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 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

Crystallization of Polymers from Solution under ShearingStress III Polybutene-1

It was shown that the fibrous crystals of isotactic polybutene-l crystallized from solution under shearing stress are also composed of the central threads with an extended chain character and the epitaxally deposited lamellae with a folded chain character. The characteristic behaviors in this polymer exist in; (1) that the resulting crystals possess the hexagonal modification of form 1'; (2) that at low polymer concentrations the lamellar crystals with an orthorhombic modification of form Ⅲ are precipitated in similar fashion to the case in the absence of stirring; (3) that the morphology in surface replica of thick deposited film is very similar to that of melt extruded polyethylene film crystallized in a highly stressed state

Crystallization of Polymers from Solution under Shearing Stress II Polypropylene

Isotactic polypropylene was crystallized in the form of fibrous crystals from solution under shearing stress. The fibrous crystals consist of the oriented cluster of micro fibrils. From the electron microscopy and the electron diffraction study, it was found that the fine texture of this fibrous crystals is also the two component systems which are composed of the central threads with an extended chain character and the lamellae with a folded chain character deposited on the threads, as in polyethylene. Relatively larger lamellar structure than that of polyethylene was observed. The effect of crystallization conditions to the formation of the fibrous crystals from solution of isotactic polypropylene was described briefly. A characteristic melting behavior due to the melting of the central threads with an extended chain character was observed from the thermogram of differential scanning calorimeter

Morphology Control of Aromatic Polymers during Polymerization

Morphology and formation mechanism of poly (4'-oxy-4-biphenylcarbonyl) (POBP) crystals obtained by solution polymerization were firstly treated. It was concluded that the formation mechanism of the bundlelike aggregates of fibrillar crystals in POBP was fundamentally simillar to that in POB whiskers. Secondly the copolymerization effects of m-acetoxybenzoic acid and 4-(4-acetoxyphenyl) benzoic acid on the morphology of POB whiskers were studied. The experimental results strongly supported our proposal for the formation mechanism of whiskers which was consisted of crystallization of oligomers with a critical length as lamellae from solution and solid state polymerizationof oligomers between lamellae. Finally, the formation mechanism of poly (p-oxycinnamoyl) spherical products during solution polymerization was treated. The formation of these spherical products could be understood by overlapped phase diagram of melting depression curve and consolute curve of oligomers-solvent system