Filled rubbers chain grafting

The rubber particles were examined with an electron microscope after the sample was treated with osmium tetroxide (27). The micrograph (Figure 7) clearly indicates the porous nature of the rubber phase and the occlusion of polystyrene. We therefore classify this type of rubber phase as filled graft rubber. Since grafting takes place before and after the rubber chain is coiled, therefore, for this case, the monomer is grafted onto the rubber both within and without the rubber phase. Polybutadiene is thus made more compatible to the polymer matrix surrounding the rubber phase and the polymer filling the rubber phase. Here we have an... 

In the rubber industry the distribution of particle size is considered to be important as it affects the mechanical properties and performance. Aggregate size also varies with particle size. Aggregates can have any shape or morphology. The fundamental property of the filler used in a filled elastomer is the particle size. This affects the reinforcement of elastomer most strongly. One of the sources of reinforcement between the carbon black surface and the rubber matrix is the van der Waals force attraction. Also, rubber chains are grafted onto the carbon black surface by covalent bonds. The interaction is caused by a reaction between the functional group at the carbon black particle surface and free radicals on polymer chains. Hence, filler-rubber interface is made up of complex physical-chemical interaction. The adhesion at the rubber-filler interface also affects the reinforcement of rubber. When the polymer composites are filled with spherical filler (aspect ratio of the particle is equal to unity), the modulus of the composite depends on the modulus, density, size, shape, volume ratio, and number of the incorporated particles. 

The results are shown in Fig. 9. A small amount of the filler strongly increases the energy contribution which is in full contradiction to the assumed increase in the concentration of active network chains caused by the filler. Curve 2 summarizes the results for filled PDMS rubber and for PDMS block and graft copolymers. It is seen that below 20% of the filler or hard phase, the energy contribution is practically independent of the amount of hard phase, but then a considerable increase of (AU/W)v>t is observed. Although in all these cases the energy contribution is... 

The mobility in both tightly and loosely bound BR and isoprene rubbers increases, and the fraction of bound rubber decreases with a decreasing concentration of silanol groups on the silica surface [124], This led to the suggestion that the silanol groups on the silica surface are active sites for the chain adsorption. The grafting of aliphatic chains to the silica surface leads to a decrease in BR-silica interactions [125]. The effect is less pronounced in BR filled with carbon black containing aliphatic chains at the surface. 

---