Stress Induced Formation of Stable & Metastable Phases in Semi-Crystalline Polymers during Cryogenic Mechanical Milling

Effect of high‐energy ball milling on the structure and mechanical properties of ultra‐high molecular weight polyethylene

“…However, in one of our earlier studies, we carried out the annealing of the deformed UHMWPE, and this experiment showed the metastability of the monoclinic phase. The metastability of the monoclinic phase was also confirmed by other authors . Such a divergence in the experimental results could be caused by the different conditions of the deformation process and the different molecular weights of the polymers used.…”

“…Figure shows that whereas before the deformation the UHMWPE powder preferentially consisted of an amorphous phase (a halo with center at 2θ = 19.45°) and an orthorhombic crystalline phase [with two intensive peaks at 2θ = 21.5° (110) and 2θ = 23.9° − (200)], after deformation a new peak appeared at 2θ = 19.55°. This peak corresponded to the monoclinic phase, which is usually formed in PEs as a result of deformation processes, including ball milling . An increase in the milling time resulted in an increase in the related monoclinic phase peak intensity.…”

“…It is known that milling can result in phase transformations and the amorphization of polymers. For instance, the milling of high‐density polyethylene (HDPE) leads to the transformation of the orthorhombic phase into a monoclinic one . Poly(vinylidene fluoride) transforms from the α to the β phase under milling, whereas the high‐energy milling of poly(vinyl acetate), polyamide 6, and polypropylene leads to the amorphization of the crystalline phase.…”

“…Poly(vinylidene fluoride) transforms from the α to the β phase under milling, whereas the high‐energy milling of poly(vinyl acetate), polyamide 6, and polypropylene leads to the amorphization of the crystalline phase. The deformation of polymers can also be accompanied by a decrease in the molecular weight, changes in the morphology and size of the crystalline particles, and the oxidation and formation of crosslinked structures . In this study, the effects of HEBM on the UHMWPE structure and properties were examined.…”

Solid‐state recycling of polyimide film waste

“…Mechanochemical treatment is a nontraditional‐polymer technique, though the one of the first researching work in solid‐state mechanochemistry of polymers was presented a long time ago 18. Systematic researches have started at the early 1990s,19–21 and by the early of the 2000s, a number of publications has increased significantly 22–30. This researches discovered a changes during a polymer solid‐state treatment which include: particle size dispersion and average size, powder morphology, molecular weight dispersion and average value, structure (crystallinity, phase transitions), thermal properties (points of melting, glass, crystallization, enthalpy of transitions, and etc.…”