Pneumatic tires including short fibers
A pneumatic tire comprising a body, a tread, a pair of bead assemblies disposed in the lower section of the body, where said bead assemblies include a bead core and a bead filler, and a pair of sidewalls, where the bead assemblies and pair of sidewalls include vulcanizated rubber, and where at least one of said bead assemblies, or at least one of said sidewalls, or both said bead assemblies and sidewalls include short fibers.
1. A pneumatic tire comprising:
a body;
a tread;
a pair of bead assemblies disposed in the lower section of the body, where said bead assemblies include a bead core and a bead filler; and
a pair of sidewalls extending radially inwardly from the tread and forming axial side exterior surfaces of the tire, where the bead assemblies and pair of sidewalls include vulcanized rubber, and where said vulcanized rubber composition in said sidewalls forms said axial side exterior surfaces of the tire and includes at least 60 parts by weight carbon black per hundred parts by weight rubber and includes at least 5 parts by weight and less than 10 parts by weight per hundred parts by weight rubber of aramid short fibers in a matrix of said vulcanized rubber.
2. The pneumatic tire of claim 1 , where said short fibers have a length of from about 0.1 to about 8 mm.
3. The pneumatic tire of claim 2 , where said short fibers have a length of from about 0.7 to about 3 mm.
4. The pneumatic tire of claim 2 , where said short fibers have an aspect ratio of length to diameter of from about 10 to about 1,000.
5. The pneumatic tire of claim 1 , where said short fibers are fibrillated.
6. The pneumatic tire of claim 1 , where said fibers are coated with epoxy, phenolic, resorcinol-formaldehyde, polyurethane, silicone, or plasticizer coatings.
7. The pneumatic tire of claim 1 , where said sidewalls include an antioxidant, an antiozonant, or both an antioxidant and antiozonant.
8. The pneumatic tire of claim 1 , where said sidewall is characterized by a Shore A hardness per ASTM-D2240 of less than 70.
9. The pneumatic tire of claim 1 , where said sidewall is characterized by a Shore A hardness per ASTM-D2240 of less than 65.
10. The pneumatic tire of claim 1 , where said sidewalls are characterized by a stress at 100% strain per ASTM-D412 of less than 8 MPa.
11. The pneumatic tire of claim 1 , where said sidewalls are characterized by a stress at 100% strain per ASTM-D412 of less than 7 MPa.
12. The pneumatic tire of claim 1 , where said aramid fibers are selected from the group consisting of poly(p-phenylene terephthalamide) fibers, poly(m-phenylene isophthalamide) fibers, and mixtures thereof.