DEGRADATION OFSODIUMALGINATE BYLOWENERGYELECTRON BEAM

DEGRADATION OFSODIUMALGINATE BYLOWENERGYELECTRON BEAM. High viscosity (HV) and low viscosity (LV) alginate prepared in 5% solutions were irradiated by low energy electron beam (LEEB) at 55oC and ambient temperature respectively. Oligoalginates with molecular weight lower than 20,000 Da and broad molecular weight distribution were obtained until 60 minutes of irradiation. The decrease in molecular weight was accompanied by appearance of UV absorbance peak at 265 nm. LV alginate was preferable to use as raw material for LEEB irradiation process than HV alginate

Radiation Yield and Radicals Produced in Irradiated Poly (Butylene Succinate)

The main chemical effects of ionizing irradiation on polymers are crosslinking and chain scission. Both processes occur simultaneously and their yields determine the final results of processing. The radiation yield of crosslinking could be determined by several methods depending on the characteristics of the material and properties of the gel. Radiation parameters of gelation, such as gelation dose and ratio of scission yield to crosslinking yield, as well as their values were estimated. In this study, those parameters depend on the amount of Trimethallyl isocyanurate (TMAIC) in Poly(butylene succinate) (PBS), molecular weight of PBS, and irradiation condition. In the absence of TMAIC, higher molecular weight of PBS required less energy to start gelation process compare to lower molecular weight of PBS. While in the presence of TMAIC all of the PBS samples require similar energy to start gelation process. The existence of macroradicals were observed by Electron Spin Resonance measurements. The result showed that the spectra consisted of signals derived from radicals on carbon nearby carbonyl, and signals derived from radicals on carbon reside between two similar carbon on polymer, both of radicals lead to crosslinking

Radiation Yield and Radicals Produced in Irradiated Poly (Butylene Succinate)

The main chemical effects of ionizing irradiation on polymers are crosslinking and chain scission. Both processes occur simultaneously and their yields determine the final results of processing. The radiation yield of crosslinking could be determined by several methods depending on the characteristics of the material and properties of the gel. Radiation parameters of gelation, such as gelation dose and ratio of scission yield to crosslinking yield, as well as their values were estimated. In this study, those parameters depend on the amount of Trimethallyl isocyanurate (TMAIC) in Poly(butylene succinate) (PBS), molecular weight of PBS, and irradiation condition. In the absence of TMAIC, higher molecular weight of PBS required less energy to start gelation process compare to lower molecular weight of PBS. While in the presence of TMAIC all of the PBS samples require similar energy to start gelation process. The existence of macroradicals were observed by Electron Spin Resonance measurements. The result showed that the spectra consisted of signals derived from radicals on carbon nearby carbonyl, and signals derived from radicals on carbon reside between two similar carbon on polymer, both of radicals lead to crosslinking

Gelatin microspheres crosslinked with γ-ray : Preparation, sorption of proteins, and biodegradability

A new type of gelatin microspheres was manufactured with the crosslinking method by using γ-ray irradiation. Microspheres thus obtained were characterized by microscopic observation and enzymatic degradability. The mean diameter of the microspheres was in the range from 2.4 to 3.6 μm and the size distribution was quite small. The size decreased with increasing the shear rate of the emulsifier used in the preparation and was not affected by the radiation dose. The enzymatic degradability decreased with increasing the radiation dose and decreasing the gelatin concentration of the microsphere. In other words, the rate of the enzymatic decomposition of microspheres can be controlled by these two parameters. These trends were consistent with our previous results for the gel sheet made of gelatin. Their sorption of proteins was also investigated with the use of three types of proteins labeled by fluorescent pigment. From the fluorescence micrographs, it was observed that the gelatin microspheres adsorbed only proteins having the opposite charge.Terao, K., Karino, T., Nagasawa, N., Yoshii, F., Kubo, M. and Dobashi, T. (2004), Gelatin microspheres crosslinked with γ-ray: Preparation, sorption of proteins, and biodegradability. J. Appl. Polym. Sci., 91: 3083-3087. https://doi.org/10.1002/app.13574

Nanometer-sized gelatin particles prepared by means of gamma-ray irradiation

Nanometer-sized gelatin particles have been prepared by means of gamma-ray irradiation and characterized by static and dynamic light scattering combined with circular dichroism measurements. The molecular weight of the nanoparticles was much larger than that of the original gelatin molecules, whereas the hydrodynamic radius was much smaller. Radius of gyration evaluated from the angular dependence of the static light scattering intensity decreased with increasing irradiation dose. Circular dichroism spectra of the gelatin nanoparticles were independent of temperature, and it is suggested that the nanoparticles consist of highly and randomly packed gelatin and their conformation is stable against the temperature change

Reagent-free crosslinking of aqueous gelatin : manufacture and characteristics of gelatin gels irradiated with gamma-ray and electron beam

This is an Author's Accepted Manuscript of an article published in include the complete citation information for the final version of the artcle as published in the Journal of Biomaterials Science, Polymer Edition, 2003-11, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1163/15685620332255343

THE HEAT STABILITY OF RADIATION CROSSLINKED OF BIONOLLE

THE HEAT STABILITY OF RADIATION CROSSLINKED OF BIONOLLE. Bionolle with chemical names Poly(butylene succinate-co-adipate), Poly(butylene succinate) (PBS), were irradiated using electron beam (EB) in presence of five different polyfunctional monomers at ambient temperature. It was pointed out that the highest amount of gel fraction could be achieved when PBS wad blend with trimethallyl isocyanurate (TMAIC). It was obtained that crosslinked BS containing 1% of TMAIC produces higher gel fraction than that crosslinked PBS containing 2 or 3% TMAIC at dose of 50 kGy. The PBS containing 1% of TMAIC also has higher glass transition (Tg) than that of original PBS. It was observed that the presence of crosslinking bonds in irradiated PBS greatly improved its heat stability as well as diminished its ability to biodegradation. Accordingly, it can be concluded that crosslinked PBS in the presence of TMAIC has significantly improved heat resistant properties

Synthesis of polysaccharide hybrid gel in ionic liquids via radiation-induced crosslinking

我々は、イオン液体を用いて難溶性天然多糖類を溶液化し、放射線を照射することで、化学処理を必要としない環境にやさしい多糖類ゲルの開発に成功した。これらの多糖類ゲルは、低毒性・生体適合性・導電性であることから生体電極への応用が期待される。一方で、これらの多糖類ゲルの収率は低く、膨潤度、弾性率も実用的な生体電極に要求される1 g/g, 10-100 kPa以下であった。本研究では、イオン液体と放射線照射法を組み合わせることで天然多糖類の複合材料を作製し、収率や物性の向上を目指す。セルロースおよびキトサンを5 wt%で混合し、含水率26 wt%の条件でイオン液体γ線照射することで、放射線架橋複合ゲルを80%以上の高収率で得ることに成功した。この複合ゲルの膨潤度および弾性率は、最大で12 g/g, 25 kPaに達した。また、この複合ゲルは生体電極に求められる37～120℃の範囲で耐熱性を有し、放射線加工した後も生分解性が維持されていることを確かめた。さらに、複合ゲルの電圧に対する屈曲運動性（曲率）は0.09 m-1 V-1であり、一般的なイオンゲルアクチュエータの値（0.1 m-1 V-1）に近いことが分かった

FORMATION OF POLYSACCHARIDE HYBRID GEL IN IONIC LIQUIDS BY USE OF RADIATION-INDUCED CROSSLINKING

我々は、イオン液体を用いて難溶性天然多糖類を溶液化し、放射線を照射することで、化学処理を必要としない環境にやさしい多糖類ゲルの開発に成功した。これらの多糖類ゲルは、低毒性・生体適合性・導電性であることから生体電極への応用が期待される。一方で、これらの多糖類ゲルの収率は低く、膨潤度、弾性率も実用的な生体電極に要求される1 g/g, 10-100 kPa以下であった。本研究では、天然多糖類の複合材料を作製し、収率や物性の向上を目指す。セルロースおよびキトサンを5 wt%で混合し、含水率18 wt%の条件でイオン液体γ線照射することで、放射線架橋複合ゲルを80%以上の高収率で得ることに成功した。この複合ゲルの膨潤度および弾性率は、最大で12 g/g, 25 kPaに達した。さらに、複合ゲルの電圧に対する屈曲運動性（曲率）は0.06 m-1 V-1であり、一般的なイオンゲルアクチュエータの値（0.1 m-1 V-1）に近いことが分かった。The 10th International Conference of Modification, Degradation and Stabilization of Polymers (MoDeSt2018