Flow and heat transfer characteristics of an epoxy molding compound were analyzed for low pressure transfer molding in circular channels and in a semicircular channel of the EMMI spiral flow mold. A molding apparatus having transducers for detecting material pressure and plunger displacement was used for the determination of apparent mean viscosity during material flowing. For the calculation of transient temperatures of the material in each channel, equations describing unsteady heat conduction in the cross section perpendicular to the axial direction were solved numerically. In the circular channels having equivalent cross-sectional areas to those of runners used for manufacturing, viscosity was shown to decrease with time due to delayed material temperature rise. In the semicircular channel of the EMMI mold having very small cross-sectional area, minimum viscosity was observed in a few seconds from the flow start and was shown to increase during most of the flowing time due to rapid material temperature rise.

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Hydroxymethylation of melamine with formaldehyde was kinetically investigated in aqueous sodium hydrogencarbonate-sodium carbonate buffers in the range of pH 8.89 ([HCO^-₃] / [CO^2-₃] =7.0) -10.57 ([HCO^-₃] / [CO^2-₃] =1/7) at 20°C. The unreacted melamine was determined by means of high pressure liquid chromatography with an ultraviolet spectrophotometer, and the rate equation and constants were obtained. The rate constants for sodium hydroxide catalyst and those without additional catalyst were also estimated. By the use of the rate constants of the general-base catalyzed reaction thus obtained, Brönsted plot was established, and the reaction mechanisms were postulated.

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The solvent effect of dimethyl sulfoxide (DMSO) on the condensation (formation of the methylene linkage) rate of trimethylolmelamine (M3F) was investigated at [HCl] ₀/ [M3F] ₀= 1/2 (i. e., half-neutralization point of M3F) in aqueous DMSO media where the mole fractions of DMSO were 0.10, 0.20, 0.28, 0.37, 0.43, 0.50, 0.59, 0.70, and 0.83. The initial rate of the condensation reached a minimum at ca. 0.5 mole fraction of DMSO, and the result was interpreted in terms of salvation. It was also discussed on the basis of the thermodynamic aspect, and the relationship between activation parameters and the mole fraction of DMSO was made clear.

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Effects of synergetic combination of polyacrylates and zinc stearate/calcium stearate soap on the thermal stabilization of poly (vinyl chloride) (PVC) were investigated by colorimetry. Poly (sodium acrylate), poly (methyl acrylate), and poly (ethyl acrylate), and partially saponified poly (methyl acrylate) and poly (methyl methacrylate) markedly enhanced the thermal stabilization of PVC containing zinc stearate/calciu stearate soap, while poly (acrylic acid), poly (butyl acrylate), poly (2-ethylhexyl acrylate), and poly (methyl methacrylate) did not exhibit measurable enhancement of the stabilization of PVC. The synergism of polyacrylates with the synergetic metal soap was enhanced with decreasing number of carbons in the side chains, and this was due to good compatibility of the polyacrylates having shorter side chains with PVC. X-Ray photoelectron spectroscopy on the polyacrylates-metal soap-PVC mixture indicated that the polyacrylates, which were effective as co-stabilizer, formed Zn-O linkages with zinc chloride. Moreover, the alkyl chlorides were detected in the pyrolysis product of the polyacrylates and zinc chloride mixtures. The synergetic effects between the polyacrylates and the metal soap were ascribed to the capture of the exessive zinc chloride by these macromolecular co-stabilizers.

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The rheological properties under steady shear flow were examined for polyethylene melts filled with one of three metal fibers (two aluminum fibers of different fiber length and a 6-4 brass fiber) or one carbon fiber. For these four kinds of melts, shear stress and viscosity increased with the increase of fiber content and aspect ratio; large changes were found at lower shear rate. Similarly, relative viscosity and yield stress also increased, but the relative viscosity decreased with the increase of shear stress. An empirical equation of the relative viscosity considering fiber volume fraction and average aspect ratio was discussed. The first normal stress difference of the metal fiber dispersed systems became slightly larger than that of polyethylene matrix at a constant shear rate, while the effect of fiber content was extremely small. That of the carbon fiber system, however, increased with the increase of fiber content.

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Cold-cured resins containing a styrene popcorn polymer (PCP) having porous structure were prepared and theproperties as a dental filling composite resin are examined. The mixture paste containing approximately 11wt% ofmethyl methacrylate (MMA), 63wt% of 2, 2-bis [4′- (3-methacryloxy-2-hydroxypropoxy) phenyl] - propane (bis-GMA), and 26wt% of a PCP powder in a size of about 50 to 70μm, was allowed to polymerize with the benzoyl peroxide/N, N-dimethyl-p-toluidine initiator system. The resulting milk-white producthad porous structure and a tensile strength ofapproximately 180kg/cm² and a water sorption of 5.9mg/cm². When the polymerization of MMA was carried out byuse of the styrene PCP. as a seed, a PCP of MMA resulted. The porous structure of the cured resin is probably due tothe seed activity of the styrene PCP and was responsible for failing to improve the physical properties for dental use. However, the incorporated PCP had protractive effect on the release of an antibacterial drug such as chlorohexidineacetate from the cured resin into water.

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The impact behavior of blunt- and sharp-notched specimens of polypropylene (PP), polycarbonate (PC), polysty-rene (PS), polyethylene (PE), poly (methyl methacrylate) (PMMA), propylene-ethylene block copolymer (PPB), andABS plates has been studied using an instrumented Charpy impact tester. The load-time or -deflection curves ofblunt-notched specimens have some oscillational load peaks before finalfracture, which does not alyways occur at amaximum load value. The fracture origin for these specimens is located at the tip or within the plastic deformation zonewhich is formed at the notch root except for PS. The energy required for impact fracture corresponds well to themaximum elastic deflection energy of the specimen. The fracture of sharp-cracked specimens is always initiated at thecrack tip with a smaller deflection. A fracture mechanics approach can be applied to the sharp-notched specimens in thatthe critical energy release rate decreases with decreasing temperature.

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¹³C NMR spectra of bulk polyurethane samples are reported. Polyurethanes are block copolymers composed ofhard and soft segments which often undergo microphase separation with the resultant formation of hard and softdomains. The hard domain component can be observed selectively by using high-power proton decoupling, crosspolarization and magic angle spinning (MAS). The soft domain component can be observed selectively by usinglow-power proton decoupling and MAS. The ¹³C NMR results show that one polyurethane sample has hard domainswhich are composed of hard segments, but the other sample does not have any hard domains. To confirm the ¹³C NMRresults, the morphology and properties of these samples were investigated by DSC, dynamic mechanical properties, stress-strain properties, pulsed NMR, WAXS, polarizing microscopy and TEM. All these results are consistent with the ¹³C NMR results. This solid state ¹³C NMR technique has the advantage that it can be easily applied to the study ofpolymer structure and motion in the solid state.

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Ultra-high molecular weight polyethylene (UHMWPE) was drawn at 120°C and cooled to room temperature. Thesamples were annealed at various temperatures above the melting point at constant length. The superstructure whichappeared when samples were cooled from the melt state was studied by small- and wide-angle X-ray analyses. Thesample which had the highest molecular weight showed the strongest memory of structure even when it was kept in themelted state for a long time. But the samples with lower molecular weights did not show the memory so much. Ingeneral, the higher the temperature, the longer the treating time, and the lower the molecular weight of sample, the lessthe memory of structure was. The memory thus depended on the molecular weight of the samples. This memory couldbe attributed to the degree of entanglements in the amorphous molecular chains and to the tie molecules between fibrilsformed in the sample before annealing. On the other hand, the superstructure of samples cooled after being redrawn atthe melt state at high temperatures strongly depended on the drawing temperature. The memory of structure, in thiscase, was considered to be due mainly to the degree of disentanglement of chains caused by drawing at hightemperatures.

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Microwave absorption of mixed solutions of: 1) the hydrogen bonding solvents (methanol, ethanol, propanol, butanol. amyl alcohol, and octyl alcohol) and each of a number of hexane, carbon tetrachloride, benzene, and methanol; and 2) aproti polar solvents (nitromethane, acetonitrile, nitrobenzene, and dimethyl sulfoxide) and polar or nonpolarsolvents was measured at 9.3 GHz in a waveguide. At the same time, the magnitude of microwave decayed energy byvarious solvents in polymer films at 9.3 GHz was estimated. The sample film containing the solvent was placed in awaveguide, and the ratio of the amount of energy transmitted by the sample film to the amount incident was determined. The microwave absorption (A) was represented by the following equation: A= KCV, where C is the amount of solventin the polymer film, V is a volume of the sample film swollen by the solvent, and K is the microwave absorption constantof the solvent in the polymer. From plots of log (K/K₀) against the solubility parameter of various solvents impregnatedwith the polymer film, we estimated the solubility parameter of various polymers: polystyrene, poly (butadiene), poly- (vinyl alcohol), and nylon-6, 6. Here, K₀ is the constant of the solvent in cuprophane film. The results suggest that themicrowave absorption is dependent on a hydrogen bonding or a dipole-dipole interaction between the polymer andsolvent.

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The effect of chemical structure on the amount of microwave absorption of water in various polymer films at 9.3 GHz was studied. The sample film, which was impregnated with a small amount of water, was placed in a waveguide, and the ratio of the amount of energy transmitted by the sample film to the amount incident was determined. This ratio was defined as the microwave absorption. The microwave absorption was directly proportional to both the volume increase of the sample film due to the water and the amount of water in the polymer. The microwave absorption constant of water in cellulose acetate films having either a hydrophilic or a hydrophobic nature showed the minimum value. The microwave absorptions of systems comprising water dissolved in twenty-one kinds of organic compounds having complete miscibility with water were also measured. The results indicate that the absorption constant decreases when water molecules strongly orient and/or fix the polymer matrix.

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Polyelectrolytes containing imidazolyl groups, which are soluble in water, have been prepared by treating chloromethylated polystyrene first with triethylamine to convert a part of chloromethyl groups to quaternary ammonium groups and then with histamine or histidine. Hydrolyses of several phenyl esters in the presence of the polyelectrolytes were much faster than those in the presence of small molecules containing an imidazolyl group such as histamine, histidine, or imidazole. The hydrolyses catalyzed by the polyelectrolytes coformed to Michaelis-Menten kinetics, except for the case of 3-acetoxy-N, N, N-trimethylanilinium iodide. The higher rate in the presence of the polyelectrolytes was due to the lowering of free energy by the formation of associated complexes between the polyelectrolytes and the substrate. The driving force of the complex formation was substantially hydrophobic interaction; however, hydrogen bonding and electrostatic attraction are suggested in some cases.

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Poly (oxytetramethylene) -aramid block copolymers 5 having inherent viscosities of 0.2-0.5dl/g were prepared by the direct polycondensation reaction using triphenyl phosphite and pyridine as condensing reagents from amine-terminated poly (oxytetramethylene) 4 and carboxyl-terminated aromatic polyamides (aramids) 3, which were prepared directly from 3, 4′-oxydianiline and a calculated excess of isophthalic acid. Block copolymers 5 were soluble in amide type solvents that were good solvents for aramids. Thermogravimetry curves of the polymers indicated that 5 decomposed in two steps, and the decomposition curves were between, those of 3 and 4.

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Wholly aromatic polyamide-imide fibers and in-plane isotropic films were made from N, N′-bis (2-chloro-4-aminophenyl) terephthalamide and pyromellitic dianhydride. The N-methylpyrrolidone solution of its precursor, poly (amic-acid), was wet-spun into fibers, which were then imidized chemically or thermally. The chemically imidized fiber had tenacity: 12.2 g/d and initial modulus (M₁): 1340 g/d. The fiber identity period of the polymer was estimated to be ca. 25.9Å from X-ray diffraction data. This value corresponds roughly to the length of the repeating unit. Films were prepared by casting. M₁ of the most stiff film reached 2530 kg/mm².

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