| POLYMERS Vol.65 No.10 |
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COVER STORY
Adhesives and Polymers |
| COVER STORY: Highlight Reviews |
| Adhesion and Polymer Surface / Interphase | Takashi NISHINO |
| <Abstract> Polymer surfaces play an important role in adhesion. Through structure analyses by grazing incidence / small angle incidence X-ray diffraction, we found that the crystallinity was lower, and the crystallite sizes were smaller near the surface (～micrometer order depth form the surface) compared with those in the bulk. These results just reveal the existence of weak boundary layers proposed by Bikerman more than 50 years ago. In addition, investigations on the structure and properties using scanning thermal microscopy, nano-Raman scattering, synchrotron microbeam X-ray diffraction and other techniques showed that the adhesion strength between poly-α-olefins highly correlates with the interfacial thickness of several micrometer. These results indicate that the three dimensional interphase is a quite suitable concept instead of using two dimensional interface models to talk quantitatively about adhesion strength. In order to understand the relationship between surface/interphase and adhesion of polymers, importance of combinatorial analyses based on different principles and methods is manifested. Keywords: Adhesion / Interphase / Surface / Nano-Analysis / Poly-α-Olefin / Weak Boundary Layer / X-ray Diffraction |
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| Activities of Polymer Materials for Adhesives | Toshio SUGIZAKI |
| <Abstract> Adhesive technology plays an important role in all areas of human life and industries such as automotive, building and electronics in particular e.g. for high-power devices. In this report, those adhesive technologies applied in various regions, for example power electronics, biomimetic adhesion and biomass plastic adhesives are presented referring recent studies on polymer synthesis, polymerization and analysis. Keywords: Adhesive / Devices / Biological / Biomass / Polymerization |
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| Research & Development of Natural Adhesives for Wood | Kenji UMEMURA |
| <Abstract> Recently, natural wood adhesives using non-fossil resources have been developed due to an alternative of synthetic adhesives derived from fossil resources. The development methodology of conventional natural wood adhesives is classified into four groups, i.e., utilization of natural substances as raw materials of synthetic resins, preparation of natural wood adhesives by chemical modification of natural substances, preparation of natural wood adhesives by adding a synthetic compound, and the combination of these methods. According to the development methodology, many natural wood adhesives such as polysaccharides, proteins, and aromatic bases have been developed, and the adhesive properties have been compared with that of synthetic adhesives. Generally, the adhesive properties of natural adhesives are not so excellent, and especially the improvement of water resistance is desired. Keywords: Natural Adhesives / Wood / Wood-Based Materials / Polysaccharide Based Adhesives / Protein Based Adhesives / Aromatic Based Adhesives / Development Methodology |
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| COVER STORY: Topics and Products |
| Dismantlable Adhesive | Chiaki SATO |
| <Abstract> The recent progress on dismantlable adhesive is reviewed in this article. For recycling of materials, a type of adhesive, which can be separated on demand, has been applied to the joining. The type of adhesive is called dismantlable adhesive. In order to realize such an adhesive, several special techniques have been applied to the adhesives such that inclusion of blowing agents or thermally expandable microcapsules. In addition, other techniques such as taking advantage of chemical degradation have recently been proposed. Keywords: Dismantlable Adhesive / Recycling / Blowing Agents / Chemical Reaction / Thermally Expandable Microcapsules / Multimaterial Structures |
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| Design of Reactive Acrylic Polymers and Their Application to Pressure-Sensitive Type Dismantlable Adhesives | Eriko SATO, Akikazu MATSUMOTO |
| <Abstract> Dismantlable adhesives require strong bonding with durability in use and easy debonding on demand. In order to satisfy the contradicting properties, we designed reactive acrylic copolymers and investigated their application to pressure-sensitive type dismantlable adhesives, in terms of the reduction in peel strengths, the achievement of interfacial failures, and quick dismantling. Reactive acrylic copolymers containing gas generating units and cross-linkable units resulted in significant reduction in the peel strength in response to heating in the presence of acid catalysts due to a decrease in the effective bonding area and an excess increase in modulus. Different failure modes were observed by changing morphology and the balance between gas generation and cross-linking. Acrylic copolymers containing hemiacetal esters achieved spontaneous debonding with both interfacial failures between adhesive layer, a metal adherend, and a support polymer film by simply soaking in boiling water. Precise polymer synthesis and the reaction control are shown to be effective for the design of high performance dismantlable adhesive materials. Keywords: Acrylic Copolymer / Pressure-Sensitive Adhesive / Dismantlable Adhesive / Gas Evolution / Cross-Linking / Failure Mode |
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| Favorable Place for Graphene Sheets in Polymer Composites | Kenji NAGATA, Ce TU |
| <Abstract> Electrically conductive polymer composites have numerous potential applications in high-voltage networks, charge dissipation, and reflective surfaces. Graphene has been shown to be an ideal component in many polymer composites. However, dispersion of graphene into non-polar polymers such as polyolefins has been difficult. Moreover, selective localization of the conductive component in the composites is critical. In this work, we prepared electrically conductive composites of graphene with polyethylene (PE) and polypropylene (PP) via melt compounding, and optimized the microstructure and electrical properties. Optimization of the processing conditions was found to significantly increase the amount of SEG located at the blend interface, resulting in an electrical conductivity of as high as 1.86 x 10-5 S/m at only 1 wt% SEG. Keywords: Graphene / Polymer Blend / Processing Sequence / Electrical Percolation Threshold / Selective Localization |
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| Polymer Science and I: A Personal Account |
| Make Change in the Environment | Yu SUZUKI |
| <Abstract> The changing environments brought me new perspectives and great encounters, and they saved my research life in various scenes. I would like to continue working with caring about new encounters and without a fear of change. |
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| Front-Line Polymer Science |
| Organic-Inorganic Hybrid Materials Utilizing Functions of Polysilsesquioxanes | Kimihiro MATSUKAWA, Seiji WATASE |
| <Abstract> Polysilsesquioxanes can be synthesized by a sol-gel method using the trialkoxysilane having an organic functional group on the silicon atom. As well-known the purified silsesquioxane of polyhedral cage and ladder structure, but they are disadvantage for the practical use by the high price. On the other hand, the random-type polysilsesquioxanes can be produced with relatively low cost that is prepared by simple sol-gel method, so we are interested in the functional organic-inorganic hybrids using the random-type polysilsesquioxanes. This paper describes about their application of novel random-type polysilsesquioxanes. Polymethylsilsesquioxanes and related compounds could be applied for the gate insulator of organic TFT devices. It was found that several functional groups provided specific properties. As polysilsesquioxanes prepared from carbazole-containing trialkoxysilane showed the characteristic of p-type semiconductor, their p-n junction device has a excellent function of rectifier. Thiol-containing polysilsesquioxanes generated the crosslinking hybrids by the thiol-ene reaction with multi-allyl compounds. These organic-inorganic hybrids showed the properties of flexible and self-healing. Keywords: Polysilsesquioxanes / Organic-Inorganic Hybrids / Organic TFT / Gate Insulator / Semiconductor / Rectifier / Thiol-Ene Reaction |
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