Covalently cross-linked rubbers are indispensable in many important fields due to their unique entropic elasticity. For rubbers cross-linking, the addition of toxic curing agents, release of toxic volatile organic compounds (VOCs), and recycling of waste rubber are three important issues. A combination of green curing chemistry and efficient recycling into commercial polyolefin rubbers is of great importance. Herein, we demonstrate a facile and promising way to incorporate dynamic covalent bonds into ethylene-propylene-diene monomer (EPDM)/carbon black (CB) composites. The epoxy-functionalized EPDM (e-EPDM) was prepared using an in situ epoxidation reaction and then cured with biobased decanedioicacid (DA) through the reactions between the epoxy groups in e-EPDM and the carboxylic groups in DA. Because of the existence of exchangeable β-hydroxyl ester, the covalently cross-linked networks in e-EPDM/CB composites were able to rearrange their topological structure at high temperature, endowing the composites with recycled and reshaped abilities. More importantly, the recycled e-EPDM/CB composites still exhibit outstanding mechanical properties which can meet the needs of practical applications. This strategy may provide an efficient, green, and sustainable way to address the problems brought from rubbers cross-linking.
Elastomers play an irreplaceable role in our society due to their unique properties. Natural rubber is directly obtained from plants and is widely used in tires, shoes, etc. Recently, modified natural rubbers are proposed to expand the application of natural rubber. However, these natural rubbers have a limited variety of molecular structures and may not be able to meet ever-demanding applications. Traditional synthetic elastomers have a variety of molecular structures and their properties are used in various fields, but mainly originate from fossil resources. This review deals with bio-based elastomers, and more specifically natural rubber and bio-based synthetic elastomers. Based on reprocessability, bio-based elastomers can also be divided into bio-based chemically cross-linked ones and thermoplastic ones. Compared to traditional fossil-based elastomers, bio-based ones may alleviate environmental pollution and promote the sustainable development of the elastomer industry. K E Y W O R D Sbio-based elastomers, chemically cross-linked, natural rubber, synthetic rubber INTRODUCTIONElastomers are polymeric materials possessing low modulus and high elasticity, and can rapidly recover their orig-This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Modified soybean oil (MSO) is synthesized from soybean oil (SO) and sulfur, aiming to reduce the double bond quantity of SO and avoid harmful effects on the crosslink density and mechanical properties of rubber. MSO modified with different weight percentages of sulfur is then used to plasticize tire tread rubber (TR). It is found that the crosslink density and modulus of MSO- plasticized rubber are significantly improved compared with that of SO-plasticized TR. MSO modified with 6 wt % sulfur (MSO-6%) exhibits the best plasticization effect on TR, thus, the plasticization effect of MSO-6% on TR was further studied by adjusting its additive content. Thereafter, the Mooney viscosity, Payne effect, mechanical property of different amount of MSO-6% plasticized TR are studied to investigate their plasticization effect. At the same additive content of plasticizer, the plasticization effect of MSO-6% and a commonly used aromatic hydrocarbon plasticizer (AO) is compared to determine the potential application of MSO on tire tread rubber. It is found MSO shows similar plasticization effect on TR compared with AO. More important, the aging resistance property and wear resistance property of MSO-6% plasticized rubber are better than those of AO-plasticized rubber. Therefore, MSO-6% is a promising bio-based plasticizer for tire tread rubber.
One of environmental crises facing the world is due to rubber auto tires destruction pollution. Tires' exploitation in vehicles consumes 6 % of the world's energy and causes 5 % of carbon dioxide emissions; it releases up to 10 % of the microplastic pollution found in oceans.We designed a new rubber nanocomposite self-assembled from hard and soft elastomer matrixes: the polybutadiene with two hydroxy chain ends reacted with 4,4'-diphenylmethane diisocyanate to form segmented polyurethane. This system first undergoes a self-assembly, forming well-defined nanoscale hard domains distributed in the soft matrix. Then, cross-linking between the soft segments was accomplished by a controlled radiation method, resulting in the double network elastomer (DN-E). Remarkably, DN-E exhibited the lowest reported loss factor value at 60 o C. The index of energy dissipation in the rolling tire This article is protected by copyright. All rights reserved. 3 demonstrated a prominent reduction of 72 %, accomplished with 88 % decrease in energy loss, and 85 % less wear loss, as compared with best earlier reported commercial tires. These new double-network materials open a new prospective for design and fabrication of ultralow energy-consumption and strong abrasion-resistance elastomers, which establishes a milestone for the development of the next generation of green low pollution tires causing much less energy dissipation.
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