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The quiescent and flow-induced crystallization of a poly(ether-block-amide) is studied by means of rheo-optical methods. Both optical microscopy and small angle light scattering have been used. The multublock copolymer has a microphase-separated structure with an order-disorder transition at 180-185°C, as measured with rheometry and SAXS. The number of nuclei, spherulitic growth rates, and the characteristic time scale for crystallization are compared with that of a polyamide of similar molar mass. For the poly(ether-block-amide)--containing a majority of amide segments--the growth rates of the spherulites during quiescent crystallization are similar for the block co-polymer and the homopolymer, even if the spherulitic structures are not the same. When flow is applied, the two materials behave differently. The flow increased the nucleation density in the homopolymer but not in the block copolymer. POLYM. ENG. SCI., 48:2418-2425, 2008. [C] 2008 Society of Plastics Engineers, INTRODUCTION Thermoplastic elastomers constitute an interesting class of materials. Such materials are typically composed of alternating, flexible soft and more rigid segments. By tuning the relative length of these segments [...]

The effect of physical compatibilization on the deformation and coalescence of droplets in immiscible polymer blends is discussed. Evidence is provided for the existence of concentration gradients in block copolymers along the interface during deformation. This causes complex changes in droplet shapes during deformation and relaxation. These concentration gradients also result in Marangoni stresses, which stabilize the droplets against deformation and breakup. Coalescence experiments have been performed, varying both the compatibilizer concentration and the shear rate. Existing coalescence models have been evaluated. An empirical extension of Chesters' partially mobile interface model is presented, that treats the effects of Marangoni stresses on the coalescence process as a higher effective viscosity ratio.

Discusses aims, objectives, and content of a safety course for chemical engineering students. Course emphasizes awareness of hazards, basic concepts and principles of safety engineering, and the ability to recognize, assess, and remedy specific risks occurring in chemical plants. Course implementation is also discussed. (JN)

In this paper, a technique for automatic robust control design and synthesis for plug and play active vibration control module is presented. Robust control theory offers the uncertainty analysis and graphical manipulation of the frequency response as well as analytical solution approach. The prior knowledge of the plant model imposes limitations on the fast and effective implementation of the robust control. Moreover, the design of the weight functions for the robust control is usually a trial and error process. The plant identification and subsequent control design becomes even more tedious for modular devices with plug and play capability. In the present paper, the plant model is identified by using polyreference least square complex frequency estimator and an innovative automatic pole clustering algorithm. The H∞ loop shaping robust control is designed, where the parameters of the weight functions are optimised using genetic algorithm. An experimental evaluation is also presented on a prototype modular structure. [ABSTRACT FROM AUTHOR]