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This topic is nylon 12 and nylon 12 elastomer (PolyTHF - nylon over 12 block copolymer), the systematic study of the structure and mechanical properties of the stretching process. Stretched nylon 12 in the yield phase, a new transitional phase, referred to as α'' phase, as the stress increases, the transition phase disappears. Nylon 12 - PolyTHF stretching same α'' phase, however, in the case of a high content of poly-tetrahydrofuran, α'' phase at room temperature and can stably exist, As temperatures and nylon content increases, α'' phase is a transition phase, only in a range of temperature and stress exists in the. First nylon 12 when the lower and higher than the glass transition temperature of the structural changes in the stretching process, with a wide angle X-ray diffraction in situ study results show that whether it is below or above the glass transition temperature, and in the yield phase, nylon transition phase from γ phase to α'' phase transition, as the temperature increases, α'' phase shortened life. When the temperature is lower than the glass transition temperature, as the strain increases, the transition phase α'' opposing mesomorphic state transition, while the high temperature, the transition phase α'' opposite gamma 'phase transition. Outside acting role in the competition with coupling and thermal excitation, leading to a different tensile final state. Below the glass transition temperature, the outside acting dominant role, resulting in the transition phase α'' phase appears as well as the transition to the mesomorphic state; higher than the glass transition temperature, increased thermal excitation effect, resulting in α'' opposite gamma 'phase transition . Α'' phase, the transition phase occurs exactly in the plastic deformation zone, indicating a close relationship between the mechanical properties and structural changes. And wide angle X-ray diffraction in situ polytetrahydrofuran - the multi-block copolymer of nylon 12 and the structural changes in the stretching process. The results showed that in a nylon 12, a low content of the block copolymer, stretched at room temperature induced the formation of α'' phase, but also to a certain extent can be α'' phase stable. Heating test results showed that the sample after the tensile α'' phase is not a thermodynamically stable phase, but a kinetically stable phase. The reply to the test, when the shed when an external force, α'' phase may be partially converted back to the initial γ phase. Such reversibility indicates the entropy contribution might lead to the elasticity of nylon 12 elastomer good reason. When the nylon 12 content is increased and the temperature is increased, the stretch induced α'' phase is the transition phase, it is only in the memory in a certain range of temperature and stress.
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