| POLYMERS Vol.72 No.3 |
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COVER STORY
To Permeate or Not to Permeate, That is The Question |
| COVER STORY: Highlight Reviews |
| The Enemy of My Enemy is My Friend? History of Oxygen Permeable Materials Research | Eri ITO |
| <Abstract> Oxygen-shielding research has made great progress and various technologies have been developed for products in which “oxidation” should be avoided. On the other hand, in the field of contact lenses, which are medical devices for vision correction, research has been conducted to achieve higher oxygen permeability since their commercialization. This paper describes the history of oxygen-permeable materials that have evolved in the midst of dissociation from technological trends, and the expectations for the future. Keywords: Contact Lens / Cornea / Oxygen Deficiency Oxygen Permeability / Silicone / Gel / Small-Angle Scattering / Phase Separation |
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| Gas Barrier Technologies for Flexible OLEDS | Mitsuhiro KODEN |
| <Abstract> Flexible OLEDs devices require extremely high gas barrier technologies that generally means lower WVTR (Water Vapor Transmission Rate) values than 10－5 g/m2/day. This review describes the evaluation technologies and the fabrication technologies to achieve such high gas barrier technologies. As for the evaluation technologies, this review describes three types of methods that are the specialized equipment for WVTR, the Ca corrosion method and the evaluation using OLED devices. As the fabrication technologies, this review describes three types of technologies that are the vacuum deposition of inorganic layers, the inorganic/organic alternating stacking, and the laminating encapsulation. Keywords: Gas-Barrier Flexible OLED |
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| Gas Barrier of Plastic Food Packaging | Kazukiyo NAGAI |
| <Abstract> Plastic food packaging is designed to protect food from dust and insects until someone opens to eat it. It also has barrier properties against oxygen and moisture, so food does not go bad quickly. Thus, the packaging contributes to food-waste reduction. Gas-barrier plastic films are prepared through four fundamental packaging techniques and can be classified into three categories. High gas-barrier films are used for emergency rations, whereas low or middle ones are used for daily foods. Food makes contact directly with the inner surface of the packaging so that film materials are selected and manufactured in accordance with national regulations/laws. Currently, plastic food packaging is prepared using multilayer films to optimize gas-barrier performance for a given packaging technique. However, using multilayer films hinders the growth ratio of recycling after use. Packaging is also single-use. Therefore, designing environment-friendly plastic food packaging and the future lifestyle related to it is important. This review article discusses the gas barrier of plastic food packaging. Keywords: Plastic Food Packaging / Gas Barrier Film / Food Waste / Food Loss / Recycling of Plastics / Single-Use Plastics / Gas Transmission Rate / Water Vapor Transmission Rate |
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| COVER STORY: Topics and Products |
| UV Cut Film from Lignin and Clay Mineral with Controllable Gas Transmittance Nature | Kazuhiro SHIKINAKA |
| <Abstract> In this topics, I present a UV cut film consisting of lignin, an aromatic plant polymer, and clay mineral, an inorganic polymer from clay, with controllable gas transmittance nature. Here, lignin is extracted from plants by simultaneous enzymatic saccharification and comminution (SESC). The combination of clay mineral and lignin results in transparent films with a UV protective property because of the UV absorption nature of lignin. The preparation procedure of the films including the extraction process of components did not require hazardous chemicals. The optical properties and gas permeability of the films could be tuned by the phase separation structure of the clay minerals and lignin derivatives, e.g., the montmorillonite, a natural clay mineral, and lignin produces films with moisture/gas transmittance ability. The present film uses mineral and plant components as high-value industrial materials and reduces the environmental load of extracting limited petroleum-based resources. Keywords: Plant Biomass / Lignin / Clay Mineral / Composite Film / Water-Gas Transmittance Nature / Gas Barrier Property |
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| Method for Controlling Gas Permeability by Double Packaging | Hideki WATANABE |
| <Abstract> This paper describes a method for keeping the qualities of vegeables such as asparagus high. It is well known that modified atomosphere packaging can expand the shelf life of asparagus. It is important to keep O2 concentration abobe the limit that is around 5％. O2 concentration abnormity occurrs due to temperature change while stored. We found that double packaging can control the O2 concentration change speed in a smaller range compared to single packaging that is caused by temperatuer change. Double packaging can avoid O2 concentration abnormity easily. Keywords: Asparagus / Modified Atomosphere Packaging / Double Pachaging / Gas Permeabirity |
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| Polymer Science and I: A Personal Account |
| With All My Gratitude | Masayuki GON |
| <Abstract> I wonder when I wanted to be a chemist. This came to my mind while I received the request to write this column. Since I was in my childhood, I have always loved adventures. I took a small “journey” in my decision for chemistry. Even now, I continue this “journey” with all my gratitude. |
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| Front-Line Polymer Science |
| Progress in Ionomers | Yohei MIWA |
| <Abstract> Recent progress in ionomers is described in this review. In ionomers, ionic groups aggregate with each other and form nanosized aggregations that physically crosslink the polymer chains. Therefore, enhancement of the mechanical strength of polymers was the main motivation for introduction of ionic groups into polymers in past studies. On the other hand, the reversible property of the ionic crosslinks in ionomers is more in focus in recent studies. The design of dynamic ionic networks that autonomically rearrange is one of the important progress in ionomer research. Such dynamic networks enable self-healing and toughening in ionomers. In this review, the perspective of ionomers isdiscussed. Keywords: Ionomer / Ion / Elastomer / Crosslink / Self-Healing / Network |
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