Olga Grigoryeva

Melt grafting of maleic anhydride onto an ethylene-propylene-diene terpolymer (EPDM)

Peroxide-initiated melt grafting of maleic anhydride (MAH) onto an ethylene–propylene–diene terpolymer (EPDM) of high ethylene content (=74 wt%) has been studied using a Brabender Plasticoder. The grafting efficiency and crosslinking degree (gel content) of the grafted EPDM rubber (EPDM-g-MAH) were determined by FTIR spectroscopy and xylene extraction, respectively. It was established that both grafting and crosslinking reactions are mostly influenced by the dosage of the MAH and peroxide (2,5-dimethyl-2,5-di-(t-butylperoxy)hexane), respectively. The targeted relative high MAH grafting at low gel content was reached at low concentrations of both MAH (<5 wt%) and peroxide (<0.2 wt%). Processing variables, as mixing temperature and time, rotor speed and filling grade of the mixing chamber, showed only a marginal effect on the competing grafting and crosslinking reactions.

Structure–thermal property relationships for polycyanurate–polyurethane linked interpenetrating polymer networks

Chemical structure and thermal-oxidative degradation of sequential IPNs based on crosslinked polyurethane (CPU) and polycyanurate network (PCN) have been studied. As a result of chemical interaction between monomer, dicyanate ester of bisphenol A (DCEBA) and CPU during PCN formation (polycyclotrimerization of DCEBA into CPU matrix), covalent bonding between the networks occurs, leading to creation of linked IPNs (LIPNs). The formation of a new hybrid network (HN) structure has been confirmed. The coexistence of CPU, PCN and HN structures in the LIPNs, confirmed by infrared spectroscopy and by the observation of degradation stages characteristic for each structure, depends on the ratio of the components. Three structures were found for the 90/10 CPU/PCN; HN and PCN were observed in the 70/30 LIPN and the hybrid network was the main structure detected for the 50/50 LIPN.

The impact of ultra-low amounts of amino-modified MMT on dynamics and properties of densely cross-linked cyanate ester resins

Thermostable nanocomposites based on densely cross-linked cyanate ester resins (CER), derived from bisphenol E and doped by 0.01 to 5 wt. % amino-functionalized 2D montmorillonite (MMT) nanoparticles, were synthesized and characterized using Fourier transform infrared (FTIR), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDXS), wide-angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), far-infrared (Far-IR), and creep rate spectroscopy (CRS) techniques. It was revealed that ultra-low additives, e.g., 0.025 to 0.1 wt. %, of amino-MMT nanolayers covalently embedded into СER network exerted an anomalously large impact on its dynamics and properties resulting, in particular, in some suppression of dynamics, increasing the onset of glass transition temperature by 30° to 40° and twofold rise of modulus in temperature range from 20°C to 200°C. Contrarily, the effects became negligibly small or even negative at increased amino-MMT contents, especially at 2 and 5 wt. %. That could be explained by TEM/EDXS data displaying predominance of individual amino-MMT nanolayers and their thin (2 to 3 nanolayers) stacks over more thick tactoids (5 to 10 nanolayers) and the large amino-MMT aggregates (100 to 500 nm in thickness) reversing the composite structure produced with increasing of amino-MMT content within CER matrix. The revealed effect of ultra-low amino-MMT content testifies in favor of the idea about the extraordinarily enhanced long-range action of the ‘constrained dynamics’ effect in the case of densely cross-linked polymer networks.PACS82.35.Np Nanoparticles in polymers; 81.05.Qk Reinforced polymers and polymer-based composites; 81.07.Pr Organic-inorganic hybrid nanostructures

Synthesis of inhomogeneous modified polycyanurates by reactive blending of bisphenol A dicyanate ester and polyoxypropylene glycol

A series of polycyanurate networks (PCN), based on the dicyanate of bisphenol A monomer (DCBA), was synthesized in the presence of different contents of polyoxypropylene glycol (PPG). The formation of very finely divided morphologies with highly interpenetrated phases, i.e. a PCN- rich phase, a mixed phase of PCN/PPG components and a PPG-rich phase was determined. It is supposed that the lowering of the glass transition temperature of modified network matrix at increasing PPG content is due to a) PPG incorporation, b) decrease of the final DCBA conversion and c) the increase of percentage of non-incorporated PPG, which acts as plasticizer.

Structure-Properties Relationships for Bisphenol A Polycyanurate Network Modified with Polyoxytetramethylene Glycol

A series of polycyanurate networks (PCNs), based on the dicyanate of bisphenol A monomer (DCBA), were synthesized in the presence of different contents of hydroxyl-terminated polyoxytetramethylene glycol (PTMG). The chemical structure, T g behaviour, modulus-composition relations and mechanical properties of the modified PCNs were investigated by Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical thermal analysis (DMTA) and mechanical testing. The oligomer modifier influences the structure of the final networks insofar as it is partly incorporates and partly dissolves in the polycyanurate matrix, and, thus, decreases the final T g of these modified thermosets. All modified polycyanurate networks exhibit a single, broad glass transition that shifted to lower temperature as the modifier content was increased.

Poly(bisphenol A)cyanurate network modified with poly(butylene glycol adipate). Thermal and mechanical properties

A poly(bisphenol A)cyanurate (PCy) network was modified by a hydroxy-terminated oligoester, poly(butylene glycol adipate), PBGA, by polycyclotrimerization of bisphenol A dicyanate in the presence of the oligoester. The modified networks with PBGA content from 5 to 20% (w/w) were characterized by a combination of FTIR, DSC, TMA, TGA, impact testing and sol-gel analysis. It has been established that almost whole of the PBGA was chemically incorporated into the PCy network structure and that the higher the content of PBGA, the stronger the interaction between the components. It is shown that introducing PBGA does not drastically reduce thermal characteristics (temperature of the thermal degradation onset and glass transition temperature) of the PCy network while the impact properties are improved significantly. It is suggested that the modified PCy can be successfully used simultaneously at high temperatures and high loading.

Irradiated Recycled High Density Polyethylene Usage as a Modifier for Bitumen

AbstractThis paper studies the use of recycled high-density polyethylene (HDPER) obtained from waste bottle crates as modifier in bitumen. Post-consumer HDPE was irradiated in order to casue a chemical interaction with bitumen. Accordingly, Fourier transform infrared (FTIR) spectroscopy was employed to determine the effects of the electron beam irradiation on the chemical structure of HDPE. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and fluorescent microscopy results signified that there might be a chemical interaction between electron beam irradiated HDPE (HDPERe) and bitumen. Physical and rheological tests were applied to the binders to investigate the effects of HDPERe polymer on the performance of the bitumen. Fundamental rheological tests performed using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR) indicate that the HDPERe modifier provides a clear improvement in temperature susceptibility of bitumen. Thus, the HDPERe modification produces enhanced ...

High Value Composites from Recycled Polyolefins and Rubbers

The novel technology for producing high value thermoplastic dynamic vulcanizates (TDVs) from recycled polyolefins and ground tire rubber (GTR) has been developed. The producing high performance composites of tensile properties on the level of TDV s based on virgin components is assured by using ethylene-propylene-diene monomer rubber (EPDM) as a rubber compatibilizer, bitumen as a devulcanizing agent for GTR as well as plasticizing and compatibilizing agent for TDV components.

Methodological effects in Fourier transform infrared (FTIR) spectroscopy: Implications for structural analyses of biomacromolecular samples

Abstract A set of experimental data obtained by Fourier transform infrared (FTIR) spectroscopy (involving the use of samples ground and pressed with KBr, i.e. in a polar halide matrix) and by matrix-free transmission FTIR or diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic methodologies (involving measurements of thin films or pure powdered samples, respectively) were compared for several different biomacromolecular substances. The samples under study included poly-3-hydroxybutyrate (PHB) isolated from cell biomass of the rhizobacterium Azospirillum brasilense; dry PHB-containing A. brasilense biomass; pectin (natural carboxylated heteropolysaccharide of plant origin; obtained from apple peel) as well as its chemically modified derivatives obtained by partial esterification of its galacturonide-chain hydroxyl moieties with palmitic, oleic and linoleic acids. Significant shifts of some FTIR vibrational bands related to polar functional groups of all the biomacromolecules under study, induced by the halide matrix used for preparing the samples for spectroscopic measurements, were shown and discussed. A polar halide matrix used for preparing samples for FTIR measurements was shown to be likely to affect band positions not only per se, by affecting band energies or via ion exchange (e.g., with carboxylate moieties), but also by inducing crystallisation of metastable amorphous biopolymers (e.g., PHB of microbial origin). The results obtained have important implications for correct structural analyses of polar, H-bonded and/or amphiphilic biomacromolecular systems using different methodologies of FTIR spectroscopy.

Use of maleic anhydride grafted recycled polyethylene treated by irradiation in bitumen modification

Most of the polymers currently used as additive in bitumen are not economically attractive. Thus, employing recycled materials in flexible highway instead of virgin ones has become a fundamental case for researchers especially in terms of cost efficiency and environmental awareness. To date, many studies have been made to investigate using of recycled polymers in bitumen and generally improved mechanical properties of bitumen were determined. This paper aims to present the modification of bitumen by maleic anhydride (MAH) grafted recycled low density polyethylene treated by irradiation (g-LDPEr-g-MA). Maleic anhydride was dissolved and mixed with recycled polyethylene which was proved by the Fourier infrared (FT-IR) spectrum. Subsequently, pre-treated LDPEr granules were subjected to gamma irradiation doze of 10kGy to provide formation of free radicals and some functional groups which can contribute to creation of strong chemical bonds between polymer modifier and bitumen. Six different binders (one base and five modified) were prepared to investigate the effects of g-LDPEr-g-MA modifier on properties of bitumen. The dispersion of g-LDPEr-g-MA modifier in bitumen was examined by florescent microscope. Conventional tests and rotational viscosity test was used to determine physical properties of bitumens. Complex shear modulus (G*) and phase angle (δ) of base and modified bitumens were measured by means of dynamic shear rheometer (DSR) for different traffic speed and in-service pavement temperature. Tests results reveal that a gradually increment in g-LDPEr-g-MA modification leads to a decrease in penetration and an increase in softening point. According to DSR test results, g-LDPEr-g-MA modifier provides an increased rutting parameter. Thus, flexible pavement could become more resistant against permeant deformations by g-LDPEr-g-MA modification.