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Bamboo plastic composites have become a hot research topic and a key focus of research. However, many strong, polar, hydrophilic hydroxyl groups in bamboo flour (BF) results in poor interfacial compatibility between BF and hydrophobic polymers. Maleic anhydride-esterified (MAH-e-BF) and lactic acid-esterified bamboo flour (LA-e-BF) were prepared while using an in situ solid-phase esterification method with BF as the raw material and maleic anhydride or lactic acid as the esterifying agent. Fourier transform infrared spectroscopy results confirmed that BF esterification with maleic anhydride and lactic acid was successful, with the esterification degrees of MAH-e-BF and LA-e-BF at 21.04 ± 0.23% and 14.28 ± 0.17%, respectively. Esterified BF was characterized by scanning electron microscopy, contact angle testing, X-ray diffractometry, and thermogravimetric analysis. The results demonstrated that esterified BF surfaces were covered with graft polymer and the surface roughness and bonding degree of MAH-e-BF clearly larger than those of LA-e-BF. The hydrophobicity of esterified BF was significantly higher than BF and the hydrophobicity of MAH-e-BF was better than LA-e-BF. The crystalline structure of esterified BF showed some damage, while MAH-e-BF exhibited a greater decrease in crystallinity than LA-e-BF. Overall, the esterification reaction improved BF thermoplasticity, with the thermoplasticity of MAH-e-BF appearing to be better than LA-e-BF.

Maleoyl xanthan oligosaccharides (XGOSMAs) and phthaloyl xanthan oligosaccharides (XGOSPAs) were prepared by reacting xanthan oligosaccharides with maleic anhydride and phthalic anhydride, respectively. The substituting degrees (DSs) of XGOSMAs and XGOSPAs were determined by a neutralization reaction. XGOAMA-1 (DS = 0.30), XGOSPA (DS = 0.31), XGOSMA-2 (DS = 0.62) and XGOSPA-2 (DS = 0.60) were selected for structural characterization and antioxidant activity evaluation. Their structural changes were confirmed by Fourier transform infrared spectra (FT-IR), and their molecular weights were determined with a gel permeation chromatography method (GPC). The pyruvate acid and reducing sugar contents were determined by ultraviolet spectrophotometry and the dinitrosalicylic acid method. The antioxidant activity was evaluated by the scavenging of the superoxide anion radical (O2⼂-), hydroxyl radical (⼂OH), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and determination of reducing power. The results indicated that XGOSPA exhibited higher antioxidant activity than XGOSMA with similar substituting degrees in all the above mentioned antioxidant evaluation systems, which may be related to the fact that phthaloyl group has a stronger electron-withdrawing effect than the maleoyl group. [ABSTRACT FROM AUTHOR]

Abstract: N-Maleoyl chitosan oligosaccharide (NMCOS) and N-succinyl chitosan oligosaccharide (NSCOS) were prepared by acylation with maleic anhydride and succinic anhydride, respectively. Their structural changes were confirmed by Fourier-transform infrared (FT-IR) spectroscopy and their substituting degrees were determined both as 0.49 by conductometric titration. Their antioxidant activities were evaluated by scavenging superoxide anion , hydroxyl radical OH and determination of reducing power. The 50% inhibition concentrations (IC50) of NMCOS and NSCOS scavenging effect on were 2.25 and 3.27mg/mL, respectively. The IC50 of NMCOS scavenging effect on OH was 0.24mg/mL, however, at the same concentration determined, the value of NSCOS on OH was 30.5%. The reducing powers of NMCOS and NSCOS at the concentration of 2.40mg/mL were determined as 0.46 and 0.41, respectively. The above results showed that NMCOS has better antioxidant activities, which may be related to the fact that maleoyl has stronger electron-withdrawing effect than succinyl. [ABSTRACT FROM AUTHOR]

Abstract: Three N-carboxymethyl chitosan oligosaccharides (N-CMCOSs) with different degrees of substitution (NA: 0.28, NB: 0.41, and NC: 0.54, respectively) were prepared by the control of the amount of glyoxylic acid in the etherification process of chitosan oligosaccharide (COS). Their antioxidant activities were evaluated by the scavenging of 1,1-diphenyl-2-picrylhrazyl radical (DPPH) radical, superoxide anion and determination of reducing power. With the increasing of substituting degree, the scavenging activity of N-CMCOSs against DPPH radical decreased and reducing power increased. As for superoxide anion scavenging, the order is NB>NC>NA. The difference may be related to the different radical scavenging mechanisms and donating effect of substituting carboxymethyl group. [Copyright &y& Elsevier]

Bamboo plastic composites have become a hot research topic and a key focus of research. However, many strong, polar, hydrophilic hydroxyl groups in bamboo flour (BF) results in poor interfacial compatibility between BF and hydrophobic polymers. Maleic anhydride-esterified (MAH-e-BF) and lactic acid-esterified bamboo flour (LA-e-BF) were prepared while using an in situ solid-phase esterification method with BF as the raw material and maleic anhydride or lactic acid as the esterifying agent. Fourier transform infrared spectroscopy results confirmed that BF esterification with maleic anhydride and lactic acid was successful, with the esterification degrees of MAH-e-BF and LA-e-BF at 21.04 ± 0.23% and 14.28 ± 0.17%, respectively. Esterified BF was characterized by scanning electron microscopy, contact angle testing, X-ray diffractometry, and thermogravimetric analysis. The results demonstrated that esterified BF surfaces were covered with graft polymer and the surface roughness and bonding degree of MAH-e-BF clearly larger than those of LA-e-BF. The hydrophobicity of esterified BF was significantly higher than BF and the hydrophobicity of MAH-e-BF was better than LA-e-BF. The crystalline structure of esterified BF showed some damage, while MAH-e-BF exhibited a greater decrease in crystallinity than LA-e-BF. Overall, the esterification reaction improved BF thermoplasticity, with the thermoplasticity of MAH-e-BF appearing to be better than LA-e-BF. [ABSTRACT FROM AUTHOR]

Maleoyl xanthan oligosaccharides (XGOSMAs) and phthaloyl xanthan oligosaccharides (XGOSPAs) were prepared by reacting xanthan oligosaccharides with maleic anhydride and phthalic anhydride, respectively. The substituting degrees (DSs) of XGOSMAs and XGOSPAs were determined by a neutralization reaction. XGOAMA-1 (DS=0.30), XGOSPA (DS=0.31), XGOSMA-2 (DS=0.62) and XGOSPA-2 (DS=0.60) were selected for structural characterization and antioxidant activity evaluation. Their structural changes were confirmed by Fourier transform infrared spectra (FT-IR), and their molecular weights were determined with a gel permeation chromatography method (GPC). The pyruvate acid and reducing sugar contents were determined by ultraviolet spectrophotometry and the dinitrosalicylic acid method. The antioxidant activity was evaluated by the scavenging of the superoxide anion radical (O2(-)), hydroxyl radical (OH), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and determination of reducing power. The results indicated that XGOSPA exhibited higher antioxidant activity than XGOSMA with similar substituting degrees in all the above mentioned antioxidant evaluation systems, which may be related to the fact that phthaloyl group has a stronger electron-withdrawing effect than the maleoyl group., (Copyright © 2014 Elsevier Ltd. All rights reserved.)