Elevated temperature nanoindentation characterization of poly(para-phenylene vinylene) conjugated polymer films

Abstract

a b s t r a c tTemperature dependent mechanical properties of poly(p-phenylene vinylene) (PPV) were investigated using quasi-static (QS) and dynamic nanoindentation (NI) at temperatures over the range of 25 to 100 C. The reduced modulus decreased from about 4.40 GPa to 3.64 GPa over this temperature range. The plasticity indices at all measurement temperatures were lower than the critical value of 0.875, characterizing material "sink-in", rather than "pile-up" during measurements. The plasticity index showed a non-monotonic trend, with a minimum value at around 70 C. Analysis of indentation stress relaxation data, obtained at different temperatures, was also performed using generalized Maxwell viscoelastic models. From these analyses, a relaxation mode, with a characteristic relaxation time of approximately 0.5 s, was evident. The characteristic time remained relatively unchanged over the temperature range of 25 to 100 C. However, the relaxation modulus associated with this mode showed the expected decrease with increase in temperature.

Ultrastiff Biobased Epoxy Resin with High Tg and Low Permittivity: From Synthesis to Properties

“…Nanoindentation is an effective method of probing the site-specific mechanical properties at a very fine scale. Because of a very tiny plastic deformation imposed, a very small sample is adequate for finishing testing to acquire mechanical results comparable to a bulk sample . During measurement, load–displacement profiles are recorded and then used to calculate Young’s (elastic) modulus, hardness and creep displacement .…”

“…Because of a very tiny plastic deformation imposed, a very small sample is adequate for finishing testing to acquire mechanical results comparable to a bulk sample. 47 During measurement, load−displacement profiles are recorded and then used to calculate Young's (elastic) modulus, hardness and creep displacement. 48 Nanoindentation has been successfully used to gauge mechanical properties of cured epoxy resins.…”

Conductive Polymers: Opportunities and Challenges in Biomedical Applications

“…This examination highlighted a relaxation mode defined by a characteristic relaxation time of around 0.5 s. Within the 25–100 °C temperature range, the characteristic time did not undergo any significant alterations. On the other hand, a temperature increase caused a reduction in the accompanying relaxation modulus, as anticipated …”

“…On the other hand, a temperature increase caused a reduction in the accompanying relaxation modulus, as anticipated. 150 The surface wettability of (diphenylamino)-s-triazinebridged p-phenylenevinylene polymer (DTOPV) can change in the presence of UV light, thereby also affecting its fluorescence quenching. For example, the patterned polymer has been exposed to UV light via a photomask.…”

Theoretical and experimental analysis of indentation relaxation test

“…Constant displacement and hold (CDH) relaxation tests might appear to be better candidates to obtain these fundamental characteristics in a wider range of conditions, as the affected volume is not supposed to vary significantly during the hold segment. [14][15][16][17][18][19] However they have not been popular. 20 As stated before, few nanoindentation apparatuses are displacement-controlled, sometimes making it difficult to maintain a constant displacement contrary to a prescribed load.…”