Rubber-filler interactions and

Leblanc, J. L. 2002. Rubber-filler interactions and rheological properties in filled compounds. Progress in Polymer Science 27 627-687. 

Any changes to filler particles SFE and its components effect on mechanical properties of rubber vulcanizates filled with the modified filler. Improvement of mechanical properties of the materials originates increased rubber-filler interaction and better dispersion of filler particles in rubber matrix. 

Payne has proposed a classical splitting of all the effects involved in rubber reinforcement which can be further refined with respect to contemporary views (Figure 5.40). In addition to the intrinsic properties of the elastomer network, the CB particles bring first mere hydrodynamic effects, which are further enhanced by strong rubber-filler interactions, and interaggregate interactions which are weaker and depending on strain level. 

Kraus equation and Kraus plots based on swelling data are largely used to explore the rubber-filler interaction in conventional composites [62]. Bandyopadhyay et al. [38] have employed the same equation for understanding the reinforcement behavior in ACM-silica and ENR-silica hybrid... 

The important yet unexpected result is that in NR-s-SBR (solution) blends, carbon black preferably locates in the interphase, especially when the rubber-filler interaction is similar for both polymers. In this case, the carbon black volume fraction is 0.6 for the interphase, 0.24 for s-SBR phase, and only 0.09 in the NR phase. The higher amount in SBR phase could be due to the presence of aromatic structure both in the black and the rubber. Further, carbon black is less compatible with NR-cE-1,4 BR blend than NR-s-SBR blend because of the crystallization tendency of the former blend. There is a preferential partition of carbon black in favor of cis-1,4 BR, a significant lower partition coefficient compared to NR-s-SBR. Further, it was observed that the partition coefficient decreases with increased filler loading. In the EPDM-BR blend, the partition coefficient is as large as 3 in favor of BR. 

See, J.L. Leblanc, Insight into elastomer—filler interactions and their role in the processing behaviour of mbber compounds, Prog. Rubber Plast. TechnoL, 10/2, 110-129, 1994, for a pictorial representation of such a morphology. 

It is well known that the lower the AGM value, the better is the rubber-filler interaction. As for the Ch/MEK solvent combination x is zero, hence the A CN, cp2X term of (27) is zero for such a solvent combination. In all other solvent combinations, where x 0. the A l N r tp2X term of (27) is positive. Thus, AGM of the system for the Ch/MEK solvent combination is the least, and dispersion (if clay is in the rubber matrix) is also best in this solvent combination, giving rise to the highest polymer-filler interaction. 

Gilliland, E. R., and GutofF, E. B. (1960). Rubber-filler interactions solution adsorption studies. J. Appl. Polym. Sci. 3 26-42. 

Lopour P et al. (1993) Silicone rubber-hydrogel composites as polymeric biomaterials. IV Silicone matrix-hydrogel filler interaction and mechanical properties. Biomaterials 14(14) 1051—1055... 

The rabber modulus increases with an increasing volume fraction of Aerosil. The modulus increase can be caused by the elastomer-filler and filler-filler interactions and by an increase of effective filler content. A very sharp peak for the tanZ is observed at 163 K for an unfilled crosslinked sample. This maximum corresponds to the glass transition of the rubber. Furthermore, it is observed that the Tg of the rubber does not change in the presence of filler. However, the second maximum of to 5 can be seen in the vicinity of 200 K for filled samples. The intensity of this maximum becomes more pronounced with increasing Aerosil content. This observation is in agreement with the results of the h and Ty relaxation study, as demonstrated in Fig. 4a and 6, respectively. Therefore, it seems reasonable to assign the maximum for at 200 K to the motion of adsorbed chain units. This maximum is observed at a lower temperature than the H and T, minimum for the adsorbed chain units (at about 280 K) due to difference in frequency of these methods 1.6 Hz and 46-90 MHz, respectively. 

Figure 15.33 shows benzene uptake by natural rubber samples. Filled samples absorb less solvent (lower swelling). The carbon black containing sample had a lower benzene uptake than the silica filled sample. The lower swelling of the carbon black containing sample is due to high bound rubber content, the crosslink density of the black filled vulcanizate, and a strong rubber-filler interaction. 

In attempting to predict the direction that future research in carbon black technology will follow, a review of the literature suggests that carbon black-elastomer interactions will provide the most potential to enhance compound performance. Le Bras demonstrated that carboxyl, phenolic, quinone, and other functional groups on the carbon black surface react with the polymer and provided evidence that chemical crosslinks exist between these materials in vul-canizates (LeBras and Papirer, 1979). Ayala et al. (1990, 1990) determined a rubber-filler interaction parameter directly from vulcanizatemeasurements. The authors identified the ratio a jn, where a = slope of the stress-strain curve that relates to the black-polymer interaction, and n = the ratio of dynamic modulus E at 1 and 25% strain amplitude and is a measure of filler-filler interaction. This interaction parameter emphasizes the contribution of carbon black-polymer interactions and reduces the influence of physical phenomena associated with networking. Use of this defined parameter enabled a number of conclusions to be made ... 

Surface acidity is controlled by the hydroxyl groups on the surface of the silica and is intermediate between those of P-OH and B-OH. This intrinsic acidity can influence peroxide vulcanization, although in sulfur curing, there is no significant effect. Rubber-filler interaction is affected by these sites. 

Both the Japanese Synthetic Rubber Company and Nippon Zeon have reported that anionically prepared elastomers that are functionally terminated by active lithium can be chain terminated with Michler ketone, benzophenone, and a variety of enamide groups. Moreover, these chains can be terminated with silicone or tin metals. Chain end functionalization did not change the viscoelasticity of the polymer chains but rather dramatically improved the elastomer-filler interaction and, therefore, reduced its hysteretic properties. 

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