Novel polycondensation method of improving high-temperature properties of microheterogeneous rolivsan copolymers modified by inserting epoxy and imide bridges between spherical microdomains

High Performance Polymers

2017

Self Cite

Rolivsan thermosetting resins (ROLs) attract constant attention due to their epoxy-like high processability; at the same time, their high-temperature performance is much better than that of epoxy resins and bismaleimides. Development of these materials involves a nontrivial approach to synthesis of thermostable resins; this approach is based on introducing a new structure-forming tool, that is, 1-arylethanol group. The present article demonstrates the important role of polycondensation in rolivsan chemistry. ROLs consist of (di)vinylaromatic ethers and thermosensitive monomeric and oligomeric (di)methacrylates, which are formed after a series of acid-catalyzed reactions between di-secondary aliphatic-aromatic diols, such as bis-[4-( α-hydroxyethyl)phenyl] ether, and unsaturated carboxylic acids, such as methacrylic acid. The process of ROL cure is a combination of polymerization and polycondensation. In the course of this process, in the temperature range from 140°С to 170°С, the initial densely cross-linked ROL-copolymer is formed as a result of three-dimensional radical copolymerization of highly unsaturated components. Post-cure of ROLs in the 200–300°С temperature interval leads to structural rearrangement (polycondensation). Cured ROLs demonstrate morphology typical of thermosets; they consist of highly cross-linked spherical microdomains that are weakly bound by less densely cross-linked polymer interlayers. Thermocatalytic transformations of rolivsans modified by small amounts of additives (epoxies and aromatic diamines) were used in the development of a new approach to synthesis of heat-resistant thermosetting resins via high-temperature polycondensation in interdomain layers (which are used as a peculiar kind of microreactors).

Section: Resultsmentioning

confidence: 99%

“…Molecules of epoxies, which are not able to participate in TFRP, were expelled from the reaction zone (which is located in surface layers of growing spherical microdomains (polymer grains)) and concentrated in microvolumes (interlayers) between grains. 17,44,45…”

Section: Resultsmentioning

confidence: 99%

Combination of polymerization and polycondensation in the synthesis, chemical modification, and cure of rolivsan thermosetting resins

High Performance Polymers

2017

Self Cite

“…However, these latent compounds, which are present in IBGs as a peculiar kind of "microreactors," can be activated under the appropriate conditions (e.g., at elevated temperatures and/or after changing acidity of a medium). After activation, they take part in additional reactions of structurization (crosslinking) of supramolecular formations (grains and interlayers) in microheterogeneous network polymer [2,[5][6][7]. Thus, we propose to use certain implications of mechanism of the network formation as a new structure-forming tool for chemical modification of thermosets.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, we propose to use certain implications of mechanism of the network formation as a new structure-forming tool for chemical modification of thermosets. The method has turned out to be effective in improving physicomechanical, thermal, and other useful properties of thermosets, as was illustrated by the example of thermochemical transformations of ROLs in binary systems containing epoxy resins [2,3,5] and aromatic di-and tetraamines [3,[5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…presents13 C NMR spectra of the samples prepared by curing ROL-II-1,3-BAPB blends according to the same thermal regime as was used in curing the neat ROL-II. Composition of the blend containing comparatively low amount FTIR spectra of heat-treated 1,3-BAPB (XV) (1) and the following cured blends: ROL-II-1,3-BAPB (XIV) (2), ROL-II-1,3-BAPB (VIII) (3), ROL-II-1,3-BAPB (XIII) (4), and neat ROL-II (IV)(5). and C Ar are p-phenylene and the aromatic C.…”

mentioning

confidence: 99%

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Studies of Formation Mechanism, Structure, and Properties of Network Copolymers Obtained by Cocuring of Rolivsan Thermosetting Resins with Aromatic Diamines

International Journal of Polymer Science

Kleptsova

Shvabskaya

2019

Rolivsan thermosetting resins (ROLs) demonstrate high glass-transition temperatures and excellent processability. In our work, high-temperature properties of ROLs were significantly improved using a novel technique for structural and chemical modification of microheterogeneous network polymers. This technique involves, among other procedures, cocuring of rolivsan resins with aromatic diamines (ADA). The most noticeable increase in storage moduli and glass transition temperatures (Tg) of these copolymers was achieved when ROLs were modified with 10-15 wt.% of ADA and the resulting blends were subjected to thermal treatment in air in the temperature range 180 to 320°C for several hours. FTIR, 13С NMR spectroscopy, and dynamic mechanical and thermal analyses were used for studying the structure and properties of the obtained products. It was demonstrated that the mechanism of formation of ROL-ADA copolymers includes the following high-temperature reactions: (i) three-dimensional radical copolymerization of unsaturated ROL components and (ii) cleavage of heat-sensitive methacrylate crosslinking units inside the polymer network. The second process is accompanied by formation of pending units of methacrylic acid and methacrylic anhydride, which participate in condensation reactions with ADA.

Thermal and thermomechanical properties of rolivsan unsaturated resins co‐cured with bisphenol A dicyanate

Polymer Engineering & Sci

Kleptsova

Shvabskaya

2023

The present work discusses the experimental verification of the efficiency of a new method of chemical modification of thermosetting resins. The method is based on the use of (nano)micron-sized interlayers that appear between densely crosslinked grains of a glassy network polymer during threedimensional radical polymerization of unsaturated monomers (oligomers). These interlayers act as self-contained microreactors, into which different polyfunctional compounds can be introduced for carrying out the desired chemical reactions. Thermal and dynamic mechanical analysis, differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to investigate the influence of regimes of thermocatalytic co-curing of rolivsan unsaturated resins (ROLs) with bisphenol A dicyanate (BADCy) on thermal and thermomechanical properties of the obtained crosslinked polymers. It was found that the cured ROL/BADCy blends with high (25-50 wt%) content of the BADCy component had less favorable thermal and mechanical parameters than the cured neat ROL. When the BADCy component of a ROL/BADCy blend played the role of a polyfunctional (modifying) additive (5-7.5 wt%) that migrated into "microreactors" and entered into ter-molecular and other reactions, the final cross-linked ROL-BADCy blends had better high-temperature strength, higher stability against thermo-oxidative and hydrolytic destruction than the individual components (i.e., the cured neat ROL and the cured neat BADCy). As the chemical structure may comprise two networks covalently bound to each other, they can be considered as block copolymers. The obtained results confirm the efficiency of the proposed method of chemical modification of unsaturated thermosetting resins, such as ROLs.