Sound absorbing material

Abstract

A sound absorbing material according to the present disclosure is provided, which includes a polymeric body having a first end, a second end opposed to the first end, and a plurality of branched passages connected to the first end and extending toward a direction of the second end. The plurality of branched passages have an average spacing of 5 μm to 50 μm therebetween and an average width of 5 μm to 50 μm.

What is claimed is: 
     
         1 . A sound absorbing material, comprising:
 a polymeric body having a first end, a second end opposed to the first end, and   a plurality of branched passages connected to the first end and extending toward a direction of the second end, wherein the plurality of branched passages have an average spacing of 5 μm to 50 μm therebetween and an average width of 5 μm to 50 μm.   
     
     
         2 . The sound absorbing material as claimed in  claim 1 , wherein each of the branched passages comprises a main passage and a plurality of side passages, the main passage is connected to the first end and extends toward the direction of the second end, and the plurality of side passages are formed around and connected to the main passage. 
     
     
         3 . The sound absorbing material as claimed in  claim 2 , wherein the plurality of side passages extend from the main passage toward the direction of the second end. 
     
     
         4 . The sound absorbing material as claimed in  claim 2 , wherein each main passage of the branched passages is parallel to the main passage of adjacent branched passages. 
     
     
         5 . The sound absorbing material as claimed in  claim 2 , wherein the plurality of side passages have an average thickness of 3 μm to 20 μm. 
     
     
         6 . The sound absorbing material as claimed in  claim 1 , wherein each of the branched passages comprises a lamellar structure, a columnar structure, or a combination thereof. 
     
     
         7 . The sound absorbing material as claimed in  claim 1 , wherein the polymeric body comprises at least 90 wt % of a water-soluble polymer. 
     
     
         8 . The sound absorbing material as claimed in  claim 7 , wherein the water-soluble polymer comprises polyvinyl alcohol or polyethylene glycol. 
     
     
         9 . The sound absorbing material as claimed in  claim 7 , wherein the polymeric body further comprises 10 wt % or less of an inorganic material. 
     
     
         10 . The sound absorbing material as claimed in  claim 9 , wherein the inorganic material comprises diatomite or activated carbon. 
     
     
         11 . The sound absorbing material as claimed in  claim 1 , having a density of 300 kg/m 3  to 400 kg/m 3 . 
     
     
         12 . The sound absorbing material as claimed in  claim 1 , having a porosity of 60% to 80%. 
     
     
         13 . The sound absorbing material as claimed in  claim 1 , having a sound absorbing coefficient of at least 0.6 at 500 Hz and at least 0.5 at 2,000 Hz. 
     
     
         14 . The sound absorbing material as claimed in  claim 1 , wherein the plurality of branched passages are made by a freeze casting method.