Ozone resistance of vulcanized isoprene rubber containing 6PPD as an amine type antioxidant was investigated at temperatures between -30 °C and 55 °C. Both pure gum compound and carbon black filled compound were prepared by mixing isoprene rubber with zinc oxide, stearic acid, sulfur, accelerator and 6PPD. Ozone exposure tests of the vulcanized rubber after 20% straining were carried out under 50 pphm ozone at -30 °C, 40 °C and 55 °C for 48 hours, respectively. Ozone cracks and surface morphology of the rubber were observed with a digital microscope and a scanning electron microscope. The crack propagation of the vulcanized rubber took place at 40 °C, whereas it was suppressed at -30 °C and 55 °C, even though the amount of 6PPD bloomed on the surface of the rubber at 40 °C was higher than that at -30 °C. It was found that the ozone resistance of rubbers containing 6PPD depends markedly on the surface morphology of rubbers blooming 6PPD, that is, the temperature under ozone exposure.

Rubber is widely used in automotive and consumer fields. We are investigating the application to electrostatic capacitive sensors and electrostrictive polymer actuators by making rubber conductive. The conductive rubber sandwiches the dielectric layer (foamed urethane) so that it detects the capacitance change of the layer due to the load stress on the sensor. By using conductive rubber, we have succeeded in developing highly reliable capacitive sensor. We are promoting sensor development that can be used in medical, nursing care and automotive fields. In addition, it can also apply to an electrostrictive polymer actuator by laminating a rubber electrode and a dielectric layer with high insulating property.

The author and coworkers have proposed a novel blending method for the fabrication of polymer nanocomposites, wherein inorganic nanoparticles without any complicated hydrophobic surface modifications were dispersed through the breakdown of loose agglomerates of their primary particles in each polymeric matrix component. In this article, using the silica/perfluoropolymer and silica/epoxy resin nanocomposites as examples, experimental techniques of the proposed method were explained with the scope of the pre-control of packing structure of spherical primary silica particles as loosely as possible to enable easy breaking down to nano-dispersion level at a blending stage with polymeric matrix components. The strategy for high dispersion of highly thermally conductive hexagonal boron nitride (h-BN) fine particles having a plate-like shape with a high aspect ratio into epoxy resin was also described on the basis of the breakdown of the loose hybridized fillers having a card-house structure pre-formed via heterocoagulation of these h-BN and spherical silica nanoparticles. The experimental results of thermal conductivity of the nanocomposites loading h-BN without surface modifications fabricated by this method suggest that a dispersion of unmodified nanofillers into polymeric matrix might be a potential candidate for useful design criteria to develop innovative polymer nanocomposites superior to conventional ones loading modified nanofillers.

Multi material bonding technologies become to be more and more important for light weight designs, compact designs etc. This article focuses on polymer-polymer interdiffusion, interfacial chemical reactions, hydrogen bonding as the bonding mechanisms and it explains about the analytical methods and the results. In the case of polymer-polymer interdiffusion, the combination of PPE and SBS is examined. The interdiffusion phenomena are observed as the changing of the morphology of SBS. About interfacial chemical reactions, a radical reaction between PPE and EPDM is picked up.

Structural designs of composites and the practical strengths are also picked up as the future subjects. It is shown that a soft layer between a metal part and a plastic part can reduce a stress concentration and it influences on the bonding area dependence of a bonding strength. Cohesive bonding was considered as one of the indications of good bonding but it could not always be observed by human eyes. These results suggest that structural designs of composites would be more important compared to a bonding strength based on a specimen, cohesive broken/interface failure as an indication of bonding performance.

Polyurethanes (PUEs) are multi-blocked-copolymers synthesized with isocyanates, polyols and curing agents as glycols or diamines. PUEs can be freely designed due to the diversity of the chemical structure, blending and reaction of raw materials.

In the development of novel polyurethanes, it is important to control the higher order structure, that is, the micro-aggregation structure in addition to the primary structure (chemical structure) of polyurethanes. The structure control factors of polyurethane will be described here.

Real polymer materials including filled rubber vulcanizates are typical complex systems. It is necessary to analyze and understand their heterogeneous structure from nano- to large scale and try to correlate their structure and properties. This series of special lecture will be consisted of 5 parts.

Part I. Studies on Heterogeneous Structure in Elastomers and Their Development.

Part II. Studies on Miscibility and Phase Separation in Polymer Alloys & Blends and Their Development.

Part III. Development of Polymer Nanotechnology and Its Future.

Part IV. Polymer Nanotechnology and Megatechnology.

Part V. Studies on Polymer Based Composite Materials and Their Future Hope.

In this lecture as Part I, heterogeneous structure in elastomers are studied from simple to more complex systems and real rubber materials in these steps.

1) Unvulcanized filled rubber systems.

2) Unvulcanized oil extended rubber systems.

3) Pure rubber vulcanizates.

4) Filled rubber vulcanizates and bound rubber.

5) Heterogeneous structure model of filled rubber vulcanizates and their correlation with physical properties.

At each step, typical evidence for the model is shown based on our experimental results including dynamic mechanical measurements, ultra small angle X-ray scattering, pulsed NMR, electron microscopy and so on. In the last, future development in this field is summarized.