Influence of number of catalyst sites in 1,3‐butadiene solution polymerizations catalyzed by titanium tetrachloride

Farias, Francisco R. L.; Vasconcelos, Mateus; Brandão, Amanda L. T.

doi:10.1002/eng2.12333

“…Butadiene rubber (BR) is an important synthetic elastomer based on high content cis-1,4 polybutadiene, and the carbon backbone also possesses double bond [24] like HTPB. In fact, HTPB is derived from chain cleavage of BR9000 [25].…”

Section: Fabrication Of the Control Samplesmentioning

confidence: 99%

Injection moldable, self-healable, and recyclable rubber-bonded NdFeB magnets with the magnetic particulates content up to 90 wt%

Cao

¹

,

Zhu

²

,

Rong

³

et al. 2023

Adv Compos Hybrid Mater

3

0

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To apply the facile injection molding technique commonly used in thermoplastics processing to rubber-bonded magnets, typical highly filled thermosetting composites, an approach based on Diels-Alder (DA) chemistry is proposed by the authors. In the proof-of-concept experiments, the oligomers of hydroxyl-terminated polybutadiene rubber are successively functionalized by furyl and trifluoromethyl, and the magnetic NdFeB particles are modified by maleimide. By taking advantage of reversible DA reaction, crosslinkages are established among the treated polybutadiene oligomers and NdFeB particles. The composite exhibits very low viscosity due to de-crosslinking when heated to retro-DA reaction temperature, which provides the highly filled system with necessary thermal processibility. In addition, the fluorine groups of the rubber phase are aggregated surrounding the particulate fillers allowing for well separation of the latter in the melt state. During the subsequent cooling, the DA bonds are re-built up in the rubber and at the particles/rubber interface, respectively, offering the robustness of traditional thermosets. As a result, the polybutadiene-bonded magnets with NdFeB content up to 90 wt% can be injection molded and possess rather high magnetic properties, mechanical properties, self-healability and recyclability. The present work combines the merits of thermoplastics and thermosets, and satisfies the contradictory requirements of high filling, efficient manufacturing and balanced performance of functional polymer composites.

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“…Therefore, a significant number of studies have been carried out from the discovery of Ziegler–Natta catalytic systems, which were aimed at increasing the activity and stereospecificity of these catalytic systems by modifying their structure. As a result, catalytic systems, which are complexes of titanium, nickel, cobalt, and neodymium, were selected for the synthesis of polybutadiene. ,,− Among this series of catalytic systems, neodymium-based catalytic systems stand out favorably. They are used in industry in the synthesis of polybutadiene and polyisoprene due to their excellent stereospecificity and high activity. − Neodymium catalytic systems make it possible to obtain polybutadiene containing cis -1,4-butadiene units (up to 98%) .…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Mechanism of Polybutadiene Synthesis in the Presence of the Neodymium Versatate + Diisobutylaluminum Hydride + Ethylaluminum Sesquichloride Catalytic System within the Solution of the Inverse Kinetic Problem

Tereshchenko

¹

,

Ulitin

²

,

Bedrina

³

et al. 2022

Ind. Eng. Chem. Res.

0

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A kinetic model is proposed for polybutadiene synthesis in the presence of the neodymium versatate + diisobutylaluminum hydride + ethylaluminum sesquichloride (NdV + DIBAH + EASC) catalytic system. As a result of solving the inverse kinetic problem, the rate coefficients of reactions were determined. At a quantitative level, it has been shown that polybutadiene synthesis in the presence of the NdV + DIBAH + EASC catalytic system can run according to the scheme, which includes only the chain propagation, chain termination, chain transfer to butadiene, and DIBAH. This fact testifies against the need to involve the reactions of the coordinative chain transfer polymerization mechanism to describe the kinetic regularities of the process in question. Based on the bimodal form of the experimental molar mass distributions of polybutadiene, it was taken into account in the proposed kinetic model that all reactions run on active sites of two types. As a result of the calculation of the characteristic times of chain limitation (in which the chain limitation is a sum of chain termination and transfer rates) on active sites of the first and second types, it was shown that the active sites of the first type are the active sites of classical coordination polymerization (the characteristic time of chain limitation is 3.35 × 10 1 −8.82 × 10 1 s) and on active sites of the second type, living chain propagation runs. This is due to the fact that the characteristic chain limitation time for active sites of the second type is 9.09 × 10 3 to 1.35 × 10 5 s, which is comparable to the time of polybutadiene synthesis until a high butadiene conversion is reached (1.00 × 10 4 s).

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Injection moldable, self-healable and recyclable rubber-bonded NdFeB magnets with the magnetic particulates content up to 90 wt%

Chen

¹

,

Zhu

²

,

Rong

³

et al. 2022

Preprint

0

View full text Add to dashboard Cite

To apply the facile injection molding technique commonly used in thermoplastics processing to rubber-bonded magnets, typical highly filled thermosetting composites, an approach based on Diels-Alder (DA) chemistry is proposed by the authors. In the proof-of-concept experiments, the oligomers of hydroxyl-terminated polybutadiene rubber are successively functionalized by furyl and trifluoromethyl, and the magnetic NdFeB particles are modified by maleimide. By taking advantage of reversible DA reaction, crosslinkages are established among the treated polybutadiene oligomers and NdFeB particles. The composite exhibits very low viscosity due to de-crosslinking when heated to retro-DA reaction temperature, which provides the highly filled system with necessary thermal processibility. In addition, the fluorine groups of the rubber phase are aggregated surrounding the particulate fillers allowing for well separation of the latter in the melt state. During the subsequent cooling, the DA bonds are re-built up in the rubber and at the particles/rubber interface, respectively, offering the robustness of traditional thermosets. As a result, the polybutadiene-bonded magnets with NdFeB content up to 90 wt% can be injection molded and possess rather high magnetic properties, mechanical properties, self-healability and recyclability. The present work combines the merits of thermoplastics and thermosets, and satisfies the contradictory requirements of high filling, efficient manufacturing and balanced performance of functional polymer composites.

show abstract

Influence of number of catalyst sites in 1,3‐butadiene solution polymerizations catalyzed by titanium tetrachloride

Cited by 3 publications

References 22 publications

Injection moldable, self-healable, and recyclable rubber-bonded NdFeB magnets with the magnetic particulates content up to 90 wt%

Injection moldable, self-healable, and recyclable rubber-bonded NdFeB magnets with the magnetic particulates content up to 90 wt%

Analysis of the Mechanism of Polybutadiene Synthesis in the Presence of the Neodymium Versatate + Diisobutylaluminum Hydride + Ethylaluminum Sesquichloride Catalytic System within the Solution of the Inverse Kinetic Problem

Injection moldable, self-healable and recyclable rubber-bonded NdFeB magnets with the magnetic particulates content up to 90 wt%

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