Some chlorine substituted aliphatic hydrocarbons exhibit strong interaction with amorphous undrawn poly (ethylene terephthalate) (PET) fiber. For example, solvent-induced crystallization in trichloroethylene develops within few seconds at 333-353K and even initiates at 256K. This fact suggests that the glass transition temperature of PET is depressed about 110K with the solvent. The spherulites develop from the surface to the center of fiber with the penetration of solvent and the transverse of fiber can be divided into two parts which are spherulite part and amorphous part. Apparent diffusion coefficient of trichloroethylene is estimated to be in the range from 3.35×10-7 to 7.05×10-5cm2/s and that of 1, 1, 1-trichloroethane to be in the range from 1.44×10-8 to 1.52×10-6cm2/s. Apparent activation energies are about 18 and 39kcal/mol, respectively. The stress-strain behavior is directly affected by the progress of solvent-induced crystallization.
The tensile and fracture properties of epoxy composites reinforced by triaxial carbon fabrics were investigated. Two kinds of triaxil reinforcements, basic-weave (BASIC) and bi-plain (BIPLN) fabrics were prepared. Carbon yarns of the above fabrics were interlaced in three directions forming 60° with each other. For comparison, composites of ordinary orthotropic cloths (ORTH) were also examined. BASIC composites had almost isotropic elasticity and higher tensile strength than ORTH. The triaxial samples showed different fracture modes depending on the yarn orientation in them, in tensile as well as acoustic emission tests. BASIC was greater than BIPLN both in tensile modulus and in strength. This result was considered to be caused by the lower degree of yarn crimp in BASIC. Not only the orientation angle but also the crimpiness of yarn is one of the most important factors which must be considered in designing the texture of reinforcement fabrics.
Polycondensation of D-glucose with polyphosphoric acid (PPA) as a condensation agent in dimethyl sulfoxide (DMSO) has been studied. The reaction conditions under which a colorless synthetic glucan was obtained were temperature of 50°C and reaction time of 12 hours. The characteristics of the synthetic glucan were as follows: yield 44.1%, specific rotation +59.8° and degree of polymerization (DP) 148.1. This synthetic glucan combined less free phosphorus, 6 monoester phosphoruses and 20-24 diester phosphoruses per 100 glucose residues. The structure of synthetic glucan was studied by the method of the peroxidation and the Smith degradation, and the results suggested that the modes of glucose condensation were C1-C'6, C1-C'3 and products had many branched chains. The synthetic glucans were cyanoethylated, and the maximam DS of cyanoethyl group was 1.90. Dielectric constant and loss of these derivatives at various frequencies and temperatures were measured. The peak of dielectric loss which was due to side chain relaxation of cyanoethyl group at -50°C was observed, and the activation energy of this side chain relaxation was calculated to be 66.1kJ/mol.
Biodegradation of pitch-based high performance carbon fibers (HPCF) by microorganisms was studied. The degraded fiber was examined by scanning electron microscopy. Aspergillus flavus ruptured surface areas of HPCF (carbon type, prepared by heat treatment at 1000°C) in 60 days. The fibril structure under the surface layer of the fiber was exfoliated by degradation. The fibrils on the second layer were 100-110 nm wide. The fibrils were oriented nearly parallel to the fiber axis. HPCF (graphite tiye, prepared by heat treatment at 2000°C) did not exhibit ruptured areas like HPCF (carbon), showing greater resistance to microbial attack. Biodegradation of HPCF (carbon) began at the point of random orientation of graphite structure on the surface layer of the fiber, proceeding to the protuberance of a limited area in the layer and to the rupture of a limited area.
Effect of halides and halogen-nitrogen compounds treatment on pyrolytic gas formation from cellulosic fibers was studied by gas chromatography and mass spectroscopy. While treatments with sodium halides were not effective in improving flame retardancy, ammonium halides, ammonium bromides in particular, with high Limiting Oxygen Index (LOI) were highly effective in flame retardation and in reducing generation of flammable gases and poisonous gases, especially acrolein. The results showed the synergistic effect of halogen and nitrogen in the treating compound, similarly in the case of phosphorus and nitrogen studied previously.
The aggregation equilibrium of acid azo dyes having alkyl groups with different carbon number was investigated in aqueous solution. The aggregation number and aggregation equilibrium constants were determined spectrophotometrically. Aggregation proceeded solely as a dimerization process for C0-C6 where the numeral indicates the carbon number of the alkyl group. On the other hand, the multiple stages of the aggregation were observed for C8 and C12. The initial stage was found to be a dimerization for C8 and a trimerization for C12. Longer alkyl group resulted in greater aggregation constant. However, the secondary butyl group resulted in the decrease in the constant. This result can be attributed to the bulkiness of the secondary butyl group. The C12 decreased the surface tension with increase in the concentration as in the case of DBS; however, the formation of the micelle was not clear in the concentration range examined.
Chemical and mechanical pulps and pure celluloses were swollen by chemical and mechanical treatments, and these swelling mechanisms were studied. The samples were treated with SO2-diethylamine in dimethyl sulfoxide as chemical swelling treatments, and were beaten with a PFI mill as mechanical treatments. Crystallinities and water retention values were measured for the treated samples, and were compared in reference to chemical and mechanical treatments, Crystallinities were controllable from the original ones to the amorphous state for chemical pulps and pure cellulose samples by controlling the amounts of SO2-diethylamine. Simultaneously, water retention values were increased from less than 100% up to more than 400%. In these decrystallization processes, there was a range of the amounts of reagents where water retention values were increased while crystallinities were equal to those of the original samples. This phenomenon was identical to those observed for chemical pulps by beating treatments. Thus, there seems to be a mechanism of beating in which hydroxyl groups in non-crystalline regions, which are originally inaccessible to water, become accessible to water by the mechanical treatments. The increase in accessibility of hydroxyl groups in non-crystalline regions may have an influence on swelling and flexibility of pulp fibers and physical properties of papersheets greater than that of fibrillation.
Smoothness of paper is customarily measured by an air-leak smoothness tester. An Oken type instrument was used in this work. The purpose of this study was to examine what roughness size level the air-leak smoothness expresses if roughness includes microroughness to macroroughness variously. A profile curve measured by a stylus instrument was separated into waves with various wavelengths by Fourier-transform. Amplitude of each waves was correlated with the Oken type smoothness. From a profile curve measured by a stylus instrument, the centerline average was calculated after removing waviness components which correspond to waves with wavelength conventionally longer than 800 μm. When this cut-off value indicating a threshold level was varied, the centerline average was correlated with the Oken type smoothness. Such correlation analyses connected with spectral analyses were applied for various kinds of handsheet. They include calendered sheets and those made from beaten pulp. As a result, the correlation between the Oken type smoothness and the centerline average with the cut-off value showed a smoother change and a more distinctive peak. Moreover, the roughness level Oken type smoothness expresses was found to be waves with wavelength equivalent to or less than about 273 μm for handsheets.
A new robot hand for cloth handling has been developed. This robot hand has a function of sensing and functions of separations, transferring and placing cloth on any position in 3 dimensions. The hardware of the hand is simple in spite of its multiple functions.