Abstract In this study, wide‐line NMR and x‐ray diffraction have been used in conjunction to study the crystal structure of poly(vinylidene fluoride). Drawn fluoride) film was found contain two phases, relative amounts each depending on draw temperature. Drawing at 50°C. yields a single phase, designated as phase I, while drawing temperatures between 120 160°C. mixture I second (phase II). The fraction II increases with increasing temperature, but never obtained without some I. A tentative...

Abstract The sorption and diffusion of low molecular weight penetrants proceeds almost exclusively through the amorphous component semicrystalline polymer solid. diffusive transport properties geometrical distribution are substantially modified by mechanical thermal treatment. Deformation spherulitic material first loosens structure then transforms it into a densely packed fibrous with great many taut tie molecules in component. Annealing lets crystals grow thickness, removes crystal...

Abstract The diffusional transport of aqueous solutes through water swollen polymer membranes is examined by the concept free volume water‐polymer systems, V f,13 . relative diffusivity (D in membrane/D water) can be expressed product probability factor finding holes equal or larger cross section, q, than section solute, q2, (sieve mechanism) and factor. An analysis experimental data indicates that within range solute size investigated (up to albumin) sieve mechanism not yet playing a role...

Abstract

Abstract The diffusive permeability of water P , which relates to flux under a concentration gradient (measured by diffusion tritiated water), and the hydraulic K pressure are defined. For case transport one has = KRT /ν 1 where ν is molar volume water. relationship between was investigated as function hydration H i.e., fraction in swollen polymer membranes. following characteristic features revealed. (a) In lowhydration region ( < 0.2), permeates even an applied . (b) higher greater than...

The deformation occurring during the drawing of polyethylene single crystals consisting only {110} fold domains was studied by means electron diffraction and bright-field dark-field microscopy. Samples several types were used; all being drawn 25% on a Mylar substrate. This paper is particularly concerned with relationship between draw direction crystal axes as it affects type deformation. Four different deformation, involving combinations twinning phase changes, can be distinguished follows:...

Abstract Temperature influences the attainable draw ratio, transparency of drawn material, long period and intensity distribution in small angle X‐ray diffraction pattern. Drawing at or below 80°C yields a first order maximum with relatively large lateral width indicating variation lamellar surface orientation between 90° 45° to direction. above reduces leads appearance second order. The thermal history starting quenched, slowly cooled, annealed, affects behavior. period, however, seems be...

Abstract The original fringed micelle model of a crystalline polymer solid assumed two phases, submicroscopical bundled chain crystals embedded in an amorphous matrix. Every macromolecule passed alternately through and regions. This ideally represented the crystallization with highly stretched rubber, but failed to explain spherulites lamellar single crystals. folded lamellae grown from dilute solution postulated inclusion all material (one phase model). x‐ray diffraction pattern density...

Abstract The crystallinity, elastic modulus, and tensile strength of samples various draw ratios together with the true stress—strain curves high‐density polyethylene were determined to establish correlations morphological changes occurring during deformation. Changes crystallinity at below 5, i.e., constancy drawing quenched film a decrease annealed film, are explained by formation microfibrils independent thermal history film. slide past each other higher ratios, generating an increasing...

Abstract Infrared spectroscopy is applied to discuss the orientation, crystallinity, and conformation of chain segments in amorphous regions drawn high-density polyethylene. The orientation crystals as well crystallinity are derived from dichroism absorbance, respectively, band at 1894 cm-1. some aspects about can be obtained bands 1400-1300 cm-1 region (gauche) 1078 (gauche trans). dichroic studies show a high degree increasing with draw ratio λ for crystals, but low reaching saturation...

Abstract Under uniaxial tensile load, the plastic deformation of unoriented crystalline polymers first transforms lamellae into a fibrous structure. Usually drawing is inhomogeneous with neck propagating through sample. The higher draw ratio, axial elastic modulus as consequence larger fraction taut tie molecules in amorphous layers connecting blocks each microfibril. As almost 1/(1 − α) times strain under are much more strained than chains crystal blocks. Hence, their contribution to...

The morphological properties as derived from wide- and small-angle x-ray scattering, IR dichroism, electron spin resonance, microscopy, the anisotropy of mechanical fiber structure can be well explained by microfibrillar concept developed on basis a detailed study plastic deformation fracture polymer single crystals. microfibrils bridging cracks fractured crystal contain in axial direction regular alternation blocks amorphous layers containing chain folds, ends large ratio (between 5 30%)...

Abstract The strength‐limiting process in the fracture of semicrystalline fibers and highly oriented films is rupture tie molecules connecting folded chain lamellae machine direction. This view supported by data on stress temperature dependence lifetime under load radical formation during experiment. observed tensile strength, however, about 10 times smaller number fractured chains between 100 1000 larger than expected basis known plane. discrepancy a consequence inhomogeneity...

Raman scattering from the longitudinal-acoustical vibration of single crystals polyethylene has been observed using an argon laser and iodine filter. The frequencies are in range 10–40 cm−1 inversely proportional to thickness which varied between 90 250 Å.