Statistical Analysis of the Microstructure and Mechanical Properties of Rolivsans in the Course of Thermal Curing

Shvabskaya

2015

J Polym Res

Rigid chemical structure provides for excellent thermal and thermo-mechanical properties of heat resistant organic polymers, but affects their fabricability. For the first time a new original chemical approach to the problem of combining high-temperature stability, durability of thermosetting polymers with environmental safety and easy processability has been developed and demonstrated in detail. The key methodological concept was introducing a new structure-forming tool (α-hydroxyethyl)phenylene functional groups) into the chemistry of thermally stable organic polymers. The main goal of this work was to reveal structure-property correlations for rolivsans and products of their cure; using the obtained data would allow to combine resin processability with high thermo-oxidative stability, good heat deformation characteristics and mechanical strength of the prepared polymeric materials. The properties of network copolymers of ( d i ) v i n y l a r o m a t i c e t h e r s w i t h t h e r m o s e n s i t i v e (di)methacrylates and copolymer-based composites were studied. These copolymers were capable of changing their (micro)structure, crosslink density and mechanical properties in the process of thermal treatment. Rolivsan resin compositions with equimolar concentrations of styrene-like and methacrylate end groups have shown optimal combination of fabricability, mechanical strength and heat deflection temperature (HDT). It was found that HDT of rolivsan castings/glassreinforced plastics was 250°C/275°С. Rolivsan copolymers/composites could withstand short-duration temperature spikes (up to 350°C).

Section: Chemistry Of Rolivsan Resinsmentioning

confidence: 99%

High-temperature properties of rolivsan thermosetting resins (network copolymers of (di)vinylaromatic ethers and cyclized (di)methacrylates)

Shvabskaya

2015

J Polym Res

“…The cured ROLs demonstrate morphology typical of densely cross-linked polymers, which can be visualized by transmission electron microscopy studies of the samples. 17,40 These studies reveal that spherical nanosized densely cross-linked microdomains (polymer grains) are weakly bound by less densely cross-linked polymer interlayers. The interlayers surrounding grains are formed at final stages of TFRP and are rich in defective polymer chains that are plasticized by various impurities present in the initial resin.…”

Section: Resultsmentioning

confidence: 99%

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

High Performance Polymers

2017

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).

“…20 ROLs find applications as thermostable non-porous impregnating compounds (clear castings), sealing compounds, vacuum-dense glues, protective coatings, and binders for composites. 6,[9][10][11][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] The following polyfunctional compounds were studied as target additives (admixtures inactive in TFRP): epoxy resins, 10,11,[37][38][39][40][41][42][43] aromatic diamines, [44][45][46][47] aromatic tetra-amines and dianhydrides of aromatic tetracarbon acids. 48 Chemical modification with these compounds improved thermal, strength and adhesive properties of the cured ROLs.…”

Section: Modification Of Rolivsansmentioning

confidence: 99%

“…According to the results of earlier studies, the cured ROLs have high thermo‐oxidative stability (250–320°С) and good dielectric properties, which are resistant to hot strong acids and alkalis 20 . ROLs find applications as thermostable non‐porous impregnating compounds (clear castings), sealing compounds, vacuum‐dense glues, protective coatings, and binders for composites 6,9–11,21–36 …”

Section: Introductionmentioning

confidence: 99%

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.