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Reinforced cement
| Details |
Inventors: Carney, Thomas E.; Champion, Allan R.; Logullo, Sr., Francis M.;
Assignee: E. I. Du Pont de Nemours and Company (Wilmington, DE)
Primary Examiner: Demers; Arthur P.
Assistant Examiner:
Attorney, Agent or Firm:
Cement product reinforced with p-aramid or acrylic fiber coated with certain sulfonyl azides. |
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DETAILED DESCRIPTION OF THE INVENTION Fiber suitable for cement reinforcement in accordance with the present invention is p-aramid fiber and acrylic fiber.
The term "aramid" is used to designate wholly aromatic polyamides.
Not all aramid fibers are useful in the present invention but only those derived from aromatic polyamides whose chain extending bonds are either coaxial or parallel and oppositely directed.
High strength, high modulus aramid fibers useful in the present invention may be prepared by the processes described in U.
S.
Pat.
Nos.
3,767,756 and 3,869,430.
The fibers are characterized by filament tenacities of at least 18 gpd and moduli of at least 400 gpd.
These fibers will be referred to hereinafter as p-aramid fibers.
Particularly preferred are p-aramid fibers based on poly(p-phenylene terephthalamide) as produced by Du Pont under the trademark Kevlar.
RTM.
.
The acrylic fibers useful in the invention are polyacrylonitrile and copolymers containing at least 85 mol % acrylonitrile.
The above fibers are coated with any of a select group of sulfonyl azides for improved fiber/cement adhesion.
The sulfonyl azides are of the formula.
##STR2## wherein X, Y and Z, which may be the same or different, are selected from the group of hydrogen, carboxyl and hydroxyl, with the proviso that at least one but not all of X, Y and Z is hydrogen, and are applied to the fiber in an amount sufficient to improve the adhesion of the fiber to the cement matrix.
In general it is found that from 1 to 2% of azide coating based on the weight of the fiber produces the desired result.
Typical azide compounds useful in this invention are: p-carboxybenzene sulfonyl azide, m-carboxybenzenesulfonyl azide, p-hydroxybenzenesulfonyl azide, and 3-carboxy-4-hydroxybenzenesulfonyl azide.
The azide coated fibers are incorporated in the cement matrix by conventional techniques, usually in the amount of from 0.
5 to 4 weight percent.
Cements in the present invention include a wide range of hydraulically setting binder materials such as Portland cement, high alumina cement, calcium silicates formed on autoclave treatment of cement and the like
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Molecular Biology 
