Clay/polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymer (SEBS) intercalated composites were prepared by melt-blending. The clays were a pristine montmorillonite (Mt) and three organically modified montmorillonites (organo-Mts) with different amounts of distearyldimethylammonium (D18) cation. The amounts of D18 were 50, 70 and 100% of the cation exchange capacity (denoted as D18Mt(50), D18Mt(70) and D18Mt(100), respectively). The clay/SEBS composites were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD). The dynamic mechanical analysis (DMA) and the tensile properties were also examined.
The size of agglomerated clay particles decreased with the increasing amount of D18. The FE-SEM image of D18Mt(100)/SEBS revealed that the clay particles were dispersed at the sub-μm level (100–500 nm). The XRD patterns suggested that the SEBS chains were inserted into the interlayers of the organo-Mts. The DMA curves indicated that the addition of the organo-Mts produced an increase in the storage modulus in the rubbery plateau region, but a slight decrease in the glass transition temperature of the polystyrene domains. The tensile properties of the organo-Mt/SEBS composites were higher than those of the unmodified Mt/SEBS. D18Mt(100)/SEBS displayed an improved tensile modulus, tear strength and hardness compared to pure SEBS, without sacrificing the tensile strength and elongation at break.

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The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Heat-aging process affects not only the material properties but also the fatigue life of vulcanized natural rubber. In this paper, the heat-aging effects on the material properties and fatigue life prediction of natural rubber were experimentally investigated. The stress-strain curves were obtained from the results of tensile test. The rubber specimens were heat-aged in an oven at the temperature ranging from 50°C to 100°C for a period ranging from 1 day to 90 days. Fatigue life prediction methodology of vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from fatigue test. Fatigue life tests were performed using the 3-dimensional dumbbell specimen, which were aged in different amounts. The Green-Lagrange strain at the critical location determined from the finite element method used for evaluating the fatigue damage parameter. Fatigue life prediction equation effectively represented by a single function using the Green-Lagrange strain.

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The advancement in the miniaturization of electric devices requires high performance diebond adhesive films for semiconductor packages. The diebond film should have high thermal-stress resistance and good retention of adhesive properties. To achieve such performance and reliability, we choose a rubber-rich epoxy adhesive. In the present work, we investigated the influence of reactive site of acrylic rubber (ACM), cure agent and curing condition on the performance of diebond film. In the early stage of curing, ACM/epoxy/curing agent (e.g., DDM: diaminodiphenylmethane) system was a single-phase mixture. As the cure reaction proceeded, phase separation took place via the spinodal decomposition, induced by the increase in the molecular weight of epoxy. The reaction-induced spinodal decomposition was confirmed by the characteristic change in light scattering profile with curing time. Phase contrast microscopy and atomic force microscopy also revealed the formation of regularly phase-separated structure characteristic to the spinodal decomposition. The periodic distance of the structure varied in a wide range, from a few μm to ten nm. The higher amount of reactive site (glycidylmethacrylate) in ACM and the lower cure temperature rendered the shorter periodic distance. The shorter periodic distance yielded the higher adhesive strength. However, much shorter distance of 10 nm resulted in poor adhesive strength. The sub-μm structure seems to lead to optimum strength. The 10 nm structure material showed low thermal expansion and nice transparency.

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The degradation analysis of NBR and Epichlorohydrin rubber was carried out by infrared micro spectroscopy (μ-IR) and micro sampling mass spectrometry (μ-MS) which gives information on the scission and crosslinking of rubber molecules. Samples were prepared by three different treatments, heat as well as ultra violet (UV) and electron beam (EB) irradiations.
It was found for NBR vulcanizates that the heat treatment induced the oxidation, scission and crosslinking of rubber molecules. By the UV treatment, chain scission and crosslinking accompanied by a slight oxidation were induced. The EB treatment enhanced the crosslinking, however, the extent of oxidation was negligible. For Epichlorohydrin rubber vulcanizates, the heat treatment accelerated chain scission rather than crosslinking. On the other hand, the oxidation and crosslinking were induced by the UV and EB treatments.

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In this paper different types of surface modification of polyester cords by low-temperature plasma at atmospheric pressure was studied.
The first type cords were activated by pulse surface positive corona discharge generated in a plasma reactor or by coplanar dielectric surface barier discharge (DCSBD) in nitrogen or ambient air plasma at atmospheric pressure. The values of the static and dynamic adhesion of untreated cords and the plasma treated cords demonstrated possitive influence of plasma surface treatment on the adhesion of cords to rubber. The mechanical properties were not significantly affected by plasma treatment.
The second type of plasma treatment involved the modification of cords by plasma polymerization in mixture of nitrogene with butadiene. The plasma layer homogenously coated the cords surface. The results shove, that values of static and dynamic adhesion for plasma polymerisation of treated cords are comparable with the standard chemical treatment based on resorcinol-formaldehyde latex (RFL).
From the study of the surface properties of the plasma treated cords by SEM, AFM and XPS is evident that both chemical interactions and morphological changes of the surface cord fibres are responsible for the improved adhesion between treated reinforcing materials and rubber blend.

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Syndiotactic polystyrene (s-PS) in dichloroethane (DCE) was gelated thermoreversibly in the presence of poly(ethylene oxide) (PEO). The effect of the dosage and molecular weight of coexistent PEO on the gelation has been investigated. The gelation temperature increased with increasing the composition ratio of PEO to DCE and the molecular weight of PEO. Wide angle X ray diffraction measurements revealed that an increase of the composition ratio of PEO to DCE in the gel led to change the crystal structure of s-PS from a helical conformation to a trans-zigzag one.
When DCE was removed from the gel completely by drying under vacuum at 70°C for 24 hours, a novel polymer blend consisting of s-PS and PEO was obtained. Dynamic modulus analysis measurements revealed that it had a unique long rubbery plateau from a grass transition temperature (T_g) or a melting temperature (T_m) of PEO’s depending with their molecular weights to T_m of s-PS. It indicates that the crystallite of s-PS not only plays a role of the network junction in the polymer blend but also prevents the macroscopic phase separation between s-PS and PEO.

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We investigated the viscoelastic effects on the early stage spinodal decomposition (SD) in semidilute polymer solutions where the coupling of stress and diffusion plays an important role. The so-called viscoelastic length ξ_ve, within which the stress suppresses the growth of the concentration fluctuations, was quantitatively evaluated experimentally. The evaluated value was found out to become as large as 9.0×10² nm. The obtained value ξ_ve agrees well with that independently estimated from the diffusion and viscoelasticity measurements, indicating that the Doi-Onuki theory can well describe the viscoelastic effects on the dynamics of the early stage SD.

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The polymerization of 1,3-butadiene (Bd) with NiCl₂/methylaluminoxane (MAO) catalyst was investigated. The reaction mixture of NiCl₂ and MAO was separated into soluble and insoluble part. Both parts initiated the polymerization of Bd to give a high cis-1,4-poly(Bd). The activity for the polymerization of the soluble part was higher than that of the insoluble part. The M_w/M_n of the polymer obtained with the soluble part was around 2.0, but that obtained with the insoluble part was 4.5. The polymerization of Bd with NiCl₂ in combination with MAO depended on a particle size, i.e., surface area of NiCl₂, and the activity for the polymerization with a small particle size of NiCl₂ was higher than that with a large particle.

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A phase-separated structure of the injection-molded isotactic polypropylene (iPP)/poly(ethylene-co-octene) (EOR) binary blend was studied in three-dimension (3D) by transmission electron microtomography (TEMT). Highly oriented EOR domains along both flow- (FD) and transverse-to-flow (TD) directions resulting in stacking lamella-sheet like structures to normal direction (ND) were confirmed. Some irregularities in morphology and intervals between the EOR sheets, and thickness heterogeneity of the sheets, were observed more frequently in the TD rather than in the FD. Using the 3D information obtained by the TEMT, we have tried to elucidate massive anisotropy in linear thermal expansion coefficient (CLTE) along the injection directions in this blend. We found that the CLTE anisotropy was well correlated with the lamella-like sheets arrays and their irregularities.

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The reactivities of hydrocarbon, the radical reactions through the allylic radicals, the results of model compound vulcanization, and the cross-link structures of vulcanizates are comprehensively discussed to understand the main reaction for accelerated sulfur vulcanization. Through this review, the author's view on the main mechanism and cross-linking structure for accelerated sulfur vulcanization are discussed.

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