Elastomer solution

AGE-Gontaining Elastomers. The manufacturing process for ECH—AGE, ECH—EO—AGE, ECH—PO—AGE, and PO—AGE is similar to that described for the ECH and ECH—EO elastomers. Solution polymerization is carried out in aromatic solvents. Slurry systems have been reported for PO—AGE (39,40). When monomer reactivity ratios are compared, AGE (and PO) are approximately 1.5 times more reactive than ECH. Since ECH is slightly less reactive than PO and AGE and considerably less reactive than EO, background monomer concentration must be controlled in ECH—AGE, ECH—EO—AGE, and ECH—PO—AGE synthesis in order to obtain a uniform product of the desired monomer composition. This is not necessary for the PO—AGE elastomer, as a copolymer of the same composition as the monomer charge is produced. AGE content of all these polymers is fairly low, less than 10%. Methods of molecular weight control, antioxidant addition, and product work-up are similar to those used for the ECH polymers described. 

The solution is transformed to an oil-in-oil emulsion in which a polystyrene solution forms the disperse phase and the elastomer polyester component solution the continuous phase. The point of phase separation is observed experimentally by the onset of turbidity, due to the Tyndall effect. The conversion required for phase separation to occur depends basically on the solubility of the polystyrene chains in the elastomer solution, which in turn is governed by the elastomer concentration and compatibility of the two polymers. 

Elastomers Solutions of NR have been used for laminating textiles for over a century. The Macintosh raincoat, invented in 1825, consisted of two sheets of cotton adhered by an inner layer of natural rubber. SBR is used as an adhesive in carpet backing and packaging. Neoprene (polychloroprene) may be blended with a terpene or phenolic resin and used as a contact adhesive for shoes and furniture. 

All polymer solutions were ozonized (1) by passing a stream of ozonized oxygen, supplying approximately 1 X 10 mole of ozone per hour, flowing at a rate of 0.05 cubic meter per hour through 600 ml. of elastomer solution, at room temperature. Aliquot portions of the ozonized solution were removed at preselected time intervals for measurement with a Cannon-Fenske-Ostwald viscometer, having a calibration constant of 0.01698 centistoke per second at 25° C. 

Elastomeric films with Cl dispersed in the polymer matrix volume as liquid drops are formed by pouring of emulsions in which the dispersive phase is the inhibitor and the dispersion medium is the elastomer solute [53]. 

A typical example of preparation of such rubber adhesive solutions is natural rubber, polychloroprene, styrene-butadiene rubbers, nitrile rubber or others, mixed and compounded in the conventional manner using internal (Banbury) mixers or mills. The unvulcanized rubber mix is then made into a solution (or cement). Dry aromatic solvents such as xylene, toluene or chlorobenzene (900 parts of solvent per hundred of rubber mix) are added and agitated to dissolve the elastomer. Forty parts of MDI are added to the elastomer solution with agitation. The cements are stored at room temperature the NR cement is stable for 7 days, the SBR keeps for 3-4 days and the polychloroprene cement is stable for 3 days. 

Developments in the anionic polymerization of butadiene were adopted for manufacture of solution SBR. While the emulsion process gave primarily 1,4-cis microstructure in the final product, the solution process gave a lower level of 1,4-cis level, typically around 45%. Furthermore the cis content as well as 1,2-vinyl content could be modified. In addition, better control of branching and molecular weight distribution attainable with anionic process made solution SBR suitable for tire applications, challenging the established use of cold SBR. Developments in the anionic process also led to new copolymer structures in which blocks of polybutadiene can be coupled to blocks of polystyrene, generating a imique class of polymers. Developments in SB block copolymers led to new materials which were thermoplastic in character, unlike SBR which is an elastomer. Solution-processes-based thermoplastic SB block copolymers form the basis of the transparent impact polystyrene (TIPS) as well as the other block copolymers used in plastics modification. The block copolymers of styrene and butadiene are the subject of the second part of this article. 

Ash a 10 g sample of elastomer solution in a platinum crucible by charring on a hot plate followed by heating over a meker burner. Add 10 cm of water and 2 cm of... 

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