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Crystallization of polyethylene from solution was studied under shear strain. Making use of a rotational viscometer, a steady state flow of the solution was achieved. The crystals grown from solution under shear strain exhibited entirely the same features as those grown under no shear strain (the single crystals usually observed). Namely, the molecular orientation in the solution facilitates ctystallization but does not affect the morphology of the resultant crystals. It was found, however, that fibers were produced from 0.1% solutions and films from 1% solutions, both having grown from a few points on the rotating inner cylinder of the viscometer. These films consist of fibers which are similar to those grown from the 0.1% solutions. Electron microscopy revealed that the lamellae were piled up along the direction of the shear and aligned perpendicularly to the shearing direction. It is concluded that this sort of texture would be nothing but a quite general texture obtained when crystallization takes place under molecular orientation. It is suggested that this texture results from a bi-components crystallization where some polymer molecules crystallize first into the extended form and then the other molecules deposit into the chain folded lamellae on the substrate of the extended chain crystals. In order to confirm this assumption, measurements of D S C thermograms, specific heat, mechanical tan δ and the tensile moduli from the velocity of the propagation. of a pulse along the fibers were made for the fibers and the films grown from the solution. All the results showed a rather low crystallinity and low melting temperature of the fibers and films. In the D S C thermograms, moreover, no distinct peak was observed at the temperatures corresponding to the extended chain crystals. Also from the morphological studies no evidence has been observed on the bi-component crystallization in question. It was postulated that fibrillar structures observed did not exist when the crystallization took place but were produced by mechnical deformation of the lamellae, which occures after the precipitation of fibers and films.

In order to examine the structure of interlamellar tie fibrils found by Keith et al. (J. Polymer Sci., A-2, 4, 267 (1966)), the mixtures of polyethylene and paraffine were crystallized at various temperatures from melt into thin films on various substrates, and the resultant textures were studied by an electron microscope before and after paraffine was extracted by xylene. When a micro cover glass was used as the substrate, sheaf-like crystals in the order of 3μ were observed, suggesting that the substrate facillitated the nucleation in the thin film. When carbon and mica sheets were used as the substrate, the ordinary two dimensional spherulites with macro fibrils grown radially and the so-called banded spherulites were observed in the thicker region of the film. In the very thin region of the film were observed ribbon like crystals, which have not been found so far. They are fibrilar but can be considered as monolayer lamellae laid on the substrate. The lack of twisting of the lamellae suggests again some effects of the substrate. Under the same conditions as those used by Keith et al., the open structure of the spherulite they found was not observed. When polethylene/C32H66 ratio was 1:2 and the mixture was crystallized under higher supercoolings, the open texture similar to the Keith's was observed. However, the interlamellar fibrils was not observable but the fibril like materials seen among the lamellae were in fact composed of small irregular shaped lamellae. In view of the pronounced effect of the substrate on the morphology of the resultant spherulites, it seems rather questionable that the interlamellar fibrils found by Keith et al. are formed in bulk crystalline polymers.

In order to examine the possibilities of a heterogeneous fold structure proposed previously, in which large irregular loops are incorporated in regular sharply reentrant folds on the surface of polymer single crystals and of the molecular ties which connect lamellae in multilayer crystals, the morphologies of the solution grown crystals of the A-B-A type block copolymers of poly(ethylene oxide) (A) and poly(α-methyl styrene) (B) have been studied mainly as a function of polymer concentration. The range of the content of polyethylene oxide (PEO) was from 0.551 to 0.860, the molecular weight of each sequence being in the order of 104 to 105. The solvents used were ethylbenzene, xylene, and isoamylacetate. It was found that the copolymers having the PEO contents beyond 0.643 crystallized from dilute solution (0.1 to 0.25%) into the form of square tablets, similar to the PEO single crystals. Electron micrographs of these crystals revealed that poly(α-methyl styrene) chains were excluded from the crystalline part and deposited on the surface of the crystals during chain-folding crystallization and long loops thus formed aggregated in the solution or on drying the crystals in a manner depending on the solvents used. When the polymer concentration was increased to 0.5%, irregularly shaped, multilayer crystals were formed where a number of holes were found on their surfaces, suggesting that the frequency of the formation of tie molecules increased rapidly with increasing concentration. Evidences have been supplied for the formation of the long loops on the surfaces of lamellar crystals and of inter-lamellar tie molecules in the chain-folding crystallization. Die morphologische Beschaffenheit von losungskristallisierten A-B-A-Blockcopolymeren aus Polyathylenoxid (A) und Poly-α-methylstyrol (B) wurde hauptsachlich als Funktion der Polymerkonzentration untersucht. Damit wurde die Moglichkeit einer bereits fruher vorgeschlagenen, heterogenen Faltstruktur gepruft, in der grose, unregelmasige Kettenschlaufen in regelmasige, strenge Falten an der Oberflache von Polymer-Einkristallen eingebettet sind. Ferner wurden Untersuchungen uber die durchgehenden Molekule angestellt, die die einzelnen Schichten in mehrschichtigen Kristallen miteinander verbinden. Der Gehalt an Polyathylenoxid (PEO) lag zwischen 0,551 und 0,860, wobei das Molekulargewicht jeder Sequenz die Grosenordnung 104 bis 105 hatte. Als Losungsmittel wurden Athylbenzol, Xylol und Isoamylacetat benutzt. Es wurde gefunden, das die Copolymeren mit einem Polyathylenoxidgehalt von 0,643 aus verdunnter Losung (0,1- bis 0,25-pros.) in quadratischen Plattchen kristallisieren, ahnlich denen der Polyathylenoxideinkristalle. Elektronenmikroskopische Aufnahmen dieser Kristalle zeigten, das die Poly-α-rnethylstyrol-Ketten aus dem kristallinen Teil ausgeschlossen und wahrend der Kristallisation auf der Oberflache der Einkristalle abgeschieden werden. So bilden sich laoge Sehlaufen, die in der Losung oder beim Trocknen der Kristalle aggregieren, je nach den angewandten Losungsrnitteln. Wenn man die Konzentration des Polymeren auf 0,5% erhoht, bilden sich unregelmasig geformte, mehrschichtige Kristalle, an deren Oberflache eine Anzahl von Lochern gefunden wird, was zur Annahme fuhrt, das die Haufigkeit des Vorkommens von Molekulen, die mehrere Schichten miteinander vernetzen, rasch mit ansteigender Konzentration steigt. Es werden experimentelle Unterlagen fur die Bildung von langen Schlaufen auf der Oberflache der lamellaren Kristalle und von molekularen Verbindungen zwischen den ein-zelnen Lamellen bei der Kettenfaltungskristallisation geliefert.