Structural polymer insert and method of making the same

Abstract

A structural polymer insert. The insert includes a substrate having a surface and an adhesive with the substrate being an admixture of a polypropylene component and a glass fiber component. The surface has a plurality of oxygen atoms, optionally introduced by air plasma, in an amount of 1 to 60 atomic percent of all the atoms present on the surface. The foam adhesive is attached to the surface through one or more reactive moieties resulted from oxidative action of the oxygen atoms.

1 . (canceled) 
     
     
         2 . A method, comprising:
 air-plasma treating a surface of a polymer substrate including 10-50 weight percent glass fibers, the air-plasma treatment exposing a plurality of glass fibers from beneath the surface and forming reactive moieties on the surface; and   applying an adhesive to the surface to form a plurality of chemical bonds between the adhesive and the reactive moieties and a plurality of mechanical bonds between the adhesive and the plurality of exposed glass fibers.   
     
     
         3 . The method of  claim 2 , wherein the adhesive is an expandable foam adhesive. 
     
     
         4 . The method of  claim 2 , wherein the air-plasma treatment deposits oxygen atoms on the surface such that the surface includes 10 to 50 atomic percent oxygen after the air-plasma treatment. 
     
     
         5 . The method of  claim 2 , wherein the air-plasma treatment deposits nitrogen atoms on the surface such that the surface includes 0.1 to 10 atomic percent nitrogen after the air-plasma treatment. 
     
     
         6 . The method of  claim 2 , wherein the air-plasma treatment deposits silicon atoms on the surface such that the surface includes up to 5 atomic percent silicon after the air-plasma treatment. 
     
     
         7 . The method of  claim 2 , wherein the air-plasma treatment deposits oxygen and nitrogen atoms on the surface such that the surface includes an oxygen-to-nitrogen atomic ratio of 5.0 to 12.0. 
     
     
         8 . The method of  claim 2 , wherein the polymer substrate includes glass fibers having a mean fiber length of at least 2 mm. 
     
     
         9 . The method of  claim 2 , wherein the air-plasma treatment exposes the plurality of glass fibers from up to 80 μm beneath the surface. 
     
     
         10 . The method of  claim 2 , wherein the polymer substrate includes about 30 weight percent glass fibers and the glass fibers have a mean fiber length of about 3 mm. 
     
     
         11 . The method of  claim 2 , wherein the polymer substrate is polypropylene. 
     
     
         12 . The method of  claim 2 , wherein the reactive moieties include one or more of hydroxyl, ether, ketone and carboxyl moieties. 
     
     
         13 . A method, comprising:
 air-plasma treating a surface of a polymer substrate including glass fibers having a mean fiber length of at least 2 mm, the air-plasma treatment exposing a plurality of glass fibers from beneath the surface and forming reactive moieties on the surface; and   applying an adhesive to the surface to form chemical bonds between the adhesive and the reactive moieties and mechanical bonds between the adhesive and the plurality of exposed glass fibers.   
     
     
         14 . The method of  claim 13 , wherein the air-plasma treatment deposits oxygen, nitrogen, and silicon atoms on the surface such that the surface includes 10 to 50 atomic percent oxygen, 0.1 to 10 atomic percent nitrogen, and up to 5 atomic percent silicon after the air-plasma treatment. 
     
     
         15 . The method of  claim 13 , wherein the polymer substrate includes 10-50 weight percent glass fibers. 
     
     
         16 . The method of  claim 13 , wherein the air-plasma treatment deposits oxygen and nitrogen atoms on the surface such that the surface includes an oxygen-to-nitrogen atomic ratio of 5.0 to 12.0. 
     
     
         17 . The method of  claim 13 , wherein the polymer substrate is polypropylene. 
     
     
         18 . The method of  claim 13 , wherein the adhesive is an expandable foam adhesive. 
     
     
         19 . A method, comprising:
 air-plasma treating a surface of a polypropylene substrate including glass fibers, the air-plasma treatment exposing a plurality of glass fibers from beneath the surface and forming reactive moieties on the surface; and   applying a foam adhesive to the surface to form a plurality of chemical bonds between the foam adhesive and the reactive moieties and a plurality of mechanical bonds between the foam adhesive and the plurality of exposed glass fibers.   
     
     
         20 . The method of  claim 19 , wherein the foam adhesive has a volume expansion of 150 to 450 percent. 
     
     
         21 . The method of  claim 19 , wherein the polypropylene substrate includes 10-50 weight percent glass fibers, the glass fibers have a mean fiber length of at least 2 mm, and the air-plasma treatment deposits oxygen, nitrogen, and silicon atoms on the surface such that the surface includes 10 to 50 atomic percent oxygen, 0.1 to 10 atomic percent nitrogen, and up to 5 atomic percent silicon after the air-plasma treatment.