Masaru Matsuo

Morphological and mechanical properties of ultrahigh-molecular-weight polyethylene/low-molecular-weight polyethylene blend films produced by gelation/crystallization from solutions

Polyethylene-polyethylene blend films were prepared by gelation/crystallization from semidilute solutions by using ultrahigh-molecular-weight polyethylene (UHMWPE) (w = 6 × 106) and low-molecular-weight polyethylene (LMWPE) (Mw = 4 × 104). The UHMWPE/LMWPE compositions chosen were 919, 6733 and 5050. Elongation was carried out in a hot oven at 115–130°C. Drawability was dependent upon the compositions. The maximum achievable draw ratios of the 5050 and 6733 blends were 200-fold, while that of the 919 blend was 300-fold. The storage modulus decreases with increasing LMWPE content, when the measurements were carried out using specimens with the same draw ratio. Such mechanical properties were discussed in terms of morphological aspects by using wide-angle X-ray diffraction, birefringence, differential scanning calorimetry and optical microscopy.

Temperature-dependence of mechanical and morphological properties of ultra-high molecular weight polyethylene cross-linked by electron beam irradiation

Cross-linking of ultra-high molecular weight polyethylene was performed with electron-beam irradiation in the range of radiation dose from 12 to 96 Mrad under nitrogen. Dry gel films and melt films were used as specimens. Two kinds of cross-linked specimens could be kept at 200°C for a prolonged time in an undeformed state and this tendency was independent of radiation dose. The elongation of the gel films hampered the heat-resistant effect and the drawn specimens were broken at temperatures lower than 175 °C. The elongation of the melt films could not be realized, because of a marked fixation of chains in the fiber network, even at a dose of 12 Mrad.

Development of high-strength and high-modulus polyethylene-starch composite films and biodegradation of the composite films

Abstract Composite films of polyethylene with ultrahigh molecular weight (6 × 106) and corn starch were prepared by gelation-crystallization from dilute solutions. The polyethylene-starch compositions chosen were 3/1, 1/1, 1/3, and 1/5. The elongation was carried out in a hot oven at 135°C. The maximum drawability was affected by the composition. The maximum draw ratios of the 1/5 composite reached 80, and the corresponding Youngs modulus was 10 GPa. The values of the films with the 3/1 and 1/1 composites were about 75 and 105 GPa, respectively, which are higher than the moduli of aluminum(70 GPa) and cast iron (90 GPa). In spite of the elongation up to such high draw ratios, most starch particles remained within the composite films. This interesting phenomenon is discussed in terms of the morphology of the composite films as studied by wide-angle x-ray diffraction, small-angle x-ray scattering, and scanning electron microscopy. Furthermore, the composite films with different compositions were put on a d...

Morphology of poly(vinyl alcohol) gels assuring the greatest significant drawability

Atactic poly(vinyl alcohol) (at-PVA) and syndiotactic poly(vinyl alcohol) (st. PVA) prepared by gelation/crystallization using dimethyl sulphoxide/water mixtures were drawn in a hot oven at 160 °C under nitrogen. The degrees of polymerization of at- and st-PVA were 2000 and 1980, respectively. The drawability of at- and st-PVA films was affected by the composition of the solvent mixture as well as by quenching temperature. The drawability of at- and st-PVA films prepared by using the solvent mixture containing 60% of dimethyl sulphoxide and 40% of water became more pronounced as the temperature of gelation/crystallization decreased and the draw ratio reached maximum value at −80 °C. Namely, the greatest significant drawability was the same condition for at- and st-PVA films in spite of the different stereo-regularity. Even in this common best condition for significant drawability, however, the morphological properties of swollen gels and of the resultant dry gel films are different each other, dependent upon the tacticity. For at-PVA, small-angle light scattering under Hv polarization condition could not be observed in the swollen gels and in the dry films when the solutions were quenched at temperatures <−10 °C. In contrast, for st-PVA, the X-type scattering pattern from swollen gels became clearer as the temperature decreased but the pattern became indistinct under drying process at ambient condition. On the other hand, the fibrillar textures within the at- and st-PVA dry films became finer and the orresponding crystallinity became lower as the temperature of gelation/crystallization decreased. Thus it turned out that the morphological properties of the swollen gels and of the dried films play an important role to assure the greatest significant drawability.

Use of the Double-illumination Method with Two Light Sources in Moiré Topography

Generalizations of the double-illumination method by two light sources in moire topography are discussed in terms of the three-dimensional analysis of its mathematical basis developed for the following two cases: (a) where, the grating has a light-intensity distribution expressed by a fundamental harmonic wave, and (b) where it has a light-intensity distribution expressed by an arbitrary periodic function with many components. The characteristics of the two cases were studied in comparison with several examples of the moire patterns observed by the double-illumination method. From the results, it can be concluded that the transmittance of the grating is of the fundamental sine-wave type in the case of the solid-grating type and that the two-source method is significant for obtaining shadow-free moire patterns from complex surfaces of an object such as a skirt.