Vulcanization


Sulfur is a component of black gunpowder, and is used in the vulcanization of natural rubber and a fungicide. It is also used extensively in making phosphatic fertilizers. A tremendous tonnage is used to produce sulfuric acid, the most important manufactured chemical.  [c.39]

These compounds are commercially important as accelerators in the vulcanization of rubber (Scheme 83).  [c.260]

In natural rubber the attractive forces between neighboring polymer chains are relatively weak and there is little overall structural order The chains slide easily past one another when stretched and return in time to their disordered state when the distorting force IS removed The ability of a substance to recover its original shape after distortion is its elasticity The elasticity of natural rubber is satisfactory only within a limited temperature range it is too rigid when cold and too sticky when warm to be very useful Rubber s elasticity is improved by vulcanization a process dis covered by Charles Goodyear in 1839 When natural rubber is heated with sulfur a chemical reaction oc curs in which neighboring polyisoprene chains be come connected through covalent bonds to sulfur Although these sulfur bridges permit only limited movement of one chain with respect to another their presence ensures that the rubber will snap back to its original shape once the distorting force is removed  [c.408]

Originally, vulcanization implied heating natural rubber with sulfur, but the term is now also employed for curing polymers. When sulfur is employed, sulfide and disulfide cross-links form between polymer chains. This provides sufficient rigidity to prevent plastic flow. Plastic flow is a process in which coiled polymers slip past each other under an external deforming force when the force is released, the polymer chains do not completely return to their original positions.  [c.1011]

The polymer can be vulcanized to give a rubber with very good chemical (solvent) resistance, excellent resistance to aging and weathering, and good color retention in sunlight.  [c.1062]

Ethylene-propylene-diene rubber is polymerized from 60 parts ethylene, 40 parts propylene, and a small amount of nonconjugated diene. The nonconjugated diene permits sulfur vulcanization of the polymer instead of using peroxide.  [c.1064]

Natural rubber, cis-1,4-polyisoprene, cross-linked with sulfur. This reaction was discovered by Goodyear in 1839, making it both historically and commercially the most important process of this type. This reaction in particular and crosslinking in general are also called vulcanization.  [c.137]

Rubber vulcanization accelerators  [c.862]

Thiazole disulfides absorb at 235 and 258 nm (320-322) and characteristic infrared bands are reported in Ref. 320. The activities of 2-cyclo-hexyldithiomethylthiazoles as vulcanization accelerators have been correlated with their mass-spectral fragmentation patterns (322).  [c.412]

Copolymerization can be carried out with styrene, acetonitrile, vinyl chloride, methyl acrylate, vinylpyridines, 2-vinylfurans, and so forth. The addition of 2-substituted thiazoles to different dienes or mixtures of dienes with other vinyl compounds often increases the rate of polymeriza tion and improves the tensile strength and the rate of cure of the final polymers. This allows vulcanization at lower temperature, or with reduced amounts of accelerators and vulcanizing agents.  [c.398]


See pages that mention the term Vulcanization : [c.10]    [c.35]    [c.52]    [c.61]    [c.73]    [c.108]    [c.136]    [c.144]    [c.148]    [c.204]    [c.254]    [c.293]    [c.347]    [c.396]    [c.423]    [c.423]    [c.428]    [c.120]    [c.397]    [c.438]    [c.440]    [c.440]    [c.1005]    [c.1011]    [c.153]    [c.338]    [c.338]    [c.349]    [c.456]    [c.604]    [c.943]    [c.989]    [c.989]    [c.1061]   
Carey organic chemistry (0) -- [ c.408 ]

Organic chemistry (0) -- [ c.408 ]