Method of making composites having improved surface properties
AssigneeE. I. Du Pont de Nemours and Company
InventorsWilliam M. Sanford, William C. Uy
Life of this patent
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Abstract
Polymeric composite materials having a decreasing concentration gradient of polymer matrix from the material's surface to the material's interior. The composite is produced by a process whereby polymer matrix is extracted from the interior of the material in such a manner that the matrix concentration at the material's surface increases.
Claims28
A process for making a solvent treated oriented, shaped composite article, comprising the following steps:
- a) forming an oriented, shaped composite article from a solution comprising at least about 30% and less than about 80% by weight of a reinforcing polymer phase consisting essentially of at least one lyotropic polymer, and at least about 20% and less than about 70% by weight of a polymer matrix consisting essentially of at least one thermally-consolidatable polymer, said reinforcing polymer phase being continuous in the direction of orientation while interpenetrating said polymer matrix throughout the article;
- b) treating the article with a solvent which dissolves the polymer matrix while not substantially dissolving the reinforcing polymer phase;
- and
- c) removing the solvent, whereby at least some of the polymer matrix is extracted from the interior of the article and the polymer matrix concentration increases at the article's surface.
A process in accordance with any one of the preceding claims, wherein the solvent is selected from the group consisting of sulfuric acid, methanesulfonic acid, formic acid and hexafluoroisopropanol.
A process for making a composite ply, comprising the following steps:
- a) forming oriented, shaped composite articles comprising at least about 30% and less than about 80% by weight of a reinforcing polymer phase consisting essentially of at least one lyotropic polymer, and at least about 20% and less than about 70% by weight of a polymer matrix consisting essentially of at least one thermally-consolidatable polymer, said reinforcing polymer phase being continuous in the direction of orientation while interpenetrating the polymer matrix throughout said articles;
- b) consolidating the articles into a ply;
- c) treating the ply with a solvent which dissolves the polymer matrix while not substantially dissolving the reinforcing polymer phase;
- and
- d) removing the solvent, whereby at least some of the polymer matrix is extracted from the interior of the ply and the polymer matrix concentration increases at the ply's surface.
A process for extracting polymer matrix from the interior of a polymeric microcomposite material, comprising the following steps:
- a) treating a microcomposite material comprising a polymer matrix and a microfibrillar reinforcing phase with a solvent which dissolves the matrix while not substantially dissolving the reinforcing phase;
- and
- b) removing the solvent, whereby at least some of the polymer matrix is extracted from the interior of the material and the polymer matrix concentration increases at the material's surface.
Dependencies are inferred from the claim text.