The effect of stacking sequence on the flexural properties of unidirectional multistack composites of two kinds of composite prepregs, carbon fiber/epoxy and alumina fiber/epoxy ones was studied. The bending test showed that the fracture of the composite depended primarily on which kind of prepreg forms the sides of the composite; when the both sides were alumina layers (A-A type), fracture began in the bottom layer (the tension side) and gradually grew, while if the both sides were carbon layer (C-C type), fracture occurred in the top layer (the compression side) accompanied by a drastic decay in the bending load; in any of these, the flexural load continued to increase even after the onset of fracture until the final destruction was reached. The flexural strength for the A-A type composites and the flexural strength at initial fracture for C-C type composites were enhanced as the number of carbon layers was increased. The quantitative dependence of the bending modulus of the composite on the number of stacked layers could be elucidated in terms of the lamination beam theory.
The anisotropic elasticity of some flexible foamed materials of polyurethane was investigated by experiment. The data of compression and shearing in various directions suggest that the tested materials are transversely isotropic around the principal direction, i.e., the direction in which the constituent foams of elongated shapes are oriented on the average. Based on this and another empirical symmetry, a formula was derived, by which the compression modulus in any direction can be estimated from the compression moduli in two axes, the principal one and any normal to it.
A simple and continuous method was developed for preparing lightly carboxymethylated cotton fibers and fabrics, which have an enhanced water absorbency, yet maintaining their natural handling characteristics as well as other textile properties. The method consists of the following unit processes: i) immersion of sample cotton into aqueous sodium hydroxide solution and squeezing, ii) neutralization of the sample surface with diluted acetic acid, followed by washing with water and squeezing, iii) extensive admixing with aqueous CH2CICOONa solution and carboxymethylation. The cotton samples thus carboxymethylated were found to possess enhanced, desirable water absorbency without changing their mechanical properties as well as their handling characteristics (F_??_-ai) when compared with the untreated.
Yellowing of two types of cocoon filaments was investigated. One type is the cocoon produced by silkworms reared with mulberry leaf diet at 4th and 5th instar (Mulberry sample). The other is that with an artificial diet containing Tofu-cake powder as a main component (Tofu-cake sample). The yellowing of Mulberry sample was remarkable after irradiation with ultraviolet light, while it was scarcely observed for Tofu-cake sample and the extent of yellowing decreased with increasing Tofu-cake content up to 50%. Tofu-cake sample contained relatively a large amount of nucleotide compounds, such as deoxycytidylic acid (dCMP) and cytidylic acid (CMP) in a hot-water-soluble fraction, and the contents of these compounds increased with increasing Tofu-cake content. On the other hand, Mulberry sample contained little amount of nucleotide compounds. The difference in the yellowing behavior between these two samples was attributed to the difference in the contents of nucleotide compounds. This was also confirmed by the fact that yellowing of Mulberry sample was drastically suppressed after immersing it in 3% dCMP aqueous solution.
There is considered to be a clear correlation between the electrical resistance and antistatic performance of fabrics. However, this correlation hasn't been established because of poor accuracy of the previous evaluation systems for fabric's antistatic performances. We found that the critical resistance to give a good antistatic performance is 1×1011Ω•cm, by using an accurate anti-static evaluation system (KB-system) newly developed by the authors. In addition, we propose a new antistatic guideline based on the newly determined “index of frictional static charge”, the integral of static charge for one minute after peeling. It was concluded that the electrical resistance measurement is not suited for evaluation of antistatic performance because of its inaccuracy and complexity.
Durable gelatinous deodorizer incorporated into cyclodextrins (CD) has been developed to restrict the decomposition of the deodorizer. Thus prepared deodorizer removed c. a. 99% of ammonia odor and c. a. 74% of methylmercaptide odor after 60min. Similar reduction rate of odor were established even after 20 days, suggesting that the deodorizer is stabilized by CD for long-term uses.
The moisture permeability of cotton and poly (ethylene terephthalate) (PET) fabrics in the isothermal system were investigated in the artificial climate room. The experiments were carried out in conformity of the JIS L 1099 A-2. The temperature of 20°C and 35°C, the relative humidity 20-80% and the windless condition were selected for the experimental conditions. The air permeability of fabric was measured at 20°C and the relative humidity 20-80%. The effect of temperature on the moisture permeability of fabrics could be replaced by the effect of the difference in moisture-vapour concentration (ΔC) on both sides of fabrics. As Δ C increased from the origin (ΔC=0), the moisture permeability of fabrics increased remarkably. The increase of the moisture permeability of fabrics by the ΔC increase at 35°C was almost on the extension of the line of that at 20°C. It can therefore be presumed that the increase of the moisture permeability by the temperature increase is caused by the ΔC increase for the temperature increase. Compared with the effect of ΔC to the moisture permeability of fabrics, the effects of materials and of the variation of the diffusion coefficient of moisture in air by temperature change were small. The total resistance (R) of system to the passage of the moisture was small at low temperature and at small ΔC. The air permeability of PET fabrics was larger than the cotton fabric, and the air permeability of fabrics changed slightly with the change of the environmental humidity.
High modulus, uniaxially drawn film and sheet were made from poly (2, 2′-dichloro-4, 4′-biphenylenepyromellitimide). The hot-drawn and thermally imidized film (15μm thick) had tenacity of 1.56GPa and initial modulus of 164GPa. In case of the sheet, the key point to obtain a high performance product was the preparation of a gel sheet for drawing which was homogeneous in through direction. The gel sheet was made by casting the poly (amic-acid) solution which was prepared in N-methylpyrrolidone/dichloroethane (DCE) (volume ratio 38/62) as the solvent and to which a cyclodehydrating agent was added, and then by drying at 40°C to remove DCE only. It was drawn at room temperature and heat treated stepwise to 300°C. The flexural modulus of the resultant sheet with thickness of 0.32mm reached 106GPa.
Commercial nylon6 fibers for apparel use (N6) and for tire code (T-N6) were dipped in a 30wt% chloroform solution of t-butyl perbenzoate (TBP) at 60°C under nitrogen for a predetermined period and then crosslinked at 150°C for 2h. TBP content in dipped fibers measured by DTA, and gel content, density and Young's modulus of crosslinked fibers increased, while their degree of crystallinity and thermal shrinkage decreased with the increase in time of dipping. The extents of these increases and decreases were more remarkable for T-N6 than N6, suggesting that the more effective crosslinking occurred for T-N6.
Silk fibers (Antheraea pen_??_yi and Bombyx mori), which were treated with a tannic acid solution and then with aluminum chloride, were dyed with acid dyes (C. I. Acid Orange 7 and Red 111). The change in the amount of adsorbed dye with those in the tannic acid content in the fiber and in the pH value of dye bath showed that tannic acid did not interact with amino end groups when fixed with aluminum chloride. A maximum of the dye adsorption was found in the dyeing of wild silk fibers to which tannic acid was fixed (2%). The small angle X-ray scattering intensity was increased due to the fixation of tannic acid to the fiber. The increase in micro-voids in the fiber seemed to cause the maximum in the dye adsorption.
Water absorption of a cotton towel treated with two types of household softeners was examined by Larose method. The conventional and latest ones contain distearyl dimethyl ammonium chloride and dioleyl dimethyl ammonium chloride, respectively, as a softener base. The former caused the deteriorated water absorption of the towel according to the increase of its bath concentration. However, almost normal water absorption was found in the latter's case over all the concentration range examined here. The latest softener would give the consumer's satisfactory water absorption even in its excess use. In addition, the consistency between Larose and Bilec methods was observed in the order.