The overall goal of this procedure is to evaluate nanomaterial release in the case of abrasion of nanocomposite materials. This method can help answer key questions in the occupation hygiene field such as risk assessment and workplace environment. The main advantage of this technique is that it allows one to evaluate nanomaterial release in the case of abrasion of nanocomposite materials.
For this experiment, use an abraser with a 140 millimeter diameter specimen rotation stage, which can rotate 30 to 80 rotations per minute, and two abrasion wheel holders. Install a disk shaped specimen on the specimen rotation stage. Use a weight to secure the abrasion wheels, that are wrapped with 100 grit sandpaper, to the abrasion wheel holder which also applies load to the test specimen.
Use stainless steel for the chamber walls to avoid particle deposition due to electrostatic force. Locate the air inlet and outlet in the upper and lower part of the chamber respectively. Place the abraser inside of the chamber, and install an additional air inlet in the abraser that is 15 millimeters above and 40 millimeters away from the center of the test specimen to provide better suspension for the abrased particles.
Next, locate the neutralizer 28 centimeters away from the center of the test specimen at a 45 degree angle to reduce the electrostatic particle deposition on the chamber walls. Install a CPC and OPC at the outlet of the chamber to measure the particle number concentration and particle size distribution respectively. Operate the blower installed at the outlet of the chamber at a flow rate of 50 liters per minute.
Following this, supply 25 liters per minute of additional particle-free suspension air using an air compressor through the additional air inlet. Check the background particle number concentration inside the chamber to reach an average particle number concentration for one hour of below one number per cubic centimeter using the condensation particle counter. Next, operate the specimen rotation stage of the abraser using a step motor that rotates the specimen rotation stage at 72 rotations per minute with 1000 rotations.
Measure and record the released particle number concentration and particle size distribution using the CPC and OPC respectively. Now, sample the released particles using a particle sampler containing filter media or a TEM grid. Stop the measurement and sampling when the particle number concentration reaches below 0.1%of the peak particle number concentration.
After saving the data, remove the samples from the instrument. The typical change in particle number concentration during the abrasion test is shown here. During the abrasion an increase in particle number concentration was observed followed by a decrease after abrasion.
The CPC measured an average of 3.67 times 10 to the nine particles, and the deviations were within 20%which represented a consistent release of particles during abrasion. The OPC measured an average of 1.98 times 10 to the nine particles, and the deviations were within 20%which represented a consistent release of particles during abrasion. After abrasion the original test specimens lost approximately 0.6 grams or 1.56%The total particle number release from nanocomposite containing carbon nanotubes by the abrasion test is shown here.
The nanocomposite containing carbon nanotubes released 12.6%more condensation particles and 1.9%more optical particles than the control composite. Most of the particles were torn due to abrasion, and field emission scanning electron microscopy revealed no free carbon nanotube structures from the nanocomposite containing 2%carbon nanotubes in the filter samples or many particle sampler samples after abrasion. After watching this video, you should have a good understanding of how evaluate nanomaterial release in the case of abrasion of nanocomposite materials.
