Turbidities of suspensions produced by adding precipitant to common solvent solution of two polymers were measured and the difference in the precipitation behavior due to the miscibility of polymeric components was elucidated. Polymers used in combination are polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), nitrocellulose (NC), cellulese butylate (CB), polyvinyl chloride (PVC) and nitrile rubber (NR). Precipitation behavior of a component of non-miscible polymers (PMMA-PMA and PMMA-CB) is not so much affected by the presence of the other one; that is, two compcnents precipitate rather independently. On the other hand, in the case of miscible polymers (PMMA-NC, PMA-NC and PVC-NR), they precipitate simultaneously, and moreover, for PMMA-NC and PMA-NC systems, they precipitate by addition of smaller quantity of precipitant than for each component. These behaviors suggest the presence of strong interaction between NC and PMA or NC and PMMA.

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The rate of crystallization of nylon 6 polymer in bulk form was measured at various temperatures with several kinds of the specimens of different molecular weight (2.6×10³ to 19×10⁴) by applying the method of determining the intensity of depolarized light, proposed by the authors in the preceding papers. The Avrami's constant n was found to be always 4 except the initial stage of crystallization of the polymer specimen with low molecular weight at higher temperatures, where the value of n was nearly 6 indicating homogeneous nucleation which would lead to sheaf-like crystal growth.
The crystallization rate 1/t_1/2 is expressed by the intrinsic viscosity [η], and the crystallization temperature T by the following equation,
where, n=4: Avrami's constant, E_D([η])=E_vis([η])/ρ([η]): activation energy for the transport of material across the liquid-crystal interface (cal/mol), E_vis ([η])=4.12×10³ T²/{51.6+T-T_g([η])}²: activation energy for viscous flow (cal/mol), T_g([η])=581.6-1076/(1.81[η]+13.45)^0.5: glass transition point (°K), ρ([η])=20.2-8.3[η]: ratio of E_vis to E_D, C₃([η])=1/(0.309-0.206[η])-8.5 and C₄([η])=10⁵/(0.82-0.52[η])+2.5×10⁵: constants independent of T, T_m([η]): melting point (°K). 1/T_m([η])=1/504+6.125×10^-6/[η]^1.435.
Temperature T_max at which the crystallization rate becomes maximum, the value of E_D, ρ. activation entropy, included in C₃ for crystallization interfacial free energy and the size of critical nuclei derived from C₄ are all dependent on the molecular weight of polymer.

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For the purpose of introducing reactive groups to nylon 6 fiber, a commercial nylon 6 fiber was hydroxymethylated with formaldehyde in water or methanol using hydrochloric acid or phosphoric acid as catalyst. The reaction products may contain methoxymethyl groups in the case of methanol medium. In this study, the degree of hydroxymethylation %(HM), including methoxy groups, was calculated from the total bound formaldehyde. The physical properties and the reactivity in heating the products were also studied.
The yield (percentage of the weight of the product to the original weight of fiber) generally decreased with the increase of HM. At the same HM, the yield decreased with the decrease of pH value of the reaction medium. The reaction condition to obtain the highest yield with the highest substitution was found at pH 0.9, 60°C, phosphoric acid catalyst, methanol medium, and reaction time of 3 hours where HM was 59% and the yield was 90%. The products having more than 40%HM began to adhere together, so that the shape of the fiber did not keep the original. Beyond about 20%HM, tensile strength and elongation of the fiber changed extremely. When the products were heated, the contents of total HCHO and of methoxymethylated type HCHO considerably decreased, and then it was suggested that hydroxymethylated nylon 6 fiber had heat reactive property.

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For the purpose of production of plastics having some strength properties of stretched fiber, hydroxymethylated nylon 6 fibers were pressed in a heated mold. The fibers were self bonded together due to the reactivity previously reported. The product was designated “Nylon 6 Fiber Plastics”.“Nylon 6 Fiber Plastics” sheet, which was made by molding 30% hydroxymethylated nylon 6 fibers under the pressure of 50kg/cm² at 145°C for 3min., had apparent specific gravity of 1.05. tensile strength of 3kg/mm², elongation at break of 70%, tear resistance of 4.5kg/mm², water absorption of 15%, Young's modulus of 15kg/mm² and abrasion loss (Taber method) of about 20mg/1000 rev. This sheet also had some moisture permeability. It is considered that its internal structure is microscopically porous. The high impact strength is also useful. Thus, “Nylon 6 Fiber Plastics” sheet has a possibility of being utilized as a substitute of leather.

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Polyacylthiosemicarbazides and polybithioureas of high molecular weight have been prepared readily by the polyaddition reaction of aromatic diisothiocyanates with dihydrazides and hydrazine in dimethyl sulfoxide, respectively. Transparent and tough films could be cast from dimethyl sulfoxide solution of polyacylthiosemicarbazides. The melting points of polyacylthiosemicarbazides and polybithioureas were lower than those of the corresponding oxygen-containing analogues, polyacylsemicarbazides and polybiureas. Those polymers were unstable abcve 100°C.

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Several organic peroxides were investigated as the initiator of the homegeneous polymerization of acrylonitrile in dimethylsulfoxide, and aliphatic diacyl peroxides and peroxyesters were found to be effective at 50deg;C. Among them, tert-butylperoxypivalate was the most favorable initiator and the kinetics of polymerization by this initiator was studied. The observed dependence of the rate and the degree of polymerization on the polymerization conditions can be explained consistently by assuming a kinetic scheme which involves the reactions of relatively unreactive radicals derived from the solvent by chain transfer.
Initiator efficiency is 35-40% which is rather low.

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It was previously found that methyl methacrylate (MMA) polymerized without initiator and emulsifier in aqueous media and the rate of polymerization of MMA was accelerated by addition of polymethacrylic acid (PMAA). In this paper, the mechanisms of initiation of polymerization and of acceleration effect of PMAA on the polymerization were studied. The results obtained were as follows. The polymerization was initiated by monomer peroxide formed by the reaction of monomer with oxygen during induction period. The acceleration of initial rate of polymerization by addition of PMAA was independent of the concentration of PMAA in the concentration range of the experiment. The rate of polymerization increased with increasing concentration of monomer and then decreased through a maximum. The addition of PMAA increased solubility of MMA in water and consequently stable emulsion was obtained. This emulsion was o/w type in the high concentration of PMAA and was w/o type in the low concentration.
From these results, it is most reasonable to conclude that the polymerization of MMA is initiated by monomer peroxide and that the increase of the polymerization rate in case of addition of PMAA is due to the consequence of adsorption of MMA on to PMAA in water phase, probably resulting in the formation of a particle.

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