Papers by Author: Marian Zaborski

Abstract: The synthesis of polymer brushes containing poly (methyl methacrylate) (PMMA) chains grafted from hydroxyapatite (HAP) particles was disscussed. Surface of commercially available hydroxyapatite was first modified with atom transfer radical polymerization (ATRP) initiator and hydrophobized with isobutyric acid, and then surface-initiated ATRP was conducted. Properties of obtained hybrids were studied by dynamic light scattering (DLS) and gel permeation chromatography (GPC). Polymers with various molecular weight up to M_n=96,100 g/mol were obtained with good control;M_w/M_n<1.2. Copolymer brushes of poly (methyl methacrylate-stat-benzophenone methacrylate) (P(MMA-stat-BPMA) were also synthesized and cross-linking ability of such materials under UV radiation was confirmed.

Abstract: This paper deals with blends of ethylene-octene rubber (POE) with nanostructured metal oxides: magnesium oxide (MgO), calcium oxide (CaO), zinc oxide (ZnO) and unsaturated acids: itaconic acid (IA), sorbic acid (SA) and crotonic acid (CA), as co-agents. Dicumyl peroxide (DCP) was used as a vulcanizing agent. Elastomer composites were prepared in Brabender measuring mixer N50. Rheometric properties of rubber mixes and crosslink density of vulcanizates were measured. Mechanical properties of the samples were also investigated. Dispersion degree of coagents in elastomer matrix was studied by SEM images. Cross-link density analysis revealed that POE vulcanizates contained both ionic bonds and covalent bonds. The results showed that the nanostructured metal oxides and unsaturated acids used as co-agents can greatly improve the modulus at 100% of elongation and tensile strength of the vulcanizates.

Abstract: The idea and methods of methylvinylsilicone rubber modification are present. Polyhedral oligomeric silsesquioxanes (POSS) functionalized by vinyl-, carboxyl or amino-organic groups were used with the goal of modifying the rubber matrix. Additionally, oxazoline derivative and itaconic acid were used as the coupling agents. Generally, the process of modification contributed to increasing of rubber-filler interactions, however the useful properties of composites depended on a kind of active groups and way of modifications. It has been shown how grafting of POSS molecules to silicone backbone affects the cross-link density, rheometrical and mechanical properties, hysteresis and relaxation rates of the methylvinylsilicone rubber vulcanizates. Moreover, both the presence of silsesquioxanes and the way of composites preparing affect the improvement of filler dispersion degree in the rubber matrix, as indicated by SEM images. The most significant effect was observed for vinylisobutyl-POSS grafting to the silicone backbone which resulted in the considerably improved mechanical properties of the resulting network.

Abstract: A series of composite materials containing polyhedral oligomeric silsesquioxanes (POSS) and hydrogenated butadiene-acrylonitrile rubber (HNBR) were prepared. The goal of the work was to evaluate the effect of the type and reactivity of functional groups in the POSS cage on properties of the resulting elastomeric nanocomposites. The paper presents some of the preliminary results obtained from the studies. The results indicate that incorporation of POSS into silica-filled HNBR elastomer network increases interfacial interactions of the systems and the POSS molecules can be successfully used as coagents of crosslinking towards the elastomer matrix and efficient additives improving the mechanical properties of elastomeric nanocomposites. Furthermore, evaluation of changes in mechanical properties, induced in a result of POSS/HNBR composites ageing, show that the inclusion of POSS in the HNBR network is directly influencing the stabilizing effect and improves the ageing resistance of elastomer composites.

Abstract: Magnetorheological elastomer composites (MREs) based on different magnetoactive fillers such as: carbonyl iron powder (CIP), gamma iron oxide (γ-Fe₂O₃), micro-and nanosize Fe₃O₄ are reported and studied. MREs were obtained from various elastomer matrixes such as: ethylene propylene, acrylonitrile butadiene, silicone, ethylene-octene and polyoctenamer rubbers. To align particles in elastomer, cross-linking process took place in magnetic field. Effect of the amount of ferromagnetic particles and their arrangement on the microstructure and properties in relation to the external magnetic field was examined. The microstructure, magnetic and magnetoreological properties of compositions were investigated with scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and ARES Rheometer with magnetic device. Cross-linking density and mechanical properties of the composites were also studied. It was found that microstructure anisotropy has significant effect on the properties of magnetorheological elastomers. Moreover, different amount of magnetoactive fillers influence mechanical and magnetic properties of the vulcanizates. Many essential conclusions occur after application the wide variety of elastomer matrixes filled with different ferromagnetic particles in the context of preparation process of smart materials based on magnetorheological elastomer composites.

Abstract: The aim of this work was to obtain elastomer composite filled with carbon fillers with different structure. Three types of carbon black were used as reinforcing fillers: FEF N550, Colour Black FW200, Printex XE2B. In order to improve dispersion of fillers, different dispersing agents were used: anionic, cationic, nonionic and ionic liquids. As an elastomer matrix the acrylonitrile-butadiene rubber (NBR) was used. The fillers were characterized by dibutylphtalate (DBP) absorption analysis, aggregates size, rheological properties of filler suspensions and Zeta potential analysis. The compounding was carried out in a laboratory rolling mill. Samples were prepared through the vulcanization process at 160°C. The vulcanization kinetics of rubber compounds, crosslink density, mechanical properties, hysteresis losses, conductive and thermal properties of vulcanizates were also measured. In order to characterize filler dispersion in elastomer matrix the SEM images were obtained.

Abstract: Montmorillonite is usually modified with ammonium salts, in our study the selected ionic liquids were applied as modifying agents for the intercalation of montmorillonite. Surface properties of modified fillers, the zeta potential of suspended solids in the water, the oil absorption number, the impact of modifications on the tendency to agglomerate in the non-polar and polar medium were studied. The modified fillers were used in two matrices with different polarity: the ethylene-propylene copolymer EPM and hydrogenated acrylonitrile-butadiene rubber HNBR. Elastomers were crosslinked with dicumyl peroxide DCP. The influence of the variously modified fillers on the cross-linking density of the vulcanizates, rheometric and mechanical properties of filled systems were investigated. The ageing studies (thermal, atmospheric and under UV radiations) were conducted.

Abstract: Composites of rubbers such as ethylene – propylene and acrylonitrile – butadiene with micro size Fe¬3O4, Fe2O3, and nano size Fe3O4 as the fillers were tested. Iron oxides were found to be active fillers which improved mechanical properties of elastomers. Additionally, they also changed their magnetic properties. Furthermore, the surface of micro size Fe3O4 was modified to upgrade mechanical properties of the vulcanizates. Itaconic acid, methacryloxypropyltrimethoxysilane and monododecyl maleate were used as modifying agents. To improve dispersion of applied fillers in polymers matrix, non-ionic (NF-PEG), anionic (calcium stearate ), cationic (DTAB, DTAC, DDAB, CTAD) and ionic liquids (HMIMBF4, BMIMPF6, OMIMPF6) were used. It was observed that both non-modified and modified micro iron oxides and nano iron oxides improved the properties of the vulcanizates the most effectively.