Several polymers are known to be miscible in blending. However, blending system of polyvinyl nitrate (PVONO₂) and completely acetylated polyvinyl alcohol (PVAc) has not yet been investigated.
The character of dynamic behaviour and the microscopic observation of the blended polymer lead to the assumption that these polymers are miscible with each other. Various kinds of partly to almost completely acetylated polyvinyl alcohols were blended with PVONO₂. All of the samples were obtained by evaporating solvent from mixed solution contained each polymer in 1: 1 weight ratio.
The effect of acetyl group on the miscibility was studied. Densities, refractive indices, glass transition temperatures, IR spectra, temperature at which the dynamic loss becomes maximum, X-ray diffractions were determined together with the observation under a phase-contrast microscope, which are characteristic to physical properties of these samples.
From above results, it is found that more than 75 wt% acetylated polyvinyl alcohol is miscible with PVONO₂.

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Isothermal crystallization of isotactic polypropylene (fractions with a range of viscosityaverage molecular weight 1.4×10⁴-1.52×10⁶) was investigated in the temperature range from 115 to 135°C by differential scanning calorimetry (DSC) and the results obtained were compared with those from dilatometry and those from the measurements on the radial growth rate of spherulite which were applied on the same specimen. The comclusions are summerized as follows:
1) The parameter n which appears in Avrami equation θ=exp.(-κtⁿ)(where, θ: uncrystallized fraction, κ: rate constant, t: crystallization time) was found to be 3.0±0.5irrespective of the methods of analysis and the methods of measurements (DSC and dilatometry), and independent of molecular weight and temperature.
2) The dependence of half timet_1/2on the molecular weight can qualitatively be interpretted in terms of molecular weight dependence of radial growth rate of spherulite. Comparing at the same degree of under-cooling, the crystallization velosity decreased with increase in molecular weight. The same crystallization isotherms were obtained by both DSC and dilatometry, if Mυ≤3.2×10⁵.
3) At the initial stage of crystallization (θ≥0.8), rise in melting temperature (ca. 1°C) was observed, but after the completion of primary crystalization the melting point was almost constant.

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As shown by the previous paper, it was possible to introduce the ionic crosslinking into isotactic polypropylene by Kneading it with maleic anhydride in molten state. But, inthis case, it was not able to avoid deterioration of the polymer. In order to prevent that, we tried to carry out the reaction between isotactic polypropylene and maleic anhydridein solvent. The results were as follows:
1) The reaction between isotactic polypropylene and maleic anhydride homogeneouslyoccurred in xylene at 120°C, using benzoyl peroxide as the initiator.
2) The deterioration of the polymer was scarcely found.
3) Ionic crosslinking could be introduced in the mixed solvent of toluene and dimethylformamide, using zinc acetate as the ionic crosslinking agent.

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Poly (vinyl alcohol)(PVA) was dissolved in water and formalized in different concentrations of formaldehyde and hydrochloric acid. The formalized PVA were acetylated.The molecular weights of the acetylated specimens were measueed by osmometry. Theobserved molecular weight was compared with the calculated value as linear polymer andit was found that the content of the crosslink in formalized PVA increased with increasingconcentration of formaldehyde and hydrochloric acid.
It is known that the content of trioxymethylene glycol in aqueous solution of formaldehydeincreaseswith increasing concentration of formaldehyde and carbonium ion producedfrom the glycol increases with increasing concentration of an acid. We think thereforethat the content of the crosslink by trioxymethylene glycol is higher than that by formaldehyde.

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The elementary reactions of isoprene polymerization initiated with n-butyllithium have been studied in n-heptane solution in order to obtain an access to a control of molecularweight distribution of the polyisoprene.
The absence of any termination and chain transfer reaction was confirmed by measuringthe concentration of Li attached to the polymer end (polymer-end-Li) and the molecularweights. The polymer-end-Li formation reaction was found to be first order with respect to the non-associated n-butyllithium, but not to the monomer concentration. It wasfound that the rate of polymerization increases with the polymer-end-Li concentration anddecreases with the initial n-butyllithium concentration, indicating reduction of the concentrationof active polymer end due to association with n-butyllithium. The rate of propagationin the polymerization where isolated low molecular weight polyisoprenyllithium is used asan initiator was found to be first order with respect to the monomer concentration, and asixfold association of the polymer-end-Li was inferred by a formula derived from therelation between the propagation rate and the polymer-end-Li concentration.
In conclusion, the elementary reactions of the n-butyllithium initiated polymerizationof isoprene are thought to consist of initiations through complex reactions between n-butyllithiumand isoprene, a propagation by non-associated polymer-end-Li, and three types ofassociation of n-butyllithium and polymer-end-Li, namely, two self-associations and across-association.

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It has been found in previous papers that vinyloxytrimethylsilane (VOSi) showed a polymerization behavior similar to vinyl ether. In the present paper, a detailed comparisonof reactivity in radical copolymerization between VOSi and vinyl isobutyl ether (VIBE) has been undertaken. Their copolymerization with acrylonitrile, methacrylonitrile, vinyl acetate, and methyl methacrylate gave monomer reactivity ratios, which showed noappreciable difference between the two monomers. The following Q and e values wereobtained,
VOSi: Q=0.018, e=-2.39, VIBE: Q=0.019, e=-2.11The inductive effect of the trimethylsilyl group is electron-releasing. This effect is consideredto be compensated with an electron-attractive effect of Si→O partial double bond, resulting in no appreciable difference in reactivity from vinyl ether.

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