In this study, the phase-specific localization of filler in NBR/NR blends was characterized by means of the selective extraction
method and wetting concept. A strong dependence of silica localization on the filler loading was found. A model based on thermodynamic
data was proposed for a quantitative prediction of filler localization in rubber blends. The filler localization can be described
by a master curve demonstrating a characteristic behavior in dependence on the filler surface tension data of blend components
and filler. The effect of filler loading on the silica localization is sufficiently explained by this model by taking into
consideration the deactivation of the silanol groups on the silica surface by adsorbed curing additives. Using the master
curve, the surface tension of filler affected by curing additives and silane addition can be estimated that may be useful
for evaluation and comparison of the effect of different coupling agents. Surface tension values of different fillers were
estimated by means of the master curve and they lie in the same order compared to those reported in literature. A potential
transfer of filler within a rubber blend can be also quantitatively predicted. 相似文献
Composites based on highly branched ethylene-1-octene copolymer (EOC) and carbon black (CB) with different dispersion degree
of CB were prepared. The method of the online measured electrical conductance/resistance was used to monitor the change of
the electrical conductance/resistance of the composites during the preparation processes, i.e. mixing and cross-linking. It
was found that the kinetics of thermally stimulated shape-memory recovery of CB filled EOC is strongly influenced by the filler
dispersion degree, which actually affects the heat transfer in the composites. Using a special arrangement of experiments
the Joule heating stimulated shape-memory behaviour was quantified. CB dispersion degree and related electrical resistivity
determine the extent of the Joule heating stimulated shape-memory behaviour. Composite collected at the maximum in the online
measured conductance–time characteristics showed the best shape-memory effect owing to the highest electrical conductivity
in the solid state. The CB filled EOC showed a negative thermal coefficient of resistivity (NTC) effect, which accelerates
the temperature increase and shape-memory recovery of the composites when applying a voltage. 相似文献
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. 相似文献
Higher-order derivative spectrophotometry is very well adapted to the analytical chemistry of native and synthetic macromolecules. This is shown with the aid of some characteristic examples. The following ones have been described: The investigation of iso-forms of LDH, of myoglobins (whale and horse), of oligomer enzymes, the studying of the surroundings of the chromophores phe, tyr and trp in proteins, and of protein powder spectra; further spectra of nucleid acid, the quantitative estimation of monomers and additives in synthetic polymers, and the characterization of poly(vinyl pyrrolidons) of different molecular weights. 相似文献
A novel model is presented for predicting the phase selective filler localization in an equilibrium state for ternary rubber blends of SBR, NBR, and NR. It is based on surface tension data of the rubber components and the filler. Phase‐selective filler localization in ternary rubber blends is determined experimentally by means of FTIR spectroscopy on the basis of the wetting concept. It is found that by preparation of ternary blends with certain silica loadings, pre‐mixed in each blend phase using the masterbatch technology, silica transfer processes between blend phases take place until the equilibrium filler distribution is reached. The sequence of the silica transfer processes can be explained by taking into consideration the formation of a phase‐in‐phase morphology of the ternary blend.
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. 相似文献