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Over the decades, ZnO has been the primary cure activator in the sulfur vulcanization of rubber, but due to its environmental impact on aquatic ecosystems, its use in rubber ...formulation must be reconsidered. This study explores the effects of MgO, known for its low toxicity, as a cure activator, either alone or in combination with ZnO, in carbon black-filled various vulcanization systems such as efficient, semi-efficient, and conventional vulcanization (EV, SEV, and CV). Curing, mechanical, and aging resistance properties were thoroughly examined. Curing studies indicate that incorporating MgO into binary cure activator systems significantly accelerates vulcanization. In the SEV vulcanization system, ZnO/MgO binary cure activators, with a 1:2 ratio totaling 3 phr (per hundred grams of rubber), exhibit a comparable tensile modulus at 100% elongation, along with higher tensile strength, elongation at break, and improved aging resistance compared to conventional ZnO as a sole cure activator. Notably, in ZnO-free compounds, MgO as a single cure activator demonstrates superior tensile strength, elongation at break, and excellent aging resistance. In conclusion, this study suggests that the usage of ZnO can be optimized in rubber vulcanization by considering the desired mechanical properties along with improved aging resistance performances.
The vulcanization process is widely used in industry for tire manufacturing. Therefore, zinc oxide is commonly utilized as an activator material, but unreacted zinc oxide remains in the final ...products and can be released into the environment with a significant impact. To reduce the amount of required zinc and to prevent leaching from tire material, zinc single site‐containing silica fillers are interesting candidates. In these materials, zinc sites are anchored on the surface of silica nanoparticles through their complexation with functionalized aminosilanes. Based on these, a novel powder sample is prepared via spray‐drying. The obtained supraparticles allow for a homogeneous distribution of the filler nanoparticles in the rubber matrix via their disintegration during the incorporation process. All synthesis steps are carried out in ethanol and water, respectively, at very mild temperatures to account for sustainability demands. As core of this study, the role of zinc ions and their amino‐complexation in nanoparticle dispersion stability and in supraparticle formation during spray‐drying is elucidated. Additionally, the superior performance of supraparticles as activator in rubber vulcanization is demonstrated. These show a higher curing efficiency, leading to lower curing time (−70%), higher torque values (+15%), and improved dynamic mechanical properties compared to the conventional ZnO activator.
In this study, the role of the zinc ions and their amino‐complexation in nanoparticle dispersion stability as well as in the obtained supraparticle morphology upon spray‐drying‐assisted assembly is elucidated. Additionally, the superior performance of such zinc single site‐containing silica supraparticles that are synthesized in an environmentally friendly, scalable manner, is demonstrated as activators in rubber vulcanization.
The discovery of inverse vulcanization has allowed stable polymers to be made from elemental sulfur, an unwanted by-product of the petrochemicals industry. However, further development of both the ...chemistry and applications is handicapped by the restricted choice of cross-linkers and the elevated temperatures required for polymerisation. Here we report the catalysis of inverse vulcanization reactions. This catalytic method is effective for a wide range of crosslinkers reduces the required reaction temperature and reaction time, prevents harmful H
S production, increases yield, improves properties, and allows crosslinkers that would be otherwise unreactive to be used. Thus, inverse vulcanization becomes more widely applicable, efficient, eco-friendly and productive than the previous routes, not only broadening the fundamental chemistry itself, but also opening the door for the industrialization and broad application of these fascinating materials.
A series of polyethylene (HDPE)/methyl vinyl silicone rubber (MVQ) TPVs was prepared by dynamic vulcanization technology with excellent tensile strength, low-temperature impact resistance and shape ...memory properties. This is the first paper to investigate the low-temperature impact resistance and shape memory properties of HDPE/MVQ TPVs.
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•A series of polyethylene (HDPE)/methyl vinyl silicone rubber (MVQ) TPVs was prepared by dynamic vulcanization technology.•These TPVs showed excellent tensile strength, low-temperature impact resistance and shape memory properties.•This is the first paper to investigate the low-temperature impact resistance and shape memory properties of HDPE/MVQ TPVs.•Especially, these TPVs showed excellent shape memory properties when the blending ratio of HDPE/MVQ was 60/40.•These TPVs are expected to be used as wrapping wires and cables.
•MoS2 and MoO3 have S-scheme charge transfer.•Interface engineering establishes a fast electron transmission path.•In-situ vulcanization strategy construct a Step-scheme heterojunction.•Sulfur-rich ...surface enhances surface reactions and provides active sites.
As a crucial part of artificial photosynthesis, the design of the catalyst is important essential. Among them, the interface engineering between semiconductors and the construction of surface-active sites play a vital role in generating and transporting light-excited electrons, which can ultimately accelerate water decomposition. Therefore, the MoS2@MoO3 step (S)-scheme heterojunction photocatalyst was prepared by in-situ partial sulfidation. The excellent interface engineering of MoS2@MoO3 nanomaterials achieves a high surface reaction rate. The in-situ vulcanization strategy gradually corrodes from the outside to the inside. The introduction of sulfur atoms can replace oxygen atoms to build a sulfur-rich surface and generate molybdenum sulfide. The amount of thioacetamide is adjusted to control vulcanization and optimizing the experimental conditions, the best hydrogen production rate is 12416.8 µmol h−1 g−1. An in-situ irradiation XPS experiments and DFT calculations provide a deeper understanding of the S-scheme electron transport mechanism in MoS2@MoO3. MoS2@MoO3 interface interaction has penetrating electron channels and a strong interface interaction force, which effectively promotes the charge transfer between interfaces. This gradual surface vulcanization strategy provides new ideas for introducing synergistic surface-active sites and optimizing interface engineering photocatalyst projects.
Inverse vulcanization is a copolymerization of elemental sulfur and alkenes that provides unique materials with high sulfur content (typically ≥50% sulfur by mass). These polymers contain a dynamic ...and reactive polysulfide network that creates many opportunities for processing, assembly, and repair that are not possible with traditional plastics, rubbers and thermosets. In this study, we demonstrate that two surfaces of these sulfur polymers can be chemically joined at room temperature through a phosphine or amine-catalyzed exchange of the S-S bonds in the polymer. When the nucleophile is pyridine or triethylamine, we show that S-S metathesis only occurs at room temperature for a sulfur rank > 2-an important discovery for the design of polymers made by inverse vulcanization. This mechanistic understanding of the S-S metathesis was further supported with small molecule crossover experiments in addition to computational studies. Applications of this chemistry in latent adhesives, additive manufacturing, polymer repair, and recycling are also presented.
Polymers made by inverse vulcanization can be assembled, repaired, and recycled at room temperature through nucleophile-catalyzed S-S metathesis.
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•P(sulfur-r-urushiol) with adaptable networks created from natural urushiol and sulfur.•Superb self-repairability and S-S exchange dynamics/kinetics revealed by ...rheology.•Self-healable adhesives with an excellent adhesion strength ∼ 3.0 MPa demonstrated.•Good hydrophobicity and antimicrobial activity against S.aureus and S.cerevisiae.
The growing cost of petroleum derivatives and the increasingly stringent environmental regulations have led the adhesive industry to re-seek solutions from natural resources in the past decades. However, most currently available natural adhesives (e.g. polysaccharides) are conflicted with low performances such as weak adhesion and easy microbial degradation, etc. On the other hand, owning self-repairability has become a popular way for a new material to extend its lifetime, to reduce its environmental footprint, and to meet the increasing demands of smart functions. This is also true to adhesive industry with self-repairable adhesive highly desirable.
In this work, plant resourced urushiol and industrial waste of elemental sulfur (S) was used to prepare sulfur-urushiol copolymers (IVurux) as a high-strength, self-repairable and antimicrobial adhesive through inverse vulcanization, a facile and green approach free of solvent and catalyst. The polymerization between unsaturated bonds of urushiol and sulfur in forming a reversibly crosslinked network with polysulfide segments has been verified by FTIR and 1H NMR analysis. The adaptable covalent S-S bonds from polysulfide segments endow the copolymer networks with a distinct self-healing property, while the rich catechol groups from urushiol moiety guarantee the material with an outstanding adhesive property.
The adaptable covalent networking was well validated by a distinct rubbery plateau in rheological measurements of both temperature ramping test and frequency sweep test. The crosslinking density was revealed to increase with sulfur content, with frequency scaling exponent of G’ in the plateau regime varying from G’∼ω0.27 in IVuru70 (S content 30 wt%) to G’∼ω0 in IVuru50 (S 50 wt%) and IVuru40 (S 60 wt%), while when S >60 wt% few unreacted sulfur presented in the product as indicated from XRD and DSC analysis. Moreover, the self-healing property was well demonstrated in a repeated breaking-healing cycle test with 92.7% recovery obtained after 4 breaking cycles for IVuru50, and the dynamic S-S bond exchange was studied by stress relaxation to be temperature dependent with an activation energy of metathesis ∼100 kJ/mol. Furthermore, the P(sulfur-r-urushiol)s were examined to exhibit a considerable adhesion strength ∼3.0 MPa, about 6 times of a commercial hide glue, with IVuru60 being the best as a balanced contribution between catechol groups and covalent networking for adhesive and cohesive bonding. Meanwhile, a very good self-repairability of the adhesive was demonstrated with heating being the trigger for S-S metathesis. Ultimately, the P(sulfur-r-urushiol) copolymers were found to be hydrophobic with a contact angle ∼ 85° and have an excellent antimicrobial activity against S. aureus and S. cerevisiae with a high inhibition efficiency >80% and >52%, respectively. Such a high-strength, self-repairable and antimicrobial adhesive material foresees promising applications in broad fields in light of its advantages of fabrication simplicity, environmentally friendliness and good durability.
In the present study, a new polythiophene derivative bearing an acryloyloxy moiety in the side chain as a functional co-monomer, poly (3-(2-acryloyloxy) methyl) thiophene (PAMT), was synthesized to ...be used for the inverse vulcanization method with elemental sulfur (S8). Highly sulfur-rich graft materials, S- poly (3-(2-acryloyloxy) methyl) thiophenes (52 and 74%) (S-PAMT), were prepared by inverse vulcanization of PAMT with different feed ratios of molten sulfur. Their structural characterizations were carried out by using appropriate standard spectroscopic methods such as FT-IR, DSC, TGA, SEM as well as XPS. The electrochemical performance of S-PAMT (74%) as a Li–S battery cathode material was evaluated. It was found that the fabricated cells delivered around 400 mAh·g−1 stable capacity at a C/5 current density over 100 cycles. Electrochemical impedance spectroscopy (EIS) was also performed before and after cycling to further investigate the lithium storage mechanism of S-PAMT (74%).
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•A new polythiophene derivative bearing an acryloyloxy moiety in the side chain as a functional co-monomer was synthesized.•Highly sulfur-rich polymeric cathode materials were prepared by inverse vulcanization.•The electrochemical performance of a polymeric cathode material as a Li–S battery cathode material was evaluated.
An insulating composite was made from the sustainable building blocks wool, sulfur, and canola oil. In the first stage of the synthesis, inverse vulcanization was used to make a polysulfide polymer ...from the canola oil triglyceride and sulfur. This polymerization benefits from complete atom economy. In the second stage, the powdered polymer was mixed with wool, coating the fibers through electrostatic attraction. The polymer and wool mixture were then compressed with mild heating to provoke S−S metathesis in the polymer, which locks the wool in the polymer matrix. The wool fibers imparted tensile strength, insulating properties, and reduced the flammability of the composite. All building blocks are sustainable or derived from waste and the composite is a promising lead on next‐generation insulation for energy conservation.
Three for one: Sulfur, canola oil, and wool are used to make a sustainable composite useful as energy‐saving insulation. The wool imparts improved mechanical properties and reduced flammability. All building blocks are sustainable or derived from waste.
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