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Organomodified clays are known to be effective in polymer blend compatibilization if located preferentially at the domain interfaces, but little is known regarding the origin of their localization. In this study, we investigate the effect of organomodifier, clay loading, and shear environment on the compatibilization extent in nonreactive polyethylene (LDPE)/ poly(ethylene oxide) (PEO) and reactive maleic anhydride functional polyethylene (PE-g-MA)/PEO polymer blends. We pose important questions: If clay is to compatibilize blends by interfacial localization, how does organomodifier affect its localization? How does an increase in clay loading affect the shape and elasticity of the interface? What is the shear intensity needed to overcome the equilibrium distribution of clays and delaminate it from the interface? We utilize laser scanning confocal microscopy and 3D image analysis to calculate characteristic phase size and gain unique insights into the connection between the clay loading and the interfacial curvature. Our experiments demonstrate that 1 wt % of interfacially localized clay is sufficient to suppress coarsening and greatly reduce phase domains. However, further increase of clay loading only saw a marginal reduction in phase size compared to 1 wt % clay loading. The interfacial curvature calculations showed that with increase in clay loadings beyond 1 wt % the shape of the interface does not change significantly; however, slight broadening of curvature distribution and increasing asymmetry are observed from 3D images. This can be attributed to the multiple layers of clay jammed at the interface at higher clay loadings. When reactive PE-g-MA was substituted for LDPE, graft copolymers were generated via in situ coupling at the interface. These copolymers combined with clay resulted in the smallest phase domains. In addition, we show that clay dispersion and localization were largely independent of shear intensity, which suggests that clay does not delaminate from the interface even in high shear environments.

The design of a porous membrane support layer derived from cocontinuous polymer blends is presented. We investigate the effect of blend composition, shear rate, residence time, and annealing time on the cocontinuous morphology of polyethylene (PE)/poly(ethylene oxide) (PEO) blends. Porous PE sheets were generated by water extraction of PEO and used as a support layer for gas separation membranes. The PE/PEO blends using nonfunctional and maleic anhydride functional PE (PE-g-MA) were mixed in a batch microcompounder and in a pilot plant scale corotating twin-screw extruder. Using PE-g-MA resulted in pore size reduction from 10 to 2 μm and suppression of coarsening of the morphology during further annealing of the blends due to formation of PE−PEO graft copolymers. Equilibrium interfacial tension, estimated by fitting the rheology of droplet blends to the Palierne viscoelastic droplet model, was 3 and 0.4 mN/m for PE/PEO and PE-g-MA/PEO systems, respectively. The specific interfacial area and phase size distribution were calculated from 3D images acquired by laser scanning electron microscopy (LSCM). We prepared gas separation membranes by solvent casting an acetone solution of ionic gel into porous PE sheets and discussed the effect of type of processing, average pore size, pore size distribution, and pore wall functionality on their performance.

In this paper, we address the problem of designing flexible plant layouts for manufacturing facilities where product demands are subject to variability. A flexible layout is one that maintains low material handling costs despite fluctuations in the product demand levels. We extend existing procedures for design of flexible layouts by (1) explicitly capturing the stochastic nature of product demands and the resulting variability in material flows between different processing departments, (2) allowing for the possibility of multiple processing departments of the same type to exist in the same facility, and (3) letting material flows between pairs of individual departments be determined simultaneously with the layout and as a function of demand scenarios. Optimal and heuristic methods are presented for generating flexible layouts and determining flow allocations under various design and operation assumptions.-2-

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