Honeycomb core having a high compression strength

Abstract

A method of making a fiber-reinforced composite structure comprising the steps of (i) forming a paper sheet having a Gurley air resistance at least 200 seconds per 100 milliliters, the sheet comprising from 30 to 70 weight percent p-aramid fiber, (ii) depositing on both surfaces of the paper sheet a compression enhancing layer in a quantity up to 5 weight percent based on the weight of the paper, (iii) forming a honeycomb from the sheet of step (ii), and (iv) applying a matrix resin coating to the honeycomb of step (iii).

What is claimed: 
     
         1 . A method of making a fiber-reinforced composite structure comprising the steps of:
 (i) forming a paper sheet having a Gurley air resistance at least 200 seconds per 100 milliliters, the sheet comprising from 30 to 70 weight percent p-aramid fiber,   (ii) depositing on both surfaces of the paper sheet a compression enhancing layer, comprising glycerolpolyglycidylether, polypeptide-carbon nanotube complexes, polypeptide-graphite complexes or combinations thereof, in a quantity up to 5 weight percent based on the weight of the paper,   (iii) forming a honeycomb from the sheet of step (ii), and   (iv) applying a matrix resin coating of phenolic, polyimide, polyetherimide, epoxy or combinations thereof to the honeycomb of step (iii).   
     
     
         2 . The method of  claim 1  wherein the wherein the paper comprises meta-aramid fibrids, para-aramid fibrids or combinations thereof. 
     
     
         3 . The method of  claim 1  wherein the paper density is greater than 0.8 g/cm 3 . 
     
     
         4 . The method of  claim 1  wherein the matrix resin is phenolic and the compression enhancing layer comprises glycerolpolyglycidylether.