Natural rubber (NR) has a strategic position in the rubber industry due to its excellent properties, but it faces the problem of insufficient output and difficulty in recycling. Here, a high-performance elastomer was prepared by the simple epoxidation modification of bio-based Eucommia ulmoides gum (EUG). For the first time, it was found that epoxidized EUG (EEUG) with an epoxy degree of 12.3%−17.4% no longer crystallized at room temperature but had the ability to strain-induced crystallization (SIC). As a result, its vulcanizates showed excellent tensile strength (17 MPa), toughness (37.8 MJ m −3 ), and elasticity (strain recovery values >97%) without filler reinforcement, which is comparable with vulcanized NR. The SIC of EEUG was studied by synchrotron radiation wide-angle X-ray diffraction (SR-WAXD), and its performance was also compared with NR under the reinforcement of carbon black. In addition, through cross-linking by disulfide bonds, EEUG could be used to prepare highperformance (tensile strength of 10.5 MPa, toughness of 30.7 MJ m −3 ), recyclable green elastomers. This new kind of elastomer can be used as the second natural rubber, which is of great significance to solve the problem of insufficient production and difficult recovery of NR.
Upcycling waste plastics (e.g., polyethylene (PE)) into value‐added carbon products is regarded as a promising approach to address the increasingly serious waste plastic pollution and simultaneously achieve carbon neutrality. However, developing new carbonization technology routes to promote the oxidation of PE at low temperature and construct the stable cross‐linking network remains challenging. Here, a facile carbon‐grown‐on‐carbon strategy is proposed using carbon black (CB) to convert waste PE into core/shell carbon nanoparticles (CN) in high yields at low temperature. The yield of CN remarkably increases when the heating temperature decreases or the dosage of CB increases. The obtained CN displays turbostratic structure and closely aggregated granular morphology with a size of ≈80 nm. It is found that, prior to the oxidation and carbonization of PE, CB forms a 3D network architecture in the PE matrix. More importantly, CB not only catalyzes the partial oxidation of PE to form PE macromolecular radicals and introduce oxygen‐containing groups at low temperature in the early stage, but also favors for the construction of a stable cross‐linking network in the latter stage. This work offers a facile sustainable strategy for chemical upcycling of PE into value‐added carbon products without post‐treatments or usage of metallic catalysts.
At present, the synthesis of body temperature triggering shape memory polymers usually requires elaborate structural design, which limits their wide application. Herein, starting from bio-based Eucommia ulmoides gum (EUG), a series of EUG/silica hybrids (ESHs) are prepared through a facile one-pot process, in which EUG is epoxied and then self-crosslinked with SiO 2 by epoxy ring-open reaction. Varying the amount of H 2 O 2 , the shape memory transition temperature (T trans ) of ESHs is adjusted to 47.4-36.6 °C, which is close to human body temperature (37 °C). Among them, ESH-17 exhibited the best body temperature triggering shape memory ability (T trans = 36.6 °C), which can restore the permanent shape within 60 s at 37 °C with a shape fixity ratio of 99% and shape recovery ratio near 100%. In addition, the shape memory mechanism is discussed and shows some application scenarios of ESHs. The as-produced materials can be used as smart biomaterials such as self-tightening sutures, self-sealing root canal filling materials, and so on.
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