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Preferred orientation of carbon nanotubes in polyethylene

Background

The extraordinary mechanical properties of carbon nanotubes can be used to improve the strength and other mechanical properties of polymer materials by hybriding carbon nanotubes into polymer materials. These nanotubes may have preferred orientation due to their natural shape.

Investigation

In Figure 1 below, X-ray diffraction patterns from polyethylene with and without added double-wall carbon nanotubes measured in reflection geometry taken using Rigaku's SmartLab multipurpose diffractometer are presented. A carbon nanotube peak is clearly observed in the sample containing carbon nanotubes. However, this geometry does not reflect the orientation of the nanotubes in this material.

X-ray diffraction patterns from polyethylene
Figure 1

 

To determine the preferred orientation of the nanotubes, transmission X-ray diffraction measurements of the sample with carbon nanotubes were taken at different azimuths. The carbon nanotube peak was seen only in an orientation along which high order polyethylene peaks are presented, as in Figure 2 below. This suggests that the nanotubes are preferentially aligned along the same direction as the polyethylene chains.

anotube peak seen only in an orientation along which high order polyethylene peaks
Figure 2