Time-Temperature Superposition Principle in Shearing Tests Compared to Tension Conditions for Polymers Close to Glass...

Area of Science:

• Polymer Science
• Materials Science
• Rheology

Background:

• Time-temperature superposition (TTS) is crucial for polymers near their glass transition.
• TTS has been validated for linear viscoelasticity and large tensile deformations.
• TTS in shear conditions, especially at high strains, remained unaddressed.

Purpose of the Study:

• To investigate the applicability of TTS in shear conditions for polymers.
• To compare TTS behavior in shear versus tensile conditions across various strain levels.
• To explore the determination of shift factors and the influence of compressibility.

Main Methods:

• Experimental testing of polymethylmethacrylate (PMMA) with varying molar masses.
• Application of TTS principle under shear and tensile loading conditions.
• Analysis of low and high strain responses to assess TTS validity.

Main Results:

• Demonstrated the successful application of TTS in shear for PMMA.
• Compared shear TTS with tensile TTS, highlighting similarities and differences at high strains.
• Identified potential dependence of shift factors on compressibility.

Conclusions:

• The principle of time-temperature superposition is relevant for shear conditions, even at large deformations.
• Compressibility should be considered when determining shift factors for complex mechanical loadings.
• This research provides new insights into polymer behavior under diverse mechanical stresses.