Abstract
α- and β-chitosan with molecular weight of 190,000 and 800,000 respectively, were depolymerized by e-beam irradiation with various doses. The radiation yield of scission (Gs) and degradation rate of the chitosans were identified. The synergistic chemical degradation in the presence of hydrogen peroxide is more effective at lower doses. Mw of β-chitosan was dramatically decreased from 800,000 to 21,030 at the irradiation dose 5 kGy, on the other hand, that of α-chitosan was decreased much more gradually from 190,000 to 36,000. The values of Gs at 10 kGy in the solution without H2O2 and with H2O2 were respectively 6.09 × 10-5 mol/cal and 30.6 × 10-5 mol/cal for α-Chitosan, and 8.18 × 10-5 mol/cal and 43.8 × 10-5 mol/cal for β-chitosan. It was obviously effective on depolymerization by using the combination of e-beam and H2O2. α-Chitosan molecules are likely to adopt a diffuse conformation in the solution and make the different morphologies depending on the concentration.
Highlights
Chitosan which is composed of a copolymer of N-acetylglucosamine and glucosamine is a linear polysaccharide composed of randomly distributed β-(1→4)linkage, deacetylated unit and acetylated unit
The values of Gs at 10 kGy in the solution without H2O2 and with H2O2 were respectively 6.09 × 10−5 mol/cal and 30.6 × 10−5 mol/cal for α-Chitosan, and 8.18 × 10−5 mol/cal and 43.8 × 10−5 mol/cal for β-chitosan. It was obviously effective on depolymerization by using the combination of e-beam and H2O2. α-Chitosan molecules are likely to adopt a diffuse conformation in the solution and make the different morphologies depending on the concentration
We will discuss the conformation of α- and β-chitosan depoloymerized by electron beam (EB) irradiation with/without hydrogen peroxide using a recent advancement in the analysis of the molar mass and size dependencies of radiation yield of scission and the MH coefficients [15]
Summary
Chitosan which is composed of a copolymer of N-acetylglucosamine and glucosamine is a linear polysaccharide composed of randomly distributed β-(1→4)linkage, deacetylated unit and acetylated unit. Depolymerization by high energy beam radiation has been recently investigated, since this technique provides a useful tool to separate oligo-chitosans without the need of additional processing [4] [5]. The dependence of intrinsic viscosity on molecular weight provides information on the conformation and extension of polymers. The slope, a, can vary from 0 (compact sphere) over 0.65 - 0.85 (random coil) to 2.0 (very rigid rod chain) revealing information about the polymer conformation in solution. Conformation of polymers is a function of its molecular weight, chain flexibility, solvent proper-. We will discuss the conformation of α- and β-chitosan depoloymerized by EB irradiation with/without hydrogen peroxide using a recent advancement in the analysis of the molar mass and size dependencies of radiation yield of scission and the MH coefficients [15]
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