2020, Vol. 5, No. 1

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Superhydrophobic modification of cellulose and cotton textiles: method-ologies and applications
David W. Wei, Wei Wei, Alec C. Gauthier, Junlong Song, Yongcan Jin, Huining Xiao
2020, 5(1): 1-15. doi: 10.1016/j.jobab.2020.03.001
Superhydrophobic cellulose-based products have immense potential in many industries where plastics and other polymers with hydrophobic properties are used. Superhydrophobic cellulose-based plastic is inherently biodegradable, renewable and non-toxic. Finding a suitable replacement of plastics is highly desired since plastics has become an environmental concern. Despite its inherent hydrophilicity, cellulose has unparalleled advantages as a substrate for the production of superhydrophobic materials which has been widely used in self-cleaning, self-healing, oil and water separation, electromagnetic interference shielding, etc. This review includes a comprehensive survey of the progress achieved so far in the production of super-hydrophobic materials based on cellulose and fiber networks. The method-ologies and applications of superhydrophobic-modified cellulose and fiber networks are emphasized. Overall, presented herein is targeting on summarizing some of the aspects that are critical to advance this evolving field of science which may provide new ideas for the developing and exploring of superhydrophobic and green-based materials.
A review on raw materials, commercial production and properties of lyocell fiber
Xiaoya Jiang, Yuanyuan Bai, Xuefeng Chen, Wen Liu
2020, 5(1): 16-25. doi: 10.1016/j.jobab.2020.03.002
As one of the regenerated cellulosic fibers,viscose fiber has the largest output. However,the wastes produced in the manufacturing process are difficult to eliminate,which restricts the development of viscose fiber. Lyocell fiber is claimed as "green and eco-friendly fiber" with a good application prospect in the 21st century. The preparation of lyocell fiber is based on the cellulosic non-derivative solution system,i.e.,N-methylmorpholine-N-oxide system which is nontoxic and recyclable. Firstly,the demands of dissolving pulp properties for regenerated-cellulosic fiber (RCF),especially for lyocell fiber,were introduced in detail. Next,the whole manufacturing processes including pretreatment,preparation of spinning dope,spinning,posttreatment and efficient solvent recovery technologies were reviewed emphatically. Then,the properties and structural characteristics of lyocell fiber were illustrated. At last,some suggestions were proposed for lyocell fiber development in China.
Utilization of discarded crop straw to produce cellulose nanofibrils and their assemblies
Xiaran Miao, Jinyou Lin, Fenggang Bian
2020, 5(1): 26-36. doi: 10.1016/j.jobab.2020.03.003
A tremendous amount of wheat straw (WS) has been generated by wheat crops every year, while only a small percentage is being used in applications, and most get burned on the field, causing a large amount of the exhaust gas that pollutes the environment. Herein, we report on the extraction of cellulose nanofibrils (CNF) from the alkali treated WS by a combination of TEMPO-oxidation and mechanical disintegration method. The crystalline structures, thermal properties, natural charge of the CNF were examined. The resultant nano-building blocks of CNF was assembled into macroscopic cellulose materials, i.e., film, aerogel, and filament in this work. Furthermore, the morphologies and microstructues as well as other properties of these three kinds of the CNF assemblies were investigated. The obtained CNF and its assemblies showed a potential application in new materials areas. This work explored a new way to utilize the discarded WS instead of being burned.
Preparation of hydrophobic transparent paper via using polydi-methylsiloxane as transparent agent
Feixiang Guan, Zhaoping Song, Furong Xin, Huili Wang, Dehai Yu, Guodong Li, Wenxia Liu
2020, 5(1): 37-43. doi: 10.1016/j.jobab.2020.03.004
Transparent paper with good hydrophobicity and flexibility was expected to act as an alternative substrate in fabrication of flexible electronics. However, conventional paper made of cellulose fibers was opaque and hydrophilic without undergoing special processing. Herein, cellulose fiber paper was treated by impregnating with hydrolyzed tetraethyl orthosilicate (TEOS) followed by coating with hydrophobic polydimethylsiloxane (PDMS) to prepare hydrophobic transparent paper. The results showed that silica nanoparticles produced by the TEOS hydrolysis improved the paper transparency to some extent, increased the paper thermal stability, but still remained the hydrophilicity of paper. After the paper was further coated with the PDMS and the PDMS was consolidated, the paper became clearly transparent and hydrophobic. The processed paper had a transmittance of more than 90% at 550 nm. The water contact angle of the paper reached about 110°. This work provided a new approach for the fabrication of hydrophobic transparent paper with conventional cellulose fiber paper.
Effect of different combinations of emulsifier and wall materials on the physical properties of spray-dried microencapsulated swida wilsoniana oil
Xiaohua Yang, Shouhai Li, Jiujuan Yan, Jianling Xia, Lixin Huang, Mei Li, Haiyang Ding, Lina Xu
2020, 5(1): 44-50. doi: 10.1016/j.jobab.2020.03.005
Spray drying was used to produce microencapsulated Wilson Dogwood (Swida wilsoniana) oil. The influences of the emulsifier and wall materials on the encapsulation were studied in order to produce high quality encapsulated S. wilsoniana oil. The emulsions were prepared by using lecithin (L) and Tween 80 (T) with different hydrophilic-lipophilic balance. Results indicate that the stable emulsion was obtained using T and L as the compound emulsifier at a ratio of 4/6 (w/w). By virtue of the compound emulsifier (T/L 4/6), the microencapsulation efficiency (MEE) reached 91%, and the oil loading up to 35% were achieved. We also examined the influence of the wall materials on the microencapsulation of S. wilsoniana oil. All the three wall materials exhibited high MEE (>85%), and the highest MEE (95.20%) was obtained with sodium caseinate/lactose. All the S. wilsoniana oil encapsulated with the three wall materials exhibited nearly spherical microcapsules without pores or cracks-thus protecting the oil from oxygen.
Remedial ability of maize (zea-mays) on lead contamination under potted condition and non-potted field soil condition
Uche Jenice Chiwetalu, Constantine Crowner Mbajiorgu, Nneka Juliana Ogbuagu
2020, 5(1): 51-59. doi: 10.1016/j.jobab.2020.03.006
This study presents the remedial ability of maize on lead (Pb) contaminated soil. Soil samples were collected randomly from the site and subjected to physico-chemical tests before experimentation. The samples were contaminated artificially at six different concentration levels of lead nitrate (Pb(N03)2). Experimental design was 4-factorial combination (6×6×2×1). The study duration was 10 weeks, and during this period, Pb contents of the soil were analyzed in intervals of two weeks. Analyzed physico-chemical properties of the soil showed that the soil was loamy with pH 6.82, electri-cal conductivity 1.62 dS/m and adequate macro nutrient elements. The average percentage removal of Pb from the soil was 2.25% and 3.67% for potted and non-potted experiments, respectively. Similarly, the average percentage of Pb in the roots was 1.10% and 1.68% for potted and non-potted experiments, respectively. The result of this study indicated that extraction of Pb by the plant system increased with the increase of lead concentration in the soil as well as in the extent of vegetation attained by the crop. It also clearly showed that the non-potted experiments demonstrated greater influence on removal of Pb from the soil system than the potted experiments.
Competitive polycondensation of model compound (MUF) resin system by 13C NMR
Jiankun Liang, Quan Li, Zhigang Wu, Guanben Du, Taohong Li, Hong Lei
2020, 5(1): 60-66. doi: 10.1016/j.jobab.2020.03.007
Melamine-urea-formaldehyde (MUF) resin is an excellent adhesive in the field of wood adhesives, however the com-petition mechanism is questionable which affects the structure control and performance optimization of the resin. In this sduty, the competitive resin synthesis polycondensation reaction of MUF system under alkaline condition was studied based on the model compound 1, 3-dihydroxymethyl urea (UF2) and melamine (M) system, and the competitive reaction mechanism in the system was deduced by 13C NMR quantitative analysis. The results show that the energy barrier of hydroxymethylation of melamine is lower than that of urea, and the priority of hydroxymethylation is lower; the addition of melamine results in a large amount of hydrolysis of UF2, and the formed free formaldehyde, resulting in hydroxymethylation of melamine; there is obvious polycondensation reaction in UF2+M system, mainly from the relationship between Hydroxymethylurea and melamine or hydroxymethylmelamine. The type I bridge bond structure of polycondensation mainly comes from the reaction of UF2 and M, which is difficult to form the type II bridge bond. At low molar ratio, the formation of bridge bond is superior to that of ether bond. With the increase of molar ratio, the formation of ether bond shows advantages, but there is obvious competition between them. There may be competitive presence of the UF self-condensation products, melamine-formaldehyde (MF) self-condensation products and MUF co-condensed products after the polycondensation reaction.
Lignin-based phenolic resin modified with whisker silicon and its ap-plication
Na Zhang, Zhuo Li, Yanan Xiao, Zheng Pan, Puyou Jia, Guodong Feng, Caiying Bao, Yonghong Zhou, Lilong Hua
2020, 5(1): 67-77. doi: 10.1016/j.jobab.2020.03.008
In this study, lignin-based phenolic resin was modified with whisker silicon and preparation of the phenolic foam is carried out. The resin and foam materials were characterized by Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analyzer (TGA), thermal conductivity test, limit oxygen index (LOI) analyzer and cone calorimeter. The results showed that if the content of lignin and whisker silicon increases, the oxygen index of the foam increases and the calorific value of combustion decreases. However, if the amount of lignin increased, the open porosity of the foam and the thermal conductivity increased. When the lignin substitution rate was 30% and the whisker silicon addition amount was 1%, the phenolic foam (PF4) has the best performance:the 57.1% mass lost at 600℃ and the thermal stability was 16.8% higher than that of ordinary resin. The LOI was 49.6%, and 39.3% higher than that of ordinary phenolic foam.