound transmission loss increased from 3.149 dB to 8.317 dB.The addition of NMP to the coagulation bath promoted the formation of sponge-like pore structures in the PEI porous membrane.The PEI porous membrane was basically a fully sponge-like structure with the NMP concentration of 80%(v/v).Increasing the NMP concentration increased the density and decreased the thickness of the PEI membrane.Due to the opposite effect of density and thickness,the effect of coagulation bath composition on the sound absorption properties and sound insulation properties of the porous membrane acoustic metamaterial was not obvious in the experimental frequency range.