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The influence of three ingredients (bran, sucrose, magnesium carbonate) commonly used in extrusion-cooking of wheat flour-type formulations was studied. Extrusion-cooking was carried out in a twinscrew corotating extruder. The effects of the ingredients were analyzed by determining extrusion parameters, physical properties (apparent density, modulus of deformability and breaking stress) and structural properties (computerized image analysis of the transverse cut of extrudate). An increase in apparent density occurred when concentration of any ingredient increased. Cell number per pixel area increased greatly while average cell size decreased as bran concentration increased from 0 to 16%. Average cell size increased as magnesium carbonate increased from 0 to 0.4%, but cell size decreased above 0.4%.

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SynopsisAU-polyamide molecular level composites composed of rigid rod and flexible coil polymers were prepared using an in situ polymerization process in which the anion of the rigid rod poly-(phenylene terephthalamide) (PPTA) was used as the initiator for the anionic polymerization of acrylamide to form the nylon 3 matrix. The rigid aramid component then serves as the reinforcing agent. This polymerization resulted in both graft and homo-nylon 3 formation. Composite films prepared using in situ processing showed greatly improved strength and modulus over unmodified nylon 3 with no loss of flexibility. The composites showed aggregation and phase separation of PPTA fibrils at PPTA weight fractions of > 30% as indicated by wide angle X-ray scattering and electron microscopic analysis. The structure of the PPTA formed is that produced from swelled liquid crystalline solutions, indicating that the in situ process involves polymerization in the liquid crystalline state.

This paper presents experimental results obtained from a harmonically excited pendulum system. The pendulum has rigid barriers which limit the amplitude variation from its central position. It is considered in both the normal (downward) position and in the upright (inverted) position. The overall dynamics of the pendulum include impacts with the rigid constraints, and the system response to sinusoidal excitation includes non-impacting motions, stable subharmonics, and chaotic motions. These were experimentally found to occur in the parameter regions predicted by previous analytical work. This system represents an example of a deceptively simple device which can undergo extremely complicated dynamics. For example, the inverted pendulum was found to have 10 distinct possible steady-state responses at a fixed driving amplitude and frequency, each of which was obtained simply by changing the initial conditions. In addition, the normal pendulum was found to be capable of having impacting steady-state dynamics which coexist with the non-impacting steady-state motion predicted from small oscillation theory.

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