TIT# Complex isothermal crystallization and melting behavior of Nylon 6 nanoclay
     hybrids
AUT# Zapata Espinosa, A.; Medellin Rodriguez, F. J.; Stribeck, N.;
     Almendarez Camarillo, A.; Vega Diaz, S.; Hsiao, B. S.; Chu, B.;
SOU# Macromolecules (2005), 38(10), 4246-4253
LOC# xv095
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ABS# The complex crystallization and melting behavior of neat Nylon-6 and two
     Nylon-6-nanoclay hybrids with different montmorillonite concentration was
     studied using several experimental techniques. The differential scanning
     calorimetry (DSC) traces were taken as a reference and experiments were
     made at several isothermal crystallization temperatures followed by
     linear heating. The results, depending on the crystallization temperature,
     indicated two sequences of melting for neat Nylon-6 and four for the
     nanoclay hybrids. After isothermal crystallization at low temperatures,
     neat Nylon-6 behaved different from the hybrids, however, after high
     crystallization temperatures there was a common melting behavior for all
     samples. Molecular orientation, molecular weight, and nanoclay
     concentration were sequentially considered in order to determine the
     origin of the regimes behavior in the DSC traces. Molecular weight was
     found as the main cause of the thermal behavior with a minimum influence
     of molecular orientation and nanoclay concentration. X-ray diffraction
     measurements indicated the formation of asymmetric ? and incomplete a and
     y crystalline structures as a result of the nanoclay presence. These last
     structures were called truncated. Modulated melting was useful to clear
     mechanisms and corroborated the similar behavior for all three samples
     after isothermal crystallization at high temperatures. A melting
     mechanism was proposed on the basis of the previous behavior which
     involved the evolution of a quiescent low concentration morphology. This
     last was associated with crystallization of nonbounded macromolecules.