STUDY OF PARTICLE INTERACTION IN A HIGHLY CONCENTRATED LATEX BY TURBIDIMETRY

A study of the low-angle region of the static structure factor S(q) (q =(4 pi/lambda) sin(theta/2); theta:scattering angle, lambda:wavelength of the radiation in the medium) of a concentrated (44 wt.%) poly(meth yl-methacrylate) (PMMA) latex by turbidimetry is presented. It is demo nstrated that S(0), i.e., the structure factor extrapolated to vanishi ng scattering angle can be obtained in excellent accuracy up to the hi ghest concentrations. Since S(0) reflects the balance between long-ran ge attractive and short-range repulsive forces between the latex parti cles, this quantity can be used to assess the stability of the latex a gainst flocculation. Special attention has been paid to the influence of polydispersity on S(0). The analysis of S(q) in the vicinity of q = 0 for the system under consideration indicates the absence of attract ive forces between the particles.