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Chitin/poly(2-hydroxyethyl methacrylate) (PHEMA) composites were synthesized via photo-polymerization in a gel state of chitin swollen with HEMA monomer as reactive impregnant. The transition behavior and phase structure of the chitin/PHEMA composites were characterized by differential scanning calorimetry, dynamic viscoelastic analysis, and solid-state 13C NMR spectroscopy. For compositions containing ≲ 20wt% chitin, it was reasonably assumed that an original network structure of chitin gels was sufficiently perpetuated into the cross-linked PHEMA matrix, resulting in the formation of an interpenetrating polymer network (IPN) type organization. Owing to this IPN effect, the lowering of the dynamic modulus E of the composites in the glass transition temperature region was extremely suppressed, compared with the corresponding E-drop observed for plain PHEMA samples. From measurements of the proton spin-lattice relaxation times t1ρh in the NMR study, the IPN-like composites were estimated to be homogeneous on a scale of less than ~2.4nm. |
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