title: Characterization of the thickness and distribution of latex coatings on polyvinylidene chloride beads by backscattered electron imaging.
abstract: Polyvinylidene chloride (PVDC) co-polymer resins are commonly formulated with a variety of solid additives for the purpose of processing or stabilization. A homogeneous distribution of these additives during handling and processing is important. The Dow Chemical Company developed a process to incorporate solid materials in latex form onto PVDC resin bead surfaces using a coagulation process. In this context, we present a method to characterize the distribution and thickness of these latex coatings. The difference in backscattered electron signal from the higher mean atomic number PVDC core and lower atomic number latex coating in conjunction with scanning electron microscopy (SEM) imaging using a range of accelerating voltages was used to characterize latex thickness and distribution across large numbers of beads quickly and easily. Monte Carlo simulations were used to quantitatively estimate latex thickness as a function of brightness in backscatter electron images. This thickness calibration was validated by cross-sectioning using a focused ion-beam SEM. Thicknesses from 100 nm up to about 1.3 µm can be determined using this method.
authors: 1Analytical Sciences,The Dow Chemical Company,1897 Bldg E52,Midland,MI 48667,USA.
authors: Clifford S
authors: CS
authors: Todd
authors: 2Packaging and Specialty Plastics R&D,The Dow Chemical Company,438 Bldg 154C,Midland,MI 48667,USA.
authors: Douglas E
authors: DE
authors: Beyer
mesh_terms: D007840:Latex / Q000032:analysis*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D011143:Polyvinyl Chloride / Q000031:analogs & derivatives* / Q000737:chemistry; D013499:Surface Properties
chemical_list: D007840:Latex; C029547:polyvinylidene chloride; D011143:Polyvinyl Chloride
keywords: backscatter