Small and large scale segmental motion in polymers: estimating cooperativity length by ordinary relaxation experiments

Abstract

Stress relaxation experiments by atomic force microscopy, and a novel method for analysing 1H‐NMR signals are used for the first time to estimate the cooperativity length in polymers.

Dynamic Heterogeneity and Cooperative Length Scale at Dynamic Glass Transition in Glass Forming Liquids

“…The evolution of the cooperativity length in glass-forming liquids with time and temperature always attracts the interest of researchers. ,− As an example, Pieruccini et al , proposed a canonical model allowing for the estimation of monomeric units cooperatively involved in the α-relaxation process. Classically, Donth’s approach allows for the estimation of the cooperativity length at the glass transition temperature using calorimetric techniques .…”

Correlated and cooperative motions in segmental relaxation: Influence of constitutive unit weight and intermolecular interactions

“…Recently Saiter et al [17] proposed an extended form of the Donth's model by combining two experimental techniques, modulated temperature differential scanning calorimetry (MTDSC) and broadband dielectric spectroscopy (BDS), enabling the calculation of the temperature dependence of the CRR size in a wide temperature range, starting from the onset of the cooperativity in the crossover region down to the T g . According to the recent literature [18][19][20][21][22], one can say that the difference between N C and N α , i.e., the difference between correlated motions and cooperative motions, is not clearly established. In a previous work concerning different fully amorphous polymers with different backbones, we observed a huge impact of the molecular weight of the constitutive units by comparing N C and N α [7].…”

In Focus - 6th International Conference on Polymer Behavior(ICPB6)

“…The first three papers (1–3), are related to Plasticity and Mechanical properties and Modeling and simulations. The first paper by Pieruccini et al, establishes a new method to estimate the size of cooperatively rearranging regions from simple stress relaxation measurements, instead of extensive NMR and dielectric spectroscopy investigations which are used here to prove the reliability of the new method. The second paper by Addiego et al, also suggests a new method, in this case to use time‐resolved Synchrotron Small Angle Scattering to assess the void volume fraction in tensile loading, unloading and recovery.…”