| POLYMERS Vol.69 No.2 |
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COVER STORY
Techniques for Bonding and Debonding |
| COVER STORY: Highlight Reviews |
| On-Demand Adhesion Bonding: Toward Integration of Dissimilar Materials Bonding and Dismantlable Adhesion | Akikazu MATSUMOTO |
| <Abstract> From the viewpoints of energy saving and low environmental impact, many polymers and composite materials are used instead of metal materials, and at the same time, the development of new methods for highly reliable bonding is an urgent issue. We proposed a new method for dissimilar materials bonding using epoxy monolith with a highly porous structure, which was fabricated by the thermal curing of epoxy resin with an amine cross-linker in the presence of polyethylene glycol as the porogen via polymerization-induced phase separation. We also developed a new type of thermally stable and thermally responsible polymers including the BOC group in the side chain and applied them as dismantlable adhesion materials. This review describes the current status of the research and development of dissimilar material bonding and dismantlable adhesion, and the future prospect of on-demand adhesive bonding for materials manufacturing design, aiming at the construction of a new system that combines dissimilar materials bonding and dismantling adhesion. Keywords: Anchor Effect / BOC Protection / Dissimilar Materials Bonding / Epoxy Monolith / Dismantlable Adhesion / Metal-Resin Bonding / Porous Materials / Thermal Decomposition |
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| Surface Structuring for Hybrid Materials Adhesion and Joining | Kiyokazu YASUDA |
| <Abstract> By forming nano/micro scale unique structures on the metal surface for adhesion and bonding of different materials, emerging concept that fundamentally differs from conventional adhesion and welding can be expected. Surface structured joining has a high degree of freedom in designing interfaces containing polymers because of the micromechanical interlocking mechanism. This paper reports the latest trend of surface structuring for adhesion and bonding of different materials. Keywords: Hybrid Bonding / Dissimilar Materials Joining / Surface Structuring / Laser Joining / Ultrasonic Bonding / Multi-Materials / Interface Design / Micro Mechanical Interlocking |
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| COVER STORY: Topics and Products |
| Adhesion of Fluoropolymers via Heat-Assisted Plasma Treatment | Yuji OHKUBO |
| <Abstract> Fluoropolymers such as polytetrafluoroethylene (PTFE) are one type of difficult polymers to adhere to other types of materials. Conventional plasma treatments, for example plasma treatment under low pressure and/or at low temperature, are not effective to improve the adhesion property of PTFE. Our research group discovered three key points for improvement of this property via plasma treatment; suitable pressure during plasma treatment, suitable surface temperature of PTFE, and no use of certain gases. In this paper, we will explain the reason why heating during plasma treatment drastically improves the adhesion property of PTFE. We realized adhesive-free strong adhesion between PTFE and unvulcanized isobutylene-isoprene rubber (IIR). We also successfully realized strong adhesion between PTFE and vulcanized polydimethylsiloxane (PDMS) rubber when the vulcanized PDMS surface was also plasma-treated. In addition, plasma-treated PDMS rubber was applied to strongly adhere PTFE to other types of materials such as copper film, stainless steel plate, and glass plate. Keywords: Fluoropolymers / Heat-Assisted Plasma Treatment / Surface Temperature / Adhesive-Free Adhesion / Cohesion Failure |
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| Novel Acrylic PSA Based on Tackifier Segregation onto the Surface | Kenichi NAKAMURA |
| <Abstract> The properties of a novel pressure sensitive adhesive (PSA) based on tackifier (TF) surface segregation were compared with the general PSAs with or without conventional TF. The peel strengths of the general PSAs were relatively high at room temperature, but decreased drastically under high temperature such as 60℃ and 85℃. On the other hand, the novel PSA based on TF surface segregation maintained high peel strength under high temperatures. The improvement of adhesion was more effective for polyolefin. Keywords: Tackifier / Surface Segregation / Pressure Sensitive Adhesive |
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| Easily Peelable PSAs with Cool-Off and Warm-Off Functions | Hiroto MURAKAMI |
| <Abstract> A side-chain crystalline acrylic pressure sensitive adhesive (PSA) is thermosensitive, because its adhesion can be controlled by a reversible order-disorder transition of the side-chain crystalline unit with a change in temperature. There are two types of thermosensitive PSAs: cool-off (CO) and warm-off (WO) types. The problem of the CO type PSA is that a treatment at high temperature over 200℃ results in a decline in CO function. The problem of the WO type PSA is that the WO function occurs in a broad temperature range earlier than the main transition temperature due to the use of a random-WO component. To solve these problems, we developed an acrylic PSA bearing a mesogenic unit and a silicone PSA containing a side-chain crystalline siloxane for the CO type, and a PSA containing an acrylic copolymer grafted with a side-chain crystalline acrylic macromonomer as the WO component. In this article, we describe the performance of these PSAs. Keywords: Side-Chain Crysatlline / Acrylic PSA / Silicone PSA / Easily Peelable |
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| Liquid-Solid Phase Change Materials Composed of Azobenzene Polymer, And its Reversible Adhesive Bonding | Haruhisa AKIYAMA |
| <Abstract> We synthesized an azobenzene polymer that exhibits a photophase transition between liquid and solid state. The length of the alkyl group is important in polymer materials exhibiting phase transitions. Fluidity in the liquid state is enhanced by long alkyl chains. It was suggested that the solid phase was stabilized by aggregation of azobenzene moieties. The performance of this material as a reversible adhesive for glass substrates has been evaluated and proven. In addition, the use of a block copolymer structure has improved toughness on thin film formation without reducing adhesive strength. Keywords: Azobenzene / Polymer / Isomerization / Reversible Adhesives / Block Copolymer |
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| Polymer Science and I: A Personal Account |
| Toward the Synthesis of Polymers | Naoya KANBAYASHI |
| <Abstract> In this essay, I describe the story of my personal research history in graduate school, and how I have developed my interests to the area of polymer synthesis from my original research backgrounds, organic and organometallic chemistry. |
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| Front-Line Polymer Science |
| Recent Development of Production, Characterization and Applications for Cellulose Nanofibers | Kojiro UETANI, Hirotaka KOGA, Masaya NOGI |
| <Abstract> Cellulose nanofibers with widths of 3～50 nm originate from bacteria, tunicates, and higher plants and have excellent physical properties such as high aspect ratio, high specific surface area, high crystallinity, high strength, high thermal dimensional stability, biocompatibility, and biodegradability. Based on these attractive properties, cellulose nanofibers have received worldwide attention from industry, academia and government as new bio-nanomaterials toward a sustainable society. Herein, we introduce preparation techniques, fundamental structures and properties of cellulose nanofibers, and show an overview of their present applications and future challenges. Keywords: Cellulose Nanofiber / Cellulose Nanopaper / Transparent Paper / Biomass / Composite / Green Chemistry / Green Electronics |
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