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| Titel: |
Fracture Surface Energy of Highly Oriented Polymers |
| Auteur: |
Prevorsek, D. C. Butler, R. H. |
| Verschenen in: |
International journal of polymeric materials |
| Paginering: | Jaargang 2 (1973) nr. 3 pagina's 167-183 |
| Jaar: |
1973-04-01 |
| Inhoud: |
A Monte Carlo technique is used to estimate the fracture surface energy of highly oriented polymers ruptured under conditions at which the contribution of plastic deformation in front of the propagating crack is small compared with the energy required to form new surfaces at the tip of the crack. The effects of molecular weight, cohesive energy, and breaking energy of the polymer chain are discussed for the cases where: (1) all molecules are fully extended and (2) chain folding occurs at random. With the extended chain model the fracture surface energy increases monotonically with the molecular weight and approaches asymptotically its maximum value NQb. (N = number of polymer chains per unit area and Qb = energy required to break the polymer chain.) The cohesive energy, while not contributing substantially to the fracture surface energy at high values of the molecular weight, strongly affects the width of the molecular weight range in which fracture surface energy shows a pronounced molecular weight dependence. The lower the cohesive energy of a polymer, the higher must be the molecular weight to utilize a given fraction of the potential offered by an isolated polymer chain. For the systems where chain folding occurs at random, the model predicts a maximum in fracture surface energy at a value of number average molecular weight (Mn) corresponding approximately to the number average molecular weight between the folds. For higher values of Mn the fracture surface energy first decreases and then assumes a near constant value. This decrease is attributed to the weakening of the structure through chain folding while the effective length of the molecules remains unchanged. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 4 van 7 gevonden artikelen
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