Tacking rapid

Good machinability Easy cleanup Good wet tack Rapid setting speed Rapid thickening response Good heat resistance Low degree of blocking Crosslinkability... 

Bromine although it adds rapidly to alkenes is too weak an electrophile to react at an appreciable rate with benzene A catalyst that increases the electrophilic properties of bromine must be present Somehow carpet tacks can do this How7... 

Cyanoacrylate adhesives (Super-Glues) are materials which rapidly polymerize at room temperature. The standard monomer for a cyanoacrylate adhesive is ethyl 2-cyanoacrylate [7085-85-0], which readily undergoes anionic polymerization. Very rapid cure of these materials has made them widely used in the electronics industry for speaker magnet mounting, as weU as for wire tacking and other apphcations requiring rapid assembly. Anionic polymerization of a cyanoacrylate adhesive is normally initiated by water. Therefore, atmospheric humidity or the surface moisture content must be at a certain level for polymerization to take place. These adhesives are not cross-linked as are the surface-activated acryhcs. Rather, the cyanoacrylate material is a thermoplastic, and thus, the adhesives typically have poor temperature resistance. 

Chlorinated rubber is also used to promote the adhesion of solvent-borne CR adhesives to metals and plasticized PVC. Addition of a low molecular weight chlorinated rubber (containing about 65 wt% chlorine) improves the shear strength and creep resistance of polychloroprene adhesives [75] but a reduction in open time is also produced. A heat reactivation (process in which the surface of the adhesive film is raised to 90-100°C to destroy the crystallinity of the film and allowing diffusion to produce polymer chain interlocking more rapidly) restores tack to the polychloroprene adhesives. 

The open tack time of the CR adhesives partially depends on the evaporation rate of the solvent blend. If a solvent evaporates slowly, the CR adhesive will retain tack longer, whereas if the solvent evaporates quickly, the cohesive strength will develop more rapidly. According to Table 13, addition of small amounts of xylene (generally lower than 5%) will increase the open time of CR adhesives. 

Their crystallization behavior compares with natural rubber, as follows (1) their rate of crystallization is more rapid and (2) their amount of crystallinity is temperature dependent, but considerably less strain dependent. These experimental rubbers have excellent green strength and building tack. 

This adhesive is a resin/solvent adhesive material compounded to supply satisfactory initial tack. The solvent system has been carefully selected for somewhat rapid evaporation, thereby requiring minimum temperature and ventilation. Useful in textiles and paper board industries. 

High humidity (85%) caused a drastic increase in tack-free time when the substrate was maintained at 35°C or less. When the substrate temperature was raised to 45°C, the effect of high humidity on tack-free time was overcome and rapid cure was observed. Under commercial UV curing conditions (i.e., multiple 200 watt per inch lamps and no control of substrate temperature), coatings would ordinarily reach or exceed 45°C on exposure to the mercury arcs and this would tend to obscure the effects of high humidity. 

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