Catalysts rheological properties

Figures 20.13 and 20.14 describe the effect of dibutyltin dilaurate (DBTDL) on the tensile strength and tensile modulus for the 25/75 LCP/PEN blend fibers at draw ratios of 10 and 20 [13]. As expected, the addition of DBTDL slightly enhances the mechanical properties of the blends up to ca. 500 ppm of DBTDL. The optimum quantity of DBTDL seems to be about 500 ppm at a draw ratio of 20. However, the mechanical properties deteriorate when the concentration of catalyst exceeds this optimum level. From the previous relationships between the rheological properties and the mechanical properties, it can be discerned that the interfacial adhesion and the compatibility between the two phases, PEN and LCP, were enhanced. Hence, DBTDL can be used as a catalyst to achieve reactive compatibility in this blend system. This suggests the possibility of improving the interfacial adhesion between the immiscible polymer blends containing the LCP by reactive extrusion processing with a very short residence time.

Besides these positive effects, a major disadvantage is introduced a liquid barrier to direct access of gaseous H2 to the catalyst particle The rheological properties of the fluid are also deeply modified, because the viscosity of liquids is many orders of magnitude higher than for gases. Finally, properties such as solubility, molecular diffusivity, etc., of H2 in organic mixtures, difficult to measure and even to estimate, have a vital influence on the mass transport phenomena, which can be schematized as follows ... 

As in traditional chain polymerization, the molecular weights are controlled by the catalyst concentration. Thus the more catalyst used, the lower the molecular weights. SEC indicates quite high MW (>130 kDa), that likely contributes to good rheological properties. PSE heated in the TGA under Ar to 1000 °C, undergoes smooth mass loss... 

Figure 3a-b illustrate the LCB effect on the melt rheological properties. The response of the rheological behaviour to the copolymerisation ability and vinyl end group selectivity of the siloxy-substituted metallocenes has been investigated from their dynamic modulus curves. The frequency dependency of the dynamic modulus of the polyethenes produced with catalysts 2 is demonstrated in Fig. 3a. For comparison dynamic modulus for a linear polyethene, prepared by the catalyst -BuCp2ZrCl2, is shown in Fig. 3b. 

Isopova ct al. described the preparation of various perovskite-based monolithic catalysts for fuel combustion by extrusion of synthesized perovskite powders [14]. Blanco ct al. [25], Lachman and Williams [97], and del Valle et al. [98] reported titania-based and other monolithic catalysts by extrusion. The titania catalysts were tested in a coal-fired power pilot plant for electrostatic separation of fly-ash [98]. Lyakhova et al. studied the W03-doped titania-vanadia monolithic catalysis for selective catalytic reduction (SCR NOx conversion) by extrusion [26]. The rheological properties of the paste for extrusion and the effect of various organic plastisizers on catalytic activity in SCR were discussed. 

PET (80-70) / EEA-GMA (20-30) TSE at 280°C / mechanical properties / SEM / rheology / properties comparison to unfunctionalized rubbers / effects of amine catalyst addition Penco et al., 1995... 

The disilane fraction or pure SiCl2Me-SiCl2Me is heated to reflux and condenses in the catalyst bed. A stream of argon removes the volatile monosilanes formed, while the oligosilane mixture flows back into the flask. An improvement of the rheologic properties of the polysilane has heen achieved by co-polymerization of SiCl2Me-SiCl2Me with styrene or by... 

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