Hemp Fiber Reinforced Composite with Recycled High Density Polyethylene and Production Thereof

Abstract

Novel structural materials composed of industrial hemp fiber with recycled high density polyethylene (HDPE) as well as methods for the production of the same are disclosed. The material's mechanical strength outperforms that of conventional lumber and could compete with glass fiber reinforced composites, particularly in tensile strength. In addition, this material offers many other significant advantages including insect free, high moisture resistance, no harmful chemical treatments, and no rapid corrosion in water environments.

1 . A composite material, comprising:
 hemp fibers embedded in a matrix of high density polyethylene.   
     
     
         2 . The composite material of  claim 1 , wherein the high density polyethylene is recycled high density polyethylene. 
     
     
         3 . The composite material of  claim 1 , wherein the hemp fibers have an aspect ratio from about 0.0015 to about 0.003. 
     
     
         4 . The composite material of  claim 3 , wherein the hemp fibers have an average length of about 0.5 inches to 2 inches. 
     
     
         5 . The composite material of  claim 1 , wherein the composite material has a high density polyethylene composition between 30 wt. % and 60 wt. % of hemp fiber. 
     
     
         6 . The composite material of  claim 2 , wherein the hemp fibers were chemically treated with an alkalization process. 
     
     
         7 . The composite material of  claim 2 , wherein the hemp fibers have the properties of hemp fibers that were chemically treated with an alkalization process. 
     
     
         8 . The composite material of  claim 2 , wherein the hemp fibers have a fiber orientation are arranged predominantly in a length direction with approximately a 20% cross directional orientation. 
     
     
         9 . The composite material of  claim 2 , wherein the composite material has a tensile strength of greater than 40 MPa. 
     
     
         10 . A method of producing a composite material, comprising:
 forming a hybrid yarn from hemp fibers and a polymeric fiber;   braiding the hybrid yarn to form a braided hybrid yarn;   pultruding the braided hybrid yarn with a high density polyethylene resin.   
     
     
         11 . The method of  claim 10 , wherein high density polyethylene resin is produced from recycled high density polyethylene. 
     
     
         12 . The method of  claim 10 , wherein the braided hybrid yarn is in a tubular shape and the method comprises cutting the braided hybrid yarn open to form an open cut braid and consolidating the hemp and polymeric fibers. 
     
     
         13 . The method of  claim 10 , wherein the polymeric fiber is a synthetic fiber 
     
     
         14 . The method of  claim 13 , wherein the polymeric fiber is a polyester or a polylactic acid. 
     
     
         15 . The method of  claim 10 , wherein the ratio of hemp fibers to polymeric fibers is in the range of about 10:1 to about 1:100. 
     
     
         16 . The method of  claim 10 , wherein the ratio of hemp fibers to polymeric fibers is in the range of 1:5 and 1:20. 
     
     
         17 . A method of producing a composite material, comprising:
 placing a hemp fibers on a vacuum assisted resin transfer mold;   covering the vacuum assisted resin transfer mold with a bag;   heating recycled high density polyethylene into a semi-liquid state above the glass transitional temperature for the recycled high density polyethylene; and   drawing the recycled high density polyethylene into the vacuum assisted resin transfer mold by a vacuum.   
     
     
         18 . The method of  claim 17 , wherein the hemp fibers are in the form of bundles of fiber bands, bands of rovings, mats woven from of single hemp fibers or woven mats made of fiber rovings.