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The phase specific localization of the reinforcing fillers like carbon black (CB), which has been known to influence the physical and mechanical performance of the rubber blends, can be determined by different characterization techniques, however, only for binary rubber blends. They have been failed so far when applied for more complicated systems like filled ternary rubber blends. In the present work we introduced a new technique using the attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with germanium crystal for characterization of the specific localization of CB in a ternary blend of solution styrene butadiene rubber (SBR), butadiene rubber (BR) and natural rubber (NR). It is the first time we could follow the change of the amount of CB localized in each phase of this blend along the mixing time. CB firstly is incorporated into the NR phase and then it obviously migrates from the NR phase to the SBR phase as a function of mixing time that corresponds very well with the theoretical prediction based on the Z-model using the surface tension values of the filler and rubber blend components. The interaction between CB and rubber components can be qualitatively proved by the shift of the FTIR peak. Thermogravimetric analysis (TGA) was used to support the results obtained by the FTIR method. The study was further extended to follow the CB distribution in multi-step mixing.

The aim of this work was to study the effect of the ionic liquids (ILs) with respect to their anion type and the length of alkyl chain as dispersing and coupling agent in carbon nanotube (CNT) filled styrene butadiene rubber (SBR)/natural rubber (NR) blends. We characterized the ILs by their surface tensions whereupon their different values explain the different compatibilities of ILs with the rubber components and the filler. The wetting concept was further developed in order to experimentally characterize the effect of the rubber-IL and CNT-IL compatibility on the selective wetting of CNTs in rubber blends. It was found that all the used ILs improved the dispersion of CNTs in rubber blends significantly. During the mixing process the IL layer pre-bound to the CNT surface was replaced mainly by the NR phase and, partly, by the SBR phase. Thus, ILs cannot be used as coupling agent in this rubber blend. For the ILs with surface tension similar to that of CNTs the filler was partly wetted by IL that imparts the mixture a high electrical conductivity directly after the mixing process. This high conductivity can be used for triggering the vulcanization of the blend by means of the Joule heating. The preferential localization of ILs in the rubber matrix - but not in rubber-filler interphase - considerably influences the cross-link behavior of the vulcanizates and thus their final mechanical properties significantly.

The formation and stability of carbon nanotube (CNT) network in natural rubber (NR), deproteinized NR (DPNR) and polyisoprene (IR) compound were investigated by means of the method of the online measured electrical conductance in a whole process from processing and rolling over pressing/cross-linking to post-stretching. The kinetics of CNT flocculation was described and explained by taking into consideration the depletion force considered as driving force and the thickness of the bound rubber layer considered as hindering factor. The presence of linked phospholipids in NR and DPNR improves the rubber-filler interaction of CNTs through the cation-π bonding that hinders the filler flocculation. The absence of the cation-π bonding in CNT/IR compound and the related thin layer of bound rubber are the reason for the strong tendency of flocculation of CNTs in IR even at room temperature. The effect of pressing time, temperature and cross-linking reaction as well as mechanical deformation on the formation and stability of CNT network in NR compounds was also investigated and discussed by taking into consideration the role of the linked phospholipids.

The present work highlighted the effect of commonly used processing and curing additives on the wetting and dispersion kinetics of filler like silica and carbon black (CB) in some examples using the methods like the wetting concept and online measured electrical conductance. The adsorption of additives and mono-functional silane on silica surface increases the wetting speed of silica in single compound of nitrile butadiene rubber (NBR), natural rubber (NR) and styrene butadiene rubber (SBR) compounds. In rubber blend, for instance NBR/NR, the extent of filler surface fraction wetted by each blend component is strongly dependent on the additive/silica and silane/silica ratio r. A model based on the surface tension data of rubber components and filler (Z-model) was used for prediction of the selective filler wetting at a thermodynamic equilibrium state. By combining the experimental results from the wetting concept and theoretical prediction from the Z-model the silica surface tension changed during mixing can be characterized. It quantitatively describes the deactivation of the silanol groups on the silica surface by adsorbed additives. The effect of adsorption of additives on filler dispersion was exemplarily demonstrated on CB filled SBR compounds by means of the method of online measured electrical conductance. The influence of additives on the CB dispersion in low styrene-content SBR mixtures is much more pronounced than that in high styrene-content SBR mixtures.

In the present work, the development of morphology and selective wetting of nanoclay and carbon nanotubes (CNTs) in rubber nanocomposites were characterized qualitatively by means of the optical microscopy, TEM and AFM and quantitatively by means of the wetting concept . Carboxylated hydrogenated nitrile butadiene rubber (XHNBR), ionic liquid and ethanol were used as dispersing agent and they show very good effect on the macro- and microdispersion of nanofillers in different rubbers. It was found that the selective wetting of filler surface by the dispersing agent and rubber matrix is controlled by thermodynamic and kinetic factors. A model basing on surface energy data of polymer components (rubber and dispersing agent) and filler was introduced in order to determine the thermodynamic equilibrium state of filler wetting, which is found to be simultaneously determined by the filler–polymer affinity and the rubber/dispersing agent mass ratio. During the mixing process a replacement process of bound polymer components takes place on the filler surface until the predicted state is reached.

According to theoretical prediction using the Z-model proposed by us a predominant localization of carbon black (CB) in the ethylene propylene diene rubber (EPDM) phase of ethylene octene copolymer (EOC)/EPDM blends was found for a thermodynamic equilibrium state, in case that rheological effects do not play a significant role. In this paper, a special mixing procedure based on the well-known dynamic vulcanization techniques was developed to localize CB in the EOC matrix in order to obtain a low electrical resistivity. Effect of size of the EPDM domains on the electrical resistivity was characterized and it was found that exceeding a critical EPDM domain size of about 30 μm the electrical resistivity decreases exponentially. An inhomogeneous CB distribution formed in the EOC matrix at EPDM domain sizes above 30 μm is the reason for the strong decay of resistivity. The effect of CB network formation during cross-linking process on the resistivity was also characterized by means of the online measured electrical resistance. The electrical resistivity changes strongly after peroxidic cross-linking process, while it remains nearly unchanged after cross-linking with high energy electrons. The Joule heating shape-memory recovery of CB filled EOC/EPDM blends cross-linked by peroxide and by high energy electrons was comparatively characterized and discussed.

The present work introduces a new method for the characterization of morphology development and kinetics of nanoclay distribution in hydrogenated acrylonitrile butadiene rubber (HNBR)/natural rubber (NR) blends based on the measurement of electrical conductance during the mixing process. It was found that the online measurable electrical conductance of rubber–clay mixtures, which is originated from the release of the ionic surfactant from the nanoclay galleries during the mixing process depends on two factors: the phase specific localization of nanoclay and the change of the blend morphology. The former is due to the favorable interaction of nanoclay with one of the blend phases whereas the latter is caused by the compatibilization effect of nanoclay. It became obvious that the presence of clay influences the morphology of the blends drastically; a significant change from the co-continuous phase morphology into an island–matrix morphology was observed in HNBR/NR/clay nanocomposites. Thus, the method of the online conductance promises to be a powerful tool to study the nanoclay dispersion processes and to monitor the quality of rubber–nanoclay composites.

In the present work a new evaluation method for the characterization of the stress relaxation behavior of rubber–carbon black (CB) composites is presented. Using the chart of the online measured electrical conductance received from the recording equipment in the mixing chamber different rubber–CB composites with well defined state of the CB network have been produced for the stress relaxation investigation. The development of CB dispersion degree and the rubber-layer bonded on the CB surface have been characterized systematically using the method of the online measured electrical conductance and the thermogravimetric analysis of rubber–filler gel. The analysis of the stress relaxation curves is based on the division of the initial stress into several stress components and the consideration of the structure of the composites as a combination of different networks. The contribution of the stress component to the corresponding network is the focus of the present work. Based on the systematic variation of material parameters and test conditions we could divide the applied stress into six stress components which are originated from the rubber matrix and CB. It is obvious that the debonding of the rubber-layer from the CB surface and the collapse of a part of the CB network can be described by the relaxing stress component ΔσCB(rubber-layer) and ΔσCB(network), respectively. The non-relaxing stress components σ∞CB(rubber-layer) and σ∞CB(network) are dependent on the amount of the time-stable bonding in the rubber-layer and the stable part of the CB network. The mechanical performance of the composites and especially the time and temperature dependent mechanical behavior could be specifically modified by CB addition.

The analysis of the stress relaxation behavior of thermoplastic elastomers (TPE) was made with the help of the two-components model, which allows a consistent description of the time and temperature dependent behavior. The effect of draw ratio, strain rate and temperature on the stress relaxation behavior of TPE was investigated. The structural background of the relaxation behavior was discussed using the two-network model shown in form of an analogy model. The assignation of the stress components to a hard phase and soft phase network is based on the experimental results taking into consideration the knowledge about the structural nature and deformation performance of TPE. Comparing dynamic vulcanizates with different TPE based on block copolymer, it was found that the characteristic differences in the time-dependent deformation behavior of the different TPE are based on the different deformation behavior of the network points.

The swelling and deswelling of isotropic and oriented polyamide 11 (PA11) with formic acid have been determined as functions of temperature and acid solution concentration. During swelling, dimension relaxation, partial dissolution of crystallites and extraction of low molecular weight chains occur. During deswelling, amorphous chains recrystallize and after complete drying, the original morphology with the same orientation is restored. This memory effect is due to strain-induced crystallization in the PA oriented gel.