The fabrication of nanospheres with tailored structure has attracted much attention in material applications. Herein we found that the food additive, butylated hydroxytoluene (BHT), was able to adjust the solid and hollow structure of lignin nanospheres. At BHT concentrations greater than 0.3 mg/mL in tetrahydrofuran (THF), the obtained lignin nanospheres displayed a hollow structure due to phase separation between THF and water caused by BHT molecules, while the lignin nanospheres obtained without adding BHT exhibited a solid structure. BHT and lignin molecules containing a high content of the carboxy group did not participate in the formation of the nanospheres. Increases in the water stirring and dropping speeds reduced the diameter of the nanospheres, while increasing the initial concentration of lignin and BHT resulted in an increase in nanospheres diameters. Moreover, the shell wall thickness and single hole size could be controlled by employing the concentration of BHT and lignin. This work provides novel insights into the preparation of lignin nanospheres with tunable structures.
A cellulose-based superabsorbent exhibits excellent water absorbency and retention performance as well as biodegradability. However, the detailed biodegradation process in soil has not been monitored yet. Yellowing is another important factor affecting its appearance and storage. In this work, cellulose from flax yarn wastes (FYW) was used as the skeleton material to synthesize a cellulose-g-P(AA-co-AM) (FYW/PAA) superabsorbent. The properties of the FYW/PAA superabsorbent were characterized, especially its biodegradation process and yellowing mechanism. The resultant FYW/PAA presented excellent water absorbency and retention capabilities of 886 g/g in deionized water and 73.2 wt% after being dried at 60 °C for 12 h, respectively. The fracturing of β-1,4-glycosidic bonds on the flax-cellulose macromolecules is the main reason for the biodegradation of FYW/PAA in soil. This causes a 70.8 wt% degradation after FYW/PAA has been buried in soil for only 60 days. The drying method and UV irradiation have important implications for the yellowing of FYW/PAA. They facilitate the generation of chromophore and auxochrome groups on the flax-cellulose macromolecules. 2,6-Di-tert-butyl-4-methylphenol (BHT) exhibits excellent antioxidant properties to inhibit the yellowing of FYW/PAA products.
Lu Ruan,Ling Lu,Xiuying Zhao,Wanwei Xiong,Haiyan Xu,Sizhu Wu
Eucommia ulmoides seed oil with high health potential is prone to oxidative rancidity due to its rich unsaturated fatty acids. In this work, three natural antioxidants were selected for exploring the oxidation resistance of the oil compared with the common synthetic antioxidant BHT. Antioxidant activity and its dispersion and migration as well as oxygen barrier performance were predicted via the bond dissociation enthalpy ( BDE ), mean square displacement ( MSD ), binding energy ( E binding ) and permeability coefficient ( S ). The predicted comprehensive performance is as follows: myricetin > epicatechin > caffeic acid > BHT. Free radical scavenging assay and Rancimat assay confirmed the antioxidant activity and protective effect on oil. That is the protective effect of three natural antioxidants on Eucommia ulmoides seed oil is better than BHT and myricetin shows the optimal comprehensive performance. The induction period of myricetin/lipid system increased 164.5% compared with the control. The experimental results are in good consistent with the simulation predictions.
Highly efficient terpolymerizations of ethylene, propylene and 5-ethylidene-2-norbornene (ENB) using a half-titanocene containing iminoimidazolidine (T5) catalyst with a methylaluminoxane (MAO) cocatalyst could be achieved in the presence of small amounts of triisobutylaluminium (TIBA) and 2,6-ditertbutyl-4-methyl-phenol (BHT) at TIBA : BHT : Ti = 20 : 20 : 1 (molar ratio). The catalytic activity reached 2.20 × 107 g polymer per mol of Ti per h for the copolymerization of ethylene and propylene and the ethylene–propylene copolymer with a high incorporation ratio of propylene (39.1 mol%) was afforded by using the T5/TIBA/BHT/MAO catalytic system. Interestingly, the catalytic activity, the incorporation ratio of propylene into the copolymer chains and the percentage of randomly distributed sequences could be improved by an increase in the BHT/Ti molar ratio from 0 to 20. Very importantly, the ENB conversion could reach more than 95%, indicating that this T5/TIBA/BHT/MAO catalytic system exhibits excellent copolymerization ability for ENB with ethylene and propylene. The content of ENB units in the resulting ethylene–propylene–diene rubbers (EPDMs) could be increased up to 6.8 mol% (20.8 wt%) by increasing the ENB concentration in the monomer feed without sacrificing the catalytic activity and ENB conversion. The extremely high ENB conversion was significant for the highly efficient production of EPDMs with relatively low cost and short processes. The EPDM with a high content of ENB units is critical for rapid vulcanization during the processing and for the preparation of a functionalized EPDM. The CC double bonds in the ENB units in the above EPDM can be cleanly converted into carboxylic functional groups via light-mediated thiol–ene reaction, leading to the production of the functionalized EPDM with various contents of carboxylic side groups. The functionalized EPDMs exhibit enhanced hydrophilicity, which may result in good compatibility with inorganic fillers and strong interaction between inorganic fillers and organic terpolymers.
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