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Volume 25, Issue 2
Displaying 1-8 of 8 articles from this issue
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Kenji Kamide, Kiyoaki Nakamura1969 Volume 25 Issue 2 Pages 53-59
Published: February 10, 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThermal analysis and X-ray diffraction measurements have been carried out on the β-form, crystals of isotactic polypropylene. Specimens showing predominantly β-form were obtained by using the techniques of crystallization of a commercial polymer (Chisso Polypropylene) with temperature gradient according to Fnjiwara et al. β-form crystals do not transform to α-form if annealed at temperatures below 143°C. However, the transformation of β-form takes place above 144°C. This kind of transformation was found to be the melting of β-form crystals followed by the crystallization of α-form from the following direct or indirect experimental evidences:
(1) Endothermic main peak gives at least more than 15cal/g, which is of magnitude as the heat of fusion of α-form crystals.
(2) A definite exothermic process indicating the crystallization of α-form was observed at temperature between main endothermic lower peak and small endothermic higher peak.
(3) The almost completely unoriented crystals of α-form were created in the annealed specimens, where in the untreated state, the normal of (110) plane of β-form is parallel to the temperature gradient.
(4) Strong negative birefringence due to β-form crystals completely disappeared during annealing above 148°C, and thereafter, weak birefringence due to α-form appeared.
The melting of β-form crystals is time-dependent, that is, the higher the annealing temperature, the more rapid the transformation. The equilibrium melting temperature and heat of fusion are found to be ca. 147°C and 24cal/g, respectively.View full abstractDownload PDF (1613K) -
ORIENTATION BEHAVIOR OF CRYSTALLINE AND NONCRYSTALLINE PHASES DURING ORTHOGONAL-BIAXIALLY STRETCHINGHirokazu Takahara, Hiromichi Kawai, Yutaka Yamaguchi, Akio Fukushima1969 Volume 25 Issue 2 Pages 60-72
Published: February 10, 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSOrientation behavior of crystalline and noncrystalline phases of an extruded isotactic polypropylene film during orthogonal-biaxially stretching was investigated by means of simultaneous measurements of x-ray diffraction and birefringence. The orthogonal-biaxially stretching was performed under the following three fashions; simultaneous, alternative, and strip biaxial.
In general, the orientation behavior of the crystalline phase can be classified into the following three types; α, β, and γ type. The α type orientation is characterized by a preferential orientation of crystal b-axis toward the film normal, around which the crystal a* and c-axis orient randomly; i.e., preferential planar orientation of (040) crystal plane along the film surface. This behavior may be interpreted in terms of lamella orientation parallel to the film surface, accompanying the lamella twisting around its axis and the lamella necking along its axis so that the crystal c-axis orients parallel to the film surface due to-the straining of tie-chains between the lamellae.
Since the oriented crystal having its b-axis perpendicular to the film surface is stable enough against possible crystal slipages along (010) and (110) planes, the only possible deformation may be (110) twining due to increasing biaxial stress, and the two possible slip planes are inclined by equal angle, 54° with respect to the film normal. This produces the β type orientation.
When the biaxial stress is removed, the oriented noncrystalline chains generate restoring force. This force acts the β type oriented crystal so as to make further (110) twinning. Therefore, (110) plane rotates about 36° and orients almost parallel to the film plane. This produces the γ type orientation.
The relative proportion of the three type orientations after the highly biaxial stretches, varies with the stretching and releasing conditions. The apperance of the γ type orientation resembles to the (110) twinning of polyethylene crystal under rolling pointed out by Frank et al.View full abstractDownload PDF (1611K) -
Yoshio Nakamura, Michiharu Negishi, Junichi Yamauchi1969 Volume 25 Issue 2 Pages 73-79
Published: February 10, 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSGrafting of ethyl acrylate (EA) onto the heat-treated polyvinyl alcohol fibers (PVA) crosslinked with glyoxal (GA) or formaldehyde (FA) was performed in aqueous Ce4+ System. Before the grafting, the fibers were swollen with a concentrated zinc chloride solution to raise the grafting rate. The graft-on of EA reaches up to about 4500%. The crystallinity of PVA fibers has the predominant influence on the grafting rate. The tensile strength and initial modulus of the grafted fibers shows a noticeable decrease, mostly corresponding with the increase in the cross-sectional area. The breaking elongation and elastic recovery show a considerable increase with the increase of graft-on. The grafted fibers with GA-crosslinks have higher elastic recovery compared with the uncrosslinked or FA-crosslinked fibers. This is considered to be due to the existence of the intermolecular GA-crosslinks. The grafted fibers with crosslinks show the great resistance for boiling water. For example, the GA-crosslinked (0.6 % by weight increase) and 2370% EA-grafted fiber give the tensile strength 0.2g/d, initial modulus 0.25g/d, elongation 88%, and elastic recovery 85 at 70% extension.View full abstractDownload PDF (511K) -
Toshisada Takahashi1969 Volume 25 Issue 2 Pages 80-87
Published: February 10, 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSIt is well known that b-axes of cellulose II crystals tend to orient parallel to a drawing direction, and (101) planes prefer to orient perpendicular to a direction in which a bulk dimension decreases on rolling. However, in most literatures the former orientation (classified as uniaxial orientation)has only been concerned in relation to mechanical properties, spinning conditions and anisotropic swelling behaviors of regenerated cellulose fibers, though the latter orientation (classified as selective uniplanar orientation) could have also the important role. It is, therefore, interesting to make further investigations on these problems, putting the emphersis on the selective uniplanar orientation of (101) planes and its relation to the bulk properties.
In this paper, the first one of the series, the selective uniplanar orientation of (101) planes is studied in relation to coagulation and regeneration conditions, and then the explanation of the anisotropic swelling of films is given in these terms.
The dominant selective uniplanar orientation of (101) planes is found for the films which are regenerated from viscose in regeneration bath containing a large amount of salt. The degree of orientation depends significantly on the concentration of sulfate. The lower the degree of swelling of fresh cellulose films are, the higher degree of orientation the dried cellulose films have. These results may be explained in the way that the orientation in this case is forced by osmotic compression, accompanied by dehydration normal to the film surface during the coagulation and regeneration process, which is different from the current explanation ascribing it to mechanical compression.
The cellulose films, in which (101) planes of cellulose II crystals orient parallel to the film surface, exhibit higher swelling and shrinkage in thickness. These behaviors may be explained on the basis of the distribution of hydroxyl groups in material. Because most hydroxyl groups locate on (101) surfaces of cellulose crystallite, these surfaces are hydrophilic, and water may permeate between them in the similar way that water may permeate between hydrophilic groups in soap micells.
It may be concluded from the results of x-ray investigations that the orientation of (101) planes takes place during the coagulation and regeneration process and not during the drying process.View full abstractDownload PDF (1976K) -
Akira Kuwahara1969 Volume 25 Issue 2 Pages 88-96
Published: February 10, 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSIn this paper, the observation of silk fibroin was performed in order to obtain the changes of their peculiar depression phenomena during the exposure to ultra-violet ray.
Silk fibroin of Bombyx mori wax exposed in textural form to ultra-violet ray for the different length of time in dry and wet states, and then the observation was made mainly about transition of the peculiar depression phenomena with the electron microscope and about variation of its physical properties.
Due to optically destructing action with ultra-violet ray, shallow linear or circular pepressions with partial cracks or partial strips were seen at the early stage of exposure, and with the increase of exposing time, depressed areas were seen expanded in both horizontal and vertical directions showing the destruction in the way of chain reacting and moreover showing the tendency of depressing and cutting the principal axis.
The phase of wet exposure was revealed more significantly and more severe than that of dry exposure.
Judging from the above result and variation of its physical properties, it can be conceived that those preculiar depression phenomena grow significant in proportion of the advance of the exposure and that those phenomena are due to weak-point of tyrosine area in silk fibroin.View full abstractDownload PDF (4001K) -
Shinya Kurosaki, Fujio Konda, Masaaki Okamura1969 Volume 25 Issue 2 Pages 97-101
Published: February 10, 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe drafting system of woollen ring spinning with false twisting has its objective to achieve such a drafting effect as in woollen mule spinning. This is an idea of levelling the uneveness of a sliver by concentrating twists on its thin portion to give greater draft to its less twisted, thick portion.
The previuos report pointed out a marked difference between the twist densities in the regions from back rollers to a tube entrance and from the tube entrance to the front nip. The twist density is smaller at the part from the tube entrance to the front nip than in the other. It may be said, therefore, that the operation of levelling the sliver may be performed only in this narrow zone.
This report deals in detail the operation of levelling the uneveness of a sliver by experimenting the influences of the thickness upon a variation in twists in the false twisting zone.
(1) In the false twist drafting, the drafting is given mainly in the less twisted zone between the tube and the front nip. (Fig. 1 and 2)
(2) In the case of twisting at one place, a sliver is twistless in the zone between the tube and the front nip in steady state. When an unven sliver enters this zone, the S twist and the Z twist appear alternately. (Fig. 5)
(3) In the case of twisting at two places, there are twists in a sliver in the main draft zone in the steady state. When uneven sliver enters the zone, a variation occurrs in such a way that its thick portion is less twisted and its thin portion more twisted. (Fig. 6)
(4) The evenness of a sliver is improved by false twist drafting in the zone between the tube and the front nip. The uneven sliver prepared by eccentric rollers was false twist-drafted and examined. It was found that its less twisted and thick portion is more elongated than its more twisted part. (Fig. 7)
(5) The wave length of uneveness of a sliver has a close connection with length of the zone L2. (Fig. 8)View full abstractDownload PDF (363K) -
Erratum to : THE CALORIMETRIC METHOD FOR DETERMINING THE CONTENT OF MOISTURE IN POLY (ε-CAPROLACTAM)1969 Volume 25 Issue 2 Pages 102b
Published: 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (69K) -
1969 Volume 25 Issue 2 Pages 102a
Published: 1969
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (69K)
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