Depth‐Sensing Macroindentation Test and Stepped Iso­thermal Method – Accelerated Assessment of the Local Retardation Behaviour of Thermoplastic Polymers

Abstract

Summary The prototype of a depth‐sensing macrohardness testing system with temperature chamber and temperature controlling unit for contact heating/cooling was upgraded in terms of control and software in such a way, that it allows application of the Stepped Isothermal Method (SIM) as for now. The SIM is a single‐specimen method, for which the temperature is raised stepwise at constant load and kept constant for a given time for each step, where the changes in indentation depth are measured as a function of time in this case. After correction of the thermally induced change in indentation depth and mathematical procedures a master curve construction is realised along a logarithmic time axis. The method was successfully applied to the assessment of the long‐term creep behaviour of different thermoplastic polymers such as PP, PE‐HD, PET and PVDF. The results obtained were compared with results of the SIM using tensile testing and the short‐term creep test using the depth‐sensing macrohardness testing system.

Time‐Lapsing Evaluation of the Retardation Behaviour of Polypropylene Homo‐ and Copolymers using the Stepped Isothermal Method based on Depth‐Sensing Macroindentation

“…The higher long‐term creep resistance found in the shoulders of the injection‐moulded specimens has a well‐known counterpart in the short‐term hardness properties with lower values in the shoulders than in the plane‐parallel area. Thus, this approach has proved to be successful to indicate local long‐time creep surface‐sensitively (this study and).…”

Influence of Media–Thermal Ageing on the Long‐Term Creep Behavior of Polypropylene

“…[ 6,7 ] or Lach et al. [ 8 ] have shown. The SIM is based on the time–temperature superposition principle which states that the molecular processes of viscoelastic materials proceed more rapidly as temperature increases.…”

Takotsubo Syndrome: Translational Implications and Pathomechanisms

“…Studies on TTS have reported that the female sex predominated, mainly aged 56-84 years [21][22][23]. However, there is no huge difference in the clinical characteristics and the course of the disease between men and women, although physical stress is more likely to cause TTS with much worse outcomes in males compared to females [24][25][26]. Interestingly, given the increased awareness of the disease entity nowadays, male TTS patients are also growingly recognized with decreasing age, the highest in younger patients [20,[27][28][29].…”

“…So far, only several TTS-relating studies using hiPSC-CMs have been reported [25,95,204]. In the last few years, TTS was not regarded as a genetic disease.…”