The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Mukerrem Cakmak - One of the best experts on this subject based on the ideXlab platform.
-
Comparative study on development of structural hierarchy in constrained annealed simultaneous and Sequential biaxially stretched polylactic acid films
Polymer, 2010Co-Authors: Mukerrem CakmakAbstract:Structural evolution during constrained annealing of PLA films biaxially stretched in simultaneous and Sequential biaxial Stretching was compared. Annealing of simultaneous biaxially stretched films yields films with in-plane isotropy with (100) crystallographic planes parallel to the surface. The first stage of Sequential Stretching where the films are stretched in Uniaxial constrained mode was found to yield films exhibiting transverse isotropy. The transverse Stretching of these films lead to formation of a distinct second population of chains primarily oriented in transverse direction, generating bimodal orientation texture. When the extent of Stretching in two directions are balanced, constrained annealed samples were found to exhibit uniplanar axial (100)[001] texture with the primary chain axial direction now switched to transverse direction. Two new superstructures, along [110] and [100] respectively were discovered in annealed PLA films.
Linxi Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Steered molecular dynamics simulation of elastic behavior of adsorbed single polyethylene chains
Journal of Polymer Science Part B: Polymer Physics, 2007Co-Authors: Yu Wang, Linxi ZhangAbstract:We investigate the dynamics of the detachment of single polyethylene (PE) chains from a strongly adsorbing surface in vacuum using a united atom model. Various statistical properties, including the mean-square end-to-end distance , the mean-square radii of gyration xy , z , the shape factor , the torsion angle distribution, the average surface adsorption energy , the average total energy , and the average force , are analyzed. The relationship between the average force and the pulling velocity υ shows two distinctive regions: a weakly dependence region at υ 10 -2 A/ps. Remarkably, the PE chain manifests force hysteresis under Sequential Stretching and releasing. These investigations may provide some insights into the elastic behavior of adsorbed polymer chains.
J.-y. Cavaillé - One of the best experts on this subject based on the ideXlab platform.
-
Influence of annealing treatments on the essential work of fracture of biaxially drawn poly(ethylene terephthalate)
Polymer International, 2012Co-Authors: H.-n. Vu, C. Gauthier, O. Lame, J.-y. CavailléAbstract:The biaxial Sequential Stretching process of poly(ethylene terephthalate) produces films with a fibrillar microstructure in which fibrils are parallel to the transverse extrusion direction. The mechanical properties of such films are strongly anisotropic due to both the orientation of crystallites and the properties of the intrafibrillar and interfibrillar amorphous phases. The idea is to modulate the properties of the amorphous phase without altering the fibrillar structure by annealing treatments. The morphology (crystallinity and orientation of the crystalline phase) of the annealed films is characterized and their mechanical properties (tensile tests and essential work of fracture) are tested in the longitudinal direction (parallel to the micro fibrils) and in the transverse direction (perpendicular to the micro fibrils). The crystalline phase orientation is the key parameter governing modulus anisotropy. Concerning crack propagation, annealing treatments lead to opposite evolution of the specific essential work of fracture parameter (w e) in the longitudinal and transverse directions. Thus, it is possible to erase fracture propagation anisotropy through an adequate annealing treatment. © 2012 Society of Chemical Industry.
E Baer - One of the best experts on this subject based on the ideXlab platform.
-
relationship between biaxial orientation and oxygen permeability of polypropylene film
Polymer, 2008Co-Authors: Peter S Dias, Anne Hiltner, Hongyu Chen, E BaerAbstract:Abstract Biaxially oriented polypropylene (BOPP) films were produced by simultaneous and Sequential biaxial Stretching to various balanced and unbalanced draw ratios. The BOPP films were characterized in terms of density, crystallinity, refractive index, oxygen permeability and dynamic mechanical relaxation behavior. It was found that the density and crystallinity of BOPP films decreased as the area draw ratio increased. Sequential Stretching led to a slightly lower density than simultaneous Stretching to the same draw ratio. Moreover, Sequential Stretching produced lower orientation in the first stretch direction and higher orientation in the second stretch direction compared to simultaneous Stretching. The study confirmed the generality of a one-to-one correlation between the oxygen permeability of BOPP films and the mobility of amorphous tie chains as measured by the intensity of the dynamic mechanical β-relaxation. Moreover, the study established the correlation for commercially important Sequentially drawn BOPP films with an unbalanced draw ratio. Finally, the chain mobility in the stretch direction was found to depend on the final stress during Stretching.
Yu Wang - One of the best experts on this subject based on the ideXlab platform.
-
Steered molecular dynamics simulation of elastic behavior of adsorbed single polyethylene chains
Journal of Polymer Science Part B: Polymer Physics, 2007Co-Authors: Yu Wang, Linxi ZhangAbstract:We investigate the dynamics of the detachment of single polyethylene (PE) chains from a strongly adsorbing surface in vacuum using a united atom model. Various statistical properties, including the mean-square end-to-end distance , the mean-square radii of gyration xy , z , the shape factor , the torsion angle distribution, the average surface adsorption energy , the average total energy , and the average force , are analyzed. The relationship between the average force and the pulling velocity υ shows two distinctive regions: a weakly dependence region at υ 10 -2 A/ps. Remarkably, the PE chain manifests force hysteresis under Sequential Stretching and releasing. These investigations may provide some insights into the elastic behavior of adsorbed polymer chains.
