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

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

Solubility, Discoloration, and Solid-State ¹³C NMR Spectra of Stereoregular Poly(Vinyl Chloride) Prepared by Urea Clathrate Polymerization at Low Temperatures

Stereoregular poly(vinyl chloride) (PVC) was obtained by urea clathrate polymerization. The sample was a white crystalline powder. Its molecular structure was studied by appearance, FT-IR, WAXD, and NMR (solid) in comparison with those of ordinary free radical one. The sample was totally insoluble to polar solvent such as DMF in contrast with good solubility of free radical one. Prolonged heating at high temperatures ensured discoloration and elimination reaction permitted formation of trans-type double bond. This structural change was traced by FT-IR and solid-state NMR. Two non-compromise characteristics, stiff molecular chain and easy discoloration, in canal PVC are described

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