1. CE 435 -- Intoduction to Polymers1 Firestone Tires Parag Patel Joshua Pun Cory Robinson

2. CE 435 -- Intoduction to Polymers2 Outline Introduction Tire Production Overview of Tread Separation Problem Legal Matters Conclusion/Questions

3. CE 435 -- Intoduction to Polymers3 Introduction Charles Goodyear 1800 – 1860 –1821: Went into hardware business –1833: Started making rubber goods –1834: Failure in first rubber venture –1837: Eliminated some of the rubber defects –1838: Bought patent from partner –1844: Discovered Vulcanization

4. CE 435 -- Intoduction to Polymers4 Tire Production Statistics: Source: http://www.rubbernews.com/subscriber/charts/global.htmlhttp://www.rubbernews.com/subscriber/charts/global.html

5. CE 435 -- Intoduction to Polymers5 Raw Materials Fabric (steel, polyester, nylon, etc.) Rubber (synthetic, natural, or blends) Reinforcing Chemicals (silica, resins, etc.) Anti-Degradant (Ozonants, paraffin waxes) Adhesion Promoters (brass, cobalt salts) Curatives (cure accelerators, activators, sulfur) Processing Oils (Oils, Tackifiers, Softeners)

6. CE 435 -- Intoduction to Polymers6 Processing & Production Mix Process Oils, Rubber, Reinforcers, Accelerators, & Anti-Degradants Coatings –Fabric –Steel Belt Bead

7. CE 435 -- Intoduction to Polymers7

8. 8 Processing & Production (con’t) Components taken to tire machine for assemble –Inner liner –Ply Fabric (two layers) – possible cause of problem –Apexes –Chafer Strips –Steel Belts –Curing –Inspection

9. CE 435 -- Intoduction to Polymers9

10. 10 Chemistry of Tires - Introduction Overview of Vulcanization Process Description of Brass-on-Wire Adhesion 2 nd Major Issue in Faulty Firestone Tires

11. CE 435 -- Intoduction to Polymers11 Vulcanization Process by which rubber is chemically crosslinked (e.g. disulfides) Makes material stronger, elastic, resistant to solvents, and moderate heat/cold. Rubber is heated in the presence of sulfur and accelerator.

12. CE 435 -- Intoduction to Polymers12 Properties Source Source: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994

13. CE 435 -- Intoduction to Polymers13 Vulcanization (con’t) Heat with and without accelerators –Without –Without: 5 hrs @ 140 o C / 8 phr sulfur –With –With: 1-3 min @ 140 o C / 0.5 phr sulfur Main Considerations: –Size and type of object (thick walled -> longer curing time) –Compound vulcanizabliity and flowability –Type of vulcanization (mould vs. boiler) –Maximum vulcanization temperature of material or system –Removal of article from mould (higher temp, more difficult)

14. CE 435 -- Intoduction to Polymers14 Mechanisms Source Source: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994

15. CE 435 -- Intoduction to Polymers15 Brass-on-Wire Adhesion Process by which brass (CuZn) deposited on steel belts Important for proper metal/rubber adhesion Care must be taken to prevent oxidation of both brass and steel

16. CE 435 -- Intoduction to Polymers16 Brass-on-Wire Adhesion Formation of Copper Sulfide Layer Rubber infiltration into porous CuS layer Prevent ZnS/FeS layers (not porous)

17. CE 435 -- Intoduction to Polymers17 Faulty Tires Brass on Wire coatings must be strictly monitored. Coated/Uncoated wire should be kept in environmentally controlled conditions. Free from particulate matter. Employee accusations of improper handling –Poor quality control –Used oxidized/improperly handled wire

18. CE 435 -- Intoduction to Polymers18 Cause of Problem The Ford Motor Company -size of the Ford Explorer -recommended tire pressure too low Drivers of the Vehicles -improper maintenance of tires -wear and tear

19. CE 435 -- Intoduction to Polymers19 Legal Matters Both Firestone and Ford are in an ongoing battle with the public Bridgestone/Firestone Position -taken the responsibility for faulty design -initiated world wide recall -offered free replacements -still believe blame should not wholly be on them

20. CE 435 -- Intoduction to Polymers20 Legal Matters (con’t) Ford Motors Corporation’s Position -stands by their design of Ford Explorers -changed recommended tire pressure Plaintiff’s Position -continue to file lawsuits -boycott product manufactured by Ford and Firestone

21. CE 435 -- Intoduction to Polymers21 Conclusions & Q/A Firestone liability in poor quality control & tread design Ford maintains 26 psi sufficient, but has changed target to 30-35 psi. Questions