Three dimensional molecular orientation of isotactic polypropylene films under biaxial deformation at higher temperatures

Raman Spectroscopic Study of High-density Polyethylene during Tensile Deformation

“…The rheo-optical apparatuses for the birefringence and the infrared (IR) absorption have been developed and applied to clarify the deformation mechanism of polyolefins [17,18]. Since the IR spectroscopy provides the molecular orientation of the amorphous chains as well as the crystalline chains, in situ IR spectroscopy has been applied for the uni-and biaxial deformation of films [19][20][21]. In radiation facilities, in situ small-and wide-angle X-ray scattering measurements have been conducted, and real-time monitoring of the crystalline orientation and the change of the crystallinity during elongation has been reported [22,23].…”

Morphological reorganization and mechanical enhancement in multilayered polyethylene/polypropylene films by layer multiplication or mild annealing

“…The WAXD pattern of the pure PP monolayer film is instead characterized by coalesced and broad reflections at about 14.9°2 θ and by a signal at about 21°2 θ . This differs from wide angle X‐ray pattern of a typical monoclinic iPP crystallographic form and resembles the diffractogram of the PP mesophase . The significant broadening of the peaks is a typical result of fast cooling of the PP film, allowing little time for the material to formulate large crystals.…”

Structural Evolution of Two-Phase Blends of Polycarbonate and PMMA by Simultaneous Biaxial Stretching

“…Biaxially stretched polymer films are often used as packaging materials for food and industrial products, because the mechanical and gas barrier properties can be improved using biaxial stretching in the manufacturing process [1]. Many researchers have investigated how the structures of polymer films obtained by biaxial stretching vary in a number of aspects [2,3] for crystalline polymers [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27], polymer blends [28,29,30,31,32,33,34] and composites [35,36,37]. The dimensional stability is enhanced due to the increase in the degree of the stress-induced crystallinity [4], surface morphology is changed [5,6], hardness is enhanced [7], and high toughness polylactide film can be obtained by development of highly-oriented small crystallites [8] in the crystalline polymers.…”

“…The silica nanofillers are elongated parallel or perpendicular to the deformation directions depending on the type of nanofiller [35] and biaxial stretching of a PP/clay nanocomposite results in delamination and orientation of clay stacks [36,37]. Orientation by biaxial stretching is characterized by wide-angle x-ray diffraction [4,9,10,11,12,13,14,15,16,17,28,31,32], birefringence [9,13,14,15,16,17,18,19,20], infrared spectroscopy [13,20,21,22,23], fluorescence anisotropy [24], stress-strain behavior [14,16,17,25,26,27,32,33]. Isotropic plane film can be produced by simultaneous biaxial stretching, in which films are stretched in the X and Y directions at the same time, so that the properties of the stretched specimen thus produced are isotropic in the in-plane direction [14,16,32].…”

“…This indicates that a uniform orientation at all in-plane direction is caused by simultaneous biaxial stretching; that is, the polymer chains and crystalline lamellae are uniformly oriented at all in-plane direction. The in-situ polarized infrared spectroscopic study by Nitta et al suggests that the molecular chain is elongated uniformly at the all in-plane direction by simultaneous biaxial stretching of PP [20,23]. Though the uniform orientation without the preferred orientation is considered in the simultaneous biaxial stretching, the bimodal orientation to the stretching directions of X and Y is also suggested by a wide angle x-ray diffraction study in crystalline polymers such as polyethylene terephthalate (PET) and polyethylene naphthalate [16,31].…”