巻号一覧
41 巻 (2013)
- 5 号 p. 271-
- 4 号 p. 187-
- 3 号 p. 113-
- 2 号 p. 45-
- 1 号 p. 1-
41 巻, 3 号
選択された号の論文の10件中1～10を表示しています
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論文
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Masaoki Takahashi, Ryuji Ishikawa, Yukihiro Nishikawa2013 年 41 巻 3 号 p. 113-120
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーIn slow melt-blending and annealing of poly(methyl methacrylate) (PMMA) and carbon nanofibers (vapor grown carbon fibers, VGCFs) with very small amount of high density polyethylene (HDPE), the flexible HDPE chains adsorb onto the rough surface of the VGCF ends and behave like a glue between VGCFs. After 4 h annealing, the percolation threshold of VGCF is determined as 1.15 vol% from dynamic viscoelastic behavior of the PMMA/HDPE/VGCF composites at 200 °C. Applying the percolation theory for gel systems to the composites, the fractal dimension dƒ is found to be 1.8 - 2.0, reflecting very effective connectivity of VGCFs facilitated by the selective adsorption of HDPE. The dimension dƒ is found to be smaller for the composite with smaller molecular weight of HDPE, while the threshold does not change. The addition of HDPE and annealing at 200 °C for 4 hours also lead to the prominent reduction in the critical concentration of VGCF to 0.71 vol% at the insulator-conductor transition (1×10-7 S/m). When the VGCF content exceeds the viscoelastic threshold (1.15 vol%), the electrical conductivity of the composite approaches up to 10 S/m.抄録全体を表示PDF形式でダウンロード (2322K) -
Yongzheng Pan, Xue Shuang Chan, Lin Li2013 年 41 巻 3 号 p. 121-128
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーThe effect of interfacial adhesion between multiwalled carbon nanotubes (MWCNTs) and the polypropylene (PP) matrix on the gel-like behaviour of the MWCNT/PP is studied. Two kinds of composites with different nanotube-polymer interactions, e.g. MWCNT/polypropylene-grafted-maleic anhydride (PP-g-MA)/polypropylene and functionalized MWCNT (MWCNT-COOH)/PP-g-MA/PP, are prepared by melt mixing. The two composites exhibit significant differences in morphological and rheological properties. The Winter-Chambon method is successfully demonstrated as an effective tool to study the gel-like behavior and percolation threshold of CNT/polymer composite systems. This method accurately reveals the gel content (cg) and quantitatively provides the gel strength Sg and exponent n of the two composites, which proves that the increased interfacial adhesion between MWCNT-COOH and the polymer matrix served a key for changing the rheological properties.抄録全体を表示PDF形式でダウンロード (915K) -
Masayuki Yamaguchi, Tadashi Yokohara, Mohd Amran Bin Md Ali2013 年 41 巻 3 号 p. 129-135
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーRheological properties of polymer composites with flexible fine fibers are studied employing poly(lactic acid) PLA containing a small amount of polymeric fibers of poly(tetrafluoroethylene) PTFE, poly(butylene terephthalate) PBT, and poly(4-methyl-1-pentene) PMP. Both PBT and PMP fibers are prepared by hot-stretching of the blends with PLA, whereas PTFE fibers are obtained by simple mixing of PLA and PTFE powder at the temperature between Tm's of both polymers. The polymer composites with PTFE and PBT fibers whose diameters are smaller than 1 µm show marked strain-hardening behavior in elongational viscosity, i.e., rapid increase in the transient elongational viscosity with time or strain. On the contrary, the composite with PMP fibers with a diameter of ca. 2 µm shows no strain-hardening, although the elongational viscosity is enhanced in the measured strain/time range irrespective of the strain rate.抄録全体を表示PDF形式でダウンロード (978K) -
Yoshinobu Isono, Takafumi Aoyama2013 年 41 巻 3 号 p. 137-144
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーMeasurements of Relaxation modulus and/or differential dynamic modulus in linear and nonlinear viscoelasticity have been made on cured styrene-butadiene rubber (SBR) 1502 gum and cured SBR containing 20-60 phr carbon black (CB). Linear viscoelastometry has been made at temperatures ranged from -60 to 80 °C and at frequencies ranged from 0.4 to 100 rad s-1. Nonlinear viscoelastometry has been made with small oscillations at dynamic strain of 0.005 and at frequency of 1.26 rad s-1 superposed on static strains of unity both for shear and extensional deformations. Cured SBR showed G" peak temperatures of -48 °C at 1.26 rad s-1. The mixing of CB filler showed no effect on the peak temperatures. It was found that all horizontal shift factors can be expressed by single WLF equation in linear viscoelasticity. The horizontal shift factors can be applied for the temperature dependent nonlinear viscoelasticity. Vertical shift factors in linear viscoelasticity depends on filler contents, showing change from entropic elasticity in gum rubber to energetic elasticity of enough filled rubber. Similar change has been found in large shear deformations, but entropic elasticity behaviors in vertical shift factors have been found irrespective of filler contents in large extension. The difference in behaviors of vertical shift factors between large shear and large extension can be understood with the change and recovery of filler network. It was concluded that the horizontal and the vertical shift factors of filled rubbers are governed by matrix polymer and filler network, respectively.抄録全体を表示PDF形式でダウンロード (730K) -
Katsuhisa Tokumitsu, Ken-ichi Nishizaka2013 年 41 巻 3 号 p. 145-150
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーTo improve the mechanical properties of poly(butylene terephthalate) (PBT), the effect of adding two types of PBT-derived elastomer, Pelprene (PEL), with and without a reactive compatibilizer, was investigated. The impact strength of neat PBT 3.5 kJ/m2 increased to 19.0 kJ/m2 at 223 K when 30 wt% PEL and 3.2 phr compatibilizer were added. SEM observations showed that neat PBT had brittle fracture patterns while PBT/PEL/compatibilizer blends had ductile properties; the morphological change was particularly clear when more than 0.8 phr compatibilizer was added. Dynamic modulus ratios, (E'T=100K- E'T=300K)2/E'T=100K, were obtained by DMA, for which some linear correlations with the Charpy impact strength of the blends was found. During tensile testing, the elongation at break of the PBT/PEL/compatibilizer blend increased remarkably with compatibilizer content in comparison with that of with PBT/PEL. Viscoelastic measurements revealed that the value of G' for the PBT/PEL/compatibilizer blends also increased with compatibilizer content. Furthermore, Takayanagi's model was employed to estimate the interaction phase between PBT and PEL, the volume fraction of which was found to increase with compatibilizer content. Consequently, when the reactive compatibilizer was added to PBT/PEL blends, an interaction interface between the PBT and PEL phases was formed, and their compatibility was improved.抄録全体を表示PDF形式でダウンロード (934K) -
Ken Morishima, Tadashi Inoue2013 年 41 巻 3 号 p. 151-156
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーLinear viscoelastic behavior for solutions of polystyrene (PS) having broad molar mass distribution (MMD) in tricresyl phosphate (TCP), which is a good solvent, was investigated at concentrations, c, around the coil-overlapping-concentration, c*. GPC measurement indicated that molar mass distribution of sample was close to most probable distribution. Below c*, the viscoelastic behavior was described well with the Rouse-Zimm (RZ) theory if considered molar mass distribution. On the other hand, at concentrations around the c*, the viscoelastic behavior was not described by the RZ mode alone and the additional long-time (LT) modes were needed, similarly to the case of monodispersed molar mass distribution system. This implies that the LT modes are originated by the inter-molecular interaction. Compared with the monodispersed system, magnitude of the LT modes showed the same c dependence, being proportional to c2 while the relaxation time of the LT mode showed a different c dependence. Owing to the broad MMD and the LT term, the viscoelastic spectra have the broad terminal flow relaxation time distribution but still can be apparently fit with the Rouse-Zimm (RZ) theory, resulting that the apparent molar mass, Mwapp, is higher molar mass than the real molar mass depending at concentrations of c > c*. At c / c* = 2.9, Mwapp was estimated at 4.1 times larger than the true molar mass. By considering the LT terms, the molar mass can be estimated by fitting with the Rouse-Zimm (RZ) term.抄録全体を表示PDF形式でダウンロード (661K) -
Takeharu Isaki, Masaoki Takahashi, Tomohiro Deguchi2013 年 41 巻 3 号 p. 157-166
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーTwo bidisperse PS samples B1 and B2 (blend of monodisperse polystyrenes) are employed to investigate the effects of bimodal molecular weight distribution on damping behavior of stress relaxation in shear and biaxial extension. The order of characteristic relaxation times, reptation time τd and contraction time τs of each component, for B1 is (τs,1 < τs,2 < τd,1 <τd,2) and that for B2 is (τs,1 < τd,1 < τs,2 < τd,2), where suffixes 1 and 2 denote lower and higher molecular weight component respectively. Time dependent damping functions in shear h(t,γ) and in biaxial extension hB(t,εB) are employed to confirm the time-strain separability for bidisperse polymer systems. Time dependent damping functions of B1 are almost constant, but B2 vary with time in both shear and biaxial extension. To investigate effects of reptative constraint release (RCR) via double reptation scheme and convective constrain release (CCR) in shear and biaxial stress relaxation for bidisperse polymer systems, we use multi-mode extension of the Ianniruberuto and Marrucci (IM) model and the Mead-Larson-Doi (MLD) model. The model predictions of h(t,γ) and hB(t,εB) well describe experimental tendency. Time dependent damping functions become independent of time after contraction of long chain and the multi mode model prediction seems almost the same strain dependence. Effect of CCR is very important to describe damping behavior for bidisperse polymer systems.抄録全体を表示PDF形式でダウンロード (1499K) -
新田 晃平, 春瑶 李2013 年 41 巻 3 号 p. 167-172
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーWe consider the fracture initiator of a pair of perfectly extended chains where the intermolecular interaction is assumed to be based on hydrogen-hydrogen interaction with a single chain. When two protons are closer together, the interaction energy is split into the grand state and excited state. The transition from the grand state to the excited state cases the disassociation of interchain interaction and this leads to the fracture initiators. Considering that the initiation of fracture occurs within overall specimen, the probability of macroscopic fracture is described by the Gaussian distribution curve. The fracture behavior under different elongation speeds at room temperature was investigated for various shapes of isotactic polypropylene (iPP) specimen It was experimentally confirmed that all the probability distribution curves of the fracture time and the ultimate stress and the tensile toughness approximately follow Gaussian statistics.抄録全体を表示PDF形式でダウンロード (790K) -
Shigeru Yao, Aya Tominaga, Youhei Fujikawa, Hiroshi Sekiguchi, Eiichi ...2013 年 41 巻 3 号 p. 173-178
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーWe investigated the molecular characteristics of virgin polypropylene and recycled polypropylene that was obtained from byproducts (for example, runners, etc.) at the injection-molding of virgin polypropylene. We also tested the tensile properties of 3 mm-thick specimens made from each sample. The results showed that the two materials had almost the same molecular characteristics and tensile properties. However, their fractured surfaces were very different. Furthermore, a 100 µm-thick film of the recycled sample was very brittle compared to a film made from the virgin polypropylene. The recycled sample had a history of shear deformation at the time of injection-molding, and may have a unique inner structure due to shear deformation. We found a unique peak in an endothermic curve with a rapid heating rate, and this result supports the above assumption. We also found that the dependence of the tensile fracture energy on the duration of UV irradiation was essentially the same in these samples. Based on these results, we propose a new theoretical equation that can estimate the fracture ratio of molecules.抄録全体を表示PDF形式でダウンロード (1004K) -
Fumihiko Tanaka2013 年 41 巻 3 号 p. 179-186
発行日: 2013/07/15
公開日: 2013/07/25
ジャーナル フリーA new transient network model of telechelic associating polymers whose main chains undergo sharp temperature-responsive coil-globule transition is developed for the study of the rheological properties near their collapse transition point. It is shown that the two fundamental relaxation times, the time scale of the conformational change and the time scale of the end-chain dissociation, compete. As a result of their coupling, two distinct slow-and fast relaxation modes appear. The complex modulus is calculated and shown to take the form of the Burgers model made up of a Maxwell and a Voigt element connected in series. In the limit of high reaction rate of the conformation change, the slow mode reduces to the average relaxation time of the end-chain dissociation, while the fast mode disappears. The two relaxation times and the plateau modulus are obtained in terms of the molecular parameters of the telechelic polymer. Possible comparison with the recent experimental data on telechelic poly(N-isopropylacrylamide) networks in water is suggested.抄録全体を表示PDF形式でダウンロード (5856K)
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