SummaryBitumen is a complex mixture of hydrocarbons for which microstructural understanding is incomplete. In an effort to detail this microstructure, a asphalt cement sample (CAP 30/45) was analysed by thermal phase detection atomic force microscopy. Phase contrast and topography images showed that sample morphology is highly dependent on temperature. The 'bee structure' changed considerably at temperatures between 50• C and 56• C. A decrease of the oscillation amplitude was observed upon heating and the 'bees' completely disappeared at temperatures above 57• C. When the temperature was decreased after melting at 170• C, the 'bees' began to nucleate gradually at temperatures of 57• C and its evolution with time was followed. Changes in morphology were compared to thermal analysis results and a model for the 'bee' structure was proposed.
This work presents different applications in progress with the aid of the atomic force microscopy (AFM) technique for biomedical and biotechnological applications, comprising both the acquisition of three-dimensional images and spectroscopic force measurements, in the following systems: first, low-density lipoprotein (LDL)-glycosaminoglycans; second, lectins-polysaccharides; third, mycobacterium leprae cellular wall and Vesicular Stomatites Virus (VSV) with fibronectin laminin, and lipidic membranes; fourth, DNA-complex; and fifth, actin, as well as the development of surface functionalizing protocols and image restoration by means of mathematical techniques.
SYNOPSISThe miscibility in the melt and solid state of blends made of poly(p-phenylene sulphide) (PPS) with a liquid crystalline polymer (LCP) from DuPont was studied by polarized light optical microscopy (PLOM) and dynamic thermal mechanical analysis. Both techniques showed that the PPS and the LCP are immiscible in both states, and that the critical concentration for the formation of fibrils C*, in this particular system, was located between 20 and 25 wt % LCP. The resultant blend morphology was studied by PLOM and scanning electron microscopy (SEM). It was observed that when LCP fibrils are formed in the PPS matrix, the PPS macromolecules will crystallize around the LCP fibrils by forming columnar layers called transcrystallites. These transcrystallites are the result of the LCP acting as a nucleating agent for the PPS, promoting heterogeneous nucleation. 0 1996 John Wiley & Sons, Inc.
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