Effect of Interfacial Free Energy on the Heterogeneous Distribution of Oxidized Carbon Black in Polymer BlendsAsai, Shigeo; Sakata, Kazuya; Sumita, Masao; Miyasaka, Keizo
doi: 10.1295/polymj.24.415pmid: N/A
The effect of oxidation of carbon black (CB) on the heterogeneous distribution in polymer blends was examined. In three kinds of polymer blends, i.e., high density polyethylene (HDPE)/isotactic polypropylene (PP), PP/atactic poly(methyl methacrylate) (PMMA), and HDPE/PMMA, the heterogeneous distribution of CB and oxidized CB were observed. The heterogeneous distribution of fillers in a polymer blend matrix was mainly due to the difference in affinity of CB particles to each component of the polymer blend. In HDPE/PP blend, the dispersion state of oxidized CB was different from that of unoxidized CB. The dispersion states of the fillers in these samples were predicted qualitatively from the values of the wetting coefficient which were calculated from the interfacial free energies, and they were coincident with the observations by scanning (SEM) and transmission (TEM) electron microscopies.
High Pressure Differential Thermal Analysis of n-PerfluoroalkanesTsubakihara, Shinsuke; Yasuniwa, Munehisa
doi: 10.1295/polymj.24.421pmid: N/A
Phase transitions of polytetrafluoroethylene (PTFE) oligomers (n-perfluoroalkanes), C20F42, C24F50, and a polydispersed sample of n-perfluoroalkanes (molecular weight, MW=ca. 5000–20000), denoted by L-PTFE, were studied at atmospheric pressure by differential scanning calorimetry and under high pressure up to 600 MPa by high pressure differential thermal analysis. Their phase diagrams were determined. The phase diagram of C20F42 is quite different from that of PTFE. Below about 300 MPa, a sequence of crystal-crystal transitions denoted by Tr1 and Tr2 occurs in the isobaric heating process. In the pressure region between 300 and 400 MPa, there are two cases of crystal-crystal transitions, one case in which a pair of Tr3 and Tr4 occurs and the other case in which only Tr5 occurs. Above about 400 MPa, only Tr3 and Tr4 occur. The transition line of Tr4 has a terminal point at about 300 MPa. The phase diagram of C24F50 is also similar to that of C20F42. On the other hand, the phase diagram of L-PTFE is different from these and identical to that of PTFE.
Thermal Properties and Orientational Behavior of Nematic Comb-Like PolyetherUjiie, Seiji; Iimura, Kazuyoshi
doi: 10.1295/polymj.24.427pmid: N/A
The liquid-crystalline comb-like polyether (PECB) was synthesized by reactions of 4-cyanobiphenyl mesogenic moieties with chloromethyl pendant groups in the repeating unit of polyepichlorohydrin. PECB exhibited an enantiotropically nematic phase. Isotropization temperatures and isotropization entropies in PECBs increased with increasing molecular weight. PECB was spinable from its nematic or isotropic melt. In the stretched sample, mesogenic pendant groups were aligned perpendicular to the stretching direction. The orientational behavior was characterized by X-ray technique, IR dichroic measurement and orthoscopic observation.
Synthesis of Electrical Conductive Polypyrrole Films by Interphase Oxidative Polymerization—Effects of Polymerization Temperature and Oxidizing AgentsNakata, Masakazu; Taga, Megumi; Kise, Hideo
doi: 10.1295/polymj.24.437pmid: N/A
Polypyrrole (PPy) films were synthesized by interphase polymerization reactions between aqueous solutions of oxidizer and organic solutions of pyrrole monomer. It was found that the conductivity and morphology of PPy films strongly depend on the diffusivity of pyrrole monomer into aqueous phase. It seems that polymerization should be carried out at lower temperatures in order to obtain homogeneous PPy films with high electrical conductivities. When PPy films were prepared with iron(III) chloride as an oxidant and toluene as an organic solvent, the conductivity increased from 2.7 to 9.7 S cm−1 and film thickness decreased largely by changing reaction temperature from 10 to −5°C. The conductivity of PPy films was also dependent on the nature of oxidizing agent. The conductivities of PPy films obtained with iron compounds as oxidizing agents decreased in the order; perchlorate, chloride>nitrate>sulfate. The result may be attributed to the difference in extent of doping by counter anions. The maximum conductivity of PPy film prepared with iron(III) perchlorate was 32.6 S cm−1.
Sorption, Dilation, and Isothermal Glass Transition of Poly(ethyl methacrylate)-Organic Gas SystemsKamiya, Yoshinori; Bourbon, Dominique; Mizoguchi, Keishin; Naito, Yasutoshi
doi: 10.1295/polymj.24.443pmid: N/A
Sorption of ethylene, ethane, and propane into poly(ethyl methacrylate) and the concomitant dilation of the polymer are measured at 15°C. Each sorption isotherm has a reverse-sigmoid shape described by the extended dual-mode sorption model, and dilation isotherms are similar in shape to the corresponding sorption isotherms. Inflection on the isotherms is due to isothermal glass transition induced by the sorbed gases, whose concentration is the glass transition concentration C
g. The C
g value for propane is in accord with concentration at an abrupt change found on a curve of the concentration dependence of diffusivity. Partial molar volumes of the gases at rubbery state and glassy state are evaluated from sorptive dilation data above and below C
g, respectively. A correlation between plasticizing ability and partial molar volume for the gases is discussed.
Gas Permeability and Permselectivity of Polyimides Prepared from 4,4′-DiaminotriphenylamineOkamoto, Ken-ichi; Tanaka, Kazuhiro; Kita, Hidetoshi; Ishida, Mina; Kakimoto, Masaaki; Imai, Yoshio
doi: 10.1295/polymj.24.451pmid: N/A
Polyimides prepared from 4,4′-diaminotriphenylamine (DATPA) had fairly large fraction of free space V
F among unfluorinated polyimides because of hindrance effect of phenyl side-groups on packing of the polymer chains. Due to the fairly large V
F, they displayed fairly high gas permeability. For H2/CH4 and CO2/CH4 systems, they had lower permselectivity as compared with the other polyimides having the similar permeability coefficients for a higher permeable gas, because of lower diffusivity selectivity attributed probably to rotational motion of phenyl side-groups. On the other hand, for CO2/N2 and O2/N2 systems, they had moderate levels of the permselectivity, because rotational motion of phenyl side-groups affected slightly on the diffusivity selectivity of these gas pairs with very small differences in the effective molecular size.
Liquid-Phase Synthesis and Cell Attachment Activity of Bioactive Pentapeptide YIGSRHirano, Yoshiaki; Okuno, Motoya; Hayashi, Toshio; Nakajima, Akio
doi: 10.1295/polymj.24.465pmid: N/A
Pentapeptide Tyr-Ile-Gly-Ser-Arg (YIGSR), an amino acid sequence existing in the cell attachment domain of the B1 chain of laminin, was synthesized by an improved liquid-phase procedure. Bioactivity of YIGSR as cell recognition determinant was investigated using L-929 fibroblast cell and A431 epidermoid cell. The YIGSR pentapeptide was immobilized to ethylene-acrylic acid copolymer (PEA) film, and the number of cells attached to the immobilized film was counted. In addition, the cell-attachment activity of YIGSR toward the cells was also evaluated by the cell inhibition test. These two tests led to a conclusion that YIGSR acts as a cell determinant toward L-929 and A431 cells.