![]() ![]() Several fractionation techniques (such as capillary hydrodynamic fractionation -CHDF-, field flow fractionation, hydrodynamic chromatography, and disc centrifugation), are also employed for measuring the PSDs. Also, the electron beam can produce a sample damage or a size contraction and the PSD evaluation may involve counting thousands of particles (Llosent et al., 1996). However, it is experimentally expensive, time-consuming, and difficult, mainly when analyzing soft latexes and/or broad PSDs. Transmission electron microscopy (TEM) is the main reference technique for directly observing and measuring the PSD. The particle size distribution (PSD) of a polymer latex is an important morphological characteristic that determines the processability and end-use properties of the material when used as an adhesive, a coating, an ink, or a paint. The estimated PSDs were better than those obtained through standard numerical techniques for 'ill-conditioned' inverse problems. The PSD predicted by the GRNN resulted close to that obtained by TEM. The standard was also characterized by 2 independent techniques: capillary hydrodynamic fractionation, and transmission electron microscopy (TEM). Then, the obtained GRNN was used for estimating the PSD of a narrow polystyrene (PS) latex standard of nominal diameter 111 nm. First, the ability of the method was tested on the basis of two synthetic examples. The GRNN was trained with measurements simulated on the basis of typical asymmetric PSDs (unimodal normal-logarithmic distributions of variable mean diameters and variances). The method utilizes a general regression neural network (GRNN), that estimates the PSD from 2 independent sets of measurements carried out at several angles: (i) light intensity measurements, by elastic light scattering (ELS) and (ii) average diameters measurements, by dynamic light scattering. ‡ INTEC (UNL - CONICET), Santa Fe,, A method for estimating the particle size distribution (PSD) of a dilute latex from light scattering measurements is presented. ![]() † CIDISI (UTN - Facultad Regional Santa Fe), Santa Fe,, Estimation of the particle size distribution of a dilute latex from combined elastic and dynamic light scattering measurements. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |