REORGANIZATION OF MOLECULAR ALIGNMENT IN NAPHTHALENE AND METHYL-NAPHTHALENE DERIVED PITCHES

Molecular alignment in methyl-naphthalene and naphthalene-derived meso phase pitch materials was studied at different levels of resolution by means of optical microscopy, X-ray, and TEM using the 002 lattice fri nge technique, to determine the influence of different solidification procedures on the molecular alignment in the solidified pitches. Rapid resolidification procedures - quenching in liquid nitrogen or extract ion - were found to reduce domain size and molecular alignment in the solidified pitch materials, whereas annealing followed by a slow cooli ng step produced better alignment, larger domains, or Brooks and Taylo r type spheres, depending upon the composition of the pitch. Such rear rangement can be compared to a rate-controlled process such as recryst allization. Quite different molecular rearrangement behavior was found for naphthalene and methyl-naphthalene pitches, reflecting variations in their molecular stacking heights. The degree of liquid crystal ali gnment and the limitations of TEM in examining these types of structur es are discussed.