Epoxidized soybean oil (ESO) was incorporated into poly(lactic acid) (PLA) to formulate fully biobased and highly tough ESO/PLA blends by using tannic acid (TA) as a green vulcanizing agent. The ...crosslinking degree of ESO molecules and the interfacial compatibility between the ESO phase and PLA matrix were thus improved. The properties of the TA-ESO phase and its interfacial adhesion with PLA matrix were tailored by changing the molar ratio of TA to ESO, which significantly influenced the crystallization behavior, mechanical properties, thermal stabilities, and morphologies of the TA-ESO/PLA blends. After the incorporation of 10 wt% TA-ESO (based on the final blend) with a ‒OH groups to epoxy rings molar ratio of 0.8 into PLA system, the elongation at break (242%) and tensile toughness (57.4 MJ/m3) of the resulting PLA blend were 7 and 4 times higher than those of the blend with 10 wt% ESO, respectively. Compared to the 10 wt% ESO/PLA blend, the glass transition temperatures and thermal stabilities of the TA-ESO/PLA blends were slightly enhanced due to the increased crosslinking density of the TA-ESO phase; however, a slightly decreased crystallinity was observed for PLA after the addition of TA into ESO phase.
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•Fully biobased and highly tough PLA blend was formulated via dynamic vulcanization.•Tannic acid was used as a green crosslinker for ESO to form rubbery phase within PLA.•Added TA increased crosslinking density of ESO phase and its compatibility with PLA.•The properties of blends were tailored by changing ‒OH/epoxy molar ratio in TA-ESO.
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•Simplest & ultrafast microwave assisted solid-state construction of S1-CF@PC from cellulose.•Surface vulcanization, larger BET, O vacancy & pyrrole N in materials with ...microwave.•4-NP complete removal in 10 min over S1-CF@PC/PMS with rate constant up to 0.564 min−1.•SO4−/OH free radical pathways promotion with well dispersed spinel & metal sulfide.•Non-radical removal pathways acceleration with O vacancies and pyrrole N in S1-CF@PC.
Herein, microwave assisted one-pot solid-state construction method was developed for cellulose carbonization and Co-Fe spinel oxide loading to prepare Co-Fe spinel oxide/porous biochar for highly efficient 4-nitrophenol (4-NP) oxidation degradation through peroxymonosulfate (PMS) activation. With just 3 min domestic microwave heating of a solid mixture of cobalt nitrate, iron nitrate, α-cellulose, ammonium bicarbonate and thiourea, Co-Fe spinel and metal sulfides well dispersed, oxygen vacancies and pyrrole N enriched as well as BET increased porous Sx-CF@PC catalytic materials could be prepared with NH4HCO3 aided chemical blowing and thiourea assisted surface vulcanization. The optimal catalyst S1-CF@PC could achieve 99.0 % 4-NP removal in 10 min with rate constant as high as 0.564 min−1. Well dispersed spinel and metal sulfides could activate PMS to generate more SO4− and OH for 4-NP degradation; Meanwhile, oxygen vacancies and pyrrole nitrogen could promote 1O2 based non-free radical 4-NP degradation pathways. This study provided the simplest microwave assisted solid-state metal oxide/porous biochar construction for energetic organic pollutants degradation.
Inverse vulcanization is a potential route to the use of the large excesses of elemental sulfur, creating high-sulfur-content polymers with many potential applications. The addition of a metal ...diethyldithiocarbamate catalyst was previously found to bring several benefits to inverse vulcanization, making the process more attractive industrially. Herein is reported the establishment and exploration of a library of catalysts for inverse vulcanization. Three ranges of catalysts and up to 32 compounds and their combinations have been investigated. By trialing these alternative catalysts, several tentative deductions about the mechanism have been made. It has been found that stronger nucleophiles give a greater rate enhancement, but with the tradeoff that harder bases may promote hydrogen sulfide byproduct formation. Monomer binding by the cation may be a crucial mechanistic step, and it is possible that the catalysts act as phase transfer agents between the immiscible sulfur and organic phases. Additionally, the versatility of catalytic inverse vulcanization has been demonstrated with several different comonomer families.
Lithium‐sulfur batteries stands out as a promising technology for energy storage owing to a combination of favorable characteristics including a high theoretical gravimetric capacity, energy density, ...inexpensive character, and environmental benignity. Covalent organic frameworks (COFs) are a rapidly developing family of functional nanostructures which combine porosity and crystallinity, and which have been already used in these kinds of batteries to build sulfur electrodes, by embedding sulfur into porous COFs in order to enhance cycle lifetimes. In this contribution, this is taken one step forward and a COF endowed with vinyl groups is used, in order to graft sulfur to the COF skeleton through inverse vulcanization. The main aim of the article is to show the synergistic effect of covalent bonding and physical encapsulation of sulfur in the pores of the COF in order to alleviate the fatal redox shuttling process, to improve the cycling performance, and to provide faster ion diffusion pathways. In addition, it is shown how the material with covalently‐bound S provides better electrochemical performance under demanding and/or changeable charge conditions than a parent analogue material with sulfur physically confined, but without covalent linkage.
COF it up: Synergistic effect of covalent bonding and physical encapsulation of sulfur in the pores of a COF alleviates the fatal redox shuttling process, improves the cycling performance and provides faster ion diffusion pathways in lithium‐sulfur batteries.
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•Eco-friendly millimeter-grade SA/PAAS/PAC (SPP) hydrogel beads were synthesized from simple cationic cross-linking.•SPP beads showed effective adsorption capacity towards ...Pb(II).•In-situ vulcanization was applied to reuse Pb(II) as photocatalyst.•Excellent photocatalytic degradation of Rhodamine-B (RhB) was obtained, compared to other conventional photocatalysts.
In this study, sodium alginate (SA), sodium polyacrylate (PAAS) and powdered activated carbon (PAC) were cross-linked by calcium ions (Ca(II) to form SA/PAAS/PAC (SPP) hydrogel beads. The hydrogel-lead sulfide (SPP-PbS) nanocomposites were successfully synthesized by in-situ vulcanization after the lead ions (Pb(II) adsorption. SPP showed an optimal swelling ratio (600% at the pH value of 5.0) and superior thermal stability (206 °C of heat-resistance index). The adsorption data of Pb(II) was compatible with the Langmuir model, and the maximum adsorption capacity of SPP was 391.65 mg/g after optimizing the mass ratio of SA to PAAS (3:1). The addition of PAC not only enhanced the adsorption capacity and stability, but also promoted photodegradation. The significant dispersive capacity of PAC and PAAS resulted in PbS nanoparticles with particle sizes of around 20 nm. SPP-PbS showed good photocatalysis and reusability. The degradation rate of RhB (200 mL, 10 mg/L) was 94% within 2 h and maintained above 80% after 5 cycles. The treatment efficiency of SPP was more than 80% in actual surface water. The results of quenching experiments and electron spin resonance (ESR) experiments revealed that the superoxide radicals (O2–) and holes (h+) were the main active species in the photocatalytic process.
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•Simulating vulcanization to evaluate S migration during pyrolysis of waste tire.•Vulcanization greatly affects activation energy, products, and S migration route.•Vulcanization ...promotes S retention in char with less S migration into gas.•H2S/CH3SH generate by C-Sx and ·H/·CH3, while COS/SO2 originate from C-Sx with O.
This paper systematically investigated sulfur transformation during pyrolysis of waste tires by simulating vulcanization process. Three formulas with rubbers, carbon black, ZnO, and typical vulcanization accelerators were prepared by vulcanization and compounded process as simulated tires. Stepwise temperature programmed pyrolysis was conducted in thermogravimetric analyzer and fixed bed reactor. Vulcanization promoted the weight loss rate for thermal degradation of vulcanized rubbers at 300–400 °C, but weakened it at 400–500 °C. The addition of vulcanization accelerators made these effects even more pronounced. Accordingly, more pyrolytic oil was obtained at 300–400 °C for vulcanized rubbers which should contribute to the partial destruction of polymer chains by vulcanization. Besides, vulcanized rubbers attained higher proportion of aromatics but less cyclenes than compounded rubbers. Vulcanized rubbers with ethyl ziram accelerator inhibited H2S release, while vulcanized rubbers with N-tert-Butyl-2-benzothiazolesulfenamide inhibited the formation of CH3SH. The detailed sulfur compounds in gas, oil, and solid char were analyzed. Vulcanization seemed to exhibit positive effect on sulfur transformation in pyrolytic products, i.e., higher retention rate in pyrolytic char but lower proportion ratio in gas. Sulfurization promoted the conversion of thiophene sulfur to inorganic sulfur and sulfides found in pyrolytic char was only ZnS.
Based on the rubber vulcanization kinetics equation and the mechanical constitutive model, the effect of vulcanization degree and residual stress on the fabric rubber composites and Ω-shaped fabric ...rubber seal molding are investigated. First, the three-dimensional homogeneous vulcanization constitutive equations of rubber materials are derived, and the thermal conduction and the rubber vulcanization kinetics are simulated by finite element method with UMATHT and UMAT subroutines. Second, the vulcanization kinetics process is analyzed and optimized which is verified by rubber seal formulation vulcanization experiments. Finally, the vulcanization degree and the residual stress of fabric rubber during the vulcanization process are analyzed, which indicates that the maximum residual stress of fabric rubber composite is ten times that of the pure rubber. The investigation on the vulcanization degree and the residual stress distribution during the vulcanization process will provide a theoretical guidance for optimizing the parameters and evaluating the properties of fabric rubber composites.
Low cost and high durability have made Portland cement the most widely‐used building material, but benefits are offset by environmental harm of cement production contributing 8–10% of total ...anthropogenic CO2 gas emissions. High sulfur‐content materials (HSMs) are an alternative that can perform the binding roles as cements with a smaller carbon footprint, and possibly superior chemical, physical, and mechanical properties. Inverse vulcanization of 90 wt% sulfur with 10 wt% canola oil or sunflower oil to yield CanS or SunS, respectively. Notably, these HSMs prepared at temperatures ≤180 °C compared to >1200 °C hours for Portland cement CanS was combined with 5 wt% fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBFS), or metakaolin (MK) to give composites CanS‐FA, CanS‐SF, CanS‐GGBFS, and CanS‐MK, respectively. The analogous protocol with SunS likewise yielded SunS‐FA, SunS‐SF, SunS‐GGBFS, and SunS‐MK. Each of these HSMs exhibit high compressive mechanical strength, low water uptake values, and exceptional resistance to acid‐induced corrosion. All of the composites also exhibit superior compressive strength retention after exposure to acidic solutions, conditions under which Portland cement undergoes dissolution. The polymer cement‐pozzolan composites reported herein may thus serve as greener alternatives to traditional Portland cement in some applications.
•Flower-like ZnS/Zn-Al composites were prepared via in situ vulcanization.•ZnS/Zn-Al exhibits the efficient adsorption-photocatalytic activity for Cr(VI) removal.•Lattice defects of ZnS/Zn-Al enhance ...the transfer and separation of charge carriers.
Flower-like ZnS-modified Zn-Al layered double oxides (ZnS/Zn-Al) were prepared from Zn-Al layered double hydroxides via the in-situ vulcanization of dielectric barrier discharge plasma. The obtained ZnS/Zn-Al composites exhibit the enhanced adsorption-photocatalytic activity for the removal of Cr(VI) in visible light region. The adsorption-photocatalytic performances of ZnS/Zn-Al are greatly affected by the vulcanized time, Cr(VI) concentration, plasma power, inorganic ions, and pH vaules. Langmuir isotherm and second-order model can well describe the adsorption isotherms and kinetics of ZnS/Zn-Al composites. The optimal 2-ZnS/Zn-Al with a Zn/Al molar ratio of 3:1 can remove Cr(VI) (40 mg L−1) of 99.88% within 140 min, and its adsorption capacity is 118.37 mg g−1. After five cycle times, the photocatalytic activity of 2-ZnS/Zn-Al is restrained by long-term irradiation. The lattice defects such as oxygen and sulfur vacancies induced by the nonthermal plasma are favorable for the effect charge transfer and the rapid separation of charge carriers at the junction interface. In addition, the vacant sites of bulk interface are likely to adsorb Cr(VI) ions via the electrostatic attraction.
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