Micromechanics of stress relaxation in amorphous glassy PMMA part II: application of the RT model

Nano-Mechanical Properties of Modified Poly(Methyl Methacrylate) Films Studied by Atomic Force Microscopy

“…It is likely that this modifier protects the polymer against photodegradation. This result means that other reactions, such as macromolecular rearrangements and relaxation processes at the surface, similar to those described previously [45][46][47][48][49], play an important role in the hardening of pure and doped PMMA during exposure to UV radiation. It is probable that the thin harder layer, or socalled ''polymer skin'', is formed at the surface, which can be detected just by nanoindentation.…”

“…Primary relaxation is caused by the movements of segments, which are restricted (frozen) below T g , whereas they are significant above T g . Secondary (subglass) relaxation is related to the rotation of side groups around the bond between them and the backbone [45][46][47][48][49]. These segmental motions are accompanied by the movements of void space.…”

“…These segmental motions are accompanied by the movements of void space. An illustration of the relaxation processes in PMMA and detailed theoretical explanations can be found in the articles by Stachurski [46,47]. The mobility of chains is also dependent on the presence of low-molecular weight additives that plasticize the polymer.…”

Effect of thiourethane filler surface functionalization on stress, conversion and mechanical properties of restorative dental composites

“…In this case, not only did the carbon–sulfur bonds likely provided stress relief, but the thio-carbamate bonds present in the thiourethane structure must have contributed to this effect [42]. In addition, other studies have demonstrated active strand behavior with oligomeric surface functionalization [43,44], and this will be further investigated in future studies utilizing stress relaxation experiments in dynamic mechanical analysis. In any event, it is important to highlight that the thiourethanemodified materials reached this lower stress result without compromise to the final conversion and elastic modulus.…”

Definition and Properties of Ideal Amorphous Solids

“…The data support the conjecture of a random body. Also, amorphous cells of poly(methyl methacrylate) (PMMA) and poly(carbonate) were simulated using standard methods [13]. Measurements of Voronoi volumes, (V V ), for all individual atoms were carried out.…”