Showing papers by "Jianqi Zhang published in 2011"

Effect of solvent annealing on the tensile deformation mechanism of a colloidal crystalline polymeric latex film.

Abstract: The influence of solvent annealing on microscopic deformational behavior of a styrene/n-butyl acrylate copolymer latex film subjected to uniaxial tensile deformation was studied by small-angle X-ray scattering. It was demonstrated that the microscopic deformation mechanism of the latex films transformed from a nonaffine deformation behavior to an affine deformation behavior after solvent annealing. This was attributed to the interdiffusion of polymeric chains between adjacent swollen latex particles in the film. It turns out that solvent annealing is much more efficient than thermal annealing due to a much slow evaporation process after solvent annealing.

Radial structure of commercial styrene- co -butyl acrylate latex particles by means of synchrotron small-angle X-ray scattering under contrast-variation conditions

Abstract: The structural information of commercial styrene-co-butyl acrylate latex particles along radial direction was observed via the contrast-variation technique using synchrotron small-angle X-ray scattering (SAXS). By manipulating the electron density of the dispersion medium, the microstructural parameters of the latex dispersion were evaluated based on quantitative discussion of the scattering intensity distribution profiles. Four isoscattering points could be identified in the contrast-variation measurements, located at the scattering vectors corresponding to the position of the sharp minima of the scattering curve of homogenous spheres. This suggests that the shape and structure of particles were not affected by adding a certain amount of sucrose and salt. This phenomenon was attributed to the existence of the thin surface layers around particle core in the system. The data indicate that the latex particles exhibit a core–shell structure, and the average thickness of the shell is about 2 nm.