Innovative γ rays irradiated styrene butadiene rubber/reclaimed waste tire rubber blends: a comparative study using mechano-chemical and microwave devulcanizing methods

Abstract

Waste tire rubber was comparatively devulcanized by using two-roll mill mechano-chemical and microwave techniques at room temperature. The former technique was performed utilizing tetramethylthiuram disulfide and mercaptobenzothiazole disulfide. The developed devulcanized elastomer was characterized by scanning electron microscopy, chemical soluble fraction indication, and cross-link density determination. The blend was mixed in two roll mills by replacing a portion of virgin styrene-butadiene rubber (SBR) in a common formulation with the devulcanized waste rubber (DWR) product at various ratios, namely 10, 20 and 50 wt%. The morphological micrographs confirmed marked improvement in compatibility between both rubbery materials. The tensile strength and elastic modulus examinations of the fabricated blends ensured successful substitution of the virgin SBR with DWR. The abrasion resistance of SBR proved unaffected by blending with DWR. The compounded blends were subjected to γ rays at different radiation doses elevated up to 200 kGy and comparatively mechanically investigated.

Thermal aging and automotive oil effects on the performance of electron beam irradiated styrene butadiene rubber/waste and microwave devulcanized rubber blends

“…32 The results show that the longer microwave exposure times lead to lower gel content, meanwhile in case of 7 min the sample was burned. Since the results in the Table 1, it is evident that microwave devulcanization value at time 6 min give the highest devulcanization percent, where soluble fraction equal 36% and this percent is higher than that obtained in the previous published work by El-nemr et al 26 who treated WR using microwave alone and by mechanochemical that recorded 23% for the two types of treatments and also Hassan et al 24,25 who treated WR using mechanochemical devulcanization that recorded 31.4%. Therefore, in this work, the simultaneous effect of spindle oil and TMTD before microwave exposure gave significantly improvement of devulcanization yield.…”

“…23 Present work concentrate to attain the highest percent of WR devulcanized by microwave exposure about which discussed before within the research team work in this field. 3,[24][25][26][27] In the previous study, El-Nemr et al 26 evaluated that, devulcanization of WR was approved via mechanochemical methods using TMTD or MBTS in the presence of spindle oil and microwave irradiation. The best consequences of devulcanization were attained at 1 and 2 phr TMTD and MBTS, respectively.…”

“…In this work, a different technique will be followed about El-Nemr et al 26 Where, the addition of TMTD and spindle oil to WR before exposure of various times of microwave irradiation, may be swells the rubber moieties and increases spacing among the rubber chains which in turn easily ready to react with SBR. After that, both obtained DWR and WR were blended with SBR to compare the best substitutes of each them with virgin SBR.…”

Regeneration and devulcanization

“…This blend was irradiated for 150 s at 1000 W [56]. Gamma rays [57] and dielectric fields [58] are also described for physical devulcanization. For all these radiation devulcanization methods it is not well described whether it is indeed devulcanization rather than regeneration.…”

Low-Temperature Mechano-Chemical Rubber Reclamation Using Terpinene as a Swelling Agent to Enhance Bond-Breaking Selectivity

“…Nowadays, over three billion tires are produced and one billion tires are abandoned around the world every year [1]. Waste tires do not decompose well due to the crosslinking structure of vulcanized rubber with sulfur bonds [2][3][4], and waste tire piles act as breeding grounds for mosquitoes and other insects that spread disease, especially contributing to the spread of diseases such as malaria and dengue fever. The waste tires still have high value and can be reused/recycled through specific techniques to produce many products, such as playgrounds, sports surfaces, rubber-modified asphalt, and even low-performance tires.…”