Phenylene oxadiazole/N-methyl

All-p-phenylene oxadiazole/N-methyl hydrazide copolymers have yielded high performance fibers with tenacities of 18-21 gpd and moduli above 300 gpd through an unconventional polycondensation reaction of terephthalic acid, dimethyl terephthalate and hydrazine sulfate in fuming sulfuric acid and subsequent "reaction spinning" into aqueous acid. 

Recently, we reported (1, 2) a new class of high strength/ high modulus fibers prepared from all-p-phenylene oxadiazole/ N-methyl hydrazide copolymers. Oxadiazole homopolymers and fibers had been described earlier by Iwakura (3), Imai (4), and Frazer (5). All-p-phenylene oxadiazole/N-methyl hydrazide copolymer fibers were shown by us to give tire cord with excellent end use performance including good fatigue characteristics. In concurrent... 

Fibers (6) of p-phenylene oxadiazole/N-methyl hydrazide copolymers were prepared by polymerization of terephthalic acid (TA), dimethyl terephthalate (DMT) and hydrazine sulfate in fuming sulfuric acid (Oleum) and "reaction spinning" of the resulting polymer solution into aqueous sulfuric acid. Replacement of some of the dimethyl terephthalate used with dimethyl isophthalate (DMI) allowed the preparation of p-/m-phenylene oxadiazole/ N-methyl hydrazide copolymers. In the polymerization, a p-/m-phenylene oxadiazole polymer is formed which is methylated during the reaction ... 

During the "reaction spinning" process, the methylated oxadiazole units are hydrolyzed to mono-methylated hydrazide linkages yielding fibers of the p-/m-phenylene oxadiazole/N-methyl hydrazide copolymers ... 

During the polymerization of aromatic diacids and diesters with hydrazine in fuming sulfuric acid, aromatic oxadiazole units are formed first which are subsequently methylated by monomethyl sulfate or its homologues (derived from reaction of the diester with H2SO4) forming an aromatic N-methyl oxadiazolium polymer. This polymer is hydrolyzed during the spinning operation to the fiber polymer, i.e., p-/m-phenylene oxadiazole/N-methyl hydrazide copolymer. 

BACH and HINDERER Phenylene Oxadiazole-N-Methyl Hydrazide 367... 

Bach HC, Dobinson F, Lea KR, Saunders JH. High-strength/high-modulus fibers of p-phenylene oxadiazole/n-methyl hydrazide copolymers - a new class of high-performance organic materials. J Appl Polym Sci 1979 23(7) 2125-31. 

Fiber Properties of Aromatic Oxadiazole/N-methyl Hydrazide Copolymers with Partial m-Phenylene Orientation... 

As shown in this paper, aromatic oxadiazole/N-methyl hydrazide copolymers with partial m-phenylene orientation give yarn with increased elongation-to-break and tire cord with improved fatigue resistance when compared to the all-para analogue. 

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