الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Ground tire rubber (GRT) poses an interesting environmental, economical, and removal problem in the world because of their crosslinked three-dimensional network structure. Rubber devulcanization is a process in which the row rubber or vulcanized waste product was changed, utilizing mechanical, thermal, or chemical energy, into the state in which it can be mixed, processed, and vulcanized again. In mechanochemical devulcanization of rubber that keeps the macromolecules of waste rubber, reduces the sulfur passive for later revulcanization, is cost effective, environmentally friendly and yields high quality devulcanized rubber to substitute virgin rubber.
(1) In this setting mechanochemical devulcanization yields high quality devulcanized rubber to substitute virgin rubber, nitrile butadiene rubber (NBR). The degree of recovery of devulcanized waste rubber (DWR) was determined by describing soluble (sol) and gel fractions utilizing soxhlet extraction through toluene. In general, the lower the gel content the more proficient the devulcanization process. In view of the counted results, table (1), the best devulcanization yield, sol fraction 20 % and gel fraction 80 %, has been chosen to serve the DWR blend fraction. The results show that the crosslinked structure of waste rubber (WR) was damaged through pan-milling, which made the soluble fractions of the sample improve.
(2) Regarding the studied system NBR/DWR, the greatest reported tensile value for DWR ratio 30 % irradiated with 150 KGy reflect the completion of the induced-radiation crosslinking network. 10 wt% DWR load enhanced hardness properties from 24 to 31%, by further increase in DWR ratio up to 40 wt% hardness reached nearly 41%. For all DWR contents, the hardness improved
(3) At temperature mass loss 75% (Tml 75%), the decomposition temperature of the virgin NBR improved gradually with DWR content, from 495.6 oC to 546.9 oC. For all Tml percent’s of composition 70/30, thermal stability slightly improved with dose. Swelling % reduced with raising DWR content and recorded the least value of motor oil resistance as DWR ratio reached 40%.
(4) The impact of the introducing of ATH into the NBR/DWR system on the behavior of the blend was investigated. Only 20 phr ATH shown optimum mechanical, thermal, physical, and oil absorbance properties of the NBR/DWR blend. The mechanical parameters of the unirradiated blends, tensile strength, hardness and elongation at break, increased as ATH concentration increases. Also flame retardant properties increase with increasing ATH concentration.
(5) The introducing of ATH improves the thermal stability as indicated by increase in temperature mass loss 75% (Tml 75%) from 546.9 oC for blend up to 563.2 oC at 20 phr ATH for the unirradiated composite, up to 597.2 oC for the irradiated one, at 50 kGy.
(6) The utmost LOI value, 22, reported for the modified blend with 20 phr ATH irradiated with 150 KGy fulfills the safe value for use in building constructions. The pristine blend swells in motor and brake oils while the trend weakens as the ATH ratio rises in the matrix.
(7) The impact of the incorporation of short glass fibers (GF) into the NBR/DWR system on the behavior of the blend was studied. 30 phr GF revealed optimum mechanical, thermal, physical, and oil absorbance properties of the NBR/DWR blend. The mechanical parameters of the unirradiated blends, tensile strength, hardness elongation at break, and modulus increased as GF concentration increases.
(8) The incorporation of GF improves the thermal stability as indicated by increase in temperature mass loss 75 % (Tml 75%) from 546.9 oC for blend up to more than 600 oC at 30 phr GF for the unirradiated composite.
(9) Under irradiation conditions, tensile improved respectively by the loading of fibers with comparatively higher values than that reported under unirradiation conditions indicating radiation-induced crosslinking. Modulus of NBR/DWR, (70/30), wt% reinforced with 30 phr of GF abruptly increases from 1.72 MPa to 10.85 MPa for the unirradiated composite and reached to 31.23 MPa for the irradiated at 200 kGy. Elastic modulus values of all composites improved with radiation dose due to the radiation-induced three-dimensional network within the polymer matrix.
(10) The impact of the incorporation of cement dust (CD) into the NBR/DWR system on the behavior of the blend was studied. 20 phr CD shown optimum mechanical, thermal, physical, and oil absorbance properties of the NBR/DWR blend. The mechanical parameters of the unirradiated blends, tensile strength, hardness elongation at break, and modulus improved as CD concentration increases.
(11) The introducing of CD increases the thermal stability as shown by raise in temperature mass loss 75 % (Tml 75%) from 546.9 oC for blend up to more than 600 oC at 20 phr CD for the unirradiated composite.