scholarly journals The Effects of Adding Different HALS on the Curing Process, Film Properties and Lightfastness of Refined Oriental Lacquer

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 990
Author(s):  
Chia-Wei Chang ◽  
Jia-Jhen Lee ◽  
Kun-Tsung Lu
Keyword(s):  
Ph Value ◽  
Oxidative Polymerization ◽  
Radical Scavenging ◽  
Polymeric Coating ◽  
Film Property ◽  
Film Properties ◽  
Drying Time ◽  
Outdoor Application ◽  
Radical Scavenging Ability ◽  
Oriental Lacquer

Oriental lacquer is a natural polymeric coating with a satiny texture and excellent characteristics, such as chemical resistance and durability. However, the poor lightfastness resulted in the natural aromatic structures of the urushiol structures limited its suitability for outdoor application. This study aimed at the improvement of the lightfastness by adding the different hindered amine light stafbilizers (HALS) with 2 phr addition as well as the effects on the coating and film property of the refined oriental lacquers (RL). The Cryptomeria japonica plate, glass sheets, and the other substrates were used for finishing. The results showed that the lightfastness of RL film was obviously improved by adding 2 phr HALS of Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (H90) containing -NH group and Bis (1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethyl ethyl) -4-hydroxyphenyl] methyl] butylmalonate (H60) containing -NCH3 groups. The HALS additions increased the pH value of RL and improved the activities of laccase-catalyzed reaction. Meanwhile, the oxidative polymerization of the side chains of RL was inhibited, caused by a radical scavenging ability of HALS. The changes in the drying process affected not only the curing time, but also the film properties. Among the 2 phr additions of different HALS, the film containing H90 had the best lightfastness. Meanwhile, it kept the most similar properties with RL and shortened the drying time of RL, and it was selected as the best HALS addition under 2 phr in this study.

scholarly journals Manufacture and Characteristics of Oil-Modified Refined Lacquer for Wood Coatings

2018 ◽  
Author(s):  
Chia-Wei Chang ◽  
Hsiu-Ling Lee ◽  
Kun-Tsung Lu
Keyword(s):  
Linseed Oil ◽  
Impact Resistance ◽  
Polymeric Coating ◽  
Drying Time ◽  
Nitrogenous Compounds ◽  
Drying Oils ◽  
Drying Oil ◽  
Wood Coatings ◽  
Speed Up ◽  
Oriental Lacquer

Oriental lacquer, a natural and renewable polymeric coating, comes from the sap produced by lacquer trees. For practical application, oriental lacquer must be refined to reduce excess water and enhance its quality. In this study, drying oils were blended with oriental lacquer during the refining process to prepare an oil-modified refined lacquer (OMRL). The type and adding amount (0, 10, and 20% by wt.) of drying oils for wood coatings utilization were evaluated. Rhus succedanea oriental lacquer is composed of 54.1% urushiols, 34.3% water, 7.2% plant gum, and 4.4% nitrogenous compounds, and drying oils, including tung oil (TO), linseed oil (LO), and dehydrated castor oil (DCO) were used as materials in this study. The results show that the drying oil acts as a diluent, which reduces the viscosity and enhances the workability and could shorten the touch-free drying time and speed up the hardened drying of the OMRL. The results also indicate that the hardness, mass retention, Tg, tensile strength, abrasion resistance, and lightfastness of OMRL films decrease as more drying oils are blended. Conversely, the bending resistance, elongation at break, impact resistance increase, and particularly, the gloss, is greatly improved through the blending of more drying oils. In conclusion, the LO-modified refined lacquer (RL) has the highest film gloss and the DCO-modified RL has the shortest drying time for coating; otherwise, the film properties are similar among the three types of drying oil.

scholarly journals Effects of Adding Antioxidants on the Lightfastness Improvement of Refined Oriental Lacquer

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1110
Author(s):  
Kun-Tsung Lu ◽  
Jia-Jhen Lee
Keyword(s):  
Color Difference ◽  
Film Properties ◽  
Drying Time ◽  
Photo Degradation ◽  
Photo Oxidation ◽  
High Durability ◽  
Brightness Difference ◽  
Bending Resistance ◽  
Main Component ◽  
Oriental Lacquer

Refined oriental lacquer (ROL) is a natural polymeric material with a satiny texture, elegant beauty, and high durability for wood furniture and handicraft finishing. However, its poor lightfastness, which results from the photo-degradation or photo-oxidation of its main component, catechol derivatives, must be improved for its widespread utilization. In this study, two experiments were performed. First, five types of antioxidants, including three primary antioxidants, such as 2,2′-methylenebis(6-nonyl-p-cresol) (coded as AO-1), 2,2′-methylenebis(6-tert-butyl-4-methylphenol) (AO-2), and bis [4-(2-phenyl-2-propyl) phenyl] amine (AO-N), and two secondary antioxidants, such as tris (2,4-ditert-butylphenyl) phosphite (AO-P) and dilauryl thiodipropionate (AO-S), were investigated to determine which is the most effective for improving the lightfastness of ROL. Secondly, the appropriate quantity of the best antioxidant, including 0, 1, 2, 3, 5, and 10 phr, was also determined. The lightfastness parameters, such as brightness difference (ΔL*), yellowness difference (ΔYI), and color difference (ΔE*), as well as other coating and film properties, were assessed. The results showed that the primary antioxidants had higher efficiency than secondary antioxidants for improving the lightfastness of ROL. Among the primary antioxidants, the 5 phr AO-N was the most effective at improving the lightfastness of ROL; however, 1 phr addition had already shown significantly improved efficiency. In addition, the drying time of ROL was extended and film properties decreased when increasing the content of AO-N, but the 1-phr-containing ROL displayed superior film properties, especially adhesion and bending resistance, compared with the raw ROL film.

scholarly journals Manufacture and Characteristics of Oil-Modified Refined Lacquer for Wood Coatings

Coatings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 11 ◽  
Author(s):  
Chia-Wei Chang ◽  
Hsiu-Ling Lee ◽  
Kun-Tsung Lu
Keyword(s):  
Linseed Oil ◽  
Impact Resistance ◽  
Polymeric Coating ◽  
Drying Time ◽  
Nitrogenous Compounds ◽  
Drying Oils ◽  
Practical Applications ◽  
Wood Coatings ◽  
Bending Resistance ◽  
Oriental Lacquer

Oriental lacquer, a natural and renewable polymeric coating, comes from the sap produced by lacquer trees. For practical applications, oriental lacquer must be refined to reduce its water content and enhance its quality. In this study, drying oils were blended with oriental lacquer during a refining process to produce oil-modified refined lacquer (OMRL). Rhus succedanea lacquer, composed of 54.1% urushiols, 34.3% water, 7.2% plant gum, and 4.4% nitrogenous compounds, and drying oils, including tung oil (TO), linseed oil (LO), and dehydrated castor oil (DCO), were used as materials in this study. The effect of type and amount (0%, 10%, and 20% by wt %) of drying oils added to lacquer on lacquer properties were evaluated. Results show that the drying oils acted as a diluent, which reduced the viscosity, and enhanced workability, shortened touch-free drying time and accelerated the hardened drying of the OMRL. The results also indicated that the hardness, mass retention, Tg, tensile strength, abrasion resistance, and lightfastness of OMRL films decreased as more drying oils were blended with lacquer. Conversely, the bending resistance, elongation at break, impact resistance increased. Gloss was greatly improved through the blending of more drying oils with lacquer. In conclusion, the LO-modified refined lacquer (RL) had the highest film gloss and the DCO-modified RL had the shortest drying time for coating. Otherwise, the film properties were similar among the three types of drying oils.

PHARMACOGNOSTIC, ANTIOXIDANT AND ACUTE TOXICITY STUDY OF Ficus sycomorus (Linn) (Moraceae) ROOT AND STEM BARK

2020 ◽  
Vol 4 (2) ◽  
pp. 605-614
Author(s):  
Murtala M. Namadina ◽  
H. Haruna ◽  
U. Sanusi
Keyword(s):  
Acute Toxicity ◽  
Radical Scavenging ◽  
Stem Bark ◽  
The Body ◽  
Toxicity Study ◽  
Bark Extract ◽  
Root Extract ◽  
Acute Toxicity Study ◽  
Radical Scavenging Ability ◽  
Phytochemical Components

Most of biochemical reactions in the body generates Reactive Oxygen Species (ROS), which are involved in the pathogenesis of oxidative stress-related disorders like diabetes, nephrotoxicity, cancer, cardiovascular disorders, inflammation and neurological disorders when they attack biochemical molecules like proteins, lipids and nucleic acid. Antioxidants are used to protect the cells or tissues against potential attack by ROS. Most medicinal plants possess a rich source of antioxidants such as flavonoids, phenols, tannins, alkaloids among others. These phytochemicals are currently pursued as an alternative and complimentary drug. In this study, phytochemical components, antioxidant and acute toxicity study of the methanol extract of stem bark and root of F. sycomorus were carried out using standard methods. Findings from this study revealed the presence of some diagnostic microscopical features such as calcium oxalate, starch, gum/mucilage, lignin, Aleurone grain, suberized/Cuticular cell wall and inulin but calcium carbonate was absent in stem bark but present in the powdered root. Quantitative physical constants include moisture contents (6.40% and 7.82%), ash value (7.20% and 9.30 %) in stem bark and root respectively. Carbohydrates, alkaloid, flavonoids, saponins, tannins, glycoside, steroid, triterpenes and phenols were present in all the extracts. They were found to exhibit potent 1,1,-diphenyl 2-picryl hydrazyl (DPPH) free scavenging activity. The DPPH radical scavenging ability of the extracts showed the following trend Ascorbic acid < stem bark extract˃ root extract. The LD50 of the methanolic stem bark and root extracts were found to be greater than 5000 mg /kg and is considered safe for use. Nonetheless, further

Relation Between Local Structure, Electric Dipole and Charge Carrier Dynamics in DHICA Melanin, a Model for Biocompatible Semiconductors

2019 ◽  
Author(s):  
Micaela Matta ◽  
Alessandro Pezzella ◽  
Alessandro Troisi
Keyword(s):  
Electronic Structure ◽  
Degrees Of Freedom ◽  
Structural Model ◽  
Computational Study ◽  
Oxidative Polymerization ◽  
Radical Scavenging ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Polymer Semiconductors ◽  
Synthetic Pigments

<div><div><div><p>Eumelanins are a family of natural and synthetic pigments obtained by oxidative polymerization of their natural precursors: 5,6 dihydroxyindole and its 2-carboxy derivative (DHICA). The simultaneous presence of ionic and electronic charge carriers makes these pigments promising materials for applications in bioelectronics. In this computational study we build a structural model of DHICA melanin considering the interplay between its many degrees of freedom, then we examine the electronic structure of representative oligomers. We find that a non-vanishing dipole along the polymer chain sets this system apart from conventional polymer semiconductors, determining its electronic structure, reactivity toward oxidation and localization of the charge carriers. Our work sheds light on previously unnoticed features of DHICA melanin that not only fit well with its radical scavenging and photoprotective properties, but open new perspectives towards understanding and tuning charge transport in this class of materials.<br></p></div></div></div>

scholarly journals Preparation of Antioxidant and Antibacterial Chitosan Film from Periplaneta americana

Insects ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 53
Author(s):  
Sicong Chen ◽  
Xunfan Wei ◽  
Zhuoxiao Sui ◽  
Mengyuan Guo ◽  
Jin Geng ◽  
...  
Keyword(s):  
Food Packaging ◽  
Periplaneta Americana ◽  
Uv Light ◽  
Radical Scavenging ◽  
Chitosan Film ◽  
American Cockroach ◽  
Raw Material ◽  
Potential Resource ◽  
Radical Scavenging Ability ◽  
Dpph Radical Scavenging

Among different insects, the American cockroach (Periplaneta americana) has been bred in industrial scale successfully as a potential resource of protein, lipid, and antibacterial peptide. However, the application of its chitosan has not been studied widely, which has hindered the sufficient utilization of P. americana. In this paper, the chitosan from P. americana was separated, characterized, and processed into film (PaCSF) to examine its potential of being applied in food packaging. As the results of different characterizations showed, PaCSF was similar to shrimp chitosan film (SCSF). However, concerning the performances relating to food packaging, the two chitosan films were different. PaCSF contained more water (42.82%) than SCSF did, resulting in its larger thickness (0.08 mm). PaCSF could resist UV light more effectively than SCSF did. Concerning antioxidant activity, the DPPH radical scavenging ability of PaCSF increased linearly with time passing, reaching 72.46% after 8 h, which was better than that of SCSF. The antibacterial activity assay exhibited that PaCSF resisted the growth of Serratia marcescens and Escherichia coli more effectively than SCSF did. The results implied that P. americana chitosan could be a potential raw material for food packaging, providing a new way to develop P. americana.

scholarly journals Inhibition of Inflammatory Response by Artepillin C in Activated RAW264.7 Macrophages

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ewelina Szliszka ◽  
Anna Mertas ◽  
Zenon P. Czuba ◽  
Wojciech Król
Keyword(s):  
Cell Viability ◽  
Radical Scavenging ◽  
Gm Csf ◽  
Raw264.7 Macrophages ◽  
Griess Reaction ◽  
Artepillin C ◽  
Anti Inflammatory ◽  
Radical Scavenging Ability ◽  
Brazilian Green Propolis ◽  
Inflammatory Effect

Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) is the main bioactive component of Brazilian green propolis. The aim of this study was to investigate the anti-inflammatory effect of artepillin C on LPS + IFN-γ- or PMA-stimulated RAW264.7 macrophages. The cell viability was evaluated by MTT and LDH assays. The radical scavenging ability was determined using DPPH•and ABTS•+. ROS and RNS generation was analyzed by chemiluminescence. NO concentration was detected by the Griess reaction. The release of various cytokines by activated RAW264.7 cells was measured in the culture supernatants using a multiplex bead array system based on xMAP technology. NF-κB activity was confirmed by the ELISA-based TransAM NF-κB kit. At the tested concentrations, the compound did not decrease the cell viability and did not cause the cytotoxicity. Artepillin C exerted strong antioxidant activity, significantly inhibited the production of ROS, RNS, NO, and cytokine IL-1β, IL-3, IL-4, IL-5, IL-9, IL-12p40, IL-13, IL-17, TNF-α, G-CSF, GM-CSF, MCP-1, MIP-1α, MIP-1β, RANTES, and KC, and markedly blocked NF-κB expression in stimulated RAW264.7 macrophages. Our findings provide new insights for understanding the mechanism involved in the anti-inflammatory effect of artepillin C and support the application of Brazilian green propolis in complementary and alternative medicine.

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