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In a conventional semi‐batch seeded emulsion copolymerization of vinyl acetate/butyl acrylate (VA/BA) using hybrid surfactants namely, dioctyl sulfosuccinate (DOSS) as an anionic surfactant, nonylphenol ethoxylate (KENON 30) as a non‐ionic type, and polydimethylsiloxane surfactant (having hydrophilic silanol‐terminated, called PDMS). The effect of PDMS on the properties of the latex synthesized was investigated by measuring solid content, viscosity, colloidal stability, particle size distributions of the base latex, viscosity average molecular weight (M¯v) of the copolymer, latex particle morphology, glass transition temperature (Tg) of a copolymer and thermal gravimetric analysis (TGA). Particle size of the base latex decreases (Z‐average from 246.48 to 143.69 nm) upon increasing the amount of PDMS surfactant in the recipe (up to 6 wt%). The presence of PDMS surfactant in the hybrid surfactants led to a significant increase in the solid content (from 48.71 to 51.31 wt%), viscosity (from 334 to 806 centipoise, cp) and M¯v (from 1.91 × 105 to 2.34 × 105 g mol−1). Thermal stability and Tg of the copolymer were increased with addition of PDMS surfactant (thermal stability from 344.77 to 389.81 °C and Tg from −20.7 to 21.7 °C). The colloidal stability evaluated using the electrolyte addition method was improved with addition of PDMS surfactant. The uniform morphological structure of the final particle is the main effect of using PDMS in the hybrid surfactants.

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For the first time, the bending analysis of a double curved sandwich panel was presented which was subjected to point load, uniform distributed load on a patch, and harmonic distributed loads and was based on a new improved higher order sandwich panel theory. Since the cross-sectional warping was accurately modeled by this theory, it did not require any shear correction factor. Also, the present analysis incorporated trapezoidal shape factor (the 1+z/R terms) of a curved panel element. Geometry was used for the consideration of different radii curvatures of the face sheets, while the core was unique. Unlike most of other reference works, the core can have non-uniform thickness. The governing equations were derived by the principle of minimum potential energy. The effects of types of boundary conditions, types of applied loads, core to panel, and radii curvatures ratios on the bending response were also studied.

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