1993 Volume 1993 Issue 1 Pages 86-91
Heat-treatment of bis[4-(3-decylureido)phenyl]methane (DUDM) particles dispersed in paraffinic mineral oil causes morphological changes to helical, tubular and helical-rope aggregates form. In order to clarify the mechanism of this morphological change, the influence of temperature, time and cooling rate on the behavior of morphological change was studied from mainly SEM observation by using DUDM having two kind of crystal structure (r and p forms). The morphological changes were initiated at temperature of 130 °C for 9 form and at that of 150 °C for r form crystals. Because these temperature nearly corresponed with that of phase transition II of each crystal, the morphological changes will relate to the change of state (formation of a form crystal) in crystals. Morphologies of the samples treated with heat at temperature above phase transition II were mixture of unchanged platelets and changed aggregates. The proportion of each aggregate and platelet in the mixture varied with temperature and time. On the basis of above data, the forming process of tube was propos ed. The process shows as follows ( 1 ) The formation of tape, by the interaction between DUDM crystal and PMO. ( 2 ) the twist of tape (open and closed helix) ( 3 ) the formation of tube, by adhesion between the side of twisted tape. The appropriateness of that proposed process was also recognized with SEM image showing morphologies in initial stage of the formation of tube.
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