We synthesized a complex branched alkane (H-shaped) with two hydroxyl groups attached to branching points and studied its crystalline structure and also compatibility with high density polyethylene (PE). Results of DSC and X-ray diffraction on solution-crystallized and bulk-crystallized H-shaped alkanes gave same lattice constants for a triclinic type of crystal, a = 1.04nm, b = 1.27nm, c = 1.60nm, α = 95.7°, β = 91.6°, and γ = 109.4°. H-shaped/PE binary system showed a solid solution region 0.05 < φH < 0.40, where φH is the volume fraction of H-shaped alkane. On the other hand, in the region 0.46 < φH < 0.90, H-shaped and PE are considered to mix athermally in the liquid state and to present separately in this binary system, taking crystal structures different from each other.
Effects of non-rubber contents on strain-induced crystallization and tensile mechanical properties were investigated using fractionated samples from fresh latex of natural rubber (NR). The upper fraction (UF) was mostly composed of cis-1,4-polyisoprene (namely, NR molecules), while the bottom fraction (BF) contained non-rubber contents of more than 13%. Vulcanized samples were prepared from the UF and the BF. Wide-angle X-ray diffraction patterns and tensile stress data were collected during 6 cycles of uniaxial deformation for the vulcanized samples. Both UF and BF samples showed the similar degree of the strain softening (the Mullins effect) in the tensile stress-strain behavior. On the other hand, the larger depression of crystallization in the 2nd cycle compared with the 1st cycle was observed for the sample prepared from the BF. The strain ratio at which crystalline reflections disappeared was almost unchanged regardless to the number of deformation cycles and the difference of the samples. On the basis of these results, the non-rubber contents in the BF were suspected to suppress strain-induced crystallization not by reducing thermodynamic driving force but by affecting the kinetic factors of crystallization.
Montmorillonites organically treated with various alkylamines were filled to the acrylic rubber and various properties including mechanical, oil resistance, and abrasion were investigated. Montmorillonite tended to exfoliate after the organic treatment and uniformly dispersed in the acrylic rubber. This uniform dispersion of the filler resulted in the improvement of the mechanical property. Number of carbon atoms in the alkylamine used for the organic treatment increased the swelling with oil at high temperature. Abrasion wear rate of the acrylic rubber was reduced when organically treated montmorillonite was well dispersed in the matrix.
Polymer blends of Poly (lactic acid) (PLA) and Polyethylene glycol (PEG) were obtained through reactive processing with maleic anhydride (MAH) and free radical initiators (POs) by simultaneous melt blending. The IR spectra of the polymer blends suggested the presence of graft copolymer, PLA-g-PEG. The effect of initiator concentration (MAH/PO ratio), residence time, reaction temperature and the free radical initiator species on grafting reaction was studied, and it was found that the polymer blend of PLA/PEG (90/10) (wt/wt) with MAH/dicumyl peroxide (DCP) (1.0/0.5) (phr/phr) at 180°C with higher residence time, gave more PLA-g-PEG product. However, the amount of the product decreased with increasing reaction temperature, with decreasing residence time. From the results of IR spectroscopy and size exclusion chromatography (SEC), the rate-determining step of this system would be additional reactions of MAH with PLA radicals, in the meanwhile, hydrogen abstraction reactions from PLA by DCP and additional reactions of PEG with maleated PLA can take place rapidly.
Simultaneous grafting of poly(ε-caprolactone) (PCL) onto cornstarch as well as cellulose diacetate (CDA) and their composite machining were tried and succeeded by reactive processing using a twin screw extruder to result in plasticization of CDA, and at the same time, to obtain water-resistant and highly biomass-containing biodegradable composite materials. The properties of the composites obtained were examined through solvent fractionation, FT-IR, 1H NMR, tensile test, thermal flow test, SEM observation, water absorption test and biodegradability test. It was demonstrated that the composite materials containing maximum 60% cornstarch and maximum 70% biomass could be produced by the reactive processing method and they have good tensile property, processability, water resistance, and biodegradability. Especially the materials of which matrix polymer, PCL grafted CDA (PCL-g-CDA) in the degree of molar substitution range, 1.72–1.84 showed desirable biodegradability, having a certain induction period before rapid degradation, being attributable to the strong interaction between cornstarch and PCL-g-CDA, which is caused by somewhat long PCL chains grafted on both starch granules and CDA molecules. Furthermore, it was found that starch could accelerate the biodegradation rate of the matrix polymer, associating with starch degradation because of increase in surface area for microbial attack and its naturalization.
We examined applicability of equal channel angular extrusion (ECAE) to improvement of plastic deformability of glassy polymers. Polycarbonate (PC) and poly(methyl methacrylate) (PMMA) were extruded at various temperatures ranging from 50°C to just below the glass transition temperature through one of three equal channel angular dies (ECA-dies) having a pass angle 2φ of 90°, 120° and 150°. Both PC and PMMA could successfully be extruded at most of all conditions examined in this study, although PMMA could not be extrudable at temperatures below about 60°C. After processed through ECAE, extruded PC and PMMA were subjected to tensile test. It was found that ECAE lessened the tensile yield stress of the glassy polymers when extrusion was performed at a lower temperature and through an ECA-die with a larger pass angle 2φ. Plastic flow stress did not so much increase in polymers extruded through an ECA-die with a larger 2φ. Thus, ECAE at a lower temperature through a die with a larger pass angle 2φ was found to be effective to improve plastic deformability of glassy polymers.
The mutual relations between the flame positions during the vertical combustion test and the thermal degradation of polyethylene (PE), polypropylene (PP) and polybutene (PB) as polyolefin and polystyrene (PS) were studied. The flame developed downward for PE and upward for PS. The flames of PP and PB remained in the middle. The combustion of polymer materials has been thought to occur on the surface of the material after having been ignited. However, from the result of the vertical combustion test, it was understood that a flame exists on the surface of the material that drips from PE. The vaporization of the sample is not thought to occur in the primary degradation, but in the secondary degradation phase, when it reacts with oxygen. In order to analyze the phenomena, the scission products of those polymers were measured by Py-GC-MS. When the combustibility of PE of different molecular weight was evaluated by the vertical combustion test, PE of lower molecular weight did not burn where as PE of higher molecular weight did. PE of the lower molecular weight only melted without ignition. Even if the Bunsen flame of the burner was applied to the thinly dripping melted material, it would not ignite. It was then concluded that PE with lower molecular weight does not degrade and vaporize in the secondary degradation.
We found a novel self-organization phenomenon leading to formation of oriented one-dimensional assemblies of nanoparticles, namely nanoparticle chains. A friction-transferred poly(tetrafluoroethylene) (FT-PTFE) substrate was prepared by sliding a PTFE rod on a glass slide at elevated temperature. The nanoparticle chains were spontaneously formed in a drying drop of colloidal solution on the FT-PTFE substrate. The resulting gold nanoparticle chains showed dichroism on far-field optical observation, which was attributable to the anisotropic near-field optical interactions. Real-time polarizing light microscopy observations during the formation of the nanoparticle chains revealed that the chains were formed in the liquid phase. A specific flow pattern that was induced by convection of the colloidal solution between the basal glass slide and the FT-PTFE film was supposed to be responsible for the formation of the nanoparticle chains along with the interparticle cohesive force.
We investigated the effect of hydrogen-bonding on the miscibility of partially p-hydroxymethylated polystyrene (PSOH) and 4-pentyl-4'-cyanobiphenyl (5CB) blends by means of polarized-optical microscopy and infrared (IR) spectroscopy. The blend of polystyrene (PS, the weight average molecular weight Mw is 15.9 × 103) and 5CB underwent phase-separation into nematic (N) and isotropic (I) phases by decreasing the temperature. We evaluated the N-I transition temperature TNI of all the blends, and examined the effect of the OH content in the PSOH on the TNI values. In the case of the OH content of 5mol% (denoted as PSOH5), the observed TNI of the PSOH5/5CB blend was lower than that of PS/5CB blend, compared at the same blend composition. We concluded that this was caused by the intermolecular hydrogen-bonding between CN group of 5CB and OH groups of PSOH, which was confirmed by the IR spectroscopy. However, as the increase of the OH content, the TNI's increased, meaning the decrease of the miscibility. Especially, the PSOH25/5CB blend showed higher TNI than that of PS/5CB blend. From the IR spectrum of this blend, the formation of the hydrogen-bonds between the OH groups (self-association) was found to become dominant. Therefore it was suggested that the hydrogen-bonds between the same species resulted in the lower miscibility of the blends.
Water adsorption and desorption processes were examined of Yezo spruce (Picea jezoensis Carr.) heated at 100 to 800°C. Their sorption properties was characterized by the parameters of the curve regressed by a logistic function. Their parameters, especially the sorption rate parameters, changed at the temperature 250°C. The parameters of adsorption and desorption differed one another in the temperature region from 250 to 700°C. It appears that a wood sample is thermally decomposed above 250°C so that micro-pores in various size create in its substances.
Change of relaxation properties of bamboo in the longitudinal and radial direction were examined on the basis of results of creep measurement and the micro-structure observation in cross section using the stereoscopic microscope. Creep compliance J(t) was greater in the bottom and inner side than in the top and outer side. J(t) versus ln(t) was represented by the Nutting equation. The number of vascular bundle per mm2, that is its dispersion, increases with locating to the top and outer side of bamboo. Various values of relaxation properties, J(t), J(t)-J(0), and dJ(t)/dlnt, was characterized by just density of bamboo which was linear to the number of vascular bundle per mm2. Our results show that bamboo changes relaxation properties in the longitudinal and radial direction by controlling the dispersion of vascular bundles.
In recent years, the global warming has been recognized as a serious problem throughout the world. In Japan, various global warming control technologies for slowing the global warming are being applied and verified. The high reflectance surface for structures has got a great deal of public attention as a promising technology that mitigates the heat island phenomenon which is a cause of the global warming. It is considered that the heat island phenomenon is generated by the temperature rise due to the heat release from the buildings which have a high heat absorptance and are warmed by the solar radiation during the daytime. Applying with solar heat high reflectance paint to the exterior surfaces of urban structures would suppress the increase in temperature, and make possible mitigating of the urban heat island. Solar heat high reflectance paint is composed of various raw materials to enhance the reflection in visible and near-infrared ray. This paper describes solar heat reflectance characteristics of the paint film by varying thickness of film, formulation of paint (pigments by binder mass ratio ; P/B) and kinds of pigments which are uesd for colorling structures in white, black, blue, red, and yellow. The conclusions obtained from this study are as follows : 1) With the increase in P/B, solar reflectance of paint films used organic pigments are devided into two groups. One is not influenced with the increase of P/B and the other is increased with the increase of P/B. The solar transmittance of paint films with most organic pigments is decreases with the increase of P/B. The solar reflectance and the solar transmittance of paint films with inorganic pigments are not influenced with the increase of P/B. 2) The solar reflectance is not influenced by the thickness of paint film and the solar transmittance decreases with the increase of thickness of paint film.
Friction stir processing (FSP) was applied to cast aluminium alloy, AC4CH, to modify the microstructure and fully reversed axial fatigue tests have been performed in the as-cast and FSPed conditions in order to study the effect of FSP on the fatigue behaviour. Two different FSPed conditions were evaluated ; as-cast/FSP for which FSP was applied to the as-cast material and FSP/T6 for which as-cast/FSP was post heat treated. In the as-cast/FSP condition, the fatigue strength decreased in the finite life region, but the fatigue limit i.e. the fatigue strength at 107 cycles significantly increased, compared with the as-cast condition. The fatigue strength in the FSP/T6 condition in the finite life region was higher or slightly lower than in the as-cast/FSP and as-cast conditions, respectively, while the fatigue limit was lower than in the as-cast/FSP condition, but still higher than in the as-cast condition. These complicated fatigue test results obtained were discussed on the basis of microstructural modification resulting from FSP and observations of crack initiation and small crack growth.
We have attempted to reveal the deformation mechanism of amorphous metal from the unique viewpoint of “local lattice instability” or the positive definiteness of atomic elastic stiffness coefficients, Bαij. In the previous report, we discussed the physical meaning of the “unstable atoms”, or the atoms of detBαij < 0, in the molecular dynamics simulations of a monatomic Ni amorphous. Unstable atoms of Ni show hydrostatic compression at the initial equilibrium. The ratio of detBαij < 0 atoms increases in the later stage of tension/compression, as if the “defect” increase in crystalline metals. We have then compared the mechanical condition of unstable atoms in amorphous Ni and Al. The unstable atoms in Al show the opposite aspect ; they show hydrostatic tension at the initial equilibrium. That is, they have more free volume than stable ones. We have carefully discussed the difference by the stress distribution, Voronoi polyhedra analysis and change in the pair distribution function. Contrary to Ni amorphous, the unstable atoms never increase both under tension and compression, but decrease in the later stage of inelastic deformation. That is, in the Al amorphous, the inelastic deformation is absorbed by unstable → stable transitions : This phenomena may correspond to common image of usage of free volume.
High temperature embrittlement and its restraint were studied about Ni-Cu-Al alloy ingot for room temperature damper of superconducting generator. Cracking of Ni-Cu-Al alloy ingot occurred when the ingot was given hot forging. It is supposed that the cracking has close relationship to high temperature embrittlement of the Ni-Cu-Al alloy ingot. It was found that increase of Cu, Al, Ti and impurities such as S, Se, Bi, Te and P promote the high temperature embrittlement and reduce elongation at 1050°C in Ni-Cu-Al alloy ingot. However addition of Mg, Zr, B, La and Hf restrain the high temperature embrittlement and increase elongation at 1050°C in Ni-Cu-Al alloy ingot. Based on the present research, the room temperature damper for 70MW class superconducting generator can successfully produced by hot forging after heating up to 1100°C without cracking using the electro-slag remelted ingot with the weight of 21 tons of the developed Ni-12.2%Cu-4.15%Al-0.36%Ti-0.15%C alloy containing 0.011% Mg and 0.039% Zr.