Reinforcement, hydrodynamic

Re-aggregation, filler cluster 76 Region of analysis 134 Reinforced rubber 76 Reinforcement, hydrodynamic 63-64 Relaxation time 118 Rubber, bound 47-50, 61 -, reinforced 33, 60, 63, 76... 

The study of the mechanical properties of filled elastomer systems is a chaUenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward mle of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fiUers hke sihca and carbon black on the reinforcement of elastomers.In general, the strucmre-property relationships developed for filled elastomers have evolved into the foUowing major areas FiUer structure, hydrodynamic reinforcement, and interactions between fiUers and elastomers. 

It is important to note here that the presence of rigid filler clusters, with bonds in the virgin, unbroken state of the sample, gives rise to hydrodynamic reinforcement of the mbber matrix. This must be specified by the strain amplification factor X, which relates the external strain of the... 

Figure 10.11 The structure of an EPDM/N550 (phr=100) vulcanisate according to the results of NMR and extraction studies - (A) and mechanical data for the case of pure hydrodynamic reinforcement - (B) [62], The volume fraction of microphases/ components is given in vol.%. According to the NMR data, the total network density in the rubber phase, l/2Mc+e+ad, equals 425 mmol/kg, where subscripts c, e and ad stand for chemical crosslinks, chain entanglements and adsorption rubber-filler junctions. The density of the adsorption junctions in the loosely bound rubber, 1/...

Fig. 1 Schematic view of filler morphology in three concentration regimes. For reinforcement is due to hydrodynamic amplification by particles ( < 1) or clusters (cp> +) with eff= or cpeff= / A) respectively. For > reinforcement is due to the deformation of a flexible filler network...

The above interpretations of the Mullins effect of stress softening ignore the important results of Haarwood et al. [73, 74], who showed that a plot of stress in second extension vs ratio between strain and pre-strain of natural rubber filled with a variety of carbon blacks yields a single master curve [60, 73]. This demonstrates that stress softening is related to hydrodynamic strain amplification due to the presence of the filler. Based on this observation a micro-mechanical model of stress softening has been developed by referring to hydrodynamic reinforcement of the rubber matrix by rigid filler... 

Hydrodynamic reinforcement of the rubber matrix by the fraction of hard, rigid filler clusters with strong filler-filler bonds that have not been broken during previous deformations. 

The first addend is the equilibrium energy density stored in the extensively strained rubber matrix, which includes hydrodynamic reinforcement by a... 

In view of an illustration of the viscoelastic characteristics of the developed model, simulations of uniaxial stress-strain cycles in the small strain regime have been performed for various pre-strains, as depicted in Fig. 47b. Thereby, the material parameters obtained from the adaptation in Fig. 47a (Table 4, sample type C60) have been used. The dashed lines represent the polymer contributions, which include the pre-strain dependent hydrodynamic amplification of the polymer matrix. It becomes clear that in the small and medium strain regime a pronounced filler-induced hysteresis is predicted, due to the cyclic breakdown and re-aggregation of filler clusters. It can considered to be the main mechanism of energy dissipation of filler reinforced rubbers that appears even in the quasi-static limit. In addition, stress softening is present, also at small strains. It leads to the characteristic decline of the polymer contributions with rising pre-strain (dashed lines in... 

Most commercial systems like Mustang from Pall and Sartobind from Sartorius make use of functionalized microporous membranes. The fibrils reinforced membranes are (pleated) layered around a porous core. The feed is forced to permeate through the membranes in radial direction. This approach results in high area to volume ratio. The 3M and Mosaic Systems approach is different. Instead of functionalization of a porous support they make use of already functionalized beads, which are embedded in a porous support. In this approach, the beads are responsible for the capacity and selectivity where the porous matrix controls the hydrodynamics. The 3M modules consist of stacked flat sheet or pleated membranes, while Mosaic Systems makes use of porous fibers in which the active particles are embedded (Figure 3.23). 

Einstein developed the concept of hydrodynamic reinforcement which is expressed by the equation ... 

Figure 7.32. Hydrodynamic reinforcement factor vs. 111 ler volume traction. [Adapted, by permission, from Eggers H, Schummer P, Rubb. Chem. Technol., 69, No.2, 1996, 253-65.]...

The data obtained in this work show convincingly that the spontaneous loss of uniformity leading to the domain regime of a heterogeneous catalytic conversion should not be considered as an occasional and exotic event. On the contrary, it is a very common occurrence in catalysis. Nonuniformities of loading and hydrodynamic conditions in actual reactors are factors that only reinforce the stratification of the regime in most cases. 

Hydrodynamic Reinforcement and the Role of Polymer-Filler Interface. 599... 

HYDRODYNAMIC REINFORCEMENT AND THE ROLE OF POLYMER-FILLER INTERFACE... 

Extrapolation of the SANS data in [4] to the isotropic state confirms, indirectly, the presence of a diffuse PS-PI transition layer between filler and rubbery matrix with thickness A 0.5 nm around the PS domain with a mean filler radius of about 84 A. Excellent agreement between measured reinforcing factor and corresponding model predictions could be realized within a very recent approach of Huber and Vilgis [5] for the hydrodynamic reinforcement of rubbers filled with spherical fillers of core-shell structures [6]. 

This is the recent theory developed by Vilgis et al The theory involves very rigorous mathematical treatment. According to Vilgis et al. there are two different hydrodynamic regimes of reinforcement mechanisms elastomer. 

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