Preparation of a Larch Bark-Based Composite and its Properties

2011 ◽  
Vol 183-185 ◽  
pp. 2005-2009
Author(s):  
Lu Wang ◽  
Shu Jun Li ◽  
Pei Pei Liu ◽  
Guang Shou Feng ◽  
Hao Zhong
Keyword(s):  
Moisture Absorption ◽  
Renewable Resource ◽  
Molar Ratio ◽  
Total Phenolic ◽  
Hydroxyl Groups ◽  
Fossil Energy ◽  
Whole Process ◽  
Swelling Rate ◽  
Phenolic Hydroxyl Groups

With the depletion of fossil energy, biology material is getting more and more attention. Bark, as a kind of renewable resource, need to be utilized urgently and reasonably. The larch bark was very extensive in northeast and the use of larch bark is limited to make tannin. However, the whole process produced much bark residue, which could not be utilized effectively. In this paper, based on the content of total phenolic hydroxyl groups, the in-situ synthesis reaction of the larch bark with formaldehyde was performed in different ratios. FTIR analysis was adopted to characterize the synthesized products. After air-drying, the synthesized product was pressed into a bark-based composite under pressure of 10~25 MPa. The effect of pressure and molar ratio of phenols and formaldehyde on the properties of the composite were analyzed. These results indicate that, pressure and molar ratio were both vital factors. The composite with higher molar ratio of phenol and formaldehyde had better abilities of anti-moisture, but the molar ratio of 1:2 made the strongest composite. With the increasing of pressure, the hardness of the composite was greater. For the composite made under 20 MPa and the molar ratio of 1:2, its hardness was 23.41 MPa and its max load was 415.83N. Its thickness and diameter swelling rate of moisture absorption in 12 d was 1.87% and 0.68%.

scholarly journals Transparent Cellulose/Technical Lignin Composite Films for Advanced Packaging

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1455 ◽  
Author(s):  
Guo ◽  
Tian ◽  
Shen ◽  
Yang ◽  
Long ◽  
...  
Keyword(s):  
Composite Films ◽  
Deep Eutectic Solvent ◽  
Value Added ◽  
Phenolic Hydroxyl ◽  
Total Phenolic ◽  
Hydroxyl Groups ◽  
Uv Shielding ◽  
Technical Lignin ◽  
Phenolic Hydroxyl Groups ◽  
Technical Lignins

Although recent work has shown natural lignin products are promising to fabricate various polymer based functional composites, high-value applications were challenged by their structural complexity and inhomogeneity. This work specially assessed the potential of four technical lignins for cellulose based functional films production. These four technical lignins were obtained by emerging pretreatment systems, i.e., lactic acid-betaine deep eutectic solvent (DES), ethanol organosolv, soda/anthraquinone (Soda/AQ) and the sodium salicylate hydrotrope, and their phenolic substructures were comparatively identified by prevalent 31P NMR technique. The influence of lignin chemical structure on the antioxidant potential and UV-shielding performance of the prepared cellulose/technical lignin composite films were assessed. Results showed severe organosolv and soda/AQ pretreatment produced technical lignins with higher total phenolic hydroxyl groups (3.37 and 3.23 mmol g-1 respectively), which also exhibited higher antioxidant activities. The composite films could effectively block the ultraviolet lights especially for UVB region (ultraviolet B, 280–315 nm) at only 5 wt.% lignin content. The contribution of lignin phenolic substructures to both antioxidant activity and UV-shielding property from high to low was syringyl > guaiacyl > p-hydroxyphenyl phenolic hydroxyl groups. This work provided some useful information that could facilitate upstream lignin extraction or downstream value-added applications.

Cellulose nanocrystals/silver nanoparticles: in-situ preparation and application in PVA films

Holzforschung ◽  
2020 ◽  
Vol 74 (5) ◽  
pp. 523-528 ◽  
Author(s):  
Li Fan ◽  
Hui Zhang ◽  
Mengxi Gao ◽  
Meng Zhang ◽  
Pengtao Liu ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Cellulose Nanocrystals ◽  
Food Packaging ◽  
Moisture Absorption ◽  
Antibacterial Properties ◽  
Nanocomposite Films ◽  
Hydroxyl Groups ◽  
In Situ Preparation ◽  
The Many

AbstractWith the increasing application of polyvinyl alcohol (PVA) films in the field of food packaging, it is important to improve its mechanical and antibacterial properties. This paper focuses on the preparation of PVA nanocomposite films and how their properties are affected by a silver-loaded nanocellulose solution. Cellulose nanocrystals (CNCs) were used as both the carrier and the dispersant of silver nanoparticles (AgNPs) prepared using glucose as the reducing agent. Ag+ was stabilized by the many hydroxyl groups located in the CNCs, and then the Ag+ was reduced to AgNPs in situ. After addition of silver-loaded nanocellulose, the tensile strength of the CNC-PVA-AgNP films increased from 47 MPa to 73 MPa, and the nanocomposite films displayed reduced moisture absorption and good antibacterial properties.

Laccase-Catalyzed Dyeing and Finishing of Textiles with Gallic Acid

2013 ◽  
Vol 631-632 ◽  
pp. 608-612
Author(s):  
Sha Sha Sun ◽  
Ren Cheng Tang
Keyword(s):  
Gallic Acid ◽  
Oxidation Product ◽  
Functional Performance ◽  
Hydroxyl Groups ◽  
Aromatic Rings ◽  
Vis Spectroscopy ◽  
Phenolic Hydroxyl Groups ◽  
Rhus Vernicifera ◽  
Dyed Fabrics

Laccase from Rhus vernicifera was applied to catalyze the polymerization of gallic acid (GA) as a way of “in situ” dyeing and finishing for wool, silk, nylon, cotton and viscose fabrics. The laccase-catalyzed polymerization of GA was confirmed by the results of UV-vis spectroscopy and differential thermal analysis. The adsorption of the GA oxidation product on the fibers contributed to the color effect and functional performance of treated fabrics. The dyed fabrics exhibited gray colors with pale to medium shades, depending on fiber categories. All the dyed fabrics showed significantly enhanced UV protection performance and antioxidant activity, and the dyed wool and silk had obviously improved deodorizing ability. These improved functional properties were related to the increased quantity of aromatic rings, phenolic hydroxyl groups and carboxyl groups in the GA oxidation product adsorbed by fibers.

scholarly journals Study on the cleavage of alkyl-O-aryl bonds by in situ generated hydroxyl radicals on an ORR cathode

RSC Advances ◽  
2017 ◽  
Vol 7 (81) ◽  
pp. 51419-51425 ◽  
Author(s):  
Lei Wang ◽  
Yongmei Chen ◽  
Shuangyan Liu ◽  
Haomin Jiang ◽  
Linan Wang ◽  
...  
Keyword(s):  
Hydroxyl Radicals ◽  
Active Sites ◽  
Bond Cleavage ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Phenolic Hydroxyl Groups

˙OH selectively attacks the active sites opposite to phenolic hydroxyl groups and leads to bond-cleavage of ether bonds.

Direct method for the determination of phenolic hydroxyl groups in pulp

Holzforschung ◽  
2007 ◽  
Vol 61 (6) ◽  
pp. 623-627 ◽  
Author(s):  
Tiina Liitiä ◽  
Tarja Tamminen
Keyword(s):  
Direct Method ◽  
Total Content ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Group ◽  
Total Phenolic ◽  
Hydroxyl Groups ◽  
Peroxide Bleaching ◽  
Uv Reflectance ◽  
Phenolic Hydroxyl Groups ◽  
Reflectance Measurements

Abstract For evaluation of changes in phenolic lignin units during kraft pulping and bleaching, a direct method based on UV reflectance measurements of pulp handsheets was tested. Similar trends in total phenolic hydroxyl-group contents were evident when UV reflectance results for isolated lignins and pulp sheets were compared. This direct method gave reliable results after alkaline cooking, oxygen delignification, and bleaching stages followed by alkaline extraction (DE, ZE). However, the phenolic content obtained after peroxide bleaching (QP) was over-estimated. This may be due to alkali-induced reactions during pH adjustment of the sheets for measurement concomitant with ionisation of the phenolic hydroxyl groups. Otherwise, this direct method based on UV reflectance measurements is a promising new approach for determining the total content of phenolic lignin units in pulp sheets without isolating the lignin.

scholarly journals The feasibility of using red mud in coatings based on glyptal resins

2020 ◽  
Vol 8 (1) ◽  
pp. 88-94
Author(s):  
Liubov Melnyk ◽  
Oleksiy Myronyuk ◽  
Volodymyr Ratushniy ◽  
Denys Baklan
Keyword(s):  
Carbonyl Group ◽  
Red Mud ◽  
Industrial Waste ◽  
Filling Factor ◽  
Moisture Absorption ◽  
Van Der Waals ◽  
Hydroxyl Groups ◽  
Surface Groups ◽  
Chemical Bonds

The possibility of industrial waste – alkaline red mud to be used as the filler of glyptal resins and coatings thereof is considered. It was determined that the most effective way of compounding of said components was in situ combinations during the synthesis of the polymer, providing systems with filling factor up to 36 wt.% with decreased moisture absorption ability in comparison to the initial resin. It was demonstrated that the most probable cause of this performance increase is the formation of chemical bonds between the hydroxyl groups of glyptal and weak van der Waals bonds between the carbonyl group of the resin and surface groups on red mud.

Studies on the dehydrogenative polymerization of monolignol β-glycosides: Part 5. UV spectroscopic monitoring of horseradish peroxidase-catalyzed polymerization of monolignol glycosides

Holzforschung ◽  
2008 ◽  
Vol 62 (5) ◽  
Author(s):  
Yuki Tobimatsu ◽  
Toshiyuki Takano ◽  
Hiroshi Kamitakahara ◽  
Fumiaki Nakatsubo
Keyword(s):  
Horseradish Peroxidase ◽  
Uv Spectroscopy ◽  
Oxidative Polymerization ◽  
Quinone Methide ◽  
Hydroxyl Groups ◽  
Aryl Ether ◽  
Spectroscopic Monitoring ◽  
Phenolic Hydroxyl Groups ◽  
Dehydrogenation Polymer

Abstract Horseradish peroxidase (HRP)-initiated dehydrogenative polymerizations of guaiacyl (G) and syringyl (S)-type monolignol γ-O-glucosides, isoconiferin (iso-G) and isosyringin (iso-S), which contain a hydrophilic glucosyl unit on γ-position of coniferyl alcohol (G-alc) and sinapyl alcohol (S-alc), respectively, were monitored by UV spectroscopy to study the formation of dehydrogenation polymer (DHP, lignin polymer model) in a homogeneous aqueous phase. During homopolymerization of iso-S, a new absorbance band at 325 nm (A 325) rapidly increased in intensity and then gradually disappeared, whereas such stable changes in absorbance were not observed during homopolymerization of iso-G. During polymerization of iso-S, A 325 rapidly disappeared when an acid, nucleophile or reductant was added to the reaction mixture, indicating that A 325 can be attributed to S-type quinone methide intermediates (QMs). Similar to iso-S polymerization, temporary absorbance at 328 nm was observed during conventional polymerization of S-alc. We interpret this observation as follows: S-type QMs accumulated in the reaction mixture and the progress of subsequent DHP formation during oxidative polymerization of iso-S or S-alc was hindered. UV monitoring of iso-G and iso-S copolymerization revealed that the presence of iso-G promoted the disappearance of A 325. Furthermore, S-type QMs generated in situ by iso-S polymerization disappeared more rapidly after guaiacol addition than after 2,6-dimethoxyphenol addition. The following mechanism for copolymerization of iso-G and iso-S can be proposed: G-type precursors with phenolic hydroxyl groups react readily by nucleophilic addition with the α-C of S-type QMs, and the molecular chains of DHPs increase via non-cyclic α-aryl ether bonds.

The Study on Nano-Silica Modified Phenolic Resin Used as the Magnesite-Carbon Brick Binder

2012 ◽  
Vol 535-537 ◽  
pp. 1529-1533
Author(s):  
Qing Ling Liao ◽  
Li Ming Zeng ◽  
Xuan Ke Li
Keyword(s):  
Phenolic Resin ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Hydroxyl Groups ◽  
Sol Gel Process ◽  
High Bulk Density ◽  
Phenolic Hydroxyl Groups ◽  
High Bulk ◽  
Nanosized Silica

The modified phenolic resin was synthesized by sol-gel process using in-situ formed nanosized silica. The improved phenolic resin was characterized by IR and TG-DTA analyses .The results show that the interaction between SiO2 nanoparticles and phenolic resin lead to the decrease of concentration of phenolic hydroxyl groups, and introduce the impurity atom Si to the phenolic resin molecule chain, which promotes the heat resistance and stability of phenolic resin. The physicochemical property analyses show that the magnesite-carbon brick using this modified phenolic resin as binder possesses a low apparent porosity and a high bulk density and compression strength.

Comparison Among Five Eucalyptus Species Based on Their Leaf Contents of Some Primary and Secondary Metabolites

2019 ◽  
Vol 20 (7) ◽  
pp. 573-587
Author(s):  
Alyaa Nasr ◽  
Tehmina Saleem Khan ◽  
Shi-Ping Huang ◽  
Bin Wen ◽  
Jian-Wen Shao ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Protocatechuic Acid ◽  
Antioxidant Activities ◽  
Reducing Power ◽  
Renewable Resource ◽  
Total Phenolic ◽  
Eucalyptus Species ◽  
Primary And Secondary Metabolites ◽  
Acetone Water ◽  
Phenolic Constituents

Background: Eucalyptus belongs to the Myrtaceae family. It is the most planted hardwood forest crop worldwide, representing a global renewable resource of fiber, pharmaceuticals and energy. Objective: To compare the five species, E. maidenii, E. robusta, E. citriodora, E. tereticornis and E. camaldulensis, seeking for the richest source of nutrients and pharmaceuticals. Methodology: Eucalyptus samples were subjected to some chemical determinations for both primary and secondary metabolites to verify their nutritional and pharmaceutical importance related to different extracts. GC-MS analysis was applied to detect the presence of some individual phenolic constituents in their leaves. Results: E. robusta recorded the maximum contents of carbohydrates (40.07%) and protein (31.91%). While E. camaldulensis contained the highest contents of total phenolic compounds (46.56 mg/g), tannins (40.01 mg/g) and antioxidant activities assayed by the phosphomolybednum method (57.60 mg/g), followed by E. citridora. However, E. tereticornis exhibited the highest reducing power ability (151.23 mg/g). The GC-MS highlighted 20 phenolic constituents and antioxidants which varied in their abundance in Eucalyptus leaves, 8 individual phenolics (hydroquinone, hesperitin, pyrogallol, resorcinol, protocatechuic acid, naringenin, chlorogenic acid and catechin) were maximally recorded with E. camaldulensis and secondly, with E. citridora in case of at least 5 components. Nevertheless, gallic and quinic acids were more abundant in the leaves of E. tereticornis, which may explain its high corresponding reducing powers. Conclusion: Acetone-water combination has enhanced phenolics extraction from Eucalyptus tissues. This is the first report aiming to compare between the aforementioned Eucalyptus species highlighting either their nutritional or medicinal importance.

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