Static and dynamic mechanical properties of polypropylene-styrene graft copolymer were studied in comparing with those of polypropylene-polystyrene blend and each homopolymer. These properties were interpreted in relation with their fine structure. Yield stress and strength at break of graft copolymer were increased with the increase of styrene content, but Young's modulus did not change remarkably and elongation at break decreased with grafting more than the value of polypropylene homopolymer but was still greater than the value for polystyrene homopolymer and blend. In stress-strain curve, a yield point was observed in graft copolymers and for polypropylene, but not observed in blend and polystyrene. The shape of loss modulus-temperature curve and the peak position of the absorption curve for the graft copolymer are different from that in the blend. Moreover, the curve for the graft copolymer whose powder or small pieces of the film was mixed and melt pressed was different from the curve for the original graft copolymer film, annealed after grafting. The absorption curve for the graft copolymer and blend showed two peaks; one at about 10°C. and another at 110-120°C. The former absorption indicates the αa-absorption of polypropylene which is due to the segmental motion of amorphous chains of the polymer and the latter absorption indicates the main dispersion of polystyrene. The peak temperature of the absorption curve at the higher temperature region for the original graft copolymer and blends agrees with the temperature for polystyrene, but the peak temperature for which was melt pressed and annealed graft copolymer shifted about 10°C. to higher temperature side from the peak temperature for polystyrene. This shift suggests that the molecular mobility of polystyrene branches in the graft copolymer may be restricted by the crystallites of polypropylene. In other words, polystyrene branches exist in the circumstance where crystallites of polypropylene may affect the molecular motions of the polystyrene branches. In the case of blends polystyrene molecules must be excluded from crystallites, and in the original graft copolymer the grafting must take place only on the amorphous chains of polypropylene.
Static and dynamic mechanical properties of the blend of polypropylene and low density polyethylene were studied. Tensile strength and Young's modulus of the blends increases with the increased weight content of polypropylene component, but the elongation at break of the blend which containes 50 wt. % of polypropylene or polyethylene is smaller than the value for each homopolymer and other blends. Also the elongation at break diminishes to a very small value by a heat treatment at a high temperature. In the viscoelastic absorption curves (dynamic loss vs. temperature curves) for blends only one apparent peak is observed in the vicinity of room temperature for samples whose content of polypropylene are more than 50 wt. % and annealed at low temperature such as 90°C., but two peaks are separated for a sample containing 25 wt. % of polypropylene. The one peak for samples containing large amount of polypropylene separates into two peaks by an annealing at a high temperature such as 120°C. or by a slow cooling from the melt. These mechanical properties are interpreted in relation with the fine structure of blends and it is concluded that the change of the mechanical properties with a heat treatment must arise from the phase separation by proceeding crystallization.
The fine structures of polynosic fiber, high-wet-modulus fiber, high-tenacity rayon and normal rayon were examined by various methods and the following results are obtained: (1) X-ray and acid hydrolysis studies indicete that polynosic. fiber aud high-wet-modulus fiber have higher crystallinity and show lower rates of recrystallisation during acid hydrolysis than in high-tenacty rayon and normal rayon. Further-more the infrared spectroscopic results of these rayon fibers show that there exists a linear relationship between the crystallinity and the apparent molar extinction coefficient α of the absorption band at 1375 cm-1, and α s of polynosic fiber and high-wet-modulus fiber are higher than in those of high-tenacity rayon and normal rayon. Next, increasing rates of α of polynosic fiber and high-wet-modulus. fiber during acid hydrolysis are lower than those of high-tenacity rayon and normal rayon. These infrared spectroscopic results show a good agreement with the conclusions which are derived from acid hydrolysis and X-ray methods. (2) The degrees of swelling by NaOH solution of polynosic fiber and high-wet-modulus fiber are lower, compared with those of high-tenacity rayon and normal rayon. Infrared spectroscopic studies indicate that the increasied rate of α of the absorption band at 1375 cm-1 during the alkali treatment of polynosic fiber is lower, compared with those of other fibers. This result suggests that the rate of decrystallisation of polynosic fiber during the alkali treatment is lower than those of other fibers.
In the previous report, relationship between Young's modulus and birefringence for drawn and heat-treated PET fibres was discussed. In this report, the mechanism of small deformation of PET fibres below glass transition temperature is discussed and a new theoretical approach between Young's modulus and molecular orientation is proposed under the following assumptions: a) A segment transforms in accordance with “affindeformation” theory: b) Intersegmental force during the affin transformation of the segment is proportional to the rotational angle of the segment. Then, Young's moduli of PET fibres heat-treated at constant length after drawing and ones drawn after crystallization are measured and compared with the theory. The results obtained are as follows: 1. The rotational angle ω of a segment due to the deformation of a sample and Young's modulus E may be expressed by following equations; where υ is Poisson ratio of the sample; θ is the angle between the fiber axis and the segmental axis; ez is tensile strain of the bulk sample; E0 and G0 are constants. 2. The relationship between Young's modulus and amorphous orientation factor may be represented in terms of the above equations. The values of E0 and G0 are 1700_??_1900kg/mm2, 80kg/mm2, respectively, for the samples drawn without heat-treatment, but these are a little smaller for the samples drawn after crystallization, Young's modulus of drawn PET fibres depends mainly upon amorphous orientation and the effect of crystallinity is rather small. 3. The above results suggest that the force constant of the amorphous segment below glass transition temperature dose not much differ from that of the crystalline chain, but a part of intermolecular strain makes a series to intra-molecular strain and lowers much the Young's modulus of bulk sample; and that there may be more parts of fold structure in samples drawn after crystallization than in ones drawn without heat-treatment.
The ionization constants for acid hydroxyazo dyes in aqueous solutions at 20°C have been measured by the spectrophotometric and the potentiometric methods. The visible absorption spectra of the dyes are not affected by the hydrogen ion concentration in the range of pH between 3 and 9, but shiftes to the short wavelength out of the range. In the range pH>9 the dissociation of the hydroxyl group, and in the range pH<3 the undissociation of the sulphonic group and the favours of the hydrazone in the tautomeric equillibrium seem to affect the spectra. The dissociation of the hydroxyl group decreases by the electron donating substituents in the coupling component. The variation of the apparent molar extinction coefficient for the dye ion (DH-) in pH4_??_9 with dye concentration indicated that the aggregation occurrs at the higher concentration. But no significant aggregations among the ions (D2-) is seen in pH>13. pH-Values in these ionic equilibriums are as follows:
The size of the dye particle is recognized as an important factor in determining the behavior of a dyestuff in the dyeing process. The effects of the salts on the irreversible phenomena of the acid dyes were investigated by the measurement of the diffusion and the mobility. For C. I. Acid Red 88, the conclusions on the diffusion of the ion was obtained that the particles have the rotary disclike form and aggregate in the manner of a stack of the discs. For C. I. Direct Red 28, the ions are rodlike particles and thus it was believed that the aggregation number calculated assuming a spherical model may deviate from the true value. The mobility of the dye ion varies with the concentration. The results suggest that the phenomenon of the aggregation of dye ion is a factor on the mobility.
It is infrared that the value of the apparent activity of the acid dye obtained by the measurement of the solubility product is influenced by the aggregations of the ions produced by addition of the electrolyte. The effects were investigated by measuring of the solubility of C. I. Acid Red 88 in the aqueous solution containg sodium chlorid and of the partition between n-amylalcohol and the aqueous solution. The results obtained are as folows: 1) The apparent activity factor obtained from the solubility of the dye increases with the concentration of sodium choride. 2) The apparent activity factor obtained by the partition of the dye under the condition of the constant ionic strength decreases with the concentration of the dye. 3) The degree of these changes is remarkable at the low temperature. As the result is in accord with the behavior where the existance of the aggregations of the dye ions is assumed, it known that the value of the apparent activity of the dye obtained by the measurement of the solubility or the partition is influenced by the aggregations of the dye.