A brief review is given of principal results obtained in the author's laboratory during last several years concerning applications of NMR absorption line measurement to the study of molecular motions in crystalline polymers. The anisotropy of NMR is measured on a highly oriented and completely crystalline polyoxymethylene obtained from tetraoxane single crystal by solid-state polymerization and is compared with the calculated. By dividing the absorption signal from polyterafluoroethylene into three parts, the third phase is found to be intermediate between the amorphous and crystalline phases. The well-known three relaxation phenomena (α, β, and γ) of polyethylene are discussed in terms of line-width narrowing and mobile fraction increase with elevating temperature. Trans-1, 4-polybutadiene gives rise to an anisotropic large scale motional narrowing at the solid phase transition temperature.

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Elastic moduli of the crystalline regions in the direction perpendicular to the chain axis (E_t) for the γ-form of nylon 6 were determined by an x-ray diffraction method. The moduli observed were as follows:
Nylon 6 (γ-form): (110) ……E_t=6.0×4kg/cmcm² (24±1°C)
(200) ……E_t=11.6×10⁴kg/cmcm² (20±1°C)
According to Bradbury et al., the (200) plane is normal to the hydrogen bond direction and the (110) plane makes an angle of about 30° with its direction, so that it is reasonable that the E_t-value for the (200) Plane is much higher than that for (110) Plane.
The results for α-and γ-forms were compared; the theory of infinitesimal deformation of an orthogonally anisotropic elastic body could be applied to the following relationship between the elastic modulus (E_φ) and the angle (φ) of the normal to the corresponding lattice plane with the hydrogen bond direction.

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The relation between column efficiency and molecular weight of a polymer sample in gel permeation chromatography was studied.
Usually, a column efficiency in the number of theoretical plates per foot is measured from a chromatogram of organic solvents, such as acetone and benzene, This method has a disadvantage that it is unsuitable for estimating undesirable broadening of chromatograms of a high molecular weight sample.
From our experiments with reverse flow technique, the following approximate relation of the height equivalent to the theoretical plate, H, and molecular weight of the sample, M, was obtained.
logH=A+BlogM
In this relation, the information about undesirable broadening of chromatograms in the high molecular weight region in GPC was given.
The reverse flow technique is a useful one in GPC to obtain a column efficiency at high molecular weight region. The application of this technique is also described in this report.

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Sliding tests were carried out on noncrystalline polycarbonate plates by dragging the nickel-coated steel spheres or cones across the surface. The force of friction and the width of the track were measured, and the contributions of the deformation around the groove and the orientation of the molecular chains in the neigbourhood of the groove to the friction resistance were estimated.
In the range of the load R between 0.1 and 200g, it was found that the friction F obeyed the relation of the type, F=αRⁿ, and the cross-sectional area of plowing A obeyed the law, A=βR^m.
Whereas the results for glass surface accorded with the theory of adhesion in plastic contact were n=1, in the same range of load, the results for polycarbonate plates deviated from the theory and the observed values of exponent n and m did not remain constant but varied as follows:
(1) When the spherical pieces of larger radius were slided more quickly (10mm/min) with loads from 0.1 to about 10g at room temperature, the adhesion terms in the elastic contact was effective, that is, n=0.7.
(2) When the spherical pieces of smaller radius were slided either quickly with heavy loads (10 to 200g) or slowly (1mm/min) with light loads (0.1 to 10g), the elastic plowing terms were predominant for the friction force and the exponent n becomes 1. For sharp-edged cone sliders similar results were obtained under light loads (0.1 to 2g) regardless of sliding speeds: that is, n=0.7 in agreemant with the theoretical values. In these cases the friction marks of track were not observed because of elastic recovery of deformation.
(3) When the small spherical pieces were slided at high temperature from 160 to 170°C, the values of n and m increased somewhat with the mechanical losses of visco-elastic hysteresis around groove: that is, n=2.5, m=1.3 at 160°C and n=4, m=1.6 at 170°C. Above 170°C, however, the friction force decreased again by the presence of plastic flow at regions of contact.
(4) When the sharp-edged cones were slided on the polycarbonate plate under the loads from 2 to 200g at room temperature, friction forces were influenced by the orientation of the molecular chains at the boundaries of groove accompanied with plastic deformation. It was found that the value of n increased more than m (=1). The degree of orientation of molecular chains which was related to the amount of displacement in the regions around the groove was estimated from extinction angles under a polarization microscope. While these orientation could not occur when slided quickly (10mm/min) with light loads (under 120g), the orientation increased to the value which would be observed in the deform strain above the yield point, when slided with heavy loads (above 120g) or slided slowly (1mm/min) with the load from 2 to 200g.
In the cases of (3) and (4), the observed values of n were larger than those of m. These results could be explained by the dependencies of yield pressure on the load and speed during plowing the polymers.

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An a-axis orientation mixed with c-axis in polypropylene fiber structure has been observed in the following cases: crystallization under molecular orientation, and annealing at high temperatures in the absence of tension after cold drawing. This study elucidates the latter case, i. e. the structural changes during annealing of cold drawn polypropylene films.
This study involves the application of the following physical techniques: wide angle X-ray diffraction, small angle X-ray diffraction, differential scanning calorimetry and dilatometry. Cold drawn films are mainly used for the experiments. Irradiated cold drawn films and drawn samples treated with fuming nitric acid are also used supplementally.
The results obtained are as follows:
1) Annealing of cold drawn polypropylene films is accompanied with lamella thickening and produces 1-8% fractions of a-axis oriented crystallites.
2) Cold drawn films are treated with fuming nitric acid at 90°C for varing times. The films treated for 5hr whose crystallinity is estimated to be more than 90%, show a-axis orientation when annealed at 134°C for 5 min. This suggests that tie chains or amorphous regions between lamella are not changed into a-axis oriented crystallites by annealing.
3) Annealing of irradiated films after cold drawing produces much more amounts of aaxis oriented crystallites than that observed in annealing cold drawn polypropylene.
4) DSC thermograms of annealed films after cold drawing suggest that high temperature peak is governed by crystallization kinetics, whereas low temperature peak is thermodynamically preferred. Especially in the case that both the double peaks and a-axis orientationare observed, low temperature peak corresponds to the melting peak of a-axis orientedCrystallites.
5) The melting point of a-axis oriented crystallites in annealed cold drawn films varieswith the dose of irradiation.

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The reactions of hydroxymethylated 2-methoxy-4, 6-diamino-s-triazines (MMT) molecules in an acidic aqueous solution were studied kinetically. The average molar number of formaldehyde (F) combined (n) of MMT was 1.49 (Sample I) and 1.53 (Sample II), respectively. The reaction consisted of both the dissociation reaction of methylol groups and the condensation (methylene bond formation) reaction of methylol with amino groups. From the previous paper, however, as the dissociation reaction might be negligibly small compared with the condensation reaction in the initial stage of the reaction, the reaction was carried out in the range where the dissociation reaction might be negligible.
The condensation reaction obeyed the second order reaction untill ca. 12.7% of na (the initial concentration of methylol groups, a: the initial concentration of MMT (mol/l) for Sample I and 11.5% for Sample II had reacted.
The maximum value (k_max) of the rate constant (k) was obtained at [H₃O⁺] =[H₂O) /K₁ (K₁: the equilibrium constant of the reaction between MMT and acid)], and k was proportional to [H₃O⁺] in a certanin range of pH where K₁[H₃O⁺]/[H₂O]<<1 was maintained. In the case of the reaction where na and the concentration of added HCl were constant, k_max and k increased with the increase of “n”. These results were in agreement with those of the previous paper.
The activation energy (E) caluculated for the reaction of Sample II was 17.7kcal/mol, and it was approximately equal to E for the reaction of MMT having “n”=0.889-1.185.

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Alkali hydrolysis of acrolein copolymers in dioxane-methanol-water was studied. Hydrolysis of acrolein-ethyl acrylate and 2-ethyl-hexyl acrylate copolymers can be divided in two stages.
In the first stage, alkali was rapidly consumed and the hydrolysis of the esters neighbouring with one acrolein unit sequence was accelerated. The second stage of the hydrolysis was slow.
It was found from the reaction of acrolein-styrene copolymers with alkali that all of the aldehyde groups in copolymers containing less than 50mol % acrolein undergo the Cannizzaro reaction.

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Polymerization and copolymerization of methyl methacrylate with a PdCl₂·H₂O catalyst system were investigated in methanol and pyridine at 30°C and 50°C. It was found that water is necessary as a co-catalyst in the polymerization. The polymerization was not accelerated by addition of amines, protonic acid and dienes. Addition of butadiene to the polymerization system containing methyl methacrylate caused the formation of polybutadiene of low molecular weight alone and the polymerization of methyl methacrylate was inhibited. The presence of hydroquinone or p-quinone prevented the polymerization of methyl methacrylate. In the copolymerization of methyl methacrylate (m₁) and acrylonitrile (m₂), the monomer-copolymer composition curve was similar to that in a radical copolymerization and the monomer reactivity matios were calculated as r₁=0.25 and r₂=0.23. From the results obtained a radical polymerization mechanism was postulated.

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Polymerization of methyl methacrylate, acrylonitrile and styrene with various metal nitrates were investigated at 100°C in acetone solution. Among the metal nitrates, especially group IIb metal (Zn, Cd, Hg) nitrates showed high catalytic activities for the polymerization of methyl methacrylate. Neither halides nor perchlorate of group IIb metal polymerized methyl methacrylate. It was found from kinetic experiments that the rate was proportional to the square root of the salt concentration. By addition of 1, 1-diphenyl-2-picrylhydrazil (DPPH) the polymerization was inhibited. Monomer-copolymer composition curves from copolymerization of methyl methacrylate with acrylonitrile and with styrene were similar to those of usual radical copolymerizations. From these facts as well as that NO₃ group was found in the poly (methyl methacrylate) obtained with the metal nitrates, a radical propagation mechanism initiated by the reaction between the monomer and the nitrates was proposed.

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In the emulsion polymerization of methyl methacrylate (MMA) initiated by monomer peroxide of MMA in the presence of polymethacrylic acid (PMAA), the behavior of PMAA as an emulsifier was mainly studied in comparison with sodium lauryl sulfate (SLS). The results obtained were as follows. The initial rate of polymerization depended on the concentration of PMAA to the 0.4 power. Moreover, the rate of polymerization decreased at about 30% conversion, at which the monomer droplets disappeared. At the same time, many small particles (100-500A) were formed and the number of particles increased. These facts led to the same results as with SLS, wheras PMAA solubilized monomer to water (0.03-0.08%) and stabilized the emulsion particles. The particle sige distribution of emulsion in the presence of PMAA was rather broader than the emulsion with SLS.
From these results, it is most reasonable to conclude that the behavior of PMAA as an emulsifier is almost the same as SLS, excepting that the ability of stabilization of emulsion particles is slightly inferior to SLS, and that the mechanism of polymerization is almost the same as SLS.

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The deterioration of the mechanical properties of polyhexamethyleneadipamide fibers was studied and its relation to their DTA curves, UV spectra, oxygen absorption and the change of their molecular weights was investigated.
It was found that the height of exothermic peak of DTA curves around 240°C showed a good correlation with the maintenance of tensile strength of the fibers and the optical density at 290mμ in 60% sulfuric acid showed the same correlation.
These experimental results suggest that DTA and UV spectra are suitable methods for the determination of the extent of the degradation of polyamide fibers on thermal oxidation, especially suitable for the estimation of the effects of stabllizers in polyamide fibers.

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