In order to discuss the thermal stability of the heat-treated P. E. T. fibers under varying heated conditions, temperature dependence of the longitudial changes and the relative optical retardation on sucessive and constant heating process were measured under tensionless state. The results obtained are shown as follows: 1) Temperature dependence of the longitudial changes for non-heated P. E. T. fibers on successive and constant heating process is that shrinkage becomes larger with increased draw ratio. While the form of distribution on ΔS/ΔT_??_T curve becomes sharp for lower stretched filament, its form may skew and broaden towards higher temperature for higher stretched one. The temperature of peaks on ΔS/ΔT_??_T curves may correspond to the transformation temperature in a range of higher temperature on (relative retardation)_??_(temperature) curves. And the apparent activation energies in a range of lower temperature on shrinkage process become larger compared with range of higher temperature. 2) Temperature dependence of the longitudial changes for heated P. E. T. filaments on successive and constant heating process is that shrinkage becomes smaller with increased heated temperature. Temperature behavior of the relative optical retardation for dry heated fibers may change extremly dependenent on heated temperature. The form of shrinkage distribution curves broadens and temperature of peaks shifts towards higher with rising heated temperarure, and height of peaks becomes lower. While the apparent activation energies of the filaments heated by drying and steaming on shrinkage process become lower with increasing heated temperature in a range of lower temperature, reversely, they may be larger in a range of higher temperature. And, their activation energies of filaments heated with hot water may be reversed for the above results. 3) The height of peak on ΔS/ΔT_??_T curves and the apparent beginning temperature by shrinking estimated from (shrinkage)_??_(temperature) curves may be highly correlative with degree of crystallinity by X-ray method and contribution of the crystalline birefringence. Besides above results, it may be seen that they depend on the effects of broadenning of shrinkage temperature distribution, that is, moleculare aggregation state.
In order to investigate the thermal properties of hot drawn P. E. T. fibers, the fine structures generated on hot drawing and heated at 170°C under a constant length, were determined by X-ray and optical polarized microscope. The drawing temperatures were selected over a range of 60_??_90°C in water and the fibers were stretched at a lower constant rate of drawing. Results obtained are shown as follows: 1) Transformation point of the relation between the draw ratio, density and birefringence of non-heated fibers may be found in the vicinity of draw ratio 2.0 in the case of a lower drawing temperatures (60 and 70°C), and their degree of crystallinity in the maximized and drawn fibers have only 20%. The values of the optical orientation factor (fr) become 0.60 and 0.24 respectively. The phenomenon of super-drawing is found in the case of drawing temperature, 80°C, and it may yet be extended beyond 650% extenstion, but the values of density are smaller as compared with non-drawn P. E. T. fiber and fr may be almost equal to zero. While effects of draw ratio on density are smaller in the case of drawing temperature, 90°C, their values of birefringence may be negative due to the crystallization occures in the immersion water and maximum value of fr becomes about -0.20. 2) The effects of draw ratio and temperature of drawing bath on density of heated P. E. T. fibers become smaller and the values of the degree of crystallinity are about 50_??_60%. On the other hand, their effects on birefringence are remarkable, that is, the birefringence at lower stretched specimens (draw ratio: 1.0 and 1.5) are negative and highly oriented specimens beyond 3.0 draw ratio develope strong positive birefringence, but the sign of birefringence at intermediate stretched (draw ratio: 2.0_??_3.0) changes from negative to positive with increased draw ratio. In both temperatures of drawing at 80 and 90°C, each stretched specimen shows a negative birefringence and it's value increase a littlle with increased draw ratio. And fr becomes negative in case of showing a negative birefringence, and then the average of orientation becomes greater than 54.6% 3) The X-ray diffraction patterns of non-heated and heated specimens do not have any intrinsic, difference except for specimens stretched at 90°C. The (100) reflection in X-ray patterns of heated specimens shows a peculiar behavior dependent on birefringence determinations, that is, the diffractive peaks of the (100) reflection is located in the meridian and equater on showing a negative and a strong positive birefringences, respectively. While its peak may be moved closer from the meridian to the equater in having a weak positive birefringence. On the other hand, the diffraction peaks of (010) reflection having any birefringence is located on the equater. Consequently, the orientation of crystallite are a-axis, c-axis and intermediate orientations respectively dependent of birefringence values. It is estimated that a-axis and c-axis oriented structures have folded and bundled crystallite respectively, but intermediate oriented structure has yet folded crystallite preferentially. 4) While intermediate oriented specimens show a strong positive value in degree of the heat-setting and consequently causes a spontaneous elongation due to the crystallization by heating, a-and c-axis oriented specimens show negative values in the degree of heat-setting followed by shrinkage.
It was apparent from the theoretical study that the response may be divided into the steady and transient states. From this results it is deduced that stress amplitude, increase of residual elongation and recovery coefficient which will be represented later are greatly dependent upon the transient state response. The cyclic extention and reciprocating cycles were adopted as parameters in this study. The extension percentage adopted are ranges of the 2nd region of each crimped yarn, already referred to the preceding paper. To reiterate; 180…200% for Nylon Helanca yarns 130…150% for Nylon False yarns 40…60% for Nylon Banlon yarns And reciprocating cycles were decided in consideration with the mean relaxation times of each synthetic crimped yarn. Their values are 0.5…2.0c/s. The experimental results are as follows: (1) The stress-amplitude due to the responds to the cyclic extension of the crimped yarn reduces to stress amplitude equilibrium of. The rates of reduction are depedent upon the cycles of reciprccating and their maximum strain amplitude. Because of the distribution of true length, it is reasonable that the rates of reduction for Helanca and Banlon yarns have the highest value and the lowest one respectively. (2) The increase of residual elongation is one of the responses to the cyclic extention, and the rates of increase are also dependent upon the reciprocating cycles and maximum strain amplitude as the stress amplitude are. It is also apparent that the rates of increase of Helanca yern has the highest value and Banlon yarn has the lowest one. The explanation of this is similar as in the case of the stress amplitude. (3) Recoveries of stress after the cyclic extension have also same tendencies to the above two cases. It is evident that Helanca has the best recovery coefficients. But False and Banlon yarns have same degree of recovery coefficients.
Dynamic properties of cellulose-P. M. M. A. graft polymer were investigated. P. M. M. A. was graft-polymerized onto cellophane in the Redox system using Ce+4 as catalyst. Dynamic modulus decreases and tan δ increases with the increase in graft ratio. Dynamic loss increases and again decreases with the increase in graft ratio. Dynamic modulus of the graft samples was verified by the following equation. Where Eg′, Ec′ and Ep′ are dynamic modulus of the graft sample, cellulose and P. M. M. A. component, respectively. vc and vp are volume fraction of cellulose and P. M. M. A. component. At lower graft ratio, Ep′ takes much higher value than that of ordinary P. M. M. A. and takes comparatively reasonable value at high graft ratio. These results show that the contribution of P. M. M. A. component to dynamic properties of the graft sample consists of two diffrent mechanisms, 1) a filler effect to cellulose component and 2) a role as a mechanical element parallel to cellulose component. The 2nd effect is very small at low graft ratio and these effects both increase with the increase in graft ratio. Dynamic properties of the graft samples are affected by relative humidity and the changes become smaller with the increase of graft ratio.
(1) There are many results suggest that the most probable action of modifier is the contribution to formation of some type of membrane by the interaction of zinc, cellulose xanthate and/or byproduct in viscose on the surface of filament during the spinning. (2) In this report, attempt is made to confirm such membrane by the observation of cross sections of filaments spun from both modified and unmodified viscoses through the bath containing high concentration of zinc sulfate at various immersion lengths. (3) As a result, it is observed distinctly that at short immersion the membranes are formed on the surfaces of slightly regenerated filaments spun from both modified and unmodified viscoses. It is also found that the modifier increases thickness and stability of the membrane and that the components of the modified membrane are presumably zinc sulfied, zinc trithiocarbonate and modifier. (4) The formation of thick and stable membrane is closely related to the formation of “all skin” structure of filament. At short immersion, though the “all skin” structure is formed in the modified filament, its gel swelling value is higher than that of unmodified filament. Therefore, it is thought that the skin structure is not formed by the dehydration of gel through the membrane before regeneration, as reported before, but by another unknown physical or chemical action to viscose inside the membrane.
The change in fine structure of rayon by graft polymerization under swollen state was already reported in our first paper1). Refering the difference between dryeure and wet cross linking in the resin treatment2), 3), it is probably possible to consider that the difference between graft polymerization under swollen state and unswollen state results in the difference in the coagulation of cellulose chains. And also it has been well known that the graft polymerization to unswollen solid polymer is very difficult, therefore the difference of the change in fine structure according to the grafting method may be considered. The sample grafted under swollen state (A) was prepared by reaction of rayon and methyl acrylate (MA) using ce+4 as the initiator in aqueous solution, and the sample grafted under unswollen state (B) was prepared by pre-irradiation method using γ-ray from Co60 followed by graft polymerization in solution containing MA, methanol and small amount of water. A and B samples of various degree of grafting, following properties were measured; Transition, temperature4), coagulation order, young's modulus, moisture regain and swelling in water. These properties are considered to be reflected by the structure of only cellulose in graft polymer, because PMA is insensitive to both ethanol and water sides its young's modulus and strength are very low compared with cellulose. The experimental results obtained are followings: (1) Lowering of transition temperature of A is more sharp than that of B. (2) Coagulation distribution is not so largely shifted to lower side by B-method as in the Amethod. (3) Lowering of the dry modulus of A is larger than that of B. About wet modulus the same result was obtained. (4) Moisture regain is increased by A-method, but not changed by B-method. (5) Degree of swelling as lowered by B-method. Comparing the two samples of same degree of grafting-one is grafted when cellulose amorphouschains are swollen with water (A) the other is not swollen (B)-from above experimental results, followings are estimated, (1) Coagulation state of cellulose is relatively preserved when B-method is employed. A-method destroys the hydrogen bonds and polymer grafted restricts the reformation of hydrogen bonds during the drying. (2) A-method ever destroys the water inaccessible region, but B-method does not. (3) Polymer grafted by B-method restricts the free swelling of cellulose chains but A-method does not These considerations imply that the coagulation state of the back bone polymer during the graft polymerization has great effects on the resulted structure of back bone polymer and polymer grafted.