The molecular mechanism of two kinds of absorption peaks, which were usually observed at 160_??_170°C (α1) and ca. 120°C (α2) in the dynamic loss tangent (tan δ)- temperature curve (100Hz.) for unoriented polyacrylonitrile (PAN) film, was studied. For this purpose, PAN samples of widely different crystallinity were prepared by using the following methods: (1) radiation-induced polymerization with and without urea-canal complex and conventional free radical polymerization, (2) different kinds of solvent (i.e., N, N′-dimethyl-formamide and 70% nitric acid) in the solvent casting process, (3) solution grown crystal, and (4) heat-treatment. The negative correlationships were found between the sum of intensities of both α1 and α2 absorptions and the crystallinity. Apparent activation energy of α1 and α2 absorptions were determined as 92.1 and 57.5Kcal/mol, respectively. α1 and α2 absorptions were attributed to the micro-Brownian movement of the chain in an amorphous region, suggesting that the fine structures of PAN solid could be reasonably expressed in terms of two amorphous phases and a single crystalline phase.
The detailed fine structure of amorphous region in unoriented polyacrylonitrile (PAN) film was studied by analyzing, according to the method proposed by the authors, the dynamic loss tangent (tanδ)-temperature curve. If a major component of solvents remaining in the solution at the instance when the solution solidifies by evaporating solvent or by adding non-solvent was poor solvent for PAN, an amorphous region with a strong intermolecular interaction (i.e., a closely-packed region) (region 1) had a tendency to be produced from the solidified gel. If a major component was good solvent in that case, an amorphous region with a weak interaction (i.e., a loosely-packed region) (region 2) appeared. Region 1 had a comparatively uniform distribution with respect to the degree of molecular packing (packing density) (i.e., small heterogeneity index nt), whereas region 2 had a broad distribution (i.e., large nt). With increase in the amount of solvent (for example, N, N′-dimethylformamide (DMF)) CD absorbed after film formation, nt for region 1 increased, but nt for region 2 decreased. Region 1 transformed to region 2 in the range CD of DMF>14wt%. Region 2 transformed to region 1 by annealing in wet state. Introduction of co-monomer (methylacrylate) increased the relative amount of region 2 and decreased nt of region 2.
The temperature rise of a sewing needle is caused by the frictional heat generated when the needle penetrates and withdraws from a fabric. Investigation on energy per cycle in needle-fabric interaction presents some informations about the heat generation in sewing. The detector for a needle penetration force being made, the experiments on needle-fabric interaction have been carried out by the use of the detector for sewing without thread. The results on the energy per cycle and the maximum penetration force are obtained as follows: (1) There are high correlations between energy per cycle and the maximum penetration force: (a) These two factors increase by increasing the machine speed ranging from 3 to about 50spm, and levels in the range from 50 to 1000spm. (b) These two factors become larger for the bulged-eye needle than for the normal one. (c) These factors increase with increasing the blade diameter at a higher rate than that of the increase of the cross-sectional area of the blade. (d) These factors are proportional to the number of fabric layers.
The studies were made to investigate the effect of treatment on silk fibroin with ammonium (A-salt) or potassium (K-salt) hexachlorostannate and to examine the binding mechanism of those salts to silk fibroin. Poor hygroscopicity and water repellent property of silk fibroin were recognized in treatment with A-salt or K-salt, and these properties were supposed to be related with shielding effect of hydrophilic radicals. From IR spectra on the treated silk fibroin, slight red shift was observed in CO (Amide I) and CN (Amide II) bands, respectively in the case of treatment with K-salt. Therefore, it was assumed that Sn is coordinated to carbonyl groups of amide linkages in the silk fibroin treated with K-salt. Moreover, the same result was observed from ESR spectra of silk fibroin. As carbonyl groups are generally a typical hydrophilic group, Sn coordinates to O atom of carbonyl groups of amide linkages. On the other hand, red shift was not recognized in the silk fibroin treated with A-salt. From the fact that A-salt suppresses the thermal degradation of silk fibroin, it was assumed that the formation of intermolecular structure is caused by hydrogen bonding to carbonyl groups in the silk fibroin.
An equipment for waveform arrangement was devised to arrange the size signal waveform of raw silk during reeling by applying the sample and hold technique. Furthermore the fundamental characteristics of the equipment were researched, the following results were obtained. The method of waveform arrangement is to integrate the applied analogue size signal for a set time and hold its value by means of integrator. In the low frequency range, the frequency of the input has an effects on the output waveform of the proposed device and the waveform is characteristic. On the other hand, the frequency of size signal (80 to 95HZ) in the practical reeling speed range (180 to 210m/min) has no effect upon the output waveform of the device. The device is a kind of low pass filter because it restrains the high frequency range. It can be concluded that the optimum range of integration time (=hold time) is from 0.7 to 1.0 sec for practical size control.
Nylon elastomers composed of polyether as soft segment and nylon as hard segment were synthesized by the interfacial or low temperature solution polycondensation of polyether (polybutylene glycol or polyethylene glycol) with diacid chloride (sebacyl chloride or adipyl chloride) and diamine (hexamethylene diamine). The reduced specific viscosities of polymers obtained by the interfacial method were remarkably higher than those of polymers obtained by the low temperature solution method. The polyether/nylon compositions of polymers estimated by the IR method coincided satisfactorily with those calculated from the monomer ratio. The melting point depressions of polymers with increasing polyether content were smaller than those of random copolymers calculated by Flory's equation when the chain length of polyether was shorter and were larger than those when the chain length of polyether was longer.
The diffusion behavior of p-aminoazobenzene (Dye I) and 4-N, N-di-hydroxyethyl aminoazobenzene (Dye II) in nylon 6 as sorbed from aqueous and aqueous sodium poly(styrene sulfonate) (PSSNa) solutions was examined. The addition of PSSNa in the dye bath causes a marked decrease in the equilibrium dye concentration on nylon 6. It is found that the proportionality holds between the equilibrium dye concentration, Cs and the free dye concentration in the bath, Cf estimated from the solubility data. This indicates that the dye bound to PSSNa has no affinity to nylon 6. Further, the effect of rotation of the film roll on the equilibrium sorption of Dye I was examined.