Nowadays, the reduction of weight is an important issue in several areas such as the furniture andautomotive industries. Lightweight wood-based panels, with appropriate mechanical performance, aredesired to facilitate handling and transportation. Concerning the automotive industry, lighter parts allowhigher vehicle efficiency and thus lower CO2 emissions.In this context, we are studying the use of low density particles (LDPs) as light fillers in wood-basedparticleboards and thermoplastics. These particles combine low density and high mechanical resistance asa result of an internal multi-alveolar structure separated by rigid polymeric walls. The structural material isunsaturated polyester crosslinked with styrene.For producing LDPs, an organic phase comprising unsaturated polyester dissolved in styrene isdispersed in an aqueous solution of polyvinyl alcohol (PVA) at high stirring rate. A base is previouslyadded to the organic phase, causing the neutralization of the polyester carboxyl groups and formingpolyester salts which leads to the diffusion from the external aqueous medium. This entrapped waterforms the internal vesicles, and the whole system becomes a water-in-oil-in-water (W/O/W) emulsion(double emulsion). Radical polymerization is then initiated by adding an organic-soluble initiator.Particles are then washed with distilled water, sieved and dried.For each application (wood panels and thermoplastics, respectively) LDPs must have significantlydifferent sizes, hence the great challenge of process optimization. The influence of stirring rate conditions,type of cure initiator and drying conditions on the final internal vesiculation, particle size and density werestudied. Well vesiculated LDPs, with two diameter ranges, 1-4 mm and 3-45 µm, were prepared. Theirperformance in lignocellulosic particleboards and in polypropylene matrix was studied
