Elastomeric compositions prepared

H.J. Barraza, F. Pompeo, E.A. O Rear, and D.E. Resasco, SWNT-filled thermoplastic and elastomeric composites prepared by miniemulsion polymerization. Nano Lett. 2, 797-802 (2002). 

Other Elastomeric Compositions Prepared by Dynamic Vulcanization... 

Excellent elastomeric NBR-nylon compositions have also been prepared by dynamic vulcanization during the melt-mixing of intimate blends of NBR with various nylons. In this case, the effect of curatives was complicated by the fact that some nitrile rubbers tend to self-cure at temperatures of mixing. Sulfur, phenolic, maleimide, or peroxide curatives can be used. The thermoplastic elastomeric compositions prepared by the dynamic vulcanization of nylon-NBR blends are highly resistant to hot oil. As in the case of the EPDM-polyolefin blends, increases in the amount of rubber in the composition reduce stiffness but increase resistance to permanent set. 

Waddell et al. (3) prepared elastomeric compositions effective as air barriers from novel C4 to C7 isoolefin oligomers and were free of long-chain branching. 

The last contribution in the prevailing volume deals with the application of a relatively new class of materials based on the addition of (electron-beam) activated polytetrafhioroethylene (PTFE) powder in rubber matrixes for preparing PTFE-based elastomeric composites. Besides other properties, the remarkably lower friction coefficient of PTFE enables its utilization for tribological applications. However, PTFE in rubbers has not been fully explored mainly due to its inherent chemical inertness and incompatibility. The present work signifies the electron modification of PTFE powder to improve its compatibility with rubber matrixes, the state of the art regarding its application in rubbers, and the preparation of PTFE-based elastomeric composites for several tribological applications. 

Fischer (1973) used the DV process to prepare compositions containing partially vulcanized rubber. It has since been found that improved, very strong elastomeric compositions of EPDM and polypropylene could be prepared by... 

Two-step fabrication of Sylgard/poly(e-caprolactone) (PCL) shape memory elastomeric composites. (Adapted from Luo, X., and Mather, P. T. 2009. Preparation and characterization of shape memory elastomeric composites. Macromolecules 42 7251-7253. Copyright ACS. Reproduced with permission.)... 

Luo, X., and Mather, R T. 2009. Preparation and characterization of shape memory elastomeric composites. Macromolecules 42 7251-7253. 

Dynamic vulcanization (DV) is also considered. DV is the crosslinking of one polymer in a blend of polymers during its mixing therein, all polymers of the blend being in the molten state. The process is used in the preparation of thermoplastic elastomeric compositions from rubber-plastic blends. 

The addition of filler results in a reduction in tan 8 iax, which is attributed to the dilution effect, that is, the viscous response of the elastomeric phase is diluted by the nonviscous response of fillers. Incorporation of nanoparticles like CNTs are reported to reduce the height of the tan 8 peak considerably and even a small amount of CNTs increase the storage modulus above the glass transition temperature. MWCNT-mbber blend composite prepared in the machine direction showed high storage modulus and low tan 8 iax because of the greater ahgnment and dispersion of most MWCNTs in the sample. 

PMMA migrate to the interfaces (i.e. act as a surfactant) and effectively compatibilise the polymer blend [234], TEM analysis of nanostructured cured elastomeric sealant compositions prepared by sonicating a mixture of silylated apophyUite filler in PDMS showed unambiguously that silicate layers are exfoliated [235]. Watkins et al. [174] have studied platinum/poly(4-methyl-l-pentene) (PMP) nanocomposites by means of TEM. For nanocomposite science and technology, cfr. also ref. [236]. 

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