AbstractThe morphology of the ionomer resin from which Nafion perfluorinated membrane products are made was studied with wide‐angle and small‐angle x‐ray diffraction. A reflection observed in the small‐angle x‐ray scan from hydrolyzed polymer is attributed to ionic clustering. The effects of equiv wt, cation form, temperature, water content, and tensile drawing on ...... hiện toàn bộ
AbstractThe Raman spectrum of partially crystalline polyethylene can be described as a superposition of three components, which originate from the orthorhombic crystalline phase, a meltlike amorphous phase, and a disordered phase of anisotropic nature, where chains are stretched but have lost their lateral order. The mass fractions involved in the three phases can ...... hiện toàn bộ
AbstractFilms of chitosan, prepared by different fabrication processes, were examined at several structural levels, from the molecular to the macroscopic. This revealed the presence of polymorphic crystal forms, which varied with film treatment. Similarly, morphological structures varying from spherulites to rods were formed, depending on film processing conditions...... hiện toàn bộ
AbstractA temperature‐dependent small‐angle x‐ray scattering and electron microscopic study on a sample of low‐density polyethylene affords a determination of the structure changes in a heating and cooling cycle and suggests a new model of partial crystallization and melting. The analysis of SAXS data is based upon some general properties of the electron‐density co...... hiện toàn bộ
R. Popli, M. Glotin, L. Mandelkern, Robert D. Benson
AbstractThe α and β relaxations of a variety of polyethylenes have been extensively studied using lowfrequency dynamic mechanical methods. The main focus of this work has been both the control and the quantitative measurement of the key structural factors that describe semicrystalline polymer systems. The structural factors that have been examined in detail include...... hiện toàn bộ
AbstractThe supramolecular organization of the aromatic polyamide fiber Kevlar 49 has been studied using a combination of electron diffraction and electron microscope dark‐field image techniques. The dark‐field images derived using selected reflections from longitudinal sections exhibit axial banding of two main types having periodicities of 500 and 250 nm. Careful...... hiện toàn bộ
AbstractInfrared spectra in conjunction with calorimetric measurements have been used to follow the crystallization process and microstructural changes of poly(ethylene oxide) (PEO) in poly(ethylene oxide) and poly(methyl methacrylate) (PMMA) blends. We have given particular attention to compositions containing low PEO concentrations. The crystallization behavior a...... hiện toàn bộ
Wen‐Chou V. Wang, Edward J. Krämer, Wolfgang Sachse
AbstractHydrostatic pressure usually increases the glass transition temperature Tg of a polymer glass by decreasing its free volume; if the pressurizing environment is soluble in the polymer, however, one might expect an initial decrease in Tg with pressure as the polyme...... hiện toàn bộ
William J. Koros, R. T. Chern, V. Stannett, H. B. Hopfenberg
AbstractA model is discussed which explains reported complex effects of feed composition and pressure on component permeabilities in high‐pressure gas separators based on glassy polymer membranes. A special form of Fick's law which accounts for the fact that penetrants in glassy polymers sorb into and diffuse through two different molecular environments provides th...... hiện toàn bộ
AbstractDoi and Edwards have recently proposed a molecular theory for the dynamics of entangled polymer liquids based on a tube model to represent the mutual constraints on configurational rearrangement of the chains. Expressions for diffusion coefficient, plateau modulus, zero‐shear viscosity, steady‐state recoverable compliance, and terminal relaxation time can b...... hiện toàn bộ
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