title: Syntheses and characterization of konjac glucomannan acetate and their thermal and mechanical properties.
abstract: Fully substituted glucomannan triacetate (GMTAc) (degree of substitution (DS)=3.0) was prepared from konjac glucomannan (KGM) treated with acetic acid and trifluoroacetic anhydride (TFAA). The peaks in the (1)H- and (13)C NMR spectra of GMTAc were assigned in detail based on two-dimensional (DQF-COSY, HSQC and HMBC) NMR analysis. Glucomannan acetate samples (GMAc) with different degrees of substitution (DS=1.3, 1.7, 2.0 and 2.8) were prepared by partial deprotection of GMTAc. Thermal properties of GMAcs including GMTAc were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Their decomposition temperatures were higher than that of KGM, and increased with increase in DS. DSC measurements revealed that GMAc had a high glass transition temperature in the range of 178-219 °C, which decreased with increase in DS. The samples did not exhibit melting peaks, indicating that the GMAcs were amorphous. All GMAcs formed transparent films upon solvent casting, and tensile tests revealed that GMAc had a higher tensile strength and elongation to break at lower DS (1.3 and 1.7) compared to higher DS (2.0, 2.8 and 3.0). This means that the mechanical properties of GMAc could be controlled by DS.
authors: Science of Polymeric Materials, Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Tokyo 113-8657, Japan.
authors: Yukiko
authors: Y
authors: Enomoto-Rogers
authors: Yusuke
authors: Y
authors: Ohmomo
authors: Tadahisa
authors: T
authors: Iwata
mesh_terms: D019342:Acetic Acid / Q000737:chemistry*; D000107:Acetylation; D060326:Chemistry Techniques, Synthetic; D008351:Mannans / Q000138:chemical synthesis* / Q000737:chemistry*; D055595:Mechanical Phenomena; D012995:Solubility; D013696:Temperature; D014269:Trifluoroacetic Acid / Q000737:chemistry*
chemical_list: D008351:Mannans; C022901:(1-6)-alpha-glucomannan; D014269:Trifluoroacetic Acid; D019342:Acetic Acid