DEVELOPMENT OF NEW POLYMERS FOR AIRCRAFT APPLICATION
Progress rept. no. 4, 1 June 1952-31 July 1952
CINCINNATI UNIV OH APPLIED SCIENCE RESEARCH LAB
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Chloroprene-methacrylic acid copolymers Optimum room-temperature cures were achieved with several agents after 10 to 14 days. The use of heat with metal oxide cures appeared unnecessary. Room-temperature cured specimens having tensile strengths of 2300 to 7900 psi were prepared for rain-erosion tests. Films cured with Zimate and diaminodiphenylmethane exhibited little change in tensile strength after aging for 2 mos higher elongations were accompanied by improved permanent sets. With an MgO cure, tensile and elastic properties improved on aging. A Goodyear rain-erosion-resistant material had a better tensile strength, elongation, and recovery after aging. A high modulus for creep specimens was associated with an effective cure. No significant differences were observed in rain erosion caused by loading. Chloroprene- methacrylamide copolymers Reproducibility of results can be achieved by controlling 1 the variation of film-conditioning time between curing and physical testing, and 2 the variable polymer solubility caused by insufficient milling. A curing system of 2 to 8 parts MgO, 3 to 12 parts ethyl Zimate, and 2 parts S gave good results. An 89 chloroprene copolymer at 62 conversion which was modified with 0.07 parts dodecyl mercaptan, had a 4780-psi tensile strength, an elongation at break of 860, and an ASTM permanent set of 11. Fractional- precipitation studies indicate that the copolymers are heterogeneous and contain an appreciable amount of polychloroprene.
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