Rubber Vulcanizates

Important properties of TPE s are their flexibility, softness, and resilience. However, compared to vulcanizable rubbers, they are inferior in resistance to deformation and solvents. 

G.R. Homed and B.H. Park, The mechanism of carbon black reinforcement of SBR and NR vulcanizates. Rubber Chem. TechnoL, 72, 946-959, 1999. 

Coran, A.Y. and Patel, R. Rubber-thermoplastic compositions. Part I. EPDM-polypropylene thermoplastic vulcanizates. Rubber Chem. TechnoL, 5, 141, 1980. 

Amberlang, J.C. and Smith, G.E.P., Jr., Behavior of reclaiming agents in sulfur and nonsulfur GR-S vulcanizates, Rubber Chem. TechnoL, 28, 322, 1955. 

Conan t F.S, The Firestone Tyre and Rubber Company, Akron Ohio, Physical Testing of Vulcanizates, Rubber Technology Second Edition, 1973 by Maurice Morton, Van Nostrand Reinhold Company, NY. 

The molecular weights estimated are 4.5 x 105 for ECH polymer and 1.4 x 106 for ECH/EO copolymers. Homopolymer ECH (I) and copolymer ECH/EO (2) are solvent-resistant rubbers. Copolymers with AGE are S-vulcanizable rubbers. 

Ethylene has been co-polymerized with virtually any conceivable a-olefin, from propylene to vinyl-terminated PE and PP macromonomers. Ethylene/propylene (E/P) copolymerization to produce saturated rubbers and ethylene/propylene/diene (EPD) terpolymerization to produce unsaturated, vulcanizable rubbers will be discussed in Section 4.09.4.1.3. 1-Butene, 1-hexene, and 1-octene are the most commonly used co-monomers for the production of LLDPE. Ethylene/octene co-polymers, developed by Dow and marketed under the Engage tradename, have been shown to have improved thermal properties compared to ethylene/butene and ethylene/hexene co-polymers.503 In ethylene/a-olefin (E/O) co-polymeriza-tions, the critical parameters are co-monomer reactivity and co-monomer distribution . The former is most conveniently described by the relative reactivity parameter, R, defined as the ratio between polymer composition and reactor medium composition. 

Nagata, N. Kobatake, T. Wantanabe, H. Uedia, A. Effect of chemical modification of solution-polymerized rubber on dynamic mechanical properties in carbon-black filled vulcanizates. Rubber Chem. Technol. 1987, 60, 837. 

Selker, M.L. Kemp, A.R. Sulfur linkage in vulcanized rubber acetone extraction of vulcanizates. Rubber Chem. Technol. 1949, 22, 8. 

Gregg E.C., Jr. Sulfur crosslinks in polybutadiene vulcanizates. Rubber Chem. Technol. 1969, 42, 1136. 

Studebaker, M.L. Nabors, L.G. Sulfur group analyses in natural rubber vulcanizates. Rubber Chem. Technol. 1959, 32, 941. 

In retrospect, the pathway to discovery was not direct. We were looking for improved vulcanizable rubbers. Instead we discovered rubbers that did not require vulcanization (Figure 2). However, the events listed in Table II suggest that one could have found a more direct pathway to the discovery of the importance of two interconnecting phases in polymers. 

Plastic sealants appeared on the world market in the 1940s and, despite stiff competition from elastic sealants made on the base of vulcanizable rubbers, they are still extensively applicable today. 

The toughness and durability of the bond may be improved by using vulcanizable rubber solution adhesives. These are normally supplied as two components which are mixed prior to use. Component A is prepared as follows ... 

Vulcanizate Rubber that had been irreversibly transformed from predominantly plastic to predominantly elastic material by vulcanization (chemical curing or cross-linking) using heat, vuleanization agents, accelerants, etc. 

Schulten, H.-R., Plage, B., and Lattimer, R. R, Pyrolysis-field ionization mass sp>ectrometry of rubber vulcanizates. Rubber Chem. Technol, 62, 698,1989. 

Wang, M. J. 1998. Effect of polymer-filler and filler-filler interactions on dynamic properties of filled vulcanizates. Rubber Chemistry and Technology 71 520-589. 

This chapter is a perspective of the science and technology of elastomers and does not include a market analysis. Nevertheless, we must mention that the global market for these materials is large (Fig. 4.1). Global vulcanizable (conventional, vulcanizable) rubber consumption was about 20 million metric tons in 2004, whereas thermoplastic elastomer (TPE) consumption was about 1.5 million metric tons. The consumption of conventional rubbers is growing at a rate of about 3 to 4 percent, whereas the growth of TPE consumption is growing at about twice that rate. 

The first rubber to be discovered and used by industry was natural rubber. After quite a long time, synthetic rubbers were introduced. In this section, we consider natural and synthetic conventional (i.e., vulcanizable) rubbers. There is some emphasis on the science and technology of natural rubber for two reasons (1) natural rubber has been the most studied, and (2) many of the synthetic elastomers are quite similar to natural rubber in many respects. 

In contrast to the rigid TPOs described above, low-modulus/flexible grades of TPO blends are also produced commercially. In flexible TPOs, the rubber content can be as high as 60 %, and in some cases, the dispersed rubber may also be partially cross-linked during the mixing without losing the thermoplastic character of the matrix. However, the latter type of dynamically vulcanized elastomeric alloys or thermoplastic vulcanizate rubbers (TPVs) are considered as a separate class of elastomeric materials and hence will be discussed under elastomer blends. On the other hand, the soft TPO blends discussed here contain a low-modulus olefln copolymer elastomer as the major component with some polypropylene added to impart melt processability. 

Hamed GR, Huang MY (1998) Tensile and tear behavior of anisotropic double networks of a black-filled natural rubber vulcanizate. Rubber Chem Technol 71(5) 846-860... 

Improved tensile strength Rubber crosslinker Thermoplastic rubbers Vulcanizable rubbers Rubber composites with improved impact... 

Sanderson discovered the adhesion of brass to sulfiir-vulcanizable rubber over 100 years ago. Interest in the mechanism of this bond formation has been spurred on by the advent of the steel-belted radial tire. Buchan and Rae postulated that chemical bonds are formed between copper atoms on the brass surface and sulfur atoms of crosslinked polymer molecules ... 

Ansarifar, A., et al. Reinforcing Effect of Silica and Silane Fillers on the Properties of Some Natural Rubber Vulcanizates. Rubber Chemistry and Technology, 2003. 76(5) 1290. 

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