Recycling natural rubber vulcanizates through mechanochemical devulcanization

Abstract

Sulfur-cured gum natural rubber vulcanizates were devulcanized using two different concentrations of diallyl disulfide. The devulcanization process was performed at 110°C for 10 min in an open two-roll cracker-cummixing mill. Natural rubber vulcanizates having various sulfur/accelerator ratios were used to study the cleavage of monosulfide, disulfide, and polysulfide bonds. The properties of devulcanized natural rubber increased upon increasing the disulfide concentration and the mechanical properties of the revulcanized natural rubber increased upon decreasing the sulfur content in the original rubber vulcanizates. The scorch time and the maximum state of cure both increased when the ground vulcanizates were treated with higher amounts of disulfide. TGA and DMA were conducted to study the effects of the devulcanization on the thermal stability and the T g behavior of the vulcanizates. SEM analysis was conducted to study how the failure mechanism was affected by the devulcanization process. It was possible to recover 70-80% of the original gum rubber properties by using this process. From IR spectroscopic analysis, we observed that the oxidation of the main chains did not occur during high-temperature milling.

Physicochemical Properties and Stress-Strain Compression Behaviors of a Waste based Magnetorheological Elastomers

“…Meanwhile, the energy recovery is realized by utilizing waste tire for clinker burning [11] and lique ed fuel through pyrolysis [12]. Direct burning of the waste tire in the world has reached nearly 30% of the total waste [13]. Burning tire for energy recovery poses a serious problem to community health and precipitates environmental degradation (air pollution) due to its toxic gasses, e.g.…”

“…The ground tire is then separated from its textiles and metals using electrostatic and magnetic methods. The pure Ground Tire Rubber (GTR) can further be used as composite material for either virgin rubber ller [13] or civil purposes such as buildings, roads, concrete ller, and pavements. In-building applications of GTRbased composite are focused on sound insulation and absorption and it is realized in the composite board for room partition, particle boards, or oor parquets.…”

“…The 100% vulcanized rubber is classi ed into thermoset materials that are commonly un-recycled. This classi cation is because the fully vulcanized rubber forms three-dimensional cross-linked network structure that contains cyclic and mono-, di-, and poly-sul des linkages [13]. According to Tobolsky et al [66], sul dic bound can easily be sliced by applying high levels of pressure and temperature at the same time.…”

Fire retardancy and environmental assessment of rubbery blends of recycled polymers

“…Utilizing options of waste rubber vulcanizates are incineration, pyrolysis [2,3], gasification [4][5][6], devulcanization (e.g. chemical [7], mechanochemical [8,9], supercritical [10,11], ultrasonic [12,13]), or blending either in thermoset [14][15][16] or in thermoplastic [17][18][19] polymer matrices. In this work we selected the last mentioned option combining it with upgrading that is to transform the rubber waste containing compound to a special flame retardant material.…”

Preparation and characterization of polypropylene/waste ground rubber tire powder microcellular composites by supercritical carbon dioxide

“…11 To improve the impact toughness and extend its application range, a number of studies on toughening PP with rubber have been made in the last 20 years and thoroughly reviewed by Liang and Li. [12][13][14] Recycling of waste ground rubber tire powder is our preference from the ecological and economical point of view. The usage of WGRT as dispersed phase in PP matrix offers an interesting opportunity for recycling of WGRT.…”