HONEYCOMB CORE HAVING A HIGH COMPRESSION STRENGTH
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).
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.