Epoxidized rubber

Another approach to the formation of the oxirane groups is the peroxidation of a carbon-carbon double bond. Various types of oligomers fall into this category epoxidized oils, epoxidized rubbers, and cycloaliphatic... 

One of the newer developments in adhesives is the growing use of ultraviolet light or electron beam radiation to cure adhesives. Adhesives designed for UV- or E-beam curing are usually pressure sensitive or hot-melt systems based on acrylates, functional rubbers, or epoxidized rubbers, and use special UV or EB lamps to provide the cure. These systems can provide greatiy improved heat resistance compared to hot melts, and avoid the soivent emission problems of some of the solvent-based systems with which they compete. 

A. Najari, P. Lang, P.C. Lacaze, and D. Mauer, A new organofunctional methoxysilane bilayer system for promoting adhesion of epoxidized rubber to zinc. Prog. Org. Coatings, 64, 392 04 (2009). 

The successful epoxidation of NR, by employing a hydrogen peroxide/formic acid system under controlled conditions, has ensured epoxidized rubber (ENR) its place in the elastomer market. Essentially, ENR of any desired level of epoxidation ranging from 1 to 90% can be prepared. Increasing the level of epoxidation systematically changes the properties of the rubber. The increase in Jg and Mooney viscosity of ENR with increase in epoxidation level is indicated in Table 12.5. Currently ENR 10, 25, 50 and 60 (10, 25, 50 and 60% mole epoxidation, respectively) can be found on the market. Scheme 12.4 shows the structural formulae of ENR. 

A vulcanized sample, obtained from a reference mixture, contained mainly SBR-2 non epoxidized and precipitated silica, presents a value of the storage modulus (G ) at low amplitude of deformation, which is 4 times higher than that value showed by a mixture of SBR-2(ep7)/silica. This reduction of G shows a slightly network, due to the favorable energetically interaction between epoxy groups of the epoxidized rubber and the sUanol groups present onto the silica surface. Because of that, it is possible to have a better dispersion leading to a reduction of the Payne effect (Fig. 20). 

Fig. 22 Schema of a proposed for the epoxidized rubber-silica interaction...

Roginovskaia, G. E, Mechanism of formation of phase structure in epoxide-rubber systems, Vysokomol. Soedin., A 25, 1979, 1983 (Russian). 

Table 5. Physical Properties of Black-Filled Epoxidized Natural Rubber ...

The first type includes vulcanising agents, such as sulphur, selenium and sulphur monochloride, for diene rubbers formaldehyde for phenolics diisocyanates for reaction with hydrogen atoms in polyesters and polyethers and polyamines in fluoroelastomers and epoxide resins. Perhaps the most well-known cross-linking initiators are peroxides, which initiate a double-bond... 

Low molecular weight liquid nitrile rubbers with vinyl, carboxyl or mercaptan reactive end groups have been used with acrylic adhesives, epoxide resins and polyesters. Japanese workers have produced interesting butadiene-acrylonitrile alternating copolymers using Ziegler-Natta-type catalysts that are capable of some degree of ciystallisation. 

The polysulphides used are relatively mobile liquids with viscosities of about 10 poise and are thus useful as reactive diluents. They may be employed in any ratio with epoxide and produets will range from soft rubbers, where only polysulphides are employed, to hard resins using only epoxide. 

In all the compositions, the DCP-cured blends showed better properties than the corresponding unvulcanized samples. Choudhary et al. [30] further demonstrated the use of EPDM, chlorinated PE, chlorosulfo-nated PE, maleic anhydride modified polyethylene, and blends of epoxidized natural rubber-sulfonated EPDM as compatibilizers in NR-LDPE (low-density PE) blends. 

ATBN - amine terminated nitrile rubber X - Flory Huggins interaction parameter CPE - carboxylated polyethylene d - width at half height of the copolymer profile given by Kuhn statistical segment length DMAE - dimethyl amino ethanol r - interfacial tension reduction d - particle size reduction DSC - differential scanning calorimetry EMA - ethylene methyl acrylate copolymer ENR - epoxidized natural rubber EOR - ethylene olefin rubber EPDM - ethylene propylene diene monomer EPM - ethylene propylene monomer rubber EPR - ethylene propylene rubber EPR-g-SA - succinic anhydride grafted ethylene propylene rubber... 

They have studied the properties of NR-epoxidized natural rubber (ENR) blend nanocomposites also. Vulcanization kinetics of natural mbber-based nanocomposite was also smdied. The effect of different nanoclays on the properties of NR-based nanocomposite was studied. The tensile properties of different nanocomposites are shown in Figure 2.7 [33]. 

FIGURE 3.12 Morphology of mbber-silica hybrid composites synthesized from solution process using different solvents (a) and (b) are the scanning electron microscopic (SEM) pictures of acrylic rubber (ACM)-silica hybrid composites prepared from THF (T) and ethyl acetate (EAc) (E) and (c) and (d) are the transmission electron microscopic (TEM) pictures of epoxidized natural rubber (ENR)-siUca hybrid composites synthesized from THF and chloroform (CH). (From Bandyopadhyay, A., De Sarkar, M., and Bhowmick, A.K., J. Appl. Polym. Sci., 95, 1418, 2005 and Bandyopadhyay, A., De Sarkar, M., and Bhowmick, A.K., J. Mater. Sci., 40, 53, 2005. Courtesy of Wiley InterScience and Springer, respectively.)... 

FIGURE 3.16 Morphology and visual appearance of acrylic rubber (ACM)-silica and epoxidized natural rubber (ENR)-silica hybrid composites prepared from different pH ranges (a) transmission electron microscopic (TEM) picture of ACM-siUca in pH 1.0-2.0, (b) scanning electron microscopic (SEM) picture of ACM-siUca in pH 5.0-6.0, (c) SEM image of ACM-siUca in pH 9.0-10.0, (d) TEM picture of ENR-silica in pH... 

FIGURE 3.19 Comparative Kraus plots of acrylic rubber (ACM)-silica and epoxidized natural rubber (ENR)-silica hybrid nanocomposites at different in situ silica concentrations. (From Bandyopadhyay, A., De Sarkar, M., and Bhowmick, A.K., J. Polym. Sci., Part B Polym. Phys., 43, 2399, 2005. Courtesy of Wiley InterScience.)... 

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