THE RELATION BETWEEN SYNTHESIS PARAMETERS AND MORPHOLOGY OF ANIONIC POLYCAPROAMIDE OBTAINED IN ORGANIC MEDIA .1. INFLUENCE OF THE NA[O(CH2)(2)OCH3](2)ALH2 ISOPHORONE DIISOCYANATE CATALYTIC-SYSTEM/

Polycaproamide granules were obtained by anionic polymerization of cap rolactam in ethylbenzene, using the sodium bis(2-methoxyethoxy)alumini um hydride/isophorone diisocyanate catalytic system. Under these condi tions, polymerization occurs heterogeneously and the nature of the par ticle growth seems to be essentially a microbulk one. The most suitabl e reaction conditions were established. The morphology of the granules was investigated by scanning electron microscopy. These granules resu lt from the coalescence of a great number of small, spherical particle s. The coalescence occurs during solidification of the separated polym er. Numerous globular formations were observed at the surface of the p articles. The particles were individualized through mechanical dispers ion and measured, and the average number of particles composing the ag gregates was calculated. Using wide-angle X-ray scattering and differe ntial scanning calorimetry technics, the crystalline structure of the granular polycaproamide was studied. It contains almost entirely the c u phase. The heat of fusion decreases slightly as compared with that c orresponding to the anionic bulk polycaproamide. A schematic mechanism containing the stages involved in the obtaining of the granular polyc aproamide is proposed. (C) 1996 John Wiley & Sons, Inc.