Novel Reinforced Elastomers

Some elucidation of the mechanism of elastomer reinforcement is being obtained by precipitating chemically-generated fillers into network structures rather than blending badly agglomerated filler particles into elastomers prior to their cross-linking. This has been done for a variety of fillers, for example, silica by hydrolysis of organosilicates, titania from titanates, alumina from aluminates, etc. [85-87], A typical, and important, reaction is the acid- or base-catalyzed hydrolysis of tetraethylorthosilicate  

Reactions of this type are much used by the ceramists in the new sol-gel chemical route to high-performance ceramics [208]. In the ceramics area itself, the 

If the hydrolyses in organosilicate-polymer systems are carried out with increased amounts of the silicate, bicontinuous phases can be obtained (with the silica and polymer phases interpenetrating one another) [213]. At still-higher concentrations of the silicate, the silica generated becomes the continuous phase, with the polymer dispersed in it. The result is a polymer-modified ceramic, variously called an ORMOCER [214,215], CERAMER [216,217], or POLY-CERAM [218,219]. It is obviously of considerable importance to determine how the elastomeric phase modifies the ceramic in which it is dispersed. 

Reinforcing fillers can be deformed from their usual approximately spherical shapes in a number of ways. For example, if the particles are a glassy polymer such as polystyrene (PS), then deforming the matrix in which they reside at a 

Uniaxial deformations give prolate (needle-shaped) ellipsoids, and biaxial deformations give oblate (disc-shaped) ellipsoids [220,221], Prolate particles can be thought of as a conceptual bridge between the roughly spherical particles used to reinforce elastomers and the long fibers frequently used for this purpose in thermoplastics and thermosets. Similarly, oblate particles can be considered as analogues of the much-studied clay platelets used to reinforce a variety of materials [70-73], but with dimensions that are controllable. In the case of non-spherical particles, their orientations are also of considerable importance. One interest here is the anisotropic reinforcements such particles provide, and there have been simulations to better understand the mechanical properties of such composites [86,222], 

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Bomal, Y, Chevallier, Y, Cochet, P., 1995. Novel method for preparing precipitated silica, novel aluminium-containing precipitated sihcas, and use thereof for reinforcing elastomers. Patent W09630303. 

In this chapter, we first describe the stmcture of networks, followed by the discussion of the simple classical models of elasticity and the more advanced theories such as the constraint and the tube models. We also give the molecular interpretation of coefficients obtained from the phenomenological theories. Some simulations relevant to mbberlike elasticity are then described, followed by a discussion of responsive gels because of their increasing interest to many groups. We then discuss the thermoelastic (force-temperature) behavior of networks, followed by the information on multimodal networks, liquid-crystalline (LG) elastomers, novel reinforcing fillers, and characterization methods. 

Mai-k J E (1992) Novel reinforcement techniques for elastomers, J Appl Polym Sci Applied Polymer Symposium 50 273-282. 

J. E. Mark, Novel reinforcement techniques for elastomers , J. Appl. Polym. Sci. Appl. Polym. Symp. 1992, 50, 273. 

Historically, polysiloxane elastomers have been reinforced with micron scale particles such as amorphous inorganic silica to form polysiloxane microcomposites. However, with the continued growth of new fields such as soft nanolithography, flexible polymer electronics and biomedical implant technology, there is an ever increasing demand for polysiloxane materials with better defined, improved and novel physical, chemical and mechanical properties. In line with these trends, researchers have turned towards the development of polysiloxane nanocomposites systems which incorporate a heterogeneous second phase on the nanometer scale. Over the last decade, there has been much interest in polymeric nanocomposite materials and the reader is directed towards the reviews by Alexandre and Dubois (4) or Joshi and Bhupendra (5) on the subject. 

For a variety of technical reasons the development of aromatic polyamides was much slower in comparison. Commercially introduced in 1961, the aromatic polyamides have expanded the maximum temperature well above 200°C. High-tenacity, high-modulus polyamide fibers (aramid fibers) have provided new levels of properties ideally suited for tire reinforcement. More recently there has been considerable interest in some new aromatic glassy polymers, in thermoplastic polyamide elastomers, and in a variety of other novel materials. 

This chapter has reviewed both the types and the properties of elastomers, compounding with a range of filler or reinforcement systems such as carbon black, and enhancement of tiller performance by novel use of compounding ingredients such as silane coupling agents. Other issues such as antioxidant systems and vulcanization systems were also discussed. The role of the modern materials scientist in the tire and rubber industry is to use materials to improve current products and develop new products. Four key parameters govern this development process ... 

Liaw, W.-C. Cheng, Y.-L. Huang, P.-C. Chen, K.-P. Fu, L.-W., SiO Reinforcement and Morphology of a Novel Poly(imide-siloxane)-Based Thermal Plastic Elastomer Composite. Polym. J. 2009,41,822-834. 

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