Curing reactions in elastomers. II. Carboxy‐terminated polybutadiene

Kishore, K.; Verneker, V. R. Pai; Vasanthakumari, R.

doi:10.1002/app.1983.070280215

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…It is more vulnerable to the attack of a nucleophilic reagent. The process proceeds with further expansion of the molecular chain to form a mesh structure and complete the solidification reaction, as the active H atoms in the t-HTLF attack the C atoms of NCO to produce -NHCOO-via a nucleophilic addition reaction [36,[57][58][59]. The curing reaction mechanism is shown in Figure 11.…”

Section: Curing Reaction Mechanismmentioning

confidence: 99%

Synthesis and Properties of the Novel High-Performance Hydroxyl-Terminated Liquid Fluoroelastomer

Chen

et al. 2023

Polymers

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Functional liquid fluoroelastomers are in high demand in new energy fields. And these materials have potential applications in high-performance sealing materials and as electrode materials. In this study, a novel high-performance hydroxyl-terminated liquid fluoroelastomer (t-HTLF) with a high fluorine content, temperature resistance, and curing efficiency was synthesised from a terpolymer of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), and hexafluoropylene (HFP). A carboxyl-terminated liquid fluoroelastomer (t-CTLF) with controllable molar mass and end-group content was first prepared from a poly(VDF-ter-TFE-ter-HFP) terpolymer using a unique oxidative degradation method. Subsequently, an efficient “one-step” reduction of the carboxyl groups (COOH) in t-CTLF into hydroxyl groups (OH) was achieved via the functional-group conversion method using lithium aluminium hydride (LiAlH4) as the reductant. Thus, t-HTLF with a controllable molar mass and end-group content and highly active end groups was synthesised. Owing to the efficient curing reaction between OH and isocyanate groups (NCO), the cured t-HTLF exhibits good surface properties, thermal properties, and chemical stability. The thermal decomposition temperature (Td) of the cured t-HTLF reaches 334 °C, and it exhibits hydrophobicity. The oxidative degradation, reduction, and curing reaction mechanisms were also determined. The effects of solvent dosage, reaction temperature, reaction time, and ratio of the reductant to the COOH content on the carboxyl conversion were also systematically investigated. An efficient reduction system comprising LiAlH4 can not only achieve an efficient conversion of the COOH groups in t-CTLF to OH groups but also the in situ hydrogenation and addition reactions of residual double bonds (C=C) groups in the chain, such that the thermal stability and terminal activity of the product are improved while maintaining a high fluorine content.

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Section: Curing Reaction Mechanismmentioning

confidence: 99%

Synthesis and Properties of the Novel High-Performance Hydroxyl-Terminated Liquid Fluoroelastomer

Chen

et al. 2023

Polymers

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“…Epoxies being brittle, the presence of these stretchable materials in such a resinous matrix and the resulting combined response has caught the attention of material scientists. Reports of improvement of toughness owing to the presence of HTBN [1][2][3], ATBN [4,5], and CTPB [6][7][8] are available. The primary interest in introducing these elastomers lies in examining their role during deformation and in particular, the part they play, when a crack approaches during its propagation phase.…”

Section: Introductionmentioning

confidence: 99%

Individual and Combined Roles of CTBN and Fly Ash in Epoxy System under Compression: Correlation between Microscopic Features and Mechanical Behavior

Kishore

Santra

2005

Journal of Reinforced Plastics and Composites

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Epoxy containing fillers of either fly ash or poly(acrylonitrile-co-butadiene), carboxy terminated (CTBN) as single reinforcing material in one program and both the filler materials as hybrid reinforcements into the system in the second were cast and the test coupons cut from the cured slabs were subjected to axial compression strength. The filler proportions in the composites were varied with a view to study the effects of differing characteristics bearing filler materials. The nondeforming, oxide bearing ceramic-type fly ash when incorporated into epoxy showed an increase in compressive strength values with fly ash content up to 10% by weight inclusion after which a drop was noticed. In the case of CTBN, the trend of recording a rise was noticed up to 5% by weight. When the two fillers were introduced simultaneously, the maximum in strength was recorded at a composition constituted by equal amounts of both the fillers comprising a total of 5% by weight. The work was extended to microscopic examination where features like morphology of fillers, the role of matrix-filler interface region as well as the part played by the two fillers when they are present as individual reinforcements were examined. Features such as shear deformation, stepped-appearance, crack blunting and elongation of the rubbery phase, crack pinning, and formation of debonds around the fly ash and CTBN were noticed. The work attempts at correlating the mechanical data to microscopic details. Thus, the drop in strength at higher levels of elastomers (10 and 20% by weight) could be traced to the coalescing of particles. The initial rise in strength noticed in these systems, could be related to the resistance to deformation offered by the well-bonded elastomeric fillers.

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“…Incorporation of a ductile phase like elastomer is expected to improve the impact properties [2]. In this connection, references in literature for the use of HTBN [3], ATBN [4,5], CTPB [6][7][8] can be cited.…”

Section: Introductionmentioning

confidence: 99%

Impact Studies in Elastomer, Fly Ash, and Hybrid-filled Epoxy Composites: Part I - Room Temperature Curing

Kishore

Santra

2005

Journal of Reinforced Plastics and Composites

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This study involves a system where epoxy as matrix and two reinforcements, namely an elastomer and a less dense oxide known as fly ash, differing in their response to mechanical loading to yield hybrid composite, are used. As rubber particles are known for their resistance to dynamic loading situations, poly(acrylonitrile-co-butadiene), carboxyl terminated, CTBN as the elastomer constitutes the first of the filler. The incorporation of rigid fly ash, as a second filler, has been made to see the change in the behavior in the response to the impact test. Their roles as individual fillers as well as hybrid fillers are studied at various compositions. The directly observed experimental values such as total energy and the derived data like ductility index (DI) are catalogued. While the fly ash-bearing composites show maximum absorption of energy at 3% by weight, the rubber-bearing ones display the same trend at 1%. The values recorded for the hybrid type having 1% were high. The DI showed highest values for the maximum filler bearing compositions in all cases. The scanning electron micrographs of the impact-failed samples helped in understanding the trends seen in the impact data.

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Curing reactions in elastomers. II. Carboxy‐terminated polybutadiene

Cited by 3 publications

References 11 publications

Synthesis and Properties of the Novel High-Performance Hydroxyl-Terminated Liquid Fluoroelastomer

Synthesis and Properties of the Novel High-Performance Hydroxyl-Terminated Liquid Fluoroelastomer

Individual and Combined Roles of CTBN and Fly Ash in Epoxy System under Compression: Correlation between Microscopic Features and Mechanical Behavior

Impact Studies in Elastomer, Fly Ash, and Hybrid-filled Epoxy Composites: Part I - Room Temperature Curing

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