Atomic force microscopy, a powerful tool to study blend morphologies basedon polyester resins

Atomic Force Microscopy (AFM) was an unusual but effective tool used to inv estigate the morphology of cured blends based on UP (unsaturated polyester) . The pertinence of AFM was evaluated by studying four miscible UP/LPA (low profile additive)/ST (styrene) blend systems. The morphology of these cure d blends before and after LPA solubilization was analogous in SEM (Scanning Electron Microscopy) and AFM. However, in AFM the particles boundaries wer e more defined compared to SEM. Before treatment, nanoparticles (less than 60 nm) and aggregates (140 to 250 nm) were discernible. After treatment, na nogels (less than 50 nm) and microgels (80 to 220 nm) were observed. The ag gregates composed of linked nanoparticles, were connected together to form a whole network. The microgels were composed of linked nanogels and were co nnected to form a polyester network. The LPA solubilization reduced the nan oparticles to nanogels in extracting the LPA phase out of the nanoparticles . The particles size depended on the miscibility of the system UP/LPA/ST an d was related to the void volume. Shrinkage and light opacity were macrosco pic properties which characterized the void volume and therefore the partic le sizes. (C) 2001 Kluwer Academic Publishers.