Splat formation of polypropylene flame sprayed onto a flat surface

The oxy-acetylene flame process with external powder feeding was employed to spray form polypropylene (PP) splats onto a glass substrate. This work examines the influence of stand-off distance on PP splat morphology to establish a fundamental understanding of processing variables on microstructural characteristics. Optical microscopy, scanning electron microscopy (SEM), 2D profilometry, non-contact optical surface profilometry and VISION software were used to measure and quantify various morphological features that are descriptors for the splat metrics. Micro-Raman spectroscopy was used to examine the molecular structure of the PP splats. These studies indicated that decreasing the stand-off distance from 35 to 15 cm produced coherent, integral disk-shaped splats that exhibited minimum splashing behavior. This observation has important fundamental implications concerning the structure-property relationships of polymer coatings since the design of these intrinsic building units also controls the composite nature of the coating. (C) 2010 Elsevier B.V. All rights reserved.