Dynamic modulus measurement, flexural test, and SEM observation for poly (vinyl chloride) (PVC), filled with aramid short fibers (AF) in the range of 0-0.22 in volume fraction (φ_r), were carried out The AF particles in the specimens were aligned parallel to the machine direction. As the φ_r increase, the glass-transition temperature (T_g) and the relative modulus (E_c′/E_m′) of the specimens become higher. The phenomena were more remarkable for the specimens cut parallel to the machine direction (MD) than those cut transverse to the machine direction (TD). In the glassy region, the E_c′/E_m′ values of MD were larger than those estimated from the rule of mixture, but those of TD were near the estimated values. In the range over T_g (pseudo-rubbery region), theE_c′/E_m′ values of TD were larger than those calculated from Mooney's equation. The ratios of flexural modulus for MD and TD increased linearly with an increase in φ_r. For MD, the ratios agreed with E_c′/E_m′ in the range of φ_r=0-0.16, but for TD, they were slightly larger than E_c′/E_m′. The increase of affinity between PVC and AF particles treated with silane and titanate coupling agents was relatively small.

View full abstract

New isopropenyl-1, 3, 5-triazines, e. g., 2-amino-4- (p-ethoxyanilino) -6-isopropeny1-1, 3, 5-triazine [1], 2-amino-4- (o-ethoxyanilino) -6-isopropenyl-1, 3, 5-triazine [2], 2-amino-4- (p-bromoanilino) -6-isopropenyl-1, 3, 5-triazine [3], 2-amino-4- (m-methoxyanilino) -6-isopropenyl-1, 3, 5-triazine [4], 2-amino-4- (o-methoxyanilino) -6-isopropenyl-1, 3, 5-triazine [5] were prepared. Both of [2] and [3] have dimorphic forms. The homopolymerization of these monomers and their copolymerization with styrene, methyl methacrylate, and methyl acrylate (M₁) were carried out using azobisisobuty-ronitrile as an initiator in dimethylsulfoxide. The copolymerization parameters (r₁, r₂, Q₂ and e₂) were determined for these monomers. Polymerization exotherm was observed in DSC curves above the melting point for [2] - [5]. The ceiling temperature (T_c) and the heat of polymerization (ΔH_p) were obtained from scanning DSC data. The equilibrium monomer concentration [M] _e were determined by isothermal DSC measurement. T_c and ΔH_p of [2] - [5] were also obtained from [M] _e. These values were in good agreement with those measured by dynamic DSC. The values of T_c and ΔH_p, of [2] - [5] were approximately 170°C and-11 kcal/mol, respectively.

View full abstract

Styrene derivatives, N-p-vinylbenzyl-O-β-_D-glucopyranosyl- (1→4) -_D-gluconamide and N-pvinylbenzyl-O-α-_D-galactopyranosyl- (1→6) -_D-gluconamide, were prepared from cellobiose and melibiose as the respective starting oligosaccharides, and the corresponding homopolymers (represented as PVCA and PVMeA) were obtained by radical polymerization in water at 60°C. The recognition functions of these polymers, together with those of previously reported oligosaccharide-carrying polymers, were investigated. Agglutination of red blood cells by concanavalin A was inhibited in the presence of the analogous polymers prepared from maltose, maltotriose, maltopentaose, and maltoheptaose, the non-reducing terminal of which was α-_D-glucopyranose. Inhibition activities of these polymers were about 10³ times as high as those of the corresponding starting oligosaccharides. A remarkable polymer effect was manifested by the polymers which carry an oligosaccharide moiety in each repeating unit. All these polymers except PVCA caused agglutination of human red blood cells; the agglutination activity of PVMeA was remarkably high.

View full abstract

The properties and structure of ultrahigh-modulus rods were investigated for wholly-aromatic copolyesters (WACP's) containing 60 and 70 mol% p-hydroxybenzoic acid (HBA). The drawn rods were prepared by extensionally drawing the nematic melts extruded from a die of 1-5 mm diameter. The degree of molecular orientation in drawn rods were varied by taking extensional draw ratio (λ) as a variable at given temperatures. Changes in the stuctural ordering with λ values were monitored by wide-angle X-ray scattering and scanning electron microscopy (SEM). It was found that the higher modulus and the higher degree of crystallite orientation are obtained for the rods prepared by using larger-diameter dies, compared with the same value of rod diameter. SEM measurements showed that the fibrils become highly aligned parallel to the drawn axis for the surface and center portions of highly drawn rods. Also, the radial profiles of stretching modulus (E_s) and the degree of crystallite orientation (Π) were measured within the drawn rods obtained by using a 5 mm-diameter die. The values of E_s and Π dropped sharply as the measurement proceeded from the surface to the center portions in the large-diameter rod drawn at a low λ value, although the high value of E_s and Π remained almost constant for the surface portions with varying λ values. The difference in E_s and Π between the surface and center portions of drawn rods was found to be relatively small for high molecular weight WACP's. The rods of high molecular weight WACP's having 70 mol% HBA yielded ultrahigh bending moduli of 90 GPa for 1.2 mm rod diameter and of 61 GPa for 2.2 mm rod diameter.

View full abstract

To obtain information concerning the dimensional changes of polypeptides in the helix-coil transition region, electric birefringence of poly (ε-carbobenzoxy _L-lysine) is examined. An expression describing the changes in the specific Kerr constant B_vp, is derived by expanding the Zimm-Bragg theory and used to analyze the results in a dichloroethane-dichloroacetic acid mixed solvent system. The observed changes in B_vp can reproduced by using the transition parameters optimized from optical rotatory dispersion data. The agreement improves further when the effect of helix flexibility is taken into account. Several factors influencing the electric birefringence are discussed showing that (i) conformer shift due to field application can be ignored, (ii) coil residues have no contribution to the birefringence, (iii) orientation of helix is driven by the permanent dipole moment, and (iv) orientation correlation of helix sequences coexisting in a chain can be ignored.

View full abstract

Effect of I^- concentration on the characteristics of absorption and circular dichroism (CD) spectra of amylose-iodine complexes was examined over a wide range of I^- concentration (0-2×10^-2M KI). The maximumabsorption band around 600 nm of the complex showed hyperchromism and also blue shift for the increase in I^- concentration. Correspondingly, the split CD bands with opposite signs (+, -) exhibited the same behavior. The dissymmetry factor (g_max) as well as the maximum absorption wavelength (λ_max) changed linearly with the molar fraction of bound I^-₃ (R), and at R=0.5, a minimum value for g_max, and an inflection point of λ_max were observed. Spectral analyses based on the spectral characteristics of the complexes at R=1 and 0.5 revealed the existence of three independent species in the complex. They were assigned to three iodine coloring species, I₂. I₂, I₂. I^-₃, and I^-₃ . I^-₃., on the basis ofelectronic theory. As a result, the spectral change with I^- concentration is explained in terms of the change in the populations of the three iodine coloring species.

View full abstract

Following previous reports, the orientation mechanism of crystallites in rolling process of high density polyethylene of different molecular weights was analyzed. The following conclusions were obtained; 1) The preferential orientation around crystalline chain axis; c-axis increased with the increment of molecular weight. 2) The increment of molecular weight causes shrinkage of films in rolling process, and then decreases the anisotropies of Young's modulus and yield stress. 3) The anisotropies of Young's modulus and yield stress in each molecular weight sample except No. 1 sample are of the Schmid type. 4) The two step polymerization sample indicates a good rolling effect due to the low molecular weight portion, while this portion restrains the c-axis orientation.

View full abstract

A computer simulation was used to optimize the molding condition and the construction of dies for injectioncompression molded plastic lenses. The simulation is based on the non-steady temperature analysis and thermal stressstrain analysis using the finite element method, and also on calculation of growing process of the plastic solid phase. The simulation confirmed that a dominant factor of sinkmark and warpage which deteriorated the dimensional accuracy of the plastic lenses was the temperature distribution at the time when thermoplastic material solidified on cooling below the softening temperature range in molding process. The sinkmark resulted from the non-uniformity of inside temperature due to the thickness variation of the lens. Althoug the warpage depended mainly of the non-uniformity of temperature at the mold cavity surface, it was also influenced by the inside temperature distribution due to differential curvatures. As a result, to enhance the precision of the plastic lens, two factors are important: dies which realizes uniform cavity-surface temperature and the mold cooling conditions which make the inside temperature of molded lens uniform on cooling below the softening temperature range in molding process.

View full abstract

Shape change of poly (p-oxybenzoyl) whiskers formed during the solution polymerization in paraffin was studied. Incipient lamellar crystals with slip dislocation which cause the spiral growth are produced at a very early stage ofpolymerization. Subsequently, crystallizable oligomeric materials are exhausted only in the crystal growth. In the firststep of whisker growth, the increase in the diameter is observed. In the final step, the angle of both pointed ends ofwhiskers becomes sharper. These changes of whisker shape was explained by the degree of supersaturation ofcrystallizable oligomeric materials in paraffin. The number of the incipient crystals was also discussed on the basis of the effect of polymerization temperature.

View full abstract

The temperature dependence of the elastic modulus E_l, of crystalline regions of polytetrahydrofuran (PTHF) in the direction parallel to the chain axis has been investigated by X-ray diffraction. Below 135°C, the value of E_l for the (3110) plane of PTHF was 183 GPa. On raising the temperature, however, the E_l value began to decrease abruptly near 135°C, and it became 37 GPa at 18°C. The thermal expansion coefficient of the (3110) spacing changed discontinuously at the temperature region where the E_l value began to decrease. These phenomena indicate that the mobility of chain molecules in the crystalline regions, i. e., incoherent thermal vibration of the crytal lattice, increases above 135°C, and that this causes the decrement of E_l. The chain molecule of PTHF probably does not have a planar zigzag conformation, and contracts owing to thermal vibration at room temperature. Futher below 135°C, the chain molecule of PTHF was found to lose its complete straightness because of the difference in the bond angle between C-C-C and O-C-C, C-O-C

View full abstract

Isopropyltridodecylbenzenesulfonyltitanate (titanate coupling agent) was used to treat with γ-Fe₂O₃ particles. The adsorption of titanate coupling agent on γ-Fe₂O₃ particles and dispersion, orientation, and packing behavior of the treated γ-Fe₂O₃ particles were investigated. The following results were obtained. 1) The adsorption behavior of titanate coupling agent on γ-Fe₂O₃ particles was of the Langmuir type. The occupied area by titanate coupling agent molecule on γ-Fe₂O₃ particles was about 125 A²/molecule, when the adsorption of titanate coupling agent was saturated. This area corresponded to the value obtained from the π-A curve of titanate coupling agent on water. 2) γ-Fe₂O₃ particles treated with titanate coupling agent were applied to magnetic tapes. The dispersibility, orientation, and packing density of γ-Fe₂O₃ were improved by such treatment, when poly (vinyl butyral) or poly (vinyl acetate) was used as binder. The optimum content of the treated γ-Fe₂O₃ particles in the magnetic tape was about 80wt%. These magnetic data were explained from the mixed adsorption of titanate coupling agent and polymer.

View full abstract

Sorption and pervaporation experiments for water-ethanol, -dioxane, and -pyridine mixtures in poly-dimethylsiloxane (PDMS) membranes and those containing silica-filler were carried out, and the concentration-averaged diffusion coefficients D were determined. The diffusion coefficients D were also determined from the transient permeation experiments. In the case of PDMS, contents of the organic components in the sorbed liquids were much higher than those in the permeates. The D for each component was independent of the feed composition. The values of D for water and ethanol were determined to be 14.5 and 4.5×10^-6cm²/s, respectively, at 25°C for pure components and also for 10 and 30wt% ethanol solutions, being in fairly good agreement with the values of D.In the case of PDMS containing silica-filler, both D and D for each component, especially for water determined to be apparently much smaller than those in PDMS, if the sorption on silica-filler was not taken into account. The preferential permeation of organic components through PDMS membranes was attributed to both their preferential sorption and rather small reduction in the selectivity in diffusion process in spite of their large molecular sizes compared to the water molecule.

View full abstract