The Optical Behavior of Polyethylene Spherulites

Polyethylene was crytallized from the molten film under temperature gradient. As a result, the optically positive spherulites were observed, though only the negative spherulites had been observed previOusly in polyethylene. When the radial structure units twisted regulary in a spherulite are formed parallel to the surface of the film, the spberulite is usually optically negative in polyethylene. In this study, the temperature gradient normal to the surface of the film gives so significant tilt of the radial structure units formed to the surface of the film that the radial refractive index becomes larger than the tangential one under the transmitted polarized light and the spherulites have optically positive behavior. The optical behaviors of the polyethylene spherulites and the crystallizing condition were studied and discussed

Studies on the electrochemical properties of copolymers of maleic acid, I : potentiometric titration at low ionic strength

In this series, the polydibasic properties of some copolymers of malefic acid are studied from the viewpoint of the neighbor interaction. In the present paper, the potentiometric titrations of two copolymers, malefic acid-vinyl acetate and malefic acid-styrene copolymers, were studied at low ionic strength, with somewhat different experimental methods from Garrett and Ferry. The empirical equations to estimate the average dissociation constants were presented in comparison with that of the monomeric dibasic acids. The average dissociation constants in various polymer concentrations were obtained and the polydibasic properties were discussed

Thermal Study on Adducts of Urea with n-Alkanes and n-l-Alkanols

Crystalline adducts of urea with n-alkanes (C(8)~C(20)) and n-l-alkanols (C(12)~C(18)) were prepared. From thermal analysis and X-ray diffraction study on the adducts, we found that the composition of adducts and the heat of decomposition can be obtained easily from the thermogram of adducts

Two Distinct Types of Spherulite in Poly (ethylene oxide)

Fujiwara's oriented crystallization method was applied to poly (ethylene oxide) to obtain a uniform texture composed of parallel fibrils which correspond to the structure of a radial direction of spherulites. Two different x-ray diffraction patterns in crystallite orientation of the spherulite radius were obtained. From these patterns and crystallization conditions it could be determined that the spherulite radius has a [401] rotation axis below about 50℃ and two [421] and [421]rotation axes above about 50℃. A reasonable interpretation was given for these two ways of spherulitic crystallization, based on the growth features of lamellar crystals of poly (ethylene oxide). That is, it is concluded that a second order transition in poly (ethylene oxide) lamellar crystals near the temperature of 50℃ is responsible for the change of the rotation axis in spherulite radius

The Molecular Mechanism of Chain Tilt in Poly (ethylene terephthalate) Fibers

The molecular mechanism of chain tilt in poly(ethylene terephthalate) (PET) fibers was proposed. The mechanism was considered basing on the ordering process from the cold drawn state of glassy PET. It was confirmed that the direction of maximum contraction on ordering agrees with the azimuth of chain tilt which varies with annealing temperature. In the stacking structure of irregular folded chain blocks of cold drawn PET, the expansion to the chain direction and the contraction to the lateral direction yield the compressive stress and tensile stress r respectively. The stress revealed as the result of the ordering from the glassy structure to crystalline structure can be relaxed by the rotation of the resulting crystallites. Therefore, we can suggest that the chain tilt is caused by the relaxation process of the stress

A Study on single Crystals of Nylon 12

Single crystals of two crystatalline forms, α and γ, in nylon 12 were obtained from dilute solutions. The single crystals of γ-form from diols solutions are ribbon like lamellae in shape, and that of α-form obtained from solution in water-formic acid are parallelogramic. Electron diffraction study shows that chain packings in single crystals of two crystalline forms are very similar to those of nylon 6, respectivel

Order-Disorder Transition in Urea-Polyethylene Complex

The phase transition of urea complexes whose guest components range from n-paraffin to polyethylene was investigated by DSC thermal analysis. The transition temperatures increased with increasing the chain length; the related heats did not change much with the chain length. An X-ray powder diffractometry for urea-polyethylene complex revealed that the complex undergoes the same kind of phase transition between orthorhombic and hexagonal as urea-n-paraffin complex. The transition is interpreted in terms of an order-disorder transition with respect to the orientation of the guest molecule

A New Model for Structure of Poly (ethylene terephthalate) in its Glassy State

A new realistic, structural model is proposed for the glassy solid state of poly(ethylene terephthalate) (PET). The model is considered basing on crystallization behaviors from the glassy state of PET, and in particular including the evidence from the estimation of chain folding energy in this report. When PET is quenched from its melt into the glassy state, irregular folds with lower conformational energy remain in glassy structure and disturb the three dimensional arrangement of the chains connected with the folds. In conclusion, we suggested that the structure of glassy PET is not in amorphous state which is represented by the interpenetrating random coil model, but in frozen metastable state which can be approached from the chain folded structure of polymer crystals

Giant Single Crystals of Poly (ethylene oxide)

The preparative method of giant single crystals of PEO and the experimental results of them by x-ray diffraction and electron microscopy are described. The crystallization of PEO was carried out in a two dimensional crystallization apparatus. From the tridirectional x-ray diffraction patterns on the resulting platelike crystals, it was confirmed that these crystals have a single crystal-like orientation at high supercoolings, the [401] axis is parallel to a growing direction and the [001] axis is perpendicular to the wide surface, and a double orientation at low supercoolings, two axes of [421] and [421] are parallel to a growing direction and the [001] axis is perpendicular to the wide surface

Polymorphism of Amylose V Complexes

Lamellar crystals of amylose V complexes with the 6(1), 7(1) and 8(1) helical configurations can be prepared from aqueous solutions of amylose by using various complexing agents. It is noted that the crystal shape can be explained by the symmetry of the unit cell in the basal plane and the chain packing in the unit cell is cOncerned with the symmetry of helical chains. The existence of 6(1), 7(1) and 8(1) heliccs which occurs stepwisc with the number of glucopyranose an intger is discussed