scholarly journals Prepolymerization of Lacquer Sap under Pure Oxygen Atmosphere and Its Effects on the Properties of Lacquer Film

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jianhong Yang ◽  
Jianfeng Zhu ◽  
Wanghui Liu ◽  
Jianping Deng ◽  
Yuanyuan Ding
Keyword(s):  
Coupling Reaction ◽  
Oxygen Atmosphere ◽  
Pure Oxygen ◽  
Hydroxyl Groups ◽  
Pencil Hardness ◽  
Stirring Time ◽  
Water Drops ◽  
Pure Oxygen Atmosphere ◽  
Ft Ir ◽  
Thermal Stability Of

A series of lacquer saps were prepared by prepolymerization under oxygen atmosphere. The prepolymerization process was investigated by GPC, UV-Vis, FT-IR, NMR, and microscope. The results showed that the polymerization of urushiol monomer was accelerated. The content of monomer in the lacquer sap swiftly decreased from 82.68% to 47.75% in 0.5 h. The mechanism of polymerization was complex and was involved in the coupling reaction of phenyl ring, the addition reaction of the unsaturated carbon-carbon double bond groups with urushiol hydroxyl groups, and other reactions that occurred on the side chains. In addition, the prepolymerization also improved significantly the drying property of lacquer film, especially at low relative humidity. At the same time, the sizes of the water drops in the lacquer saps significantly decreased with increasing the stirring time and the surface of lacquer film became smoother, which resulted in its excellent gloss (109–125). Due to the prepolymerization, the pencil hardness and the thermal stability of lacquer film were slightly improved as well.

scholarly journals Surface oxidation of nickel base alloys and stainless steel under pure oxygen atmosphere: Application to oxygen safety

2019 ◽  
Vol 31 (2) ◽  
pp. 022518
Author(s):  
Frédéric Coste ◽  
Martina Ridlova ◽  
Nicolas Gallienne ◽  
Jacques Quintard ◽  
Gabriel Bert
Keyword(s):  
Stainless Steel ◽  
Surface Oxidation ◽  
Oxygen Atmosphere ◽  
Pure Oxygen ◽  
Pure Oxygen Atmosphere ◽  
Nickel Base

Enhanced Thermal Stability of Esterified Lignin in Different Solvent Mediums

2018 ◽  
Vol 9 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Sharifah Nurul Ain Syed Hashim ◽  
Sarani Zakaria ◽  
Chin Hua Chia ◽  
Sharifah Nabihah Syed Jaafar
Keyword(s):  
Thermal Stability ◽  
Alkaline Solution ◽  
Room Temperature ◽  
Hydroxyl Groups ◽  
Aqueous Alkaline Solution ◽  
Alkali Lignin ◽  
Weight Percentage ◽  
H Nmr ◽  
Ft Ir ◽  
Thermal Stability Of

In this study, soda alkali lignin from oil palm empty fruit bunch (EFB-AL) and kenaf core (KC-AL) are esterified with maleic anhydride under two different conditions, namely i) pyridine at temperature of 120°C for 3h and ii) aqueous alkaline solution at room temperature for 4h. As a result, the weight percentage gain (WPG) of the esterified EFB-AL (EFB-EL) and esterified KC-AL (KC-EL) in pyridine demonstrated a higher compared to aqueous alkaline solution. The FT-IR results of EFB-EL and KC-EL in both solvents exhibited some changes at the carbonyl and hydroxyl groups. Furthermore, the esterification process induced the carboxylic peak to appear in both alkali lignin samples. The outcome is confirmed by conducting H-NMR analysis, which demonstrated ester and carboxylic acid peaks within the spectral analysis. Finally, the TGA results showed both EFB-EL and KC-EL that are exposed to aqueous alkaline actually possessed better thermal stability and higher activation energy (Ea) compared to the esterified samples in pyridine.

Properties of Montmorillonite-Reinforced Thermoplastic Sago Starch Composites

2012 ◽  
Vol 445 ◽  
pp. 469-474 ◽  
Author(s):  
Ahmad Zuraida ◽  
Y. Yusliza ◽  
O. Nurizan ◽  
H. Anuar ◽  
Zahurin Halim ◽  
...  
Keyword(s):  
Morphological Properties ◽  
Wave Number ◽  
Hydroxyl Groups ◽  
Sago Starch ◽  
X Ray Diffraction ◽  
Pressing Method ◽  
X Ray ◽  
Ft Ir ◽  
Thermal Stability Of ◽  
Better Than

In this work, biodegradable polymer was prepared from thermoplastic sago starch (TPSS) plasticized with glycerol. In order to improve the properties of the TPSS, Montmorillonite (MMT), a kind of reinforced additive was used in the preparation of montmorillonite-reinforced thermoplastic sago starch (MTRSS) composites via hot pressing method. The fabricated samples were investigated through X-ray diffractometry, Fourier transform infrared (FT-IR) as well as thermal and morphological properties. FT-IR patterns show that in the MTRSS composites, the C-O groups of sago starch molecules shifted to higher wave number, while the reactive hydroxyl groups of MMT shifted to the lower wavenumber. On the other hand, X-ray diffraction revealed that MMT restrained the crystallization of MTRSS and intercalated in TPSS. Thermogravimetric analysis (TGA) revealed that the thermal stability of MTRSS was better than those of TPSS. In addition, the scanning electron micrograph results show that MMT were uniformly dispersed in the TPSS.

Effect of pure oxygen atmosphere on antioxidant enzyme and antioxidant activity of harvested litchi fruit during storage

2011 ◽  
Vol 44 (7) ◽  
pp. 1905-1911 ◽  
Author(s):  
Xuewu Duan ◽  
Ting Liu ◽  
Dandan Zhang ◽  
Xinguo Su ◽  
Hetong Lin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Enzyme ◽  
Oxygen Atmosphere ◽  
Pure Oxygen ◽  
Pure Oxygen Atmosphere ◽  
Litchi Fruit
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