It is the purpose of this work to investigate the phenomena of gelation point and the mechanism of polymerization reaction of three dimensional polyester resins. Three kinds of resin consisting of trimethylolpropane and 3, 6 endomethylene-1, 2, 3, 6 tetrahydro-cis-phthalic anhydride were hardened at different temperatures. The hardening reaction of resins composed of equivalent, of excessive carboxylic and of excessive hydroxylic functional groups was studied kinetically by analyzing the decrease of solubility of the reaction product for such solvents as acetone, chloroform, n-butanol, ethanol and benzene. Rate constants and activation energies of the insolubilization were determined. At the same time, the relationship between the extent of reaction of soluble fraction and the yield of insoluble fraction was obtained, and properties of soluble resins were studied well. On the gelation point, it was pointed out that the extent of reaction was considerable larger value than the theoretical one, and a side reaction was observed to occur at this point.
The hardening of the resin composed of excessive hydroxylic functional groups was extremely different from that of resins which were composed of equivalent and of excessive carboxylic functional groups. That is to say, the resin being insoluble once after gelation, became soluble, and the extent of reaction of soluble fraction in all solvents was almost constant having no relation with reaction time, temperature and solubility. It was estimated that this soluble fraction was made up of the original molecule of the reaction and its annular molecule, and they were kept in an equilibrium relation each other.

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Fractions from several types of commercial polypropylene (boiling n-heptane insolubles 98.5%) and from their ether-solubles were used for the solution viscosity measurements with a modified Ubelohde type viscometer under the nitrogen atmosphere. For various solvents (decalin, tetralin, α-chloronaphthalene, p-xylene, diphenylether, i-amylacetate) Huggins' equation ηsp/c= [η] +k'[η] ²c (where, ηsp/c, reduced viscosity, [η], intrinsic viscosity, k', Huggins'constant) was consistently applicable, and k' showed a minimum for some molecular weight which depends on the polymer types. The following Mark-Houwink equations [η] =KmM^a (where, Km and a are constants) were determined on the basis of Chiang's equation for decalin at 135°C, [η] =1.10×10-4 Mw^0.80;[η] =9.90×10-4 Mv^0.584 for phenylether at 145.2°C, [η] =7.60×10-5 Mv^0.806 for p-xylene at 120°C, [η] =7.46×10-5 Mv^0.817 for tetralin at 130°C, [η] =1.20×10-4 Mv^0.745 for α-chloronaphthalene at 139.2°. The relations, d [η]/dT>0 for isotactic polypropylene-decalin system and d [η]/dT<0 for atactic polypropylene-decalin system were observed. Since the rigidity of the polymer chain of the former is considered to be larger (or, at least, not smaller) than that of the latter, the great difference of the dependency of temperature of [η] must be explained mainly as due to the difference of thermodynamic parameters according to Kamide-Ohno-Kawai's treatment (Chem. High Polymer, Japan, 20, 151 (1963)). Flory's constant K=1.66×10^-3 (34°C) and 1.29×10^-3 (153.3°C) were evaluated for atactic polypropylene respectively. Plots of -log K_m+ (3/2) log [1+ (4/3){(a-0.5) ^-1-2} ^-1] vs. a-0.5 appearing in Kamide-Kawai treatmet (Chem. High Polymer, Japan, in press), using the Mark-Houwink equations obtained above, showed that Flory constant K=1.39×10^-3 (120-140°C) for isotactic polymer and the draining effect could be ignored if Kurata-Stockmayer-Roig's theory are adopted, the flexibility parameter of the polymer chain only slightly changed with tacticity, but the thermodynamic properties were remarkably differed from each other.

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In order to investigate the effect of the change of the molecular structures in the masticated rubber on crystallinity, crystallinities of the frozen rubbers were measured by X-ray gaiger counter method. From the result, it was found that crystallinity decreased with the increase of the mastication time; the effects of the increase of molecular chain ends and the bulky structures involving oxygen molecule are assumed as the cause of the interference with crystallization

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Infrared and density measurements were made on unoriented and uniaxially oriented polyethylene terephthalate films after heat setting under various conditions.
Each sample was subjected to dry-heating or steam setting for half an hour at temperatures ranging from 60°C to 220°C.
The relationship between the degree of crystallinity (α) and optical densities (D) at 972, 845 and 794cm^-1 is as follows:_??_or_??_
α increases monotonously with temperature in the range 120°C to 200°C. In the case of dry-heat setting, minimum crystallization temperature for unoriented samples lies between 100°C and 120°C, while in steam setting this temperature is lowered to 80-100°C.
The difference in crystallinity between dry-heat and steam set samples increases with setting temperature.
For uniaxially oriented samples the following equation holds between dry-heat and steam setting temperatures which produce the same order of crystallinity;
T_d=1.16T_w-6.8 (80°C≤T_w≤180°C), where T_d and T_w are the dry-heat and the steam setting temperatures, respectively.
These phenomena suggest that on steam setting the interaction between polymer molecules in the amorphous region is weakened by penetration of water, and the thermal crystallization is thereby accelerated.

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The well-known phenomenon that the thickness of single crystal of high polymer increases upon heat treating can be explained on the basis of the concepts of the partial melting and the nucleation for thickening process.
If the elemental process for melting is assumed to be the unfolding of unit sequence in single crystal, the crystallinity near the melting point α(T) is given by the equation;α(T)=(Δh₀s₀L/kT_m⁰T) ΔT. The thickening rate is considered to be proportional to the number of thickening nuclei and the density of sequences at melting state, and is represented by dL/dt=Ae^-BL, B=(1/kT)(Δh₀s₀ΔT/T_m⁰+d₀σ_s²/2σ_e). Here L is the thickness of single crystal, Δh₀ the heat of fusion for unit volume of the polymer, σ_s and σ_e the surface free energies for unit area of upper and lateral surfaces of the lamellar single crystal, respectively, d₀ and s₀ the diameter and the cross sectional area of the polymer chain, T_m⁰ the equilibrium melting temperature and ΔT=T_m⁰-T.

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Polyvinylalcohol (PVA) has not yet been obtained in the form of single crystal or spherulite, in spite of its excellent crystallinity in fiber form. The authors succeeded in obtainning PVA single crystals from triethyleneglycol, 1, 3-butanediol and 1, 2-propanediol solutions. The single crystals of PVA obtained from triethyleneglycol solution take the form of parallelogramic platelet where the ratio of the length to the width is about 6. Smaller single crystals with the similar shape were obtained from 1, 3-butanediol and 1, 2-propanediol solutions. The lamella thickness of these single crystals is reasonably constant and is about 120 Å. The spacings and the intensities of the reflections due to a selected-area electron diffraction of a PVA single crystal nearly correspond to those of (h0l) planes reflections which appear in the X-ray fiber diagram. Thus, PVA chain molecules in a single crystal have also the folding structure in which the chain axes orient normal to the lamella. The correlation of the electron micrograph and the electron diffraction pattern shows that the longer side of the parallelogramic crystal corresponds to the (101) plane and the shorter side to the (100) plane. PVA single crystal aggregate were exfoliated in flakes. The X-ray study parallel to the film surface was made. The low angle X-ray diffraction of the film gives the long period of lamella thickness of a single crystal, and the wide angle X-ray diffraction gives a fiber like pattern corresponding to the single crystal orientation where the chain axes orient normal to the film surface.

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