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首页> 外文会议>International Symposium on Metastable, Mechanically Alloyed and Nanocrystalline Materials(ISMANAM 2004); 20040822-26; Sendai(JP) >Stress Induced Formation of Stable Metastable Phases in Semi-Crystalline Polymers During Cryogenic Mechanical Milling
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Stress Induced Formation of Stable Metastable Phases in Semi-Crystalline Polymers During Cryogenic Mechanical Milling

机译：低温机械研磨过程中应力诱导半结晶聚合物中稳定和亚稳相的形成

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摘要

Cryogenic Mechanical Milling (CMM) is applied on various homopolymers (e.g. high density polyethylene (HDPE), isotactic polypropylene (iPP) and polyvinylidenefluoride (PVDF)) in a liquid nitrogen bath. The resultant pulverized polymers are characterized by means of X-ray diffraction and Differential Scanning Calorimetry DSC. Regarding the observed structural changes the most striking result is a stress induced "martensitic like transformation" at cryogenic temperatures without noteworthy plastic deformation. The initially orthorhombic crystal structures of PVDF as well as HDPE are transformed into monoclinic ones. Moreover, the stability of the newly formed phases is investigated by annealing the milled samples above their respective α_c-relaxation temperatures. For the underlying mechanism of such phase transformations we propose a simple model that takes the possible conformations of the macromolecules in the crystal unit cells into consideration.
机译：在液氮浴中，将低温机械研磨（CMM）应用于各种均聚物（例如高密度聚乙烯（HDPE），全同立构聚丙烯（iPP）和聚偏二氟乙烯（PVDF））。通过X射线衍射和差示扫描量热法DSC表征所得的粉碎的聚合物。关于观察到的结构变化，最显着的结果是在低温下应力引起的“马氏体样转变”，而没有明显的塑性变形。 PVDF和HDPE的最初正交晶体结构转变为单斜晶体结构。此外，通过将研磨后的样品在各自的α_c弛豫温度之上退火，可以研究新形成相的稳定性。对于这种相变的潜在机理，我们提出了一个简单的模型，该模型考虑了晶体晶胞中大分子的可能构象。

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