The covalent cross-linking of tire rubbers is prerequisite for acquiring high elasticity and environmental resistance. However, the irreversibility of these chemical cross-links make the recycling of tire rubber products inherently difficult, which is a persistent obstacle encountered in thermosetting polymers. About 150 thousand tons of waste rubbers is scrapped each year in domestic, the bulk of which is incinerated for lowefficiency energy recovery and dumped as landfill, causing serious environmental pollution and resource wastage. This project was developed the three kinds of devulcanized rubber including truck tires, car tires and motor tires by twin-screw extruder. Also, the three kinds of reclaimed rubber will be formulated with virgin rubber and re-cured to evaluate its mechanical properties for conveyor belt application. 1. Completed the continuous devulcanization process of truck tires, car tires and motor tires. Experimental results suggest that the reclaimed rubber of truck tires sol component content is about 6.1%, decrosslinking degree is about 72%; car tires sol component content is about 15.3%, decrosslinking degree is about 79%; motor tires sol component content is about 17.1%, decrosslinking degree is about 84%. TGA analysis for before and after devulcanization of waste tire rubber, indicated the polymer, volatiles and filler content showed not much different between pristine and reclaimed rubber. No increasing volatiles indicated no add other chemical additives or process oil in de-vulcanization process. 2. Evaluated the physical properties of reclaimed rubber according to CNS 2230. Experimental results suggest that the reclaimed rubber of truck tires’s density is about 1.15 Mg/m3, tensile strength is about 9.86 MPa, elongation at break is about 347%, and tensile strength retention rate is about 107% which attain to comply with a CNS 2230 BT type requirements； reclaimed rubber of car tires’s density is about 1.108 Mg/m3, tensile strength is about 6.62 MPa, elongation at break is about 282%, and tensile strength retention rate is about 72% which attain to comply with a CNS 2230 BP type requirements； reclaimed rubber of motor tires’s density is about 1.105 Mg/m3, tensile strength is about 4.12 MPa, elongation at break is about 155%, and tensile strength retention rate is about 48% which attain to comply with a CNS 2230 C1 type requirements. 3. Evaluated the cyclic application of reclaimed rubber for conveyor belt’s cover layer blends and middle layer blends. Experimental results suggest that the 75% reclaimed rubber of truck tires were formulated with 25% virgin rubber. The physical properties of cover layer blends (CVC/DTT-04-25) that the mooney viscosity is 50, density is about 1.173 Mg/m3, tensile strength is 156 kgf/cm2, elongation at break is about 416.3%, tear strength is 46 kgf/cm2, abrasion resistance is 196 mm3, hardness (Shore A) is 61, ozone-resistant deterioration grade is A1, tensile strength retention is about 80%, and elongation retention is about 77%. The physical properties of middle layer blends (CVL/DTT-04-30) that the hardness (Shore A) is 48, density is about 1.189 Mg/m3, tensile strength is 61 kgf/cm2, elongation at break is about 611.8 %, tear strength is 24 kgf/cm2, and rubber adhesion to textile fabrics is about 15 kgf/inch.

waste tire, reclaimed rubber, rubber conveyor belt