Melt spinning of syndiotactic 1, 2‐polybutadiene for preparation of carbon fibers

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Abstract
The thermal crosslinking and loss of vinyl unsaturation of syndiotactic 1, 2‐polybutadiene(s‐PB) at 180–230°C were prevented by stabilizers with 3, 5‐di‐t‐butyl‐4‐hydroxybenzyloxy group. The s‐PB samples (mp 140–198°C and MW 20,000–70,000) that contained the stabilizers could be melt‐spun at a temperature below 220°C into 1‐denier fibers to be used for the preparation of carbon fibers. The s‐PB fibers with higher mp and/or higher MW could be obtained by the addition of a high boiling solvent such as tetralin. The relationship between the molecular structures of s‐PB and the properties of resulting s‐PB fibers, including the degree of molecular orientation measured by birefringence and x‐ray diffraction, is presented. Spun fibers showed small swellings here and there along the fiber axis, which would have resulted from the inhomogeneity of the melt of s‐PB spun at a temperature slightly above the melting point. The gelation was unlikely to occur.
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