Essential Rubber Formulary: Formulas for Practitioners
Authored by a seasoned rubber technologist of four decades, this book gives practical information on compounding techniques, coloring, ingredients, as well as typical rubber testing methods.
TABLE OF CONTENTS Essential Rubber Formulary: Formulas for Practitioners
Chapter 12: Retreading Rubber Compounds and Cements
12.1 Introduction
Tire retreading is a prospective industry. Old tires of cars, trucks, and other transport vehicles are repaired and retreaded with suitable tread compounds to give satisfactory mileage. The components that are used in the retreading industry are tire tread compound (camel back, slab), under tread strips, cushion gum, fractioned cord fabric, and vulcanizing cement. Tire tread compounds are mostly made of natural rubber and styrene-butadiene rubbers with good abrasion and fatigue resistance. The other layers above the carcass of a tire are repaired with cushion gum compound and under tread strips. Cushion compound has less fillers; under tread strips are resilient and the tread has high abrasion resistance. Some often-used formulations in the retreading industry are given below. Some laboratory scale formulations with different doses of accelerators, process oils, and filler loadings are also given for comparative study.
12.2 Tire Tread or Camel Back 1
| Ingredient | phr |
|---|---|
| 100.00 |
| 1.50 |
| 5.00 |
| 0.65 |
| 45.00 |
| 6.00 |
| 3.00 |
| 2.25 |
| Total | 163.40 |
| Note: | |
| Cure for 60 minutes at 153 C in retreading molds. | |
| Tensile strength = 2500 psi; Modulus at 100% elongation = 200 psi; Modulus at 300% elongation = 900 psi; Ultimate elongation = 500%; Shore hardness = 59 A; Rebound resilience = 30%. |
The compound is mixed and extruded in a suitable extruder with a camel back/slab die profile. The accelerator dose is to be monitored as and when required to prevent...
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