Finite difference solutions to the Doi equation with a quadratic closure approximation in two-dimensional channel flows, such as inlet developing flow between parallel plates and 2:1 contraction flow, were obtained. In the case of the inlet developing flow, a uniform velocity profile at the channel entrance was once overshot to become a profile similar to a Newtonian Poiseuille flow before reaching a fully-developed flat profile. The developing profile of velocity is in a wavy form because of the effect of molecular orientation. Because of the deceleration of the flow in the vicinity of channel wall near the entrance, the order parameter in the area became small. Afterwards, it recovered to a higher value owing to shear flow in the downstream, and a region of low order parameter was limited near the channel centerline, where the effect of the shear on the molecular orientation is small. In the developing region, the order parameter along the centerline was high because of extensional flow. It is quite interesting that the order parameter in an area between channel wall and the centerline near the entrance was lowered than the value of equilibrium state. For the contraction flow, the curvature of streamlines near the contraction was small compared to Newtonian flow, and resultantly larger vortices occured at channel corners. The order parameter in those regions was low and the effect of the secondary flow was reflected on the preferred angles.

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[in Japanese]

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Combinations of inorganic fibers and organic matrices can produce high performance composites such as CFRP and GFRP. Normally, the adhesion between these two material types is not good due to their Completely different nature. Composites that consist of a matrix reinforced with fibers of the same material however, may have excellent interfacial strength. Often, the melting temperature of thermoplastic fibers is higher than that of the corresponding bulk material due to molecular orientation in the fibers. Therefore, a processing window between the two melting temperatures of the fibers and the bulk materials may enable fabrication of composites with a high strength interface and fiber reinforcement. We call this class of composites “Interface-less Composites”. In this paper, UHMWPE fibers and PE film were selected as the first step in the validation of this concept. Knitted PE fabric with good drapeability was also used as a reinforcement. The effects of processing temperature and time in film stacking method on mechanical properties were investigated. Even at a low fiber volume fraction (12%) PE/PE composites showed two times higher tensile strength than the neat PE matrix. On the other hand, the tensile strength of PE/Epoxy composites was lower than that of Epoxy resin. This concept can be extended to any thermoplastic material. The use of these composites could greatly improve the recycle ability since matrix and reinforcement are the same materials.

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