What Does Nanoindentation Mean?

What does "nanoindentation" mean? Nanoindenters are mainly used to ensure micro or nanoscale mechanical properties or performance through powerful techniques called nanoindentation technology. Nanoindentation is used to ensure material parameters such as hardness (H), modulus of elasticity (Es), viscosity or plasticity parameter, and experimental reading by penetration (h) and head load (P) . It should be noted that the force involved is usually in the range of micro Newtons or milliNewtons and the depth is in the nanometer range.

Hardness (H) and elastic modulus (E) were measured by using instrumented indentation by using Oliver and Pharr's method. The applied load is in the range of 0.1 to 400 mN. Indentation was performed by multiple loading-removal nano-indentation test under increased load at the same indentation point using Nanoindenter XPTM with Bekovich indenter from MTS Systems. Prague-Brentano X-ray diffraction pattern was obtained from Shamadzu XRD 7000, CuKα, 40 KV, 20 mA. Modification of the polymer surface after irradiation was investigated using a contact mode atomic force microscope. The scanning area was 30 μm × 30 μm. Images were obtained using Shimadzu's SPM - 9500 apparatus. The Shore D hardness test was carried out at room temperature in Wutest Shore D type MP-2a according to the procedure described in ASTM D 2240-75. For each sample type, test three times and apply the probe to different sample areas and calculate the average.

Effect of γ and ultraviolet irradiation on hardness, elastic modulus and viscoelasticity of castor oil (PU) derived polyurethane was investigated by nanoindentation test. Modification of the surface morphology induced by radiation was observed by atomic force microscopy. Polyurethane derivatives derived from castor oil have little change in hardness, elastic modulus, viscoelasticity and contact angle, and exhibit good resistance to gamma rays. Due to UVA radiation, the hardness of PU increases in the region near the surface, after UVC radiation the hardness of PU decreases. Although the roughness increases markedly, the contact angle of water droplets after UVC irradiation decreases but does not decrease after gamma ray irradiation. These results are due to the different reaction of polyurethane to radiant energy. The increase in hardness caused by UVA is due to higher crosslinking at shallow depth and the reduction of mechanical properties may be due to chain cutting.