This study investigated in vitro antioxidant activity of Sonchus oleraceus L. by extraction solvent, which were examined by reducing power, hydroxyl radical-scavenging activity(HRSA) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. 70% MeOH extract had the greatest reducing power while EtOH extract had the greatest HRSA. The antioxidant activity of S. oleraceus extracts was concentration dependent and its IC50 values ranged from 47.1 to 210.5 µg/ml and IC50 of 70% MeOH, boiling water and 70% EtOH extracts were 47.1, 52.7 and 56.5 µg/ml, respectively. 70% MeOH extract of S. oleraceus contained the greatest amount of both phenolic and flavonoid contents. The extracts tested had greater nitrite scavenging effects at lower pH conditions. The cytotoxic activity showed that EtOH extract had the best activity against the growth of stomach cancer cell. These results suggest that S. oleraceus extract could be used as a potential source of natural antioxidants.

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Kraft lignin (KL) or plasticized KL (PKL)/poly(lactic acid) (PLA) composites, containing different lignin contents and with and without the coupling agent, were prepared in this study using twin-screw extrusion at 180 • C. Furthermore, ε-caprolactone and polymeric diphenylmethane diisocyanate (pMDI) were used as a plasticizer of KL and a coupling agent to improve interfacial adhesion, respectively. It was found that lignin plasticization improved lignin dispersibility in the PLA matrix and increased the melt flow index due to decrease in melt viscosity. The tensile strength of KL or PKL/PLA composites was found to decrease as the content of KL and PKL increased in the absence of pMDI, and increased due to pMDI addition. The existence of KL and PKL in the composites decreased the thermal degradation rate against the temperature and increased char residue. Furthermore, the diffusion coefficient of water in the composites was also found to decrease due to KL or PKL addition.PLA is considered one of the most promising biopolymers due to its excellent properties, which include biodegradability, biocompatibility, and renewability, as well as good mechanical properties [10][11][12]. PLA is derived from agricultural products (e.g., corn and potato) and is usually produced by ring-opening polymerization of lactide and condensation of lactic acid without polluting the environment during the production process [6,10,13]. However, despite its properties, the application of PLA has been limited because of its higher price and lower resistance to heat and water [11,13]. It has been proposed that compounding PLA with filler can improve its properties and remove some of its drawbacks [5,[11][12][13][14][15]. Recently, some studies have introduced lignin to improve the performance of PLA and reduce the cost [10,13,14].Lignin is one of the most abundant biopolymers, accounting for nearly 25% of lignocellulosic biomass [16][17][18][19]. It is usually easily obtained as a byproduct of the pulping industry and has some positive properties, including being biodegradable, non-toxic, and low-cost and having low density and excellent thermal and moisture resistance [20][21][22][23]. Due to these properties, research on lignin application for bioplastics has increased. Lignin has been known to have positive effects on composite properties. Some studies have observed that lignin addition enhances resistance for heat and moisture [14,15,24]. Furthermore, lignin has also been utilized as a stabilizer to prevent oxidation on plastic composites [25]. However, some studies have reported that the presence of lignin can deteriorate the mechanical properties of lignin-based composites. Lignin has been found to be incompatible with most aliphatic polyesters, including PLA, PBS, and PCL, thus deteriorating the mechanical properties of the composites [26][27][28]. However, it has been found that this strength deterioration, which is caused by lignin addition, can be overcome by adding coupling agents [26,[29][30][31]. Isocyanate coupling agents, such...

Cellulose and chitosan solutions were prepared in 60% LiBr and mixed with a different weight ratio. The washing and drying of the prepared cellulose–chitosan composite films were performed under identical conditions. The color of the liquefied mixtures and films was initially transparent but changed from colorless to brownish yellow depending on the ratio of chitosan in the solution. The cross section observed in the SEM results indicated that the film developed with a higher ratio of chitosan was more robust and possessed greater antibacterial properties. FT-IR analysis of the films showed that hydrogen bonds between cellulose and chitosan in composite films were successfully achieved and retained excellent mechanical properties. The proper ratio of chitosan in the cellulose solution can increase the tensile strength and improve the elongation of the films; however, the E-modulus property was consistently reduced. The antibacterial activity and mechanical properties of the films were greatly improved as the amount of chitosan in the film increased.

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