Tetramethylene urea (TeU) is successfully copolymerized with γ-butyrolactone (γBL), leading to an alternating poly(amide urethane) with alternating carbonyl-amino-tetramethylene-amino and carbonyl-trimethylene-oxy repeating units (M h n ) 12 600; M h w ) 21 100; M h n ) 1.67) and with a Tm of 196.5 °C and a Tg of 36.4 °C. Small defects in the microstructure of the alternating poly(amide urethane) arise from the formation of TeU-TeU diads. Furthermore, TeU is successfully copolymerized with mixtures of γBL and ethylene carbonate (EC) or 1,2-propylene carbonate (PC). From NMR spectroscopic data of the terpolymers obtained, it is concluded that the reactivity of the five-membered cycles used increases in the following order: EC . PC ≈ γBL. It is possible to increase the content of γBL repeating units in the poly[(TeU-γBL)-stat-(TeU-EC)] or poly[(TeU-γBL)-stat-(TeU-PC)] by increasing the fraction of γBL in the feed. 13 C NMR spectroscopy reveals that TeU-EC or TeU-PC and TeU-γBL units are randomly distributed in the polymer chain. This conclusion is supported by the thermal properties.
We present an anytime-capable fast deterministic greedy algorithm for smoothing piecewise linear paths consisting of connected linear segments. With this method, path points with only a small influence on path geometry (i.e. aligned or nearly aligned points) are successively removed. Due to the removal of less important path points, the computational and memory requirements of the paths are reduced and traversing the path is accelerated. Our algorithm can be used in many different applications, e.g. sweeping, path finding, programming-by-demonstration in a virtual environment, or 6D CNC milling. The algorithm handles points with positional and orientational coordinates of arbitrary dimension.
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