Structure and rheological properties of polymers
| Autor: | G. V. Vinogradov |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
chemistry.chemical_classification
Materials science Polymers and Plastics General Mathematics General Engineering Thermodynamics Polymer Apparent viscosity Condensed Matter Physics Industrial and Manufacturing Engineering Viscoelasticity Condensed Matter::Soft Condensed Matter Biomaterials Viscosity Rheology chemistry Mechanics of Materials Solid mechanics Polymer chemistry Ceramics and Composites Dissipative system Deformation (engineering) |
| Zdroj: | Polymer Mechanics. 11:139-149 |
| ISSN: | 1573-8922 0032-390X |
| DOI: | 10.1007/bf00855434 |
| Popis: | The viscoelastic properties of linear flexible-chain polymers with a narrow distribution, for which M > 5Mc (Mc corresponds to the formation of a three-dimensional entanglement network), their mixtures, and concentrated solutions are examined. It is established that under the influence of deformation the polymer may undergo a transition to the rubbery state, which thus defines the limit of its flow state; this transition is also observed in mixtures and concentrated solutions of high-molecular-weight polymers with a narrow distribution. The relative simplicity of the rheological properties of linear high-molecular-weight polymers and their mixtures is determined by the sharpness of the transition to the rubbery state. It has been found that in mixtures of high-molecular-weight polymers the apparent viscosity mechanism associated with a decrease in dissipative losses on transition of the high-molecular-weight components to the rubbery state is dominant; on a broad range of molecular weights (M > Mc), and moreover for polymer solutions, the decrease in entanglement network density under the influence of deformation acquires considerable importance. It is established that the separate effect of the high-molecular-weight components on the viscoelastic properties of their mixtures contradicts the idea of a random network of macromolecular chains. Attention is drawn to the temperature dependence of the viscosity of polymers with a narrow distribution and the dynamic properties of their mixtures. Problems of theoretical and practical interest associated with the particular rheological properties of polymer systems at high deformation rates are defined. |
| Databáze: | OpenAIRE |
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