In textile industry, performance of the fabrics is still out of the engineering design, because of the difficulty in designing the proper mechanical properties of fabrics, and also of the difficulty in evaluating the performance where the evaluation has been done by a sensory method named "hand-feel" by experts.
In this article, recent developments in the theoretical research on the mechanical properties of fabrics are introduced. Theoretical methods of calculating the non-linear property in biaxial and uniaxial tensile deformations of plain woven, plain knitted and inter-lock fabrics are presented here. And bending and shear properties of plain woven fabrics are also dealt with.
Furthermore, a new method for evaluating "hand-feel" is introduced; the mechanical properties of fabrics are first characterized and represented by sixteen number of characteristic values obtained by the measurements of mechanical, physical and geometrical properties of the fabrics, and then using a linear model, the "hand-feel" value is calculated from these characteristic values. The agreement between the conventional sensory and the new instrumental methods is demonstrated.

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The laminar radial flow between the parallel stationary disks is one of the basic flows used to evaluate the viscous behaviour of the fluid, and its application to the viscometer or the rheometer is worth noting.
Here, using the Reiner-Rivlin model, how a non-Newtonian fluid behaves in the abovementioned flow was studied analytically. And, on the basis of the results of the numerical calculation, the cross viscosity effect to the pressure-and the stress-distributions on the disk was discussed. And the present solution was compared with those of the author's approximate analysis as well as the Schwarz-Bruce's analysis in the radial flow between the parallel stationary disks.
It was found possible to obtain the exact solution of the flow field by the series expansion method. And, the solution in this paper was effective in the region of R_E-1 and/or R_C-1 and agreed with the Schwarz-Bruce's solution in this range. Furthermore the agreement with the present analysis confirmed the usefulness of the approximate analytical method for the power law fluid.

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For the measurement of normal stress difference by the capillary tube method, the basic equations are derived under the following two assumptions.
Assump. 1. Velocity profile is fully developed at the tube exit.
Assump. 2. Exit pressure on the center-line of the tube is a function of shear stress at the wall.
The results are shown in Table I. In this Table, the equations proposed by several investigators are also shown with their assumptions and approximations.
By using the nondimensional group N defined by Eq. (5), which represents the ratio of inertia force to normal stress difference, the exit stress P_w(L) is expressed by Eq. (6). For the range of N<<1, P_w(L) is approximately equal to the normal stress difference T_n and increases with wall shear rate. Generally, P_w(L) depends on N as well as on wall shear rate, and cannot be considered as the material function. It may be anticipated that there is the range of N where P_w(L) becomes a decreasing function of N.
Since the pressure term in P_w(L) cannot be neglected and it cannot be determined by the capillary tube method, it is impossible to determine each component of normal stress differences only by the capillary tube method.

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Hereunder discussed is the applicability of integral constitutive equations to some nonlinear and non-steady viscoelastic behaviors of concentrated polymer systems. Two types of models based on Lodge's model are considered. One of them is the generalization of the so-called WJFLMB model and has the after-effect function depending on the invariants of the rate-ofdeformation tensor through both the spectral density and the value of the relaxation time itself. The other is the generalized WKZ model with the after-effect function depending on the invariants of the relative deformation tensor between the excitation and the current times. Both the models can well explain the rate-of-deformation dependences of the viscosity coefficient and of the normal stress differences for steady simple shearing flow. The rate-of-deformation dependent model is simpler and rather good than the relative deformation dependent model in the explanation of some nonlinear non-steady viscoelastic behaviors such as the stress development at the beginning of flow, and the stress relaxation after stoppage of the flow. The former model is, however, rather difficult to give the deformation dependence of the relaxation modulus in the stress relaxation in the usual sense for large shearing deformation.

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The mechanical and optical constitutive equations for the Tresca type plastic materials are defined, which are subjected to the Tresca yield condition. The stress in simple shear is analyzed and the dimensionless stress components are calculated for three values of the dimensionless material constant. The shear stress shows the hypo-elastic yield and the maximum difference between the principal stresses increases monotonically against the angle of shear and approaches to a yield value. The birefringence also shows the Tresca yield, which is called the optical yield, while the extinction angle does not show any yield phenomenon.

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The behavior and the mechanism of rheopexy are not well understood. We found that the suspensions. of spherical particles, such as ZnO and TiO₂, show the rheopexy, and that it depends on the concentration of dispersing agent (NaPO₃)₆. The mechanism of the rheopexy and the rheopexy structure may be related to the colloid stability. ζ potential is measured as a parameter of colloid stability.
It can be assumed that there are two sorts of aggregation; one is the aggregation corresponding to the second minimum of the potential energy curve for the interaction of two charged particles and the other to the primary minimum. The mechanism of the rheopexy may be attributed to the solidification process in which the particles pass from the secondary to the primary minimum under the gentle shear, resulting in remarkable increase of apparent viscosity.

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Some flow behavior of the ZnO-water system was observed over a wide shearing range using three sorts of viscometers, and the following results were obtained:
(1) For the concentrated systems, so-called extended Ostwald flow patterns were obtained.
(2) In dilatant and even in III-Newtonian ranges, the remarkable dependence of flow curves on capillary dimensions was found, suggesting the distinct contribution of normal stress effect.
(3) The normal stress difference determined by both PGB and jet expansion methods was always larger than the shearing stress.
(4) The calculated values for (SS₁₁-SS₂₂)/SW were 6.0-11 for the 73.6wt% suspension and 5.8-8.6 for the 70.4wt% suspension, respectively.
(5) The observed values of (S₁₁-S₂₂)PGB were always larger than those of (S₁₁-S₂₂)_jet·

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Stearic acid dispersions in the aqueous phase stabilized by sodium stearate or potassium stearate have been examined by their flow and creep curves. The flow curves, obtained by using a Couett type viscometer, showed hysteresis loops between "up" and "down" curves. The creep curves suggested that the systems can be represented by a mechanical model of one Voigt unit in series with a Maxwell unit. The compliances increased sharply with decreasing weight fraction of dispersed phase from 0.10 to 0.05, and also showed an increase by ageing over several weeks after the preparation. These rheological properties may be explained by the presence of a network structure of the soap micelles solubilized partially by fatty acid, in the aqueous phase.

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The bulk modulus κ^* and the rigidity μ^* of dilute dispersions of spherical shell structures have been calculated by using the following equations:
κ^*=Q-4cμQ'/Q+3cQ' and μ^*/μ=Γ-3/2cΓ'/Γ+cΓ'
where κ and μ are the bulk modulus and the rigidity of the medium, c is the volume concentration of the structures composed of the shell region with κ_m, μ_m and the inside region with κ', μ', Q=(3κ'+4μ_m)(3κ_m+4μ)+12A³(κ'-κ_m)(μ_m-μ), Q'=(κ-κ_m)(3κ'+4μ_m)-A³(κ'-κ_m)(3κ+4μ_m), Γ=Γ_Aμ_mμ_m²+Γ_Bμ_mμ+Γ_Cμμ², Γ'=Γ_A'μ_mμ_m²+Γ_B'μ_mμ+Γ_C'μμ², Γ_A=-38μ₂μ₄+(450-672AA²)A³+μ₁μ₄+400A⁷μ₁μ₃-1824A¹⁰μ₁μ₁²=-Γ_A', Γ_B=-89μ₂μ₄+(150-336AA²)A³μ₁μ₄+200A⁷μ₁μ₃+3648A¹⁰μ₁μ₁², Γ_B'=-6μ₂μ₄+(500-1344AA²)A³μ₁μ₄+800A⁷μ₁μ₃-608A¹⁰μ₁μ₁², Γ_C=-48μ₂μ₄-(600-1008AA²)A³μ₁μ₄-600A⁷μ₁μ₃-1824A¹⁰μ₁μ₁²=3/2Γ_C', μ₁=μ_m-μ', μ₂=3μ_m+2μ', μ₃=18μ_m+19μ', μ₄=16μ_m+19μ', A=a'/a, a and a' are the inner and the outer radii of the shell, respectively.

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Dynamic and steady-flow properties of disperse systems of styrene-divinylbenzene copolymer particles in polystyrene solution have been measured in wide ranges of frequency and shear rate by means of a cone-plate type rheometer.
The disperse systems show Newtonian flow at extremely low shear rates. This fact indicates that the systems have no yield stress, though they appear to have the yield stress when one gives attention only to the behavior at higher shear rates. At extremely low frequencies, the disperse systems show linear viscoelasticity regardless of the magnitude of strain amplitudes, and G' and G" are proportional, respectively, to ωω² and ω. In this region, |η^*| coincides well with Newtonian viscosity, but the empirical law proposed by Cox and Merz does not hold at higher frequencies and shear rates.

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In order to serve for studies of viscoelastic and steady-flow properties of various non-Newtonian liquids, a self-recording rheometer has been manufactured, which can be employed not only as a cone-and-plate but also as a Couette type rheometer by exchanging minor parts. It is possible to drive or stop the rheometer suddenly by the use of electro-magnetic clutch. This enables us to measure transient phenomena such as stress-overshoot and thixotropy of polymeric and disperse systems. The thermostat has been equipped to keep temperature constant from room temperature to 300°C. The frequency and number of revolution range rospectively from 10^-4 to 1H_z and from 0.05 to 500rpm.
Steady-flow properties of several disperse systems and polymer solutions as well as dynamic properties of polystyrene melt have been measured by means of this rheometer.

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Stress relaxation behaviours of synthetic flour doughs, prepared by mixing the major components of wheat flour such as gluten protein and wheat starch granule with water, have been measured to obtain informations on the factors affecting the rheological properties of wheat flour dough.
A slow relaxation phenomenon appears in the synthetic systems under a constant normal strain, and this is not very much influenced by addition of reducing glutathione which may induce an interchange reaction between thiol groups and disulfide bonds in the gluten protein. The presence of wheat starch granule plays an important role not only in cementation of dough but also in exhibition of non-linear viscoelastic behaviour. The results obtained are considered to arise from the formation of a weak scaffolding structure of starch granules in the dough system.

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The viscoelastic properties of dilute aqueous solutions of sodium alginate at ultrasonic frequencies were investigated by means of a torsional method with crystal resonators. The new type resonators such as a huge crystal resonator and a jointed resonator used in this study enabled us to cover the frequency range from 26KH_z to 131KH_z.
In order to examine the configuration of carbohydrate in an aqueous solution, the complex intrinsic rigidity which was obtained from the present data by extrapolation to zero concentration was quantitatively compared with those obtainable from the existing molecular theories at infinite dilution. In this study, the concentration dependence of the normalized loss shear moduli was found to be non-linear, so that Fuoss-Strauss equation was used to obtain the intrinsic values.
In an aqueous solution of sodium alginate which is assumed to take a "stringlike" configuration, the measured values and their frequency dependences could not be predicted by any of the existing theories. However, with the addition of NaCl, the experimental values approached the theoretical curves given by the Kirkwood's theory for "rodlike" polymer. It was supposed that some electrostatic structures, which can be dissociated with the addition of urea, were formed in the presence of NaCl.

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The molecular weight dependence of ultrasonic absorption for solutions of polystyrene in toluene was measured by the pulse method in the frequency range 5-130MH_z and in temperature range 0-50°C. The molecular Weights of polystyrene samples used were 2100, 4000 and 2000000.
It has been found that the ultrasonic absorption of polystyrene can be represented by a single relaxation equation over entire ranges of molecular weight and temperature. In the low molecular weight region, the temperature dependences of the relaxation frequency and relaxation strength are quite different from those in the high molecular weight region. This relaxation mechanism at the low molecular weight region is considered to be due to the motion of the end segments of polymer chains.

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The viscoelastic properties of star-shaped polystyrenes having six branches and their solutions were measured and compared with those of four-branch and linear polystyrenes. The dependence of the rheological parameters, such as zero-shear viscosity η₀ and steady-state compliance J_e⁰, on the molecular weight and concentration were discussed. At a constant molecular weight, η₀ decreases with increasing number of branches in the polymer molecule. Molecular weight dependence of η₀ for branched polystyrenes having a constant molecular weight of branch, is very similar to that for comb-shaped and randomly branched polystyrenes. J_e⁰ clearly depends on the molecular weight even in the entanglement region, and the critical concentration evaluated from J_e⁰ is two times higher than that from η₀ for branched polystyrenes.

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The shear rate-dependent relaxation spectra of polymer melt were experimentally determined by using an improved rotatory viscometer so as to keep a constant shear strain during the relaxation measurement. The maximum relaxation time τ_M is independent of shear rate in the Newtonian flow region, but it decreases with increasing shear rate in the non-Newtonian flow region. The viscosity calculated as a function of shear rate interpreted satisfactorily the observed viscosity and its dependency of shear rate. The close agreement between the theoretically predicted and observed values of the first normal stress difference was also obtained.

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The objective of the present study is to compare experimentally the capillary flow behavior determined by using a KOKA-type flow tester with the concentric cylindrical flow behavior by using a rotational viscometer at the critical condition of the irregular flow of high-density polyethylene and polypropylene melts.
In general, the yield shear stress τ_y obtained by the rotational viscometer test is lower than the critical shear stress τ_w^* obtained by the capillary flow test. This is because the yield shear stress decreases considerably with increasing temperature while the critical stress increases slightly with temperature in the higher temperature region.
The characteristic curves, or the relationship between the shear rate and shear stress, for the concentric cylindrical and capillary flow tests under a constant temperature showed discontinuity in the temperature range of the present study, and it is reasonably considered that one of the reasons for such difference between the flow curves is the effect of the hydrostatic pressure in the reservoir of the capillary flow test.

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Recently, the detailed experimental data about the unidirectional filling of high density polythene in a uniformly elongated flat cavity by Amano (1971) became available. In the present study, the filling length, Λ, or the linear rate of filling, V(≡dΛ/dt), has been related to the filling time, t, by a scheme similar to that proposed by Shibayama (1971) originally for the processes involving amorphous thermoplastics.
The present scheme assumes, along with several other assumptions, Y_U/Y=Υexp(-m_Et_U/t_E) over a small segment of the cavity, where Y_U is half the thickness of the molten layer and plays the role of Y_II (that of the flowing layer) in the original scheme, and Y is half the thickness of the cavity. t_U is the time measured from the instant when the flow front passed the segment. Υ, m_E and t_E are constants. In the outset of the filling, the rate stays higher than predicted, perhaps owing to the constant-rate behavior of the hydraulic system during this period. This condition is different from the constant-pressure one assumed in the prediction. The rate approaches gradually to the prediction. A small discrepancy between the measured and the predicted is possibly due to the errors in fitting a curve to the Λ-t data and in differentiation. Also the applicability of other scheme by Grinblet (1970) has been tested.

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The two kinds of strain-time factorized type (type I and type II), and the strain-time reduced type (type III) of superposition principle are examined, for two kinds of polyethylene film. The values of tensile stress calculated from the theory of type III, compared to the other types, agree fairly well with the experimental data.
When the additional strain is positive in the two-step relaxation, the type III has better applicability than the other types at small strain. On the other hand, when the additional strain is negative, all the predicted curves are apparently above the observed curves.
For high density polymers, in contrast to low density polymers, the theory can be applied only in the limited range of small strain.

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The time-dependent birefringence was measured simultaneously with stress relaxation for annealed low-density polyethylene films at various temperatures ranging from 15 to 80°C under relatively large strains of about 10%, at which the films showed nonlinear stress-strain and birefringence-strain curves during the tests with a constant rate of elongation.
The master curves of the strain-optical coefficient at relatively large strains of about 10% were very similar to that obtained at a small strain of about 3%. The strain-optical coefficient increased with increasing time and reached an equilibrium at long time. However, the larger the strain was sustained the higher the equilibrium value became.

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For the slightly plasticized polyvinyl chloride (PVC), one observes not only a usual plasticization in the glass transition region but also "antiplasticization" in the glassy state.
The α-dispersion of the PVC is broadened and shifted toward the low temperature side by the presence of a small amount of plasticizers, while the β-dispersion of the PVC is suppressed. The effect on the α-dispersion depends on each plasticizer species, while the effect on the β-dispersion is independent of the plasticizer species.
The characteristics of the antiplasticization phenomenon are summarized and discussed on the basis of the results of the new viscoelastic measurements.

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A non-equilibrium thermodynamical theory of linear volume viscoelasticity of amorphous polymers is presented. The relation describing the motion of polymer chain is essentially equivalent to that derived by Bueche, but the present method naturally can be used to generalize the randam spring model for the bulk system. At low frequencies, the relaxation spectrum for the isothermal complex bulk modulus is given in the same expression as for the complex shear modulus. Furthermore, the real part of isothermal compressibility is closely related with the free volume change in our theory. These results are in good agreement with the experimental data.

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Polyethylene terephthalate films, both unannealed and annealed, were drawn to various lengths. With increasing extension the transition temperature where the drawn samples begin to shrink on heating decreases for small elongation whereas it increases for large elongation. Such variation of the transition point with extension is similar to the density change of the sample; the point is considered to correspond to T_g. This correlation is well explained by assuming "iso-hole fraction" at T_g on the basis of the lattice theory.
Isotherms of recovery for the unannealed sample were closely superposable by horizontal shifts as in the case for the annealed one; the temperature dependence of logarithmic shift factor is in good accord with the Arrhenius equation rather than the WLF equation.

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This paper deals with the mechanical dispersions and the thermal shrinkage of cold-drawn polypyromellitimide in relation to its structure. Three mechanical dispersions were found in our measurements. The lowest one found around 80°C has been ascribed to the translational movement of chain segments against their intermolecular interaction. The activation energy of this molecular motion was about 10kcal/mol, obtained from the analysis of TMA curves. The second and the third ones were found at around 200°C and 360°C, respectively. Both of them were influenced by annealing and were strengthened by cold-drawing. The molecular motions of these mechanical dispersions were not clarified yet. However, it was certain that they are related to the main chain motion, from the analysis of thermal shrinkage of cold-drawn samples. The activation energies of these two processes were about 25Kcal/mol and 33Kcal/mol, respectively.

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Wood has a tendency to shrink during drying. This creates stress within the wood. The present paper deals with the effect of moisture distribution on the normal stress along the direction of board width, based on the equation (3) in the text which had been derived previously from the assumption of superposition of unsteady creep compliances during drying. The stress apparently increases with increasing moisture gradient and its development greatly depends on the progress of moisture gradient. These results suggest that some of the known types of stress developments during drying can be derived from appropriate combinations of these two factors.

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A stress-strain relation, f={G-B(1-1/α)+C(αα²-1)}(α-1/αα²), was used to analyse the large deformation behavior of styrene-butadiene rubber (SBR) with various concentrations of oil ranging from 0 to 40 PHR. In the above relation, f denotes nominal stress at extension ratio α, G corresponds to rigidity, B and C are coefficients. The theoretical character of this relation will be discussed in another paper⁵⁾ by one of the authors. The present results can be summarized as follows; The value of G is proportional to the crosslink density ν_e, but larger than those calculated from ν_ekT. The value of B is almost unaffected by ν_e and shows almost same tendencies as G against oil concentration υ₁ and strain rate ε. The value of C is about 1/100 of those of G and B, and had the maximum against ν_e and ε.

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The effect of adhesion between glass fibre and matrix on the tensile strength of two kinds of F.R.P. containing continuous or discontinuous glass fibres has been theoretically and experimentally discussed.
The tensile behavior of F.R.P. containing continuous glass fibres is entirely similar to that of the blended fibres composed of two different kinds of fibres, so that the adhesion effect on the tensile strength of such F.R.P. is negligible.
The shearing strength of adhesion τ_jmax between glass fibre and matrix of polystylene in the composite material containing discontinuous glass fibres has been obtained from the experimental data by means of the following formulae.
σ_c=V_f·(1-l_c/2l)·σ_fmax+(1-V_f)·σ_m1 and l_c=σ_fmaxd/2τ_jmax,
and its value is about 0.08-0.18kg/mmmm². In those formulae, σ_c is the tensile strength of the composite, V_f the volume content of glass fibres, l_c the critical length, l the fibre length, σ_fmax the tensile strength of fibre, σ_m1 the tensile strength of matrix at the breaking strain of fibre and d the diameter of fibre.
The value of τ_jmax, obtained experimentally here to be 0.08-0.18kg/mmmm², decreases with increasing fibre length, and is far lower than the shearing strength of matrix or that of joint between glass plate and polystylene knob.

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In order to clarify the viscoelastic behavior characteristic of FRTP, the stress relaxation measurements of polyethylene films filled with glass fiber fragments were carried out at various strains below 5% at a constant temperature of 23°C.
The analysis of the experimental data showed that the correspondence principle, which is a well known formula in the theoretical treatment of linear viscoelasticity, is useful to evaluate the relaxation modulus of FRTP under small strain.

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As a molecular model of the longitudinal wave relaxation at MHz range for a polymer solution, Miyahara et al. proposed the crankshaft model with single thermal relaxation. Ludlow et al. reported the model with double motions in polymer chain, regarding it as a double relaxation. Recently, Ikeda et al. reported that the MH_z range compressibility of PMA in acetone solution was abnormal and the compressibility of high molecular weight PMA was smaller than that of the low molecular weight PMA when the molecular weight was higher than 1×10⁶. It was suggested that the phenomena were related with the molecular motion during the longitudinal wave relaxation at MH_z range for the polymer solution.
In this study, the molecular weight dependence of the molecular motion taking place during the longitudinal wave relaxation at MHz range in PMA-acetone solution was determined by the ultrasonic method, Two PMA samples with different molecular weights (B-3, 1×10⁶ and C-3, 56×10⁴) were prepared.
The excess absorption of PMA-acetone solution was estimated from the difference between the absorption of polymer solution and that of solvent. The result of C-3 solution was a single relaxation (hypothetical thermal relaxation). The result of B-3 solution was analyzed by the double relaxation theory. The relaxation frequencies obtained were 4MH_z and 40MH_z. The molecular model of relaxation for C-3 sample was given as the rotational isomer of a head-tail bond in polymer chain (ΔH°=220cal/mol, ΔH_??_=1600cal/mol). The second relaxation at 40MHz for B-3 sample was presumed to be correlated with the spreading of polymer chain, based on the solvent dependence of the relaxation.

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In order to obtain the data of the stability of high viscosity standard oils, the variation of viscosity with age was measured by means of a caoillary master viscometer for nolybutenes having viscosities of 55, 340, and 1010 poises at 25°C, and for polybutene-mineral oil mixtures having viscosities of 20, 100, and 540 poises at 25°C.
The results obtained can be summarized as follows:
(1) The viscosity increments for the test samples, which were stored under the condition that the volume of the samples in each 640ml bottle is 500ml, are less than 0.2%/year, except for the hydrogenated polybutene.
(2) The viscosity increments for the test samples, which were stored under the condition that the volume of the samples in each 640ml bottle is less than 500ml, are larger than 0.2%/year, and the viscosity increments for a year are inversely proportional to the volume of the sample in 640ml bottle, except for the polybutene-mineral oil mixtures having viscosity of 20 poises at 25°C.
(3) A correlation between the acid value and viscosity increment for a year exists for all the test samples.

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The dynamic mechanical and thermal properties of drawn silk fibroin have been investigated. The conformation of silk fibroin treated by methanol or other organic polar solvents is known as β-form, while that of untreated and undrawn specimens is known as α-form. The latter can be transformed to β-form by mechanical drawing.
The dynamic moduli (E') of untreated silk fibroin specimens drawn in the draw ratio of 1, 2 and 10 were 7.5×10⁹, 2.5×10¹⁰ and 1.5×10¹¹dyne/cmcm² at 30°C, respectively, where as those of the methanol-treated specimens were 1.6×10¹⁰, 3.5×10¹⁰ and 2.0×10¹¹dyne/cmcm², respectively.
The temperature dependence of dynamic modulus was determined. Below 100°C, the modulus decreased with increasing temperature, which is considered due to the water evaporation in the specimen. Above 160°C, the modulus still decreased but more slowly, which is caused by the molecular motion of main chain or a partial decomposition of silk fibroin. The tanδ curve showed the evaporation of water at temperatures below 100°C for the drawn specimens and the relaxation of the main chain at around 240°C for the well-oriented β-form specimens. The peak due to the relaxation of the main chain was observed at around 230°C and 240°C for α-and β-forms, respectively.
There were two endothermic peaks in DTA curves: One is due to the evaporation of water at the temperature around 100°C and the other at 270°C for the undrawn α-form specimen and 290°C for the undrawn β-form specimen. The decomposition peak appeared at about 320°C for well-oriented specimens.

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