Physical aging of polymers can be defined as the changes in spatial arrangement of macromolecules and side chains with respect to one another. Thermal properties, such as melting point, glass transition, and crystallization, can become modified, possibly transforming the solubility and optical ...
Exposure to extended periods of sub-Tg temperatures causes physical changes in the molecular structure of epoxy resins and epoxy-based materials to occur. These physical aging mechanisms include the reduction in free volume and changes to the molecular configuration. As a result, mechanical, thermodyna...
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Instead it attempts to consolidate the strong theoretical principles upon which the PALS is based, and to correlate those principles with the equally strong theoretical principles associated with the physical aging of polymers. Both sets of principles are centered around the concept of free volume, ...
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Physical agingPolyrnethylmethacrylateViscoelasticity.Amorphous polymers are viscoelastic materials. When they are subjected to dynamical loads, their behavior can be modeled by transform functions of stress and strain in the complex plane. In our work, a model based on the fractional calculus concept ...
Constitutive equations are derived for the viscoelastic response and enthalpy recovery in amorphous polymers quenched far below the glass transition temperature. The model is based on the concept of cooperative relaxation, which treats a polymer as an ensemble of independent relaxing regions. Any flow ...
Native proteins use hydration frustration—regulating the dehydration of hydrophilic residues and the hydration of hydrophobic residues—to enhance their activity. Now it has been shown that single-polymer-chain nanoparticles made from random heteropolymers can exhibit similar hydration frustration, following...
Physical aging of glassy normal and waxy rice starches: Effect of aging temperature on glass tran- sition and enthalpy relaxation[J]. Carbohydrate Polymers, 2003, 53(2): 205-211H. J. Chung and S. T. Lim, "Physical aging of glassy normal and waxy rice starches: effect of aging ...
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