Matsuo Hirami

SAXD studies on bulk crystallization of nylon 6.I. Changes in crystal structure, heat of fusion, and surface free energy of lamellar crystals with crystallization temperature

Abstract Measurements of small-angle x-ray diffraction (SAXD) were performed for nylon 6 samples quenched from the melt at various crystallization temperatures T (°K). The spacing estimated from the position of maximum intensity in a SAXD diagram, which is assumed to be equal to the thickness of lamellar crystals l, decreases with the decrease of T. The behavior was analyzed in terms of nucleation theory. In applying the theory. the contribution of γ-form crystals for the samples crystallized at lower T was considered. For this purpose wide-angle x-ray diffraction and infrared data obtained for the same samples used in SAXD measurements were used. It was shown that the relation of l versus T deviates remarkably from the theoretical prediction under the premise that the surface free energy σe (ergs/square centimeter) is constant with T. We present an approach to the analysis of the data from the standpoint that σe is a parameter changing with T, where σe should be interpreted as related to the degree of ir...

Structure–microhardness correlation in blends of nylon 6/nylon 66 monofilaments

The microstructure (crystallinity, long spacing) and the micromechanical properties (microhardness H) of two series of nylon 6 and nylon 66 monofilaments and their blends were investigated as a function of annealing temperature TA and uniaxial deformation in a wide composition range. In case of the homopolymers, the gradual rise of microhardness with TA is interpreted in the light of the increasing values of the crystallinity a and the hardness of the crystals Hc. The depression of the hardness values of the blends from the additive behavior of the hardness of individual compo- nents is discussed in the basis of the crystallinity depression of one component by the second one and viceversa. Finally, the influence of drawing and pressing the blends at 130°C which leads to a hardness increase is also explained in the light of an increase in the Hc value of nylon 66 due to orientation.

Intrinsic Birefringence of γ‐Form Crystal of Nylon 6: Application to Orientation Development in High‐Speed Spun Fibers of Nylon 6

The intrinsic birefringences of the α- and the γ-form crystals of nylon 6 were calculated from the atomic coordinates and the bond polarizabilities using the Lorentz-Lorenz equation. The intrinsic birefringence of the γ-form crystal was found to be significantly smaller than that of the α-form crystal. Those values were applied to the evaluation of the orientation function of the amorphous phase of the nylon 6 fibers produced by the high-speed spinning process. The molecular orientation in the amorphous phase increased to the maximum point and then decreased with the spinning speed. These results suggested that an inhomogeneous structure in the fiber was formed for the higher take-up speed.

Analysis of polarized fluorescence intensity in an anisotropic polymer medium and its application to the orientation measurements for nylon 6 fibres

Abstract Polarized components of the fluorescence emitted from rod-like molecules (probes) oriented in a polymer medium are analysed theoretically. An ‘envelope curve’ of the polarized fluorescence intensity obtained in a rotating frame of two polaroids in the measuring system, is useful for characterizing the molecular orientation distribution. The model calculations are carried out in terms of three basic molecular orientation modes, i.e. uniaxial, random, and planar orientation modes. Generally, the envelope curve is affected by the birefringence due to the optical anisotropy of the polymer medium. In the highly uniaxial orientation mode, however, the shapes of the envelopes are scarcely distorted by the effect of birefringence. The fluorescence technique to measure envelope curves is employed to investigate the structural change of nylon 6 fibres upon drawing. The transformation of molecular orientation pattern in the non-crystalline phase of the drawn fibres is described satisfactorily by using a combination model composed of the three basic modes mentioned above, with their fractional parameters. A considerable portion of molecules in the amorphous regions may orient perpendicular to the draw direction, before the uniaxial orientation mode becomes predominant above ca 100% elongation.

Theory of melting in multicomponent systems of polymers

A theory is developed for the equilibrium crystalline state and melting in multicomponent systems of crystallizable polymers (species μ) and solvents (species m) by extending the Flory theory for binary systems of a single polymer and a solvent. Relationships deduced from the free energy of fusion for multicomponent systems are examined. The formula for the equilibrium crystallite length ζα for μ=α is common for all polymer components μ. The relationship of melting temperature Tm(α) for μ=α involves the degree of crystallinity (1−λμ) for all μ and interaction parameters of all polymer–polymer, polymer–solvent, and solvent–solvent contacts, i.e., χμν, χμm, and χmn. The degree of crystallinity (1−λα) for each component μ=α can be obtained by solving the simultaneous equations of melting temperatures Tm(μ) for the components μ which are coexistent in the crystalline state under a given condition of the system. The theory is applied to systems involving two crystallizable polymer components and the features o...

Biodegradable Fibers Made from Truly-Biodegradable Thermoplastics

The term “biodegradable fibers” has different meanings for different people. In this review, this term is used to refer widely to fibers which will degrade in biological environment, including any environment where in vivo or in vitro biological or biochemical processes are occurring, regardless of the degradation mechanisms.

Structure development in the melt spinning of nylon 6

Abstract It is known that nylon 6 (poly-E-aminocaproamide) assumes a variety of crystal structures, namely, the a form [1, 2] the y form [3–7], and a series of intermediate hexagonal structures [8–13]. The different types of crystal form appear under different crystalli-zation conditions. It has been reported that a metastable hexagonal structure is observed in as-spun nylon 6 fibers [8–13]. However, the mechanism by which this structure forms during the melt spinning process has not been examined systematically.

New developments in the rayon industry

Abstract In August 1988 the International Symposium of Macromolecules (MACRO 88) was held at the International Conference Hall located in the northeastern part of Kyoto. At the same time, at the National Museum in the southeastern part of the city, an exhibition of Treasures of Ancient Egypt, including rolls of papyrus (the origin of paper) was displayed. At the symposium, Prof. Nishijima [l], President of Kyoto University, gave an address in which he stated “… I feel there is some- thing more than mere coincidence that both this symposium of MACRO 88 and the exhibition of Egyptian Art and Technology are held at the same time in the North and South of Kyoto. The civilization of 5000 years ago meets most recent develop- ments of integrated science and technology as MACRO 88. It is the accession over the span of millennia.”

Some Topics in Polymer Recycle in Japan

In this report, I would like to talk about the efforts of the polymer recycle in Japan which has been made and is being performed by Japanese polymer industry (synthetic fiber producers and plastics producers). After the War, Japan succeeded in the great economical growth by rapid development of industry. However, it also brought about environmental pollution of air and water. Around 1970, the regulation of air and water started, and due to the efforts of municipal governments and industrial companies, the situation of air and water pollution has been greatly improved. However, there still remains a big problem, that is, the pollution of environment by waste disposals.

Über den osmotischen Druck von Polyelektrolytlösungen mit Zusatzsalz

Es wurde beobachtet, das bei geringem Zusatz von Natrium- bzw. Calciumchlorid die graphische Darstellung des osmotischen Druckes einer Losung von celluloseglykolsaurem Natrium mit der Polymerkonzentration nicht linear verlauft, sondern merklich nach oben gekrummt ist. In Verbindung mit dieser Erscheinung wurde eine Gleichung fur den osmotischen Druck der Polyelektrolytlosung unter Anwendung der Donnanschen Theorie abgeleitet. Hierbei wurden zwei Effekte in Erwagung gezogen, und zwar das ausgeschlossene Volumen (excluded volume) des Makroions, durch welches die Konzentration der permeierenden Ionen hoher als die stochiometrische erscheint, und die Gegenionenassoziation mit den Makroionen. Ferner wurde eine Gleichung fur den Dissoziationsgrad des Makroions unter der Annahme abgeleitet, das die Donnansche Theorie fur das Membrangleichgewicht an der Innen- und Ausenseite der raumlichen Ausdehnung des Makroions noch gultig ist. Mit Hilfe dieser Gleichungen wurde festgestellt, das die Theorie im Vergleich mit den Experimenten gute ubereinstimmung bei geringem Salzzusatz zeigt. Andererseits wurde jedoch eine Diskrepanz bei relativ grosem Salzzusatz gefunden.