Grafted para-aramid fiber and method of making
View Patent ↗A method of making a fiber comprised of poly(p-phenylene terephthalamide) having monomer groups grafted onto the fiber surface, the method comprising the steps of (i) providing a fiber of poly(p-phenylene terephthalamide) that has been dried to remove adsorbed moisture, (ii) treating the fiber, in a non-polar solvent that will not dissolve the fiber, with a phosphazene base that exhibits a pKa in dimethylsulfoxide of at least 21 so as to generate anions at the amide sites on the surface of the poly(p-phenylene terephthalamide) fiber, (iii) washing the base-activated fiber with an aprotic solvent, (iv) grafting a monomer onto the anion sites so as to introduce reactive functional groups onto the surface of the poly(p-phenylene terephthalamide) fiber, and (v) washing the grafted fiber of step (iv) with a protic solvent to extract any residual base compounds and grafting agents that are unbound to the surface of the fibers.
1. A method of making a fiber comprised of poly(p-phenylene terephthalamide) having monomer groups grafted onto the fiber surface, the method comprising the steps of:
(i) providing a fiber of poly(p-phenylene terephthalamide) that has been dried to remove adsorbed moisture,
(ii) treating the fiber, in a non-polar solvent that will not dissolve the fiber, with a phosphazene base that exhibits a pKa in dimethylsulfoxide of at least 21 so as to generate anions at the amide sites on the surface of the poly(p-phenylene terephthalamide) fiber, and
(iii) grafting a monomer onto the anion sites so as to introduce reactive functional groups onto the surface of the poly(p-phenylene terephthalamide) fiber.
2. The method of claim 1 wherein the phosphazene base exhibits a pKa in dimethylsulfoxide of at least 30.
3. The method of claim 1 wherein the solvent is toluene or tetrahydrofuran.
4. The method of claim 1 wherein the phosphazene base is an iminophosphorane, phosphazophosphazene, aminophosphazene, guanidinophosphazene, or phosphatrane.
5. The method of claim 1 wherein the phosphazene base is tertiary-butyl-P 4 -phosphazene.
6. The method of claim 1 wherein the monomer is an allyl halide, a substituted benzyl chloride, a substituted N-phenylmaleimide or a substituted epoxy.
7. The method of claim 6 wherein the substituted benzyl chloride is 4-vinylbenzyl chloride or 3-vinylbenzyl chloride, the substituted N-phenymaleimide is N-(4-vinylphenyl)maleimide, and the substituted epoxy is 4,4′-methylene-bis(N,N-diglycidylaniline), epichlorohydrin, or epibromohydrin.
8. A method of making a fiber comprised of poly(p-phenylene terephthalamide) having monomer groups grafted onto the fiber surface, the method comprising the steps of:
(i) providing a fiber of poly(p-phenylene terephthalamide) that has been dried to remove adsorbed moisture,
(ii) treating the fiber, in a non-polar solvent that will not dissolve the fiber, with a phosphazene base that exhibits a pKa in dimethylsulfoxide of at least 21 so as to generate anions at the amide sites on the surface of the poly(p-phenylene terephthalamide) fiber,
(iii) grafting a monomer onto the anion sites so as to introduce reactive functional groups onto the surface of the poly(p-phenylene terephthalamide) fiber, and
(iv) washing the grafted fiber of step (iii) with a protic solvent to extract any residual base compounds and grafting agents that are unbound to the surface of the fibers.
9. A method of making a fiber comprised of poly(p-phenylene terephthalamide) having monomer groups grafted onto the fiber surface, the method comprising the steps of:
(i) providing a fiber of poly(p-phenylene terephthalamide) that has been dried to remove adsorbed moisture,
(ii) treating the fiber, in a non-polar solvent that will not dissolve the fiber, with a phosphazene base that exhibits a pKa in dimethylsulfoxide of at least 21 so as to generate anions at the amide sites on the surface of the poly(p-phenylene terephthalamide) fiber,
(iii) washing the base-activated fiber with an aprotic solvent to eliminate excess base compounds,
(iv) grafting a monomer onto the anion sites so as to introduce reactive functional groups onto the surface of the poly(p-phenylene terephthalamide) fiber, and
(v) washing the grafted fiber of step (iv) with a protic solvent to extract any residual base compounds and grafting agents that are unbound to the surface of the fibers.
10. A continuous filament yarn, cord, spun staple yarn, nonwoven fabric, floc, pulp or chopped strand comprising fiber treated by the method of claim 1 , 8 or 9 .
11. A fiber-reinforced composite comprising fiber treated by the method of claim 1 , 8 or 9 .
12. A fiber-reinforced rubber article comprising fiber treated by the method of claim 1 , 8 or 9 .
13. A dipped cord suitable for use in a rubber compound comprising fiber treated by the method of claim 1 , 8 or 9 coated with a styrene-butadiene-vinylpyridine rubber latex.
14. A fibrous pulp comprising fiber treated by the method of claim 1 , 8 or 9 .