Physical characteristics of nanoparticles emitted during drilling of silica based polyamide 6 nanocomposites

During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the emission rates of particles from these material. In this study, real-time characterization of the size distribution and number concentration of sub-micrometer-sized particles (5.6-512 nm) emitted from polyamide 6 nanocomposites during mechanical drilling was made. For the first time, four different silica based filler of commonly use were assessed. Further, the respective emission rates were determined based on the particle population and the time. The measurements showed that the particle emission rates ranged from 1.16E+07 (min^-1) to 1.03E+09 (min ^-1) and that the peak diameters varied from 29.6 to 75.1 nm. Airborne particles in the nanometer range (11.1-46.8 nm), in the ultrafine range (51.3-101.1 nm) and in the accumulation mode range (111.9-521 nm) accounted for 34.1% to 76.6%, 8.3% to 47% and 4.1% to 24.2% of the total emission rates, respectively, depending on the type of filler. Additionally, deposited particles were sampled and characterized, to explore any possible correlation between deposited and airborne particles. The result clearly showed that with increasing airborne particle concentration the deposit particle concentration decreased and vice verse.