This paper describes the crystallization of l-glutamic acid polymorphs in both quiescent and forced solution flow membrane crystallizers. The β polymorph was selectively obtained in static conditions, while the α form was preferentially grown in dynamic configuration, depending on the rate of solvent removal. According to concepts of the classical nucleation theory, the nucleation rate of the two polymorphs α and β have been calculated taking into account the quiescent/forced solution fluid dynamics regime and the homogeneous/heterogeneous nucleation activation mechanism. By this approach, the number-based polymorph fraction a, which is considered as an indication of the chance for a specific polymorphs to nucleate, was calculated. On these bases, the effect of supersaturation control and heterogeneous nucleation on the porous membrane surface was analyzed. Theoretical calculations have been compared with the experimental polymorphic outcome of the crystallization of l-glutamic acid (LGA) and an appropriate crystallization mechanism, for the different operative environments, has been formulated. Although it is obvious, classical theory was a helpful tool in describing experimental results obtained in the membrane-based equipment.

This study examines moisture sorption behaviors of two glassy polymers, epoxy and vinylester, immersed in different fluids at two temperatures below the glass transition temperatures of the polymers. The main purpose of this study is to understand the effect of volume‐dependent temperatures and deformations on the diffusion process of solid polymers. Diffusivity coefficients are first determined by assuming the diffusion to follow the classical Fickian diffusion. In some cases, moisture sorption led to quite significant changes of volume, and the diffusion process cannot be well described by the Fickian diffusion. In such situation, the coupled deformation–diffusion model for linear elastic isotropic materials presented by Gurtin is adopted, as a first approximation. This coupled deformation‐diffusion model reduces to a Fickian diffusion model when the coupling parameters are absent and the volume changes in the solid polymers during diffusion are negligible. A finite difference method is used in order to solve for the coupled deformation‐diffusion model. The model is used to predict the one‐dimensional moisture diffusion in thin plates and the multiaxial three‐dimensional moisture diffusion in dogbone specimens. The multiaxial diffusion in the dogbone specimens is used to validate the calibrated material parameters from the standard thin plate diffusion characterization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45151.

This study examines the effects of temperature and fiber and matrix diffusivities on the diffusion of fluid in glass fiberreinforced polymer composites. Glass fiber-reinforced polymer thin plates were immersed in deionized water at two temperatures: room temperature and 50 C. During the diffusion process, the overall mass changes and dimension changes were recorded, which relate to the volumetric change and the through-the-thickness strain. Different constitutive models are considered in order to understand the diffusion of fluid through the glass fiber-reinforced polymer plates. The macroscopic models of this work, Fickian and Gurtin coupled deformation-diffusion, are first considered in order to describe the macroscopic diffusion behaviors. Two microscopic models that include fiber volume contents and diffusivities of the constituents (fiber and matrix) are then considered in order to gain fundamental insight into the effects of microstructural morphologies and constituents' diffusivities on the diffusion process in the glass fiber-reinforced polymer specimens.

The paper presents ongoing research and development of novel concepts for deployable space structures using self-latching, flexural joints to replace mechanical hinges. The mechanics of deformation of Fiber-Reinforced-Polymers (FRP) joints for in-plane deployment mechanisms are studied. Methods for characterizing these joints via experiments and numerical simulations are proposed. A failure criterion suitable for ultra-thin, plain-weave composites is used to predict failure of the joints and achieve a successful design.

The paper presents topology optimization studies of selfs-deployable joints in thin-walled tubular structures. The joints are made entirely of ultra-thin, fiber reinforced composite materials. The objective of this research is to strategically position cutouts on the joints so that they can fold without failing, while maximizing the deployed bending stiffness. The optimal shape and position of cutouts are the results of concurrent topology optimization of these composite, thin-shell joints with geometrical non-linearities, due to their folding and self-deployable nature. Numerical methods to accurately detect failure are implemented and results from a novel level-set method for topology optimization are compared to results from classical parametric optimization and preliminary designs based on physical intuition.

The paper presents topology optimization studies of selfs-deployable joints in thin-walled tubular structures. The joints are made entirely of ultra-thin, fiber reinforced composite materials. The objective of this research is to strategically position cutouts on the joints so that they can fold without failing, while maximizing the deployed bending stiffness. The optimal shape and position of cutouts are the results of concurrent topology optimization of these composite, thin-shell joints with geometrical non-linearities, due to their folding and self-deployable nature. Numerical methods to accurately detect failure are implemented and results from a novel level-set method for topology optimization are compared to results from classical parametric optimization and preliminary designs based on physical intuition.

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