The relation between crystallinity and miscibility of semicrystalline polymer blends of poly(vinyl isobutyl ether) (PVIBE) and poly(ε-L-lysine) (ε-PL) is investigated by ¹³C cross-polarization with magic-angle-spinning (CPMAS) NMR (nuclear magnetic resonance) and DSC measurements. Analysis of the ¹H spin-lattice relaxation curves observed from both PVIBE and ε-PL signals, which are indirectly obtained from well-resolved ¹³C CPMAS NMR spectra, suggested that the domains of ε-PL in the blends are in the range of 50–100 nm scale. Two-spin or three-spin models were used to simulate the ¹H relaxation curves taking into account the contribution of a ¹H spin-diffusion rate between PVIBE and ε-PL. Furthermore, it was found that blending ε-PL largely influences the crystallinity of PVIBE but that of ε-PL is little affected by blending PVIBE except for 10/1 composition. The observed melting point of ε-PL shifted towards lower temperature accompanied by PVIBE content. This shift was explained by the Gibbs-Thomson effect that the decrease of thickness of crystalline phase causes the depression of the melting point.

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Polyamide (PA) was blended with a reactive polyolefin, poly(ethylene-co-glycidyl methacrylate), using an extremely long (L/D=100, L: screw length, D: screw diameter) twin-screw extruder. The reactive blending yielded a unique morphology of the sub-μm polyolefin particles in which 20 nm PA micelles were occluded. It implies that the in situ-formed graft copolymer was pulled in the dispersed particles. The blend showed ultra-high toughness (non-break at Izod impact test) and non-viscoelastic tensile property: the higher deformation rate led to the lower modulus and the larger elongation at break. In the tensile stress–strain curve, the sharp yielding point characteristic to crystalline polymer was hardly seen and the necking stress was maintained almost constant without strain hardening. It suggests a potential application for the energy absorbing car parts, to be friendly for pedestrian and driver.

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Rubber materials are made of two networks, chemical and filler networks. The networks are characterized usually by overall network density estimated at equilibrium condition. However, rubbers are used in nonlinear conditions where the filler network may change from the one at equilibrium. We need additional information on the filler network. Hence, differential dynamic modulus (DDM) in large compression (ε=−0.1) and recovery (ε=0) were measured for the samples filled with carbon blacks (CB) having different primary particle sizes. The change in E′ for unfilled sample was reversible in large compression followed by recovery, while those for filled samples were irreversible, showing change in filler network in large deformation. The differences in DDM at the recovered and the initial states were compared for characterization of the filler network. The difference for the sample filled with smaller CB was larger than the one with larger CB. The results show that the rubber filled with CB having smaller particle size makes weaker filler network. In addition, we observed the restoration behavior of the filler network structure. Recovery of filler network ruptured due to large compression and recovery in shape was attained at a time scale depending on particle size. The characteristic time was found to increase with increase in the CB particle size. It was concluded that the restoration process of CB filler network is based on diffusion of CB aggregate.

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The importance of large deformation problems in the manufacture of rubber products is increasing. Thus far, these deformations can be analyzed by FEM. However, large deformation cause severe mesh distortions in elements near the boundary, thereby reducing the stable time increment while obtaining the solution. On the other hand, particle methods are meshless techniques that no longer use connectivity data. Therefore, users do not encounter such problems.

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Correspondence between nonlinear viscoelastic properties and change in various networks in carbon black (CB) filled, uncured SBRs has been studied by using combined measurements of relaxation modulus, differential dynamic modulus, and volume resisitivity in wide range of filler concentrations at various shear strains. Volume resistivity at no deformation showed step-off like change which can be explained by the percolation theory. This indicates formation of contact filler network at high filler loading. In addition, change in volume resistivity showed clear correspondence with linear-nonlinear transition in viscoelasticity. By the use of simple three-network model, contributions of contact filler, bridged filler, and entanglement networks to relaxation modulus were estimated. It was found that contact filler and bridged filler networks were dominant at lower and at higher filler concentrations, respectively. It was proposed, furthermore, that differential dynamic modulus can be used as the probes for changes in contact filler and bridged filler networks, respectively.

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Measurements of storage and loss moduli G′ and G″ in linear viscoelasticity have been made on SBR SL-574 containing 50 phr N330 carbon black, silica AQ with coupling agent, and silica AQ, both cured and uncured, and compared with similar measurements on the cured and uncured gum rubbers. The rage of temperature was −60 to 70°C, and of frequency 0.4 to 100 rad s⁻¹. The cured and uncured samples showed G″ peak temperatures of −42 and −45°C at 6.28 rad s⁻¹ latter of which was close to the glass transition temperature of uncured gum of −48°C. The mixing of various fillers showed no effect on the peak temperatures. Time-temperature superposition procedures were applied to the samples through the next way; frequency shifts were determined firstly for tanδ curves, then shifts in magnitude were made for G′ and G″. All shift factors can be expressed by single WLF equation with C₁=13.2 and C₂=39.7, if we chose G″ peak temperatures as the reference temperatures. It may be concluded that the temperature dependence of the matrix polymer determines that of linear viscoelasticity of rubber materials.

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Poly(phenylene ether) (PPE) is a high temperature polymer (T_g=210°C). Neat PPE is hardly melt-processed below its thermal decomposition temperature. It is believed that the melt-processability is only achieved by blending with polystyrene as a polymeric plasticizer. The polymeric plasticizer sacrifices the heat resistance; the T_g decreases almost linearly with polystyrene content. We found that PPE can react with poly(ethylene-co-glycidylmethacrylate) (EGMA) by melt mixing. Reactive blending of PPE with EGMA yielded an excellent engineering plastic with nice melt-processability, even when a small amount of EGMA (e.g., 5 wt%) was incorporated. The injection molded parts showed high impact strength, high temperature resistance, high tensile strength, and low dielectric loss. It can be classified as a super-engineering plastics. The computer simulation based on a particle-slip model revealed why the melt-processability is attained by the incorporation of polyolefin in pure PPE matrix.

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Aliphatic poly(carbonate) glycols (PC-glycols) with different methylene unit lengths were synthesized from ethylene carbonate and 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol or 1,10-decanediol. The samples were coded 3002, 4002, 5002, 6002, 7002, 8002, 9002 and 10002 respectively, for each of these PC-glycols. Wide-angle X-ray diffraction (WAXD) and Differential Scanning Calorimetry (DSC) measurements were carried out to examine the structure of PC-glycols. A WAXD profile of 3002 showed only an amorphous halo with no particular crystalline peaks. Also, a DSC thermogram of 3002 showed the glass transition point but no melting peaks were observed. In the case of 5002, relatively weak WAXD peaks were observed, but no melting peaks were observed in the DSC thermogram. On the other hand, the other PC-glycols exhibited crystalline peaks in WAXD profiles and a melting peak in DSC thermograms. These results indicated that PC-glycols with odd numbered methylene unit length were more amorphous than those with even numbered methylene unit length.

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A phase control of butadiene rubber (BR)/styrene-butadiene rubber (SBR) blends was examined by using silica particles. The phase structure of the blends was qualitatively evaluated from transmission electron microscope (TEM) observation and temperature dependence of mechanical tanδ. It was found that the temperature dependence of tanδ was dependent on the size of agglomerate formed by silica particles in the blend. The vulcanized blends with small agglomerates showed a single tanδ peak suggesting a pseudo-miscible state. The vulcanized blends with large agglomerates showed two tanδ peaks corresponding to the T_gs of BR and SBR. The mutual dissolution of BR and SBR phases above the UCST line where the vulcanization was carried out might be disturbed by large agglomerates formed by silica particles in the blends.

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