Enhancing the performances of polybenzoxazines by modulating hydrogen bonds

Luan, Xiaosheng; Wang, Bin; Yang, Po; Gu, Yi

doi:10.1007/s10965-019-1741-5

Cited by 21 publications

(4 citation statements)

References 44 publications

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“…Nanofillers essentially act as decelerators in the gel network, which could prevent the gels from fracturing and cracking through energy dissipation . By bridging any cracks, nanocellulose segments can retard further growth of the existing fractures and improve the strength of the gels. − We observed that the NC-st-PG samples remained stable at the strain of ε = 85%, and the maximum σ reached 500.49 kPa (G AM‑NCF‑20 wt%/0.1 wt% ) and 315.72 kPa (G AM‑NCC‑20 wt%/0.2 wt% ), respectively. The compression strength of the gels at high AM contents (15% and 20 wt %) was not positively responsive to nanocellulose dosage, presumably caused by the induced steric effect.…”

Section: Results and Disccusionmentioning

confidence: 81%

Nanocellulose-Strengthened Particle Gel for Conformance Control in Fractured Tight Formations. Part I: Preparation and Mechanical Stability

et al. 2020

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Conformance control in fractured tight formations remains a challenge because of large permeability contrasts between fractures and the matrix. Therefore, there is an emerging interest in particle gels that possess favorable mechanical properties and low production costs. To address this issue, we proposed a kind of nanocellulose-strengthened particle gel, named NC-st-PG, which was prepared by sparsely interpenetrating cellulose nanofibrils (NCF) and nanocrystals (NCC) respectively into a polyacrylamide (PAAm) matrix. The characteristics of NC-st-PG from the chemical structure to mechanical and thermal stability were investigated thoroughly. We noted that the PAAm network was noticeably strengthened and toughened by introducing stiff NC segments without compromising the elasticity of the gels. The optimum amount of NCF and NCC in the PAAm was found to be 0.1 wt %. We cycled the deformation and observed that NC-st-PG exhibited fatigue-resistance and remained highly elastic after 10 cycles of stress load and unload. In addition, the swelling and thermal decomposition of NC-st-PG were restrained by the presence of NCC and NCF. These characteristics render NC-st-PG superior stability under consecutive shearing in fractures and are indicative of the efficiency and durability of conformance treatment using NC-st-PG. The results of this study supplement earlier observations and provide an alternative to conventional gels to address conformance issues in tight formations.

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Section: Results and Disccusionmentioning

confidence: 81%

Nanocellulose-Strengthened Particle Gel for Conformance Control in Fractured Tight Formations. Part I: Preparation and Mechanical Stability

et al. 2020

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“…The characteristic peaks of the 1, 2, 4, 6-tetrasubstituted benzene ring appeared at 1487 cm À1 (Figure 4(b)). 38 This could be attributed to the phenol ortho-Mannich bridge structure observed at 140 C. The intensity of this peak increased with temperature. This structure was observed at 180 C for the BA-a (Figure S4) and 5 wt.% -CD/BA-a blend systems (Figure S5).…”

Section: Chemical Structure Of -Cd-mah and The Curing Mechanism Of -Cd/ba-a And -Cd-mah/ba-amentioning

confidence: 88%

Thermal properties of polybenzoxazine exhibiting improved toughness: Blending with cyclodextrin and its derivatives

Zhao

et al. 2021

High Performance Polymers

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Polybenzoxazines are emerging as a class of high-performance thermoset polymers that can find their applications in various fields. However, its practical application is limited by its low toughness. The cyclic β-cyclodextrin and a newly synthesized derivative (β-cyclodextrin-MAH) were separately blended with benzoxazine to improve the toughness of polybenzoxazine. The results revealed that the maximum impact strength of the blend was 12.24 kJ·m−2 and 14.29 kJ·m−2 when 1 wt.% of β-Cyclodextrin and β-Cyclodextrin-MAH, respectively, were used. The strengths were 53% and 86% higher than that of pure polybenzoxazine. The curing reaction, possible chemical structures, and fractured surface were examined using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques to understand the mechanism of generation of toughness. The results revealed that the sea-island structure and the presence of hydrogen bonds between polybenzoxazine and β-cyclodextrin and β-cyclodextrin-MAH resulted in the generation of toughness. Furthermore, the curves generated during thermogravimetric analysis did not significantly change, revealing the good thermal properties of the system. The phase-separated structure and the hydrogen bonds present in the system can be exploited to prepare synergistically tough polybenzoxazine exhibiting excellent thermal properties. This can be a potential way of modifying the thermoset resins.

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“…On the other hand, considering the existence of many kinds of hydrogen bonds that inhibit the high degree polymerization of benzoxazine and lead to the brittleness of the final product [16], the idea of adding small molecules hydrogen bond donor or acceptor to adjust the hydrogen bond structure of benzoxazine to achieve toughening effect has been favored by researchers. [87,88] Luan et al [89] introduced 4,4-bipyridine (Bpy) as a hydrogen bond acceptor into benzoxazine and increased the performance of polybenzoxazine by increasing the crosslink density. The optimal performance can be obtained when the molar ratio of BA-a to Bpy is 1:0.5 (PBAaB-0.5), the tensile strength increases from 32.5 MPa for PBA-a to 43 MPa for PBAaB-0.5, the elongation at break reaches 2.04%, but Tg decreases from 206 ℃ to 178 ℃.…”

Section: Scheme 7 Synthesis Of Cardanol-based Aromatic Diamine Benzoxazinementioning

confidence: 99%

Research Progress in Toughening Modification of Polybenzoxazine

Zhao¹,

Li²,

Li³

et al. 2020

Eng. Sci.

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Benzoxazine is a new kind of phenolic resin developed in recent years. It possesses a lot of interesting properties including flexible molecular design, nearly zero curing shrinkage and corresponding polybenzoxazine shows excellent mechanical and heat resistance properties. However, like other thermosetting resins, polybenzoxazine also faces the disadvantages of high brittleness and low impact strength during use. This paper briefly summaries the research progress of the toughening modification of polybenzoxazine, including rubber elastomer, inorganic particles, thermoplastic engineering plastic, other thermosetting resin, hyperbranched polymer and benzoxazine molecular design modification. Furthermore, the development direction of the toughening modification of polybenzoxazine has prospected.

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Enhancing the performances of polybenzoxazines by modulating hydrogen bonds

Cited by 21 publications

References 44 publications

Nanocellulose-Strengthened Particle Gel for Conformance Control in Fractured Tight Formations. Part I: Preparation and Mechanical Stability

Nanocellulose-Strengthened Particle Gel for Conformance Control in Fractured Tight Formations. Part I: Preparation and Mechanical Stability

Thermal properties of polybenzoxazine exhibiting improved toughness: Blending with cyclodextrin and its derivatives

Research Progress in Toughening Modification of Polybenzoxazine

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