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Semicrystalline polymers usually undergo multilevel microstructural evolutions under high-temperature annealing and stretching deformation; this is essential to tailor the physical properties of polymer products in industrial processing. Here, we choose poly(p-dioxanone) (PPDO), a typical biodegradable, biocompatible, and bioresorbable polymer, as a model semicrystalline polymer and investigated its polymorphic structural transition and crystalline lamellar evolution under high-temperature annealing and stretching. High-temperature annealing caused the α'-to-α crystal transition of PPDO, accompanied by the improvement of crystallinity (Xc) and thickening of crystalline lamellae. Tensile strength and Young's modulus of PPDO increased but the breaking strain decreased as the annealing temperature increased. Stretch-induced phase transition of PPDO depended strongly on the initial structure and stretching temperature (Ts). The α-form PPDO transformed into its α' counterpart during stretching at low Ts; this phase transition was irreversible and did not retain to α form with the release of stress. However, no phase transition took place for the α-form PPDO stretched at high Ts ( ≥ 40 °C). Original lamellae of α-form PPDO changed into the fibrillar lamellae during stretching via melt-recrystallization mechanism.
This article was published in the following journal.
Name: The journal of physical chemistry. B
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The techniques used to produce molecules exhibiting properties that conform to the demands of the experimenter. These techniques combine methods of generating structural changes with methods of selection. They are also used to examine proposed mechanisms of evolution under in vitro selection conditions.
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The interdisciplinary science that studies evolutionary biology, including the origin and evolution of the major elements required for life, their processing in the interstellar medium and in protostellar systems. This field also includes the study of chemical evolution and the subsequent interactions between evolving biota and planetary evolution as well as the field of biology that deals with the study of extraterrestrial life.
Evolution at the molecular level of DNA sequences and proteins. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
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